hello world

1 lab/.gitignore

@@ -0,0 +1,37 @@
+HELP.md
+.gradle
+build/
+!gradle/wrapper/gradle-wrapper.jar
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/main/**/bin/
+!**/src/test/**/bin/
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+out/
+!**/src/main/**/out/
+!**/src/test/**/out/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+### VS Code ###
+.vscode/

1 lab/build.gradle

@@ -0,0 +1,27 @@
+plugins {
+	id 'java'
+	id 'org.springframework.boot' version '3.2.2'
+	id 'io.spring.dependency-management' version '1.1.4'
+}
+
+group = 'com.example'
+version = '0.0.1-SNAPSHOT'
+
+java {
+	sourceCompatibility = '17'
+}
+
+repositories {
+	mavenCentral()
+}
+
+dependencies {
+	implementation 'org.springframework.boot:spring-boot-starter-web'
+	implementation 'org.springdoc:springdoc-openapi-starter-webmvc-ui:2.3.0'
+
+	testImplementation 'org.springframework.boot:spring-boot-starter-test'
+}
+
+tasks.named('test') {
+	useJUnitPlatform()
+}

1 lab/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,7 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.5-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

1 lab/gradlew

@@ -0,0 +1,249 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/HEAD/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+# This is normally unused
+# shellcheck disable=SC2034
+APP_BASE_NAME=${0##*/}
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
+APP_HOME=$( cd "${APP_HOME:-./}" > /dev/null && pwd -P ) || exit
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    if ! command -v java >/dev/null 2>&1
+    then
+        die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Collect all arguments for the java command:
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#     and any embedded shellness will be escaped.
+#   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
+#     treated as '${Hostname}' itself on the command line.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"

1 lab/gradlew.bat

@@ -0,0 +1,92 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%"=="" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if %ERRORLEVEL% equ 0 goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if %ERRORLEVEL% equ 0 goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

1 lab/index.html

@@ -0,0 +1,64 @@
+<!DOCTYPE html>
+<html lang="en">
+
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>Document</title>
+</head>
+
+<body>
+    <p id="out">Push the button</p>
+    <input id="name" />
+    <br />
+    <button onclick="get()">Get</button>
+    <br />
+    <button onclick="getTest()">Get Test</button>
+    <br />
+    <button onclick="post()">Post</button>
+    <br />
+    <button onclick="put()">Put</button>
+</body>
+<script>
+    const url = "http://localhost:8080/messages";
+    const out = document.getElementById("out");
+    const name = document.getElementById("name");
+    const get = async () => {
+        const res = await fetch(`${url}?name=${name.value}`);
+        const text = await res.text();
+        out.innerText = text;
+    }
+    const getTest = async () => {
+        const res = await fetch(`${url}/test`);
+        const text = await res.text();
+        out.innerText = text;
+    }
+    const post = async () => {
+        if (!name.value) {
+            alert("Name is required");
+            return;
+        }
+        const res = await fetch(url, {
+            method: 'post',
+            headers: { 'Content-Type': 'application/json' },
+            body: name.value
+        });
+        const text = await res.text();
+        out.innerText = text;
+    }
+    const put = async () => {
+        if (!name.value) {
+            alert("Name is required");
+            return;
+        }
+        const res = await fetch(`${url}/${name.value}`, {
+            method: 'put',
+            headers: { 'Content-Type': 'application/json' },
+            body: name.value
+        });
+        const text = await res.text();
+        out.innerText = text;
+    }
+</script>
+
+</html>

1 lab/settings.gradle

@@ -0,0 +1 @@
+rootProject.name = 'demo'

1 lab/src/main/java/com/example/demo/ApiController.java

@@ -0,0 +1,54 @@
+package com.example.demo;
+
+import java.util.ArrayList;
+import java.util.List;
+
+//import org.slf4j.Logger;
+//import org.slf4j.LoggerFactory;
+import org.springframework.web.bind.annotation.DeleteMapping;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.PutMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import jakarta.validation.Valid;
+
+@RestController
+@RequestMapping("/message")
+public class ApiController {
+    // private final Logger log = LoggerFactory.getLogger(ApiController.class);
+
+    public List<UserDto> dataList = new ArrayList<UserDto>();
+
+    @PostMapping
+    public UserDto create(@RequestBody @Valid UserDto testDto) {
+        dataList.add(testDto);
+        return testDto;
+    }
+
+    @GetMapping
+    public List<UserDto> readAll() {
+        return dataList;
+    }
+
+    @GetMapping("{id}")
+    public UserDto read(@PathVariable(name = "id") int id) {
+        return dataList.get(id);
+    }
+
+    @PutMapping("/{id}")
+    public UserDto update(@PathVariable Integer id, @RequestBody UserDto testDto) {
+        dataList.set(id, testDto);
+        return testDto;
+    }
+
+    @DeleteMapping("/{id}")
+    public UserDto delete(@PathVariable(name = "id") int id) {
+        UserDto temp = dataList.remove(id);
+        return temp;
+    }
+
+}

1 lab/src/main/java/com/example/demo/DemoApplication.java

@@ -0,0 +1,12 @@
+package com.example.demo;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class DemoApplication {
+
+	public static void main(String[] args) {
+		SpringApplication.run(DemoApplication.class, args);
+	}
+}

1 lab/src/main/java/com/example/demo/UserDto.java

@@ -0,0 +1,43 @@
+package com.example.demo;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+public class UserDto {
+    private Integer groupId;
+    private Integer senderId;
+    private String msg;
+    private String time;
+
+    public UserDto() {
+    }
+
+    @JsonCreator
+    public UserDto(
+            @JsonProperty(value = "groupId") Integer groupId,
+            @JsonProperty(value = "senderId") Integer senderId,
+            @JsonProperty(value = "msg") String msg,
+            @JsonProperty(value = "time") String time) {
+        this.groupId = groupId;
+        this.senderId = senderId;
+        this.msg = msg;
+        this.time = time;
+    }
+
+    public Integer getGroupId() {
+        return groupId;
+    }
+
+    public Integer getSenderId() {
+        return senderId;
+    }
+
+    public String getMsg() {
+        return msg;
+    }
+
+    public String getTime() {
+        return time;
+    }
+
+}

1 lab/src/main/java/com/example/demo/WebConfig.java

@@ -0,0 +1,15 @@
+package com.example.demo;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.lang.NonNull;
+import org.springframework.web.servlet.config.annotation.CorsRegistry;
+import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
+
+@Configuration
+public class WebConfig implements WebMvcConfigurer {
+    @Override
+    public void addCorsMappings(@NonNull CorsRegistry registry) {
+        registry.addMapping("/**")
+                .allowedMethods("GET", "POST", "PUT", "DELETE");
+    }
+}

1 lab/src/main/resources/application.properties

@@ -0,0 +1 @@
+

1 lab/src/test/java/com/example/demo/DemoApplicationTests.java

@@ -0,0 +1,13 @@
+package com.example.demo;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.test.context.SpringBootTest;
+
+@SpringBootTest
+class DemoApplicationTests {
+
+	@Test
+	void contextLoads() {
+	}
+
+}

2 lab/.gitignore

@@ -0,0 +1,37 @@
+HELP.md
+.gradle
+build/
+!gradle/wrapper/gradle-wrapper.jar
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/main/**/bin/
+!**/src/test/**/bin/
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+out/
+!**/src/main/**/out/
+!**/src/test/**/out/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+### VS Code ###
+.vscode/

2 lab/.vs/ProjectSettings.json

@@ -0,0 +1,3 @@
+{
+  "CurrentProjectSetting": null
+}

2 lab/.vs/VSWorkspaceState.json

@@ -0,0 +1,7 @@
+{
+  "ExpandedNodes": [
+    ""
+  ],
+  "SelectedNode": "\\.gitignore",
+  "PreviewInSolutionExplorer": false
+}

2 lab/build.gradle

@@ -0,0 +1,28 @@
+plugins {
+	id 'java'
+	id 'org.springframework.boot' version '3.2.3'
+	id 'io.spring.dependency-management' version '1.1.4'
+}
+
+group = 'com.example'
+version = '0.0.1-SNAPSHOT'
+
+java {
+	sourceCompatibility = '17'
+}
+
+repositories {
+	mavenCentral()
+}
+
+dependencies {
+	implementation 'org.springframework.boot:spring-boot-starter-web'
+	implementation 'org.springdoc:springdoc-openapi-starter-webmvc-ui:2.3.0'
+	implementation 'org.modelmapper:modelmapper:3.2.0'
+
+	testImplementation 'org.springframework.boot:spring-boot-starter-test'
+}
+
+tasks.named('test') {
+	useJUnitPlatform()
+}

2 lab/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,7 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.5-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

2 lab/gradlew

@@ -0,0 +1,249 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/HEAD/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+# This is normally unused
+# shellcheck disable=SC2034
+APP_BASE_NAME=${0##*/}
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
+APP_HOME=$( cd "${APP_HOME:-./}" > /dev/null && pwd -P ) || exit
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    if ! command -v java >/dev/null 2>&1
+    then
+        die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Collect all arguments for the java command:
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#     and any embedded shellness will be escaped.
+#   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
+#     treated as '${Hostname}' itself on the command line.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"

2 lab/gradlew.bat

@@ -0,0 +1,92 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%"=="" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if %ERRORLEVEL% equ 0 goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if %ERRORLEVEL% equ 0 goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

2 lab/settings.gradle

@@ -0,0 +1 @@
+rootProject.name = 'demo'

2 lab/src/main/java/com/example/demo/DemoApplication.java

@@ -0,0 +1,85 @@
+package com.example.demo;
+
+import java.sql.Time;
+import java.util.ArrayList;
+import java.util.Objects;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.boot.CommandLineRunner;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+import java.util.List;
+
+import com.example.demo.comments.model.CommentEntity;
+import com.example.demo.comments.service.CommentService;
+import com.example.demo.messages.model.MessageEntity;
+import com.example.demo.messages.service.MessageService;
+import com.example.demo.posts.model.PostEntity;
+import com.example.demo.posts.service.PostService;
+import com.example.demo.users.model.UserEntity;
+import com.example.demo.users.service.UserService;
+
+@SpringBootApplication
+public class DemoApplication implements CommandLineRunner {
+	private final Logger log = LoggerFactory.getLogger(DemoApplication.class);
+
+	private final UserService userService;
+	private final PostService postService;
+	private final CommentService commentService;
+	private final MessageService messageService;
+
+	public DemoApplication(UserService userService, PostService postService, CommentService commentService,
+			MessageService messageService) {
+		this.userService = userService;
+		this.postService = postService;
+		this.commentService = commentService;
+		this.messageService = messageService;
+	}
+
+	public static void main(String[] args) {
+		SpringApplication.run(DemoApplication.class, args);
+	}
+
+	@Override
+	public void run(String... args) throws Exception {
+		if (args.length > 0 && Objects.equals("--populate", args[0])) {
+
+			log.info("Create default items values");
+			final List<UserEntity> blank = new ArrayList<UserEntity>();
+			final var user1 = userService.create(new UserEntity(null, "sardq", "aasd@asd", "asdsd", blank));
+			final var user2 = userService.create(new UserEntity(null, "sardasdq", "aasdsad@asd", "123", blank));
+			final List<UserEntity> friends = new ArrayList<>();
+			friends.add(user1);
+			friends.add(user2);
+			final var user3 = userService.create(new UserEntity(null, "sxzcvardq", "aaxsd@asd", "asfgd", friends));
+			final var user4 = userService.create(new UserEntity(null, "sarbvljdq", "aacbxcsd@asd", "zxvb", blank));
+			log.info("Create default posts values");
+			final var post1 = postService.create(
+					new PostEntity(null, user1, new Time(System.currentTimeMillis()), "test", Long.valueOf(0),
+							Long.valueOf(0)));
+			final var post2 = postService.create(
+					new PostEntity(null, user3, new Time(System.currentTimeMillis()), "test", Long.valueOf(11),
+							Long.valueOf(2)));
+			final var post3 = postService.create(
+					new PostEntity(null, user4, new Time(System.currentTimeMillis()), "test", Long.valueOf(40),
+							Long.valueOf(15)));
+
+			log.info("Create default comments values");
+			commentService
+					.create(new CommentEntity(null, user1, post2, new Time(System.currentTimeMillis()), "my comment"));
+			commentService
+					.create(new CommentEntity(null, user3, post1, new Time(System.currentTimeMillis()), "my comment2"));
+			commentService
+					.create(new CommentEntity(null, user4, post3, new Time(System.currentTimeMillis()), "my comment3"));
+
+			log.info("Create default messages values");
+			messageService.create(new MessageEntity(null, user1, user2, new Time(System.currentTimeMillis()), "hello"));
+			messageService
+					.create(new MessageEntity(null, user1, user2, new Time(System.currentTimeMillis()), "how are you"));
+			messageService
+					.create(new MessageEntity(null, user2, user1, new Time(System.currentTimeMillis()), "I'm ok"));
+		}
+	}
+}

2 lab/src/main/java/com/example/demo/comments/api/CommentController.java

@@ -0,0 +1,78 @@
+package com.example.demo.comments.api;
+
+import java.util.List;
+
+import org.modelmapper.ModelMapper;
+import org.springframework.web.bind.annotation.DeleteMapping;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.PutMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import com.example.demo.comments.model.CommentEntity;
+import com.example.demo.comments.service.CommentService;
+import com.example.demo.core.convert;
+import com.example.demo.core.configuration.Constants;
+import com.example.demo.posts.service.PostService;
+import com.example.demo.users.service.UserService;
+
+import jakarta.validation.Valid;
+
+@RestController
+@RequestMapping(Constants.API_URL + "/comment")
+public class CommentController {
+    private final UserService userService;
+    private final PostService postService;
+    private final CommentService commentService;
+    private final ModelMapper modelMapper;
+
+    public CommentController(CommentService commentService, UserService userService, PostService postService,
+            ModelMapper modelMapper) {
+        this.userService = userService;
+        this.commentService = commentService;
+        this.postService = postService;
+        this.modelMapper = modelMapper;
+    }
+
+    private CommentDto toDto(CommentEntity entity) {
+        var model = modelMapper.map(entity, CommentDto.class);
+        convert time = new convert();
+        model.setTime(time.dateToString(entity.getTime()));
+        return model;
+    }
+
+    private CommentEntity toEntity(CommentDto dto) {
+        final CommentEntity entity = modelMapper.map(dto, CommentEntity.class);
+        entity.setUser(userService.get(dto.getUserId()));
+        entity.setPost(postService.get(dto.getPostId()));
+        return entity;
+    }
+
+    @GetMapping
+    public List<CommentDto> getAll() {
+        return commentService.getAll().stream().map(this::toDto).toList();
+    }
+
+    @GetMapping("/{id}")
+    public CommentDto get(@PathVariable(name = "id") Long id) {
+        return toDto(commentService.get(id));
+    }
+
+    @PostMapping
+    public CommentDto create(@RequestBody @Valid CommentDto dto) {
+        return toDto(commentService.create(toEntity(dto)));
+    }
+
+    @PutMapping("/{id}")
+    public CommentDto update(@PathVariable(name = "id") Long id, @RequestBody CommentDto dto) {
+        return toDto(commentService.update(id, toEntity(dto)));
+    }
+
+    @DeleteMapping("/{id}")
+    public CommentDto delete(@PathVariable(name = "id") Long id) {
+        return toDto(commentService.delete(id));
+    }
+}

2 lab/src/main/java/com/example/demo/comments/api/CommentDto.java

@@ -0,0 +1,62 @@
+package com.example.demo.comments.api;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+import jakarta.validation.constraints.Min;
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
+
+public class CommentDto {
+    private Long id;
+    @NotNull
+    @Min(1)
+    private Long userId;
+    @NotBlank
+    private String text;
+    @NotNull
+    @Min(1)
+    private Long postId;
+    @NotBlank
+    private String time;
+
+    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public Long getUserId() {
+        return userId;
+    }
+
+    public void setUserId(Long userId) {
+        this.userId = userId;
+    }
+
+    public Long getPostId() {
+        return postId;
+    }
+
+    public void setPostId(Long postId) {
+        this.postId = postId;
+    }
+
+    public String getText() {
+        return text;
+    }
+
+    public void setText(String text) {
+        this.text = text;
+    }
+
+    public String getTime() {
+        return time;
+    }
+
+    public void setTime(String time) {
+        this.time = time;
+    }
+}

2 lab/src/main/java/com/example/demo/comments/model/CommentEntity.java

@@ -0,0 +1,78 @@
+package com.example.demo.comments.model;
+
+import java.util.Date;
+import java.util.Objects;
+
+import com.example.demo.core.model.BaseEntity;
+import com.example.demo.posts.model.PostEntity;
+import com.example.demo.users.model.UserEntity;
+
+public class CommentEntity extends BaseEntity {
+    private UserEntity user;
+    private PostEntity post;
+    private Date time;
+    private String text;
+
+    public CommentEntity() {
+        super();
+    }
+
+    public CommentEntity(Long id, UserEntity user, PostEntity post, Date time, String text) {
+        super(id);
+        this.user = user;
+        this.post = post;
+        this.time = time;
+        this.text = text;
+    }
+
+    public UserEntity getUser() {
+        return user;
+    }
+
+    public void setUser(UserEntity user) {
+        this.user = user;
+    }
+
+    public PostEntity getPost() {
+        return post;
+    }
+
+    public void setPost(PostEntity post) {
+        this.post = post;
+    }
+
+    public Date getTime() {
+        return time;
+    }
+
+    public void setTime(Date time) {
+        this.time = time;
+    }
+
+    public String getText() {
+        return text;
+    }
+
+    public void setText(String text) {
+        this.text = text;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, user, post, text, time);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null || getClass() != obj.getClass())
+            return false;
+        final CommentEntity other = (CommentEntity) obj;
+        return Objects.equals(other.getId(), id)
+                && Objects.equals(other.getUser(), user)
+                && Objects.equals(other.getPost(), post)
+                && Objects.equals(other.getText(), text)
+                && Objects.equals(other.getTime(), time);
+    }
+}

2 lab/src/main/java/com/example/demo/comments/repository/CommentRepository.java

@@ -0,0 +1,10 @@
+package com.example.demo.comments.repository;
+
+import org.springframework.stereotype.Repository;
+
+import com.example.demo.comments.model.CommentEntity;
+import com.example.demo.core.repository.MapRepository;
+
+@Repository
+public class CommentRepository extends MapRepository<CommentEntity> {
+}

2 lab/src/main/java/com/example/demo/comments/service/CommentService.java

@@ -0,0 +1,43 @@
+package com.example.demo.comments.service;
+
+import java.util.List;
+import java.util.Optional;
+
+import org.springframework.stereotype.Service;
+
+import com.example.demo.comments.model.CommentEntity;
+import com.example.demo.comments.repository.CommentRepository;
+import com.example.demo.core.error.NotFoundException;
+
+@Service
+public class CommentService {
+    private final CommentRepository repository;
+
+    public CommentService(CommentRepository repository) {
+        this.repository = repository;
+    }
+
+    public List<CommentEntity> getAll() {
+        return repository.getAll();
+    }
+
+    public CommentEntity get(Long id) {
+        return Optional.ofNullable(repository.get(id))
+                .orElseThrow(() -> new NotFoundException(id));
+    }
+
+    public CommentEntity create(CommentEntity entity) {
+        return repository.create(entity);
+    }
+
+    public CommentEntity update(Long id, CommentEntity entity) {
+        final CommentEntity existsEntity = get(id);
+        existsEntity.setText(entity.getText());
+        return repository.update(existsEntity);
+    }
+
+    public CommentEntity delete(Long id) {
+        final CommentEntity existsEntity = get(id);
+        return repository.delete(existsEntity);
+    }
+}

2 lab/src/main/java/com/example/demo/core/configuration/Constants.java

@@ -0,0 +1,8 @@
+package com.example.demo.core.configuration;
+
+public class Constants {
+    public static final String API_URL = "/api/1.0";
+
+    private Constants() {
+    }
+}

2 lab/src/main/java/com/example/demo/core/configuration/MapperConfiguration.java

@@ -0,0 +1,13 @@
+package com.example.demo.core.configuration;
+
+import org.modelmapper.ModelMapper;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+public class MapperConfiguration {
+    @Bean
+    ModelMapper modelMapper() {
+        return new ModelMapper();
+    }
+}

2 lab/src/main/java/com/example/demo/core/configuration/WebConfiguration.java

@@ -0,0 +1,15 @@
+package com.example.demo.core.configuration;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.lang.NonNull;
+import org.springframework.web.servlet.config.annotation.CorsRegistry;
+import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
+
+@Configuration
+public class WebConfiguration implements WebMvcConfigurer {
+    @Override
+    public void addCorsMappings(@NonNull CorsRegistry registry) {
+        registry.addMapping("/**")
+                .allowedMethods("GET", "POST", "PUT", "DELETE");
+    }
+}

2 lab/src/main/java/com/example/demo/core/convert.java

@@ -0,0 +1,17 @@
+package com.example.demo.core;
+
+import java.text.DateFormat;
+import java.text.SimpleDateFormat;
+import java.util.Date;
+
+public class convert {
+    public Date stringToDate(String string) throws Exception {
+        DateFormat format = new SimpleDateFormat("HH:mm:ss");
+        return (Date) format.parse(string);
+    }
+
+    public String dateToString(Date date) {
+        DateFormat dateFormat = new SimpleDateFormat("dd.MM.YYYY hh:mm:ss");
+        return dateFormat.format(date);
+    }
+}

2 lab/src/main/java/com/example/demo/core/error/NotFoundException.java

@@ -0,0 +1,7 @@
+package com.example.demo.core.error;
+
+public class NotFoundException extends RuntimeException {
+    public NotFoundException(Long id) {
+        super(String.format("Entity with id [%s] is not found or not exists", id));
+    }
+}

2 lab/src/main/java/com/example/demo/core/model/BaseEntity.java

@@ -0,0 +1,20 @@
+package com.example.demo.core.model;
+
+public abstract class BaseEntity {
+    protected Long id;
+
+    protected BaseEntity() {
+    }
+
+    protected BaseEntity(Long id) {
+        this.id = id;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+}

2 lab/src/main/java/com/example/demo/core/repository/CommonRepository.java

@@ -0,0 +1,17 @@
+package com.example.demo.core.repository;
+
+import java.util.List;
+
+public interface CommonRepository<E, T> {
+    List<E> getAll();
+
+    E get(T id);
+
+    E create(E entity);
+
+    E update(E entity);
+
+    E delete(E entity);
+
+    void deleteAll();
+}

2 lab/src/main/java/com/example/demo/core/repository/MapRepository.java

@@ -0,0 +1,57 @@
+package com.example.demo.core.repository;
+
+import java.util.List;
+import java.util.Map;
+import java.util.TreeMap;
+
+import com.example.demo.core.model.BaseEntity;
+
+public abstract class MapRepository<E extends BaseEntity> implements CommonRepository<E, Long> {
+    private final Map<Long, E> entities = new TreeMap<>();
+    private Long lastId = 0L;
+
+    protected MapRepository() {
+    }
+
+    @Override
+    public List<E> getAll() {
+        return entities.values().stream().toList();
+    }
+
+    @Override
+    public E get(Long id) {
+        return entities.get(id);
+    }
+
+    @Override
+    public E create(E entity) {
+        lastId++;
+        entity.setId(lastId);
+        entities.put(lastId, entity);
+        return entity;
+    }
+
+    @Override
+    public E update(E entity) {
+        if (get(entity.getId()) == null) {
+            return null;
+        }
+        entities.put(entity.getId(), entity);
+        return entity;
+    }
+
+    @Override
+    public E delete(E entity) {
+        if (get(entity.getId()) == null) {
+            return null;
+        }
+        entities.remove(entity.getId());
+        return entity;
+    }
+
+    @Override
+    public void deleteAll() {
+        lastId = 0L;
+        entities.clear();
+    }
+}

2 lab/src/main/java/com/example/demo/messages/api/MessageController.java

@@ -0,0 +1,75 @@
+package com.example.demo.messages.api;
+
+import java.util.List;
+
+import org.modelmapper.ModelMapper;
+import org.springframework.web.bind.annotation.DeleteMapping;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.PutMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import com.example.demo.core.convert;
+import com.example.demo.core.configuration.Constants;
+import com.example.demo.messages.model.MessageEntity;
+import com.example.demo.messages.service.MessageService;
+import com.example.demo.users.service.UserService;
+
+import jakarta.validation.Valid;
+
+@RestController
+@RequestMapping(Constants.API_URL + "/message")
+public class MessageController {
+    private final UserService userService;
+    private final MessageService messageService;
+    private final ModelMapper modelMapper;
+
+    public MessageController(MessageService messageService, UserService userService, ModelMapper modelMapper) {
+        this.messageService = messageService;
+        this.userService = userService;
+        this.modelMapper = modelMapper;
+    }
+
+    private MessageDto toDto(MessageEntity entity) {
+        var model = modelMapper.map(entity, MessageDto.class);
+        convert time = new convert();
+        model.setTime(time.dateToString(entity.getTime()));
+        return model;
+    }
+
+    private MessageEntity toEntity(MessageDto dto) {
+        final MessageEntity entity = modelMapper.map(dto, MessageEntity.class);
+        entity.setFriend(userService.get(dto.getFriendId()));
+        entity.setPerson(userService.get(dto.getPersonId()));
+        return entity;
+
+    }
+
+    @GetMapping
+    public List<MessageDto> getAll() {
+        return messageService.getAll().stream().map(this::toDto).toList();
+    }
+
+    @GetMapping("/{id}")
+    public MessageDto get(@PathVariable(name = "id") Long id) {
+        return toDto(messageService.get(id));
+    }
+
+    @PostMapping
+    public MessageDto create(@RequestBody @Valid MessageDto dto) {
+        return toDto(messageService.create(toEntity(dto)));
+    }
+
+    @PutMapping("/{id}")
+    public MessageDto update(@PathVariable(name = "id") Long id, @RequestBody MessageDto dto) {
+        return toDto(messageService.update(id, toEntity(dto)));
+    }
+
+    @DeleteMapping("/{id}")
+    public MessageDto delete(@PathVariable(name = "id") Long id) {
+        return toDto(messageService.delete(id));
+    }
+}

2 lab/src/main/java/com/example/demo/messages/api/MessageDto.java

@@ -0,0 +1,62 @@
+package com.example.demo.messages.api;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+import jakarta.validation.constraints.Min;
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
+
+public class MessageDto {
+    private Long id;
+    @NotNull
+    @Min(1)
+    private Long friendId;
+    @NotNull
+    @Min(1)
+    private Long personId;
+    @NotBlank
+    private String text;
+    @NotBlank
+    private String time;
+
+    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public Long getPersonId() {
+        return personId;
+    }
+
+    public void setPersonId(Long personId) {
+        this.personId = personId;
+    }
+
+    public Long getFriendId() {
+        return friendId;
+    }
+
+    public void setFriendId(Long friendId) {
+        this.friendId = friendId;
+    }
+
+    public String getTime() {
+        return time;
+    }
+
+    public void setTime(String time) {
+        this.time = time;
+    }
+
+    public String getText() {
+        return text;
+    }
+
+    public void setText(String text) {
+        this.text = text;
+    }
+}

2 lab/src/main/java/com/example/demo/messages/model/MessageEntity.java

@@ -0,0 +1,78 @@
+package com.example.demo.messages.model;
+
+import java.util.Date;
+import java.util.Objects;
+
+import com.example.demo.core.model.BaseEntity;
+import com.example.demo.users.model.UserEntity;
+
+public class MessageEntity extends BaseEntity {
+    private UserEntity person;
+    private UserEntity friend;
+    private Date time;
+    private String text;
+
+    public MessageEntity() {
+        super();
+    }
+
+    public MessageEntity(Long id, UserEntity person, UserEntity friend, Date time, String text) {
+        super(id);
+        this.person = person;
+        this.friend = friend;
+        this.text = text;
+        this.time = time;
+    }
+
+    public UserEntity getFriend() {
+        return friend;
+    }
+
+    public void setFriend(UserEntity friend) {
+        this.friend = friend;
+    }
+
+    public UserEntity getPerson() {
+        return person;
+    }
+
+    public void setPerson(UserEntity person) {
+        this.person = person;
+    }
+
+    public Date getTime() {
+        return time;
+    }
+
+    public void setTime(Date time) {
+        this.time = time;
+    }
+
+    public String getText() {
+        return text;
+    }
+
+    public void setText(String text) {
+        this.text = text;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, friend, person, time, text);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null || getClass() != obj.getClass())
+            return false;
+        final MessageEntity other = (MessageEntity) obj;
+        return Objects.equals(other.getId(), id)
+                && Objects.equals(other.getPerson(), person)
+                && Objects.equals(other.getFriend(), friend)
+                && Objects.equals(other.getText(), text)
+                && Objects.equals(other.getTime(), time);
+    }
+
+}

2 lab/src/main/java/com/example/demo/messages/repository/MessageRepository.java

@@ -0,0 +1,10 @@
+package com.example.demo.messages.repository;
+
+import org.springframework.stereotype.Repository;
+
+import com.example.demo.core.repository.MapRepository;
+import com.example.demo.messages.model.MessageEntity;
+
+@Repository
+public class MessageRepository extends MapRepository<MessageEntity> {
+}

2 lab/src/main/java/com/example/demo/messages/service/MessageService.java

@@ -0,0 +1,43 @@
+package com.example.demo.messages.service;
+
+import java.util.List;
+import java.util.Optional;
+
+import org.springframework.stereotype.Service;
+
+import com.example.demo.core.error.NotFoundException;
+import com.example.demo.messages.model.MessageEntity;
+import com.example.demo.messages.repository.MessageRepository;
+
+@Service
+public class MessageService {
+    private final MessageRepository repository;
+
+    public MessageService(MessageRepository repository) {
+        this.repository = repository;
+    }
+
+    public List<MessageEntity> getAll() {
+        return repository.getAll();
+    }
+
+    public MessageEntity get(Long id) {
+        return Optional.ofNullable(repository.get(id))
+                .orElseThrow(() -> new NotFoundException(id));
+    }
+
+    public MessageEntity create(MessageEntity entity) {
+        return repository.create(entity);
+    }
+
+    public MessageEntity update(Long id, MessageEntity entity) {
+        final MessageEntity existsEntity = get(id);
+        existsEntity.setText(entity.getText());
+        return repository.update(existsEntity);
+    }
+
+    public MessageEntity delete(Long id) {
+        final MessageEntity existsEntity = get(id);
+        return repository.delete(existsEntity);
+    }
+}

2 lab/src/main/java/com/example/demo/posts/api/PostController.java

@@ -0,0 +1,89 @@
+package com.example.demo.posts.api;
+
+import java.util.List;
+
+import org.modelmapper.ModelMapper;
+import org.springframework.web.bind.annotation.DeleteMapping;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.PutMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import com.example.demo.core.convert;
+import com.example.demo.core.configuration.Constants;
+import com.example.demo.posts.model.PostEntity;
+import com.example.demo.posts.service.PostService;
+import com.example.demo.users.service.UserService;
+
+import jakarta.validation.Valid;
+
+@RestController
+@RequestMapping(Constants.API_URL + "/post")
+public class PostController {
+    private final UserService userService;
+    private final PostService postService;
+    private final ModelMapper modelMapper;
+
+    public PostController(PostService postService, UserService userService, ModelMapper modelMapper) {
+        this.postService = postService;
+        this.userService = userService;
+        this.modelMapper = modelMapper;
+    }
+
+    private PostDto toDto(PostEntity entity) {
+        var model = modelMapper.map(entity, PostDto.class);
+        convert time = new convert();
+        model.setTime(time.dateToString(entity.getTime()));
+        return model;
+    }
+
+    private PostEntity toEntity(PostDto dto) {
+        final PostEntity entity = modelMapper.map(dto, PostEntity.class);
+        entity.setPerson(userService.get(dto.getPersonId()));
+        return entity;
+
+    }
+
+    @GetMapping
+    public List<PostDto> getAll() {
+        return postService.getAll().stream().map(this::toDto).toList();
+    }
+
+    @GetMapping("/{id}")
+    public PostDto get(@PathVariable(name = "id") Long id) {
+        return toDto(postService.get(id));
+    }
+
+    @PostMapping
+    public PostDto create(@RequestBody @Valid PostDto dto) {
+        return toDto(postService.create(toEntity(dto)));
+    }
+
+    @PostMapping("/like/{id}")
+    public PostDto addLike(@PathVariable(name = "id") Long id) {
+        return toDto(postService.addLike(id));
+    }
+
+    @DeleteMapping("/like/{id}")
+    public PostDto removeLike(@PathVariable(name = "id") Long id) {
+        return toDto(postService.removeLiked(id));
+    }
+
+    @PostMapping("/view/{id}")
+    public PostDto addView(@PathVariable(name = "id") Long id) {
+        return toDto(postService.addView(id));
+    }
+
+    @PutMapping("/{id}")
+    public PostDto update(@PathVariable(name = "id") Long id, @RequestBody PostDto dto) {
+        return toDto(postService.update(id, toEntity(dto)));
+    }
+
+    @DeleteMapping("/{id}")
+    public PostDto delete(@PathVariable(name = "id") Long id) {
+        return toDto(postService.delete(id));
+    }
+}

2 lab/src/main/java/com/example/demo/posts/api/PostDto.java

@@ -0,0 +1,73 @@
+package com.example.demo.posts.api;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+import jakarta.validation.constraints.Min;
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
+
+public class PostDto {
+    private Long id;
+    @NotBlank
+    @Min(1)
+    private Long personId;
+    @NotBlank
+    private String time;
+    @NotBlank
+    private String text;
+    @NotNull
+    @Min(0)
+    private Long viewed;
+    @NotNull
+    @Min(0)
+    private Long liked;
+
+    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public Long getPersonId() {
+        return personId;
+    }
+
+    public void setPersonId(Long personId) {
+        this.personId = personId;
+    }
+
+    public String getText() {
+        return text;
+    }
+
+    public void setText(String text) {
+        this.text = text;
+    }
+
+    public String getTime() {
+        return time;
+    }
+
+    public void setTime(String time) {
+        this.time = time;
+    }
+
+    public Long getViewed() {
+        return viewed;
+    }
+
+    public void setViewed(Long viewed) {
+        this.viewed = viewed;
+    }
+
+    public Long getLiked() {
+        return liked;
+    }
+
+    public void setLiked(Long liked) {
+        this.liked = liked;
+    }
+}

2 lab/src/main/java/com/example/demo/posts/model/PostEntity.java

@@ -0,0 +1,89 @@
+package com.example.demo.posts.model;
+
+import java.util.Date;
+import java.util.Objects;
+
+import com.example.demo.core.model.BaseEntity;
+import com.example.demo.users.model.UserEntity;
+
+public class PostEntity extends BaseEntity {
+    private UserEntity person;
+    private Date time;
+    private String text;
+    private Long viewed;
+    private Long liked;
+
+    public PostEntity() {
+        super();
+    }
+
+    public PostEntity(Long id, UserEntity person, Date time, String text, Long viewed, Long liked) {
+        super(id);
+        this.person = person;
+        this.text = text;
+        this.time = time;
+        this.viewed = viewed;
+        this.liked = liked;
+    }
+
+    public UserEntity getPerson() {
+        return person;
+    }
+
+    public void setPerson(UserEntity person) {
+        this.person = person;
+    }
+
+    public Date getTime() {
+        return time;
+    }
+
+    public void setTime(Date time) {
+        this.time = time;
+    }
+
+    public String getText() {
+        return text;
+    }
+
+    public void setText(String text) {
+        this.text = text;
+    }
+
+    public Long getViewed() {
+        return viewed;
+    }
+
+    public void setViewed(Long viewed) {
+        this.viewed = viewed;
+    }
+
+    public Long getLiked() {
+        return liked;
+    }
+
+    public void setLiked(Long liked) {
+        this.liked = liked;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, person, time, text, viewed, liked);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null || getClass() != obj.getClass())
+            return false;
+        final PostEntity other = (PostEntity) obj;
+        return Objects.equals(other.getId(), id)
+                && Objects.equals(other.getPerson(), person)
+                && Objects.equals(other.getText(), text)
+                && Objects.equals(other.getTime(), time)
+                && Objects.equals(other.getLiked(), liked)
+                && Objects.equals(other.getViewed(), viewed);
+    }
+
+}

2 lab/src/main/java/com/example/demo/posts/repository/PostRepository.java

@@ -0,0 +1,10 @@
+package com.example.demo.posts.repository;
+
+import org.springframework.stereotype.Repository;
+
+import com.example.demo.core.repository.MapRepository;
+import com.example.demo.posts.model.PostEntity;
+
+@Repository
+public class PostRepository extends MapRepository<PostEntity> {
+}

2 lab/src/main/java/com/example/demo/posts/service/PostService.java

@@ -0,0 +1,61 @@
+package com.example.demo.posts.service;
+
+import java.util.List;
+import java.util.Optional;
+
+import org.springframework.stereotype.Service;
+
+import com.example.demo.core.error.NotFoundException;
+import com.example.demo.posts.model.PostEntity;
+import com.example.demo.posts.repository.PostRepository;
+
+@Service
+public class PostService {
+    private final PostRepository repository;
+
+    public PostService(PostRepository repository) {
+        this.repository = repository;
+    }
+
+    public List<PostEntity> getAll() {
+        return repository.getAll();
+    }
+
+    public PostEntity get(Long id) {
+        return Optional.ofNullable(repository.get(id))
+                .orElseThrow(() -> new NotFoundException(id));
+    }
+
+    public PostEntity create(PostEntity entity) {
+        return repository.create(entity);
+    }
+
+    public PostEntity addLike(Long id) {
+        final PostEntity existsEntity = get(id);
+        existsEntity.setLiked((existsEntity.getLiked() + 1));
+        return repository.update(existsEntity);
+    }
+
+    public PostEntity removeLiked(Long id) {
+        final PostEntity existsEntity = get(id);
+        existsEntity.setLiked((existsEntity.getLiked() - 1));
+        return repository.update(existsEntity);
+    }
+
+    public PostEntity addView(Long id) {
+        final PostEntity existsEntity = get(id);
+        existsEntity.setViewed((existsEntity.getViewed() + 1));
+        return repository.update(existsEntity);
+    }
+
+    public PostEntity update(Long id, PostEntity entity) {
+        final PostEntity existsEntity = get(id);
+        existsEntity.setText(entity.getText());
+        return repository.update(existsEntity);
+    }
+
+    public PostEntity delete(Long id) {
+        final PostEntity existsEntity = get(id);
+        return repository.delete(existsEntity);
+    }
+}

2 lab/src/main/java/com/example/demo/users/api/UserController.java

@@ -0,0 +1,82 @@
+package com.example.demo.users.api;
+
+import java.util.List;
+
+import org.modelmapper.ModelMapper;
+import org.springframework.web.bind.annotation.DeleteMapping;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.PutMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import com.example.demo.core.configuration.Constants;
+import com.example.demo.users.model.UserEntity;
+import com.example.demo.users.service.UserService;
+
+import jakarta.validation.Valid;
+
+@RestController
+@RequestMapping(Constants.API_URL + "/user")
+public class UserController {
+    private final UserService userService;
+    private final ModelMapper modelMapper;
+
+    public UserController(UserService userService, ModelMapper modelMapper) {
+        this.userService = userService;
+        this.modelMapper = modelMapper;
+    }
+
+    private UserDto toDto(UserEntity entity) {
+        var model = modelMapper.map(entity, UserDto.class);
+        if (entity.getFriends() != null) {
+            for (UserEntity user : entity.getFriends()) {
+                model.addFriendId(user.getId());
+            }
+        }
+        return model;
+
+    }
+
+    private UserEntity toEntity(UserDto dto) {
+        return modelMapper.map(dto, UserEntity.class);
+    }
+
+    @GetMapping
+    public List<UserDto> getAll() {
+        return userService.getAll().stream().map(this::toDto).toList();
+    }
+
+    @GetMapping("/{id}")
+    public UserDto get(@PathVariable(name = "id") Long id) {
+        return toDto(userService.get(id));
+    }
+
+    @PostMapping
+    public UserDto create(@RequestBody @Valid UserDto dto) {
+        return toDto(userService.create(toEntity(dto)));
+    }
+
+    @PostMapping("/friends/{id}")
+    public UserDto addFriend(@PathVariable(name = "id") Long id, @RequestBody UserDto dto) {
+        return toDto(userService.addFriend(id, toEntity(dto)));
+    }
+
+    @DeleteMapping("/friends/{id}")
+    public UserDto removeFriend(@PathVariable(name = "id") Long id, @RequestBody UserDto dto) {
+        return toDto(userService.removeFriend(id, toEntity(dto)));
+    }
+
+    @PutMapping("/{id}")
+    public UserDto update(@PathVariable(name = "id") Long id, @RequestBody UserDto dto) {
+        return toDto(userService.update(id, toEntity(dto)));
+    }
+
+    @DeleteMapping("/{id}")
+    public UserDto delete(@PathVariable(name = "id") Long id) {
+        return toDto(userService.delete(id));
+    }
+
+}

2 lab/src/main/java/com/example/demo/users/api/UserDto.java

@@ -0,0 +1,65 @@
+package com.example.demo.users.api;
+
+import java.util.ArrayList;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+import java.util.List;
+import jakarta.validation.constraints.Min;
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
+
+public class UserDto {
+    private Long id;
+    @NotNull
+    @Min(1)
+    private String nickname;
+    @NotBlank
+    private String email;
+    @NotBlank
+    private String password;
+    private List<Long> friendsId = new ArrayList<>();
+
+    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getNickname() {
+        return nickname;
+    }
+
+    public void setNickname(String nickname) {
+        this.nickname = nickname;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public void setPassword(String password) {
+        this.password = password;
+    }
+
+    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
+    public List<Long> getFriendsId() {
+        return friendsId;
+    }
+
+    public void addFriendId(long Id) {
+        friendsId.add(Id);
+    }
+
+}

2 lab/src/main/java/com/example/demo/users/model/UserEntity.java

@@ -0,0 +1,76 @@
+package com.example.demo.users.model;
+
+import java.util.ArrayList;
+import java.util.Objects;
+import java.util.List;
+import com.example.demo.core.model.BaseEntity;
+
+public class UserEntity extends BaseEntity {
+    private String nickname;
+    private String email;
+    private String password;
+    private List<UserEntity> friends = new ArrayList<>();
+
+    public UserEntity() {
+        super();
+    }
+
+    public UserEntity(Long id, String nickname, String email, String password, List<UserEntity> friends) {
+        super(id);
+        this.nickname = nickname;
+        this.email = email;
+        this.password = password;
+        this.friends = friends;
+    }
+
+    public String getNickname() {
+        return nickname;
+    }
+
+    public void setNickname(String nickname) {
+        this.nickname = nickname;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public void setPassword(String password) {
+        this.password = password;
+    }
+
+    public List<UserEntity> getFriends() {
+        return friends;
+    }
+
+    public void setFriends(List<UserEntity> friends) {
+        this.friends = friends;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, nickname, email, password, friends);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null || getClass() != obj.getClass())
+            return false;
+        final UserEntity other = (UserEntity) obj;
+        return Objects.equals(other.getId(), id)
+                && Objects.equals(other.getFriends(), friends)
+                && Objects.equals(other.getNickname(), nickname)
+                && Objects.equals(other.getEmail(), email)
+                && Objects.equals(other.getPassword(), password);
+    }
+}

2 lab/src/main/java/com/example/demo/users/repository/UserRepository.java

@@ -0,0 +1,10 @@
+package com.example.demo.users.repository;
+
+import org.springframework.stereotype.Repository;
+
+import com.example.demo.core.repository.MapRepository;
+import com.example.demo.users.model.UserEntity;
+
+@Repository
+public class UserRepository extends MapRepository<UserEntity> {
+}

2 lab/src/main/java/com/example/demo/users/service/UserService.java

@@ -0,0 +1,57 @@
+package com.example.demo.users.service;
+
+import java.util.List;
+import java.util.Optional;
+
+import org.springframework.stereotype.Service;
+
+import com.example.demo.core.error.NotFoundException;
+import com.example.demo.users.model.UserEntity;
+import com.example.demo.users.repository.UserRepository;
+
+@Service
+public class UserService {
+    private final UserRepository repository;
+
+    public UserService(UserRepository repository) {
+        this.repository = repository;
+    }
+
+    public List<UserEntity> getAll() {
+        return repository.getAll();
+    }
+
+    public UserEntity get(Long id) {
+        return Optional.ofNullable(repository.get(id))
+                .orElseThrow(() -> new NotFoundException(id));
+    }
+
+    public UserEntity create(UserEntity entity) {
+        return repository.create(entity);
+    }
+
+    public UserEntity addFriend(Long id, UserEntity entity) {
+        final UserEntity existsEntity = get(id);
+        existsEntity.getFriends().add(entity);
+        return repository.update(existsEntity);
+    }
+
+    public UserEntity removeFriend(Long id, UserEntity entity) {
+        final UserEntity existsEntity = get(id);
+        existsEntity.getFriends().remove(entity);
+        return repository.update(existsEntity);
+    }
+
+    public UserEntity update(Long id, UserEntity entity) {
+        final UserEntity existsEntity = get(id);
+        existsEntity.setNickname(entity.getNickname());
+        existsEntity.setEmail(entity.getEmail());
+        existsEntity.setPassword(entity.getPassword());
+        return repository.update(existsEntity);
+    }
+
+    public UserEntity delete(Long id) {
+        final UserEntity existsEntity = get(id);
+        return repository.delete(existsEntity);
+    }
+}

2 lab/src/main/resources/application.properties

@@ -0,0 +1 @@
+

2 lab/src/test/java/com/example/demo/CommentServiceTests.java

@@ -0,0 +1,92 @@
+package com.example.demo;
+
+import java.util.Date;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.MethodOrderer.OrderAnnotation;
+import org.junit.jupiter.api.Order;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestMethodOrder;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+
+import com.example.demo.comments.model.CommentEntity;
+import com.example.demo.comments.service.CommentService;
+import com.example.demo.core.error.NotFoundException;
+import com.example.demo.users.model.UserEntity;
+import com.example.demo.posts.model.PostEntity;
+import com.example.demo.users.service.UserService;
+import com.example.demo.posts.service.PostService;;
+
+@SpringBootTest
+@TestMethodOrder(OrderAnnotation.class)
+class CommentServiceTests {
+        @Autowired
+        private UserService userService;
+        @Autowired
+        private PostService postService;
+        @Autowired
+        private CommentService commentService;
+
+        @Test
+        void getTest() {
+                Assertions.assertThrows(NotFoundException.class, () -> commentService.get(0L));
+        }
+
+        @Test
+        @Order(1)
+        void createTest() {
+                var user1 = userService.create(new UserEntity(null, "sardq", "as2@asd", "asdsd", null));
+                var user2 = userService.create(new UserEntity(null, "eafqr", "aasd@asd", "1234r", null));
+                var user3 = userService.create(new UserEntity(null, "asf", "aaasfsfs@asd", "332a", null));
+                var post1 = postService.create(new PostEntity(null, user1, new Date(), "test",
+                                Long.valueOf(0), Long.valueOf(0)));
+                var post2 = postService
+                                .create(new PostEntity(null, user3, new Date(), "asfgczv", Long.valueOf(20),
+                                                Long.valueOf(15)));
+                var post3 = postService.create(new PostEntity(null, user2, new Date(), "asvbsfd", Long.valueOf(30),
+                                Long.valueOf(3)));
+                commentService.create(new CommentEntity(null, user1, post2, new Date(), "my comment"));
+                commentService.create(new CommentEntity(null, user3, post1, new Date(), "my comment2"));
+                final var last = commentService
+                                .create(new CommentEntity(null, user2, post3, new Date(), "my comment3"));
+                Assertions.assertEquals(3, commentService.getAll().size());
+                Assertions.assertEquals(last, commentService.get(3L));
+        }
+
+        @Test
+        @Order(2)
+        void updateTest() {
+                final String test = "TEST";
+                final CommentEntity entity = commentService.get(3L);
+                final String oldText = entity.getText();
+                var user1 = userService.create(new UserEntity(null, "sardq", "as2@asd", "asdsd", null));
+                var post1 = postService.create(new PostEntity(null, user1,
+                                new Date(), "test",
+                                Long.valueOf(0), Long.valueOf(0)));
+
+                final CommentEntity newEntity = commentService.update(3L,
+                                new CommentEntity(1L, user1, post1, new Date(), test));
+                Assertions.assertEquals(3, commentService.getAll().size());
+                Assertions.assertEquals(newEntity, commentService.get(3L));
+                Assertions.assertEquals(test, newEntity.getText());
+                Assertions.assertNotEquals(oldText, newEntity.getText());
+        }
+
+        @Test
+        @Order(3)
+        void deleteTest() {
+                commentService.delete(3L);
+                Assertions.assertEquals(2, commentService.getAll().size());
+                final CommentEntity last = commentService.get(2L);
+                Assertions.assertEquals(2L, last.getId());
+                final var user1 = userService.create(new UserEntity(null, "sardq", "as2@asd", "asdsd", null));
+                final var post1 = postService.create(new PostEntity(null, user1,
+                                new Date(), "test",
+                                Long.valueOf(0), Long.valueOf(0)));
+                final CommentEntity newEntity = commentService.create(
+                                new CommentEntity(null, user1, post1, new Date(), "jgdssd"));
+                Assertions.assertEquals(3, commentService.getAll().size());
+                Assertions.assertEquals(4L, newEntity.getId());
+        }
+}

2 lab/src/test/java/com/example/demo/MessageServiceTests.java

@@ -0,0 +1,77 @@
+package com.example.demo;
+
+import java.util.Date;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.MethodOrderer.OrderAnnotation;
+import org.junit.jupiter.api.Order;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestMethodOrder;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+
+import com.example.demo.core.error.NotFoundException;
+import com.example.demo.messages.model.MessageEntity;
+import com.example.demo.messages.service.MessageService;
+import com.example.demo.users.model.UserEntity;
+import com.example.demo.users.service.UserService;
+
+@SpringBootTest
+@TestMethodOrder(OrderAnnotation.class)
+class MessageServiceTests {
+    @Autowired
+    private UserService userService;
+    @Autowired
+    private MessageService messageService;
+
+    @Test
+    void getTest() {
+        Assertions.assertThrows(NotFoundException.class, () -> messageService.get(0L));
+    }
+
+    @Test
+    @Order(1)
+    void createTest() {
+        var user1 = userService.create(new UserEntity(null, "sardq", "as2@asd", "asdsd", null));
+        var user2 = userService.create(new UserEntity(null, "eafqr", "aasd@asd", "1234r", null));
+        var user3 = userService.create(new UserEntity(null, "asf", "aaasfsfs@asd", "332a", null));
+        messageService.create(new MessageEntity(null, user1, user2, new Date(), "test"));
+        messageService.create(new MessageEntity(null, user3, user2, new Date(), "asfgczv"));
+        final MessageEntity last = messageService
+                .create(new MessageEntity(null, user2, user1, new Date(), "asvbsfd"));
+        Assertions.assertEquals(3, messageService.getAll().size());
+        Assertions.assertEquals(last, messageService.get(3L));
+    }
+
+    @Test
+    @Order(2)
+    void updateTest() {
+        final String test = "TEST";
+        final MessageEntity entity = messageService.get(3L);
+        final String oldText = entity.getText();
+        final MessageEntity newEntity = messageService.update(3L,
+                new MessageEntity(1L,
+                        new UserEntity(null, "safsaf", "aasd@asd", "qazq", null),
+                        new UserEntity(null, "safnkkjaslf", "safsaf@asd", "2qhf", null),
+                        new Date(), test));
+        Assertions.assertEquals(3, messageService.getAll().size());
+        Assertions.assertEquals(newEntity, messageService.get(3L));
+        Assertions.assertEquals(test, newEntity.getText());
+        Assertions.assertNotEquals(oldText, newEntity.getText());
+    }
+
+    @Test
+    @Order(3)
+    void deleteTest() {
+        messageService.delete(3L);
+        Assertions.assertEquals(2, messageService.getAll().size());
+        final MessageEntity last = messageService.get(2L);
+        Assertions.assertEquals(2L, last.getId());
+        var user1 = userService.create(new UserEntity(null, "sardq", "as2@asd", "asdsd", null));
+        var user2 = userService.create(new UserEntity(null, "sasfardq", "asfg@asd", "asfsaf", null));
+        final MessageEntity newEntity = messageService.create(
+                new MessageEntity(null, user1, user2, new Date(), "test"));
+        Assertions.assertEquals(3, messageService.getAll().size());
+        Assertions.assertEquals(4L, newEntity.getId());
+    }
+}

2 lab/src/test/java/com/example/demo/PostServiceTests.java

@@ -0,0 +1,81 @@
+package com.example.demo;
+
+import java.util.Date;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.MethodOrderer.OrderAnnotation;
+import org.junit.jupiter.api.Order;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestMethodOrder;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+
+import com.example.demo.core.error.NotFoundException;
+import com.example.demo.users.model.UserEntity;
+import com.example.demo.posts.model.PostEntity;
+import com.example.demo.users.service.UserService;
+import com.example.demo.posts.service.PostService;;
+
+@SpringBootTest
+@TestMethodOrder(OrderAnnotation.class)
+class PostServiceTests {
+    @Autowired
+    private UserService userService;
+    @Autowired
+    private PostService postService;
+
+    @Test
+    void getTest() {
+        Assertions.assertThrows(NotFoundException.class, () -> postService.get(0L));
+    }
+
+    @Test
+    @Order(1)
+    void createTest() {
+        var user1 = userService.create(new UserEntity(null, "sardq", "as2@asd", "asdsd", null));
+        var user2 = userService.create(new UserEntity(null, "eafqr", "aasd@asd", "1234r", null));
+        var user3 = userService.create(new UserEntity(null, "asf", "aaasfsfs@asd", "332a", null));
+        postService.create(new PostEntity(null, user1,
+                new Date(), "test",
+                Long.valueOf(0), Long.valueOf(0)));
+        postService.create(new PostEntity(null, user3, new Date(), "asfgczv", Long.valueOf(20), Long.valueOf(15)));
+        final PostEntity last = postService
+                .create(new PostEntity(null, user2,
+                        new Date(), "asvbsfd", Long.valueOf(30),
+                        Long.valueOf(3)));
+        postService.addLike(1L);
+        postService.addView(1L);
+        Assertions.assertEquals(3, postService.getAll().size());
+        Assertions.assertEquals(last, postService.get(3L));
+    }
+
+    @Test
+    @Order(2)
+    void updateTest() {
+        final String test = "TEST";
+        final PostEntity entity = postService.get(3L);
+        final String oldText = entity.getText();
+        final PostEntity newEntity = postService.update(3L,
+                new PostEntity(1L, new UserEntity(1L, "safsaf", "aasd@asd", "qazq", null),
+                        new Date(), test, Long.valueOf(30), Long.valueOf(3)));
+        Assertions.assertEquals(3, postService.getAll().size());
+        Assertions.assertEquals(newEntity, postService.get(3L));
+        Assertions.assertEquals(test, newEntity.getText());
+        Assertions.assertNotEquals(oldText, newEntity.getText());
+    }
+
+    @Test
+    @Order(3)
+    void deleteTest() {
+        postService.delete(3L);
+        Assertions.assertEquals(2, postService.getAll().size());
+        final PostEntity last = postService.get(2L);
+        postService.removeLiked(1L);
+        Assertions.assertEquals(2L, last.getId());
+        var user1 = userService.create(new UserEntity(null, "sardq", "as2@asd", "asdsd", null));
+        final PostEntity newEntity = postService.create(
+                new PostEntity(null, user1, new Date(), "test", Long.valueOf(0), Long.valueOf(0)));
+        Assertions.assertEquals(3, postService.getAll().size());
+        Assertions.assertEquals(4L, newEntity.getId());
+    }
+}

2 lab/src/test/java/com/example/demo/UserServiceTests.java

@@ -0,0 +1,68 @@
+package com.example.demo;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.MethodOrderer.OrderAnnotation;
+import org.junit.jupiter.api.Order;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestMethodOrder;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+
+import com.example.demo.core.error.NotFoundException;
+import com.example.demo.users.model.UserEntity;
+import com.example.demo.users.service.UserService;
+
+@SpringBootTest
+@TestMethodOrder(OrderAnnotation.class)
+class UserServiceTests {
+    @Autowired
+    private UserService userService;
+
+    @Test
+    void getTest() {
+        Assertions.assertThrows(NotFoundException.class, () -> userService.get(0L));
+    }
+
+    @Test
+    @Order(1)
+    void createTest() {
+        List<UserEntity> friends = new ArrayList<UserEntity>();
+        friends.add(new UserEntity(2L, "eafqr", "aasd@asd", "1234r", new ArrayList<UserEntity>()));
+        userService.create(new UserEntity(1L, "sardq", "as2@asd", "asdsd", friends));
+        userService.create(new UserEntity(2L, "eafqr", "aasd@asd", "1234r", new ArrayList<UserEntity>()));
+        final UserEntity last = userService.create(new UserEntity(3L, "fgwrewr", "sf123@asd", "zxvb",
+                new ArrayList<UserEntity>()));
+        userService.addFriend(1L, last);
+        Assertions.assertEquals(3, userService.getAll().size());
+        Assertions.assertEquals(last, userService.get(3L));
+    }
+
+    @Test
+    @Order(2)
+    void updateTest() {
+        final String test = "TEST";
+        final UserEntity entity = userService.get(3L);
+        final String oldName = entity.getNickname();
+        final UserEntity newEntity = userService.update(3L, new UserEntity(1L, test, "aasd@asd", "qazq", null));
+        Assertions.assertEquals(3, userService.getAll().size());
+        Assertions.assertEquals(newEntity, userService.get(3L));
+        Assertions.assertEquals(test, newEntity.getNickname());
+        Assertions.assertNotEquals(oldName, newEntity.getNickname());
+    }
+
+    @Test
+    @Order(3)
+    void deleteTest() {
+        userService.delete(3L);
+        Assertions.assertEquals(2, userService.getAll().size());
+        final UserEntity last = userService.get(2L);
+        userService.removeFriend(2L, last);
+        Assertions.assertEquals(2L, last.getId());
+        final UserEntity newEntity = userService.create(new UserEntity(null, "asfzxv", "aasd@asd", "qwtg", null));
+        Assertions.assertEquals(3, userService.getAll().size());
+        Assertions.assertEquals(4L, newEntity.getId());
+    }
+}

3 lab/.gitignore

@@ -0,0 +1,36 @@
+HELP.md
+.gradle
+build/
+!gradle/wrapper/gradle-wrapper.jar
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/main/**/bin/
+!**/src/test/**/bin/
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+out/
+!**/src/main/**/out/
+!**/src/test/**/out/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+data.*.db

3 lab/.vscode/extensions.json

@@ -0,0 +1,12 @@
+{
+  "recommendations": [
+    // fronted
+    "AndersEAndersen.html-class-suggestions",
+    "dbaeumer.vscode-eslint",
+    // backend
+    "vscjava.vscode-java-pack",
+    "vmware.vscode-boot-dev-pack",
+    "vscjava.vscode-gradle",
+    "redhat.vscode-xml"
+  ]
+}

3 lab/.vscode/launch.json

@@ -0,0 +1,14 @@
+{
+    "configurations": [
+        {
+            "type": "java",
+            "name": "Demo",
+            "request": "launch",
+            "cwd": "${workspaceFolder}",
+            "mainClass": "com.example.demo.DemoApplication",
+            "projectName": "lec3",
+            "args": "--populate",
+            "envFile": "${workspaceFolder}/.env"
+        }
+    ]
+}

3 lab/.vscode/settings.json

@@ -0,0 +1,21 @@
+{
+    "editor.tabSize": 4,
+    "editor.detectIndentation": false,
+    "editor.insertSpaces": true,
+    "editor.formatOnPaste": true,
+    "editor.formatOnSave": true,
+    "editor.formatOnType": false,
+    "java.compile.nullAnalysis.mode": "disabled",
+    "java.configuration.updateBuildConfiguration": "automatic",
+    "[java]": {
+        "editor.pasteAs.enabled": false,
+    },
+    "gradle.nestedProjects": true,
+    "java.saveActions.organizeImports": true,
+    "java.dependency.packagePresentation": "hierarchical",
+    "spring-boot.ls.problem.boot2.JAVA_CONSTRUCTOR_PARAMETER_INJECTION": "WARNING",
+    "spring.initializr.defaultLanguage": "Java",
+    "java.format.settings.url": ".vscode/eclipse-formatter.xml",
+    "java.project.explorer.showNonJavaResources": true,
+    "java.codeGeneration.hashCodeEquals.useJava7Objects": true,
+}

3 lab/build.gradle

@@ -0,0 +1,43 @@
+plugins {
+	id 'java'
+	id 'org.springframework.boot' version '3.2.4'
+	id 'io.spring.dependency-management' version '1.1.4'
+}
+
+group = 'com.example'
+version = '0.0.1-SNAPSHOT'
+
+defaultTasks 'bootRun'
+
+jar {
+    enabled = false
+}
+
+bootJar {
+    archiveFileName = String.format('%s-%s.jar', rootProject.name, version)
+}
+
+assert System.properties['java.specification.version'] == '17' || '21'
+java {
+	sourceCompatibility = '17'
+}
+
+repositories {
+	mavenCentral()
+}
+
+dependencies {
+	implementation 'org.springframework.boot:spring-boot-starter-web'
+	implementation 'org.springframework.boot:spring-boot-starter-validation'
+	implementation 'org.springdoc:springdoc-openapi-starter-webmvc-ui:2.3.0'
+	implementation 'org.modelmapper:modelmapper:3.2.0'
+
+	implementation 'org.springframework.boot:spring-boot-starter-data-jpa'
+	implementation 'com.h2database:h2:2.2.224'
+
+	testImplementation 'org.springframework.boot:spring-boot-starter-test'
+}
+
+tasks.named('test') {
+	useJUnitPlatform()
+}

3 lab/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,7 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.5-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

3 lab/gradlew

@@ -0,0 +1,249 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/HEAD/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+# This is normally unused
+# shellcheck disable=SC2034
+APP_BASE_NAME=${0##*/}
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
+APP_HOME=$( cd "${APP_HOME:-./}" > /dev/null && pwd -P ) || exit
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    if ! command -v java >/dev/null 2>&1
+    then
+        die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Collect all arguments for the java command:
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#     and any embedded shellness will be escaped.
+#   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
+#     treated as '${Hostname}' itself on the command line.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"

3 lab/gradlew.bat

@@ -0,0 +1,92 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%"=="" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if %ERRORLEVEL% equ 0 goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if %ERRORLEVEL% equ 0 goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

3 lab/readme.md

@@ -0,0 +1,18 @@
+Swagger UI: \
+http://localhost:8080/swagger-ui/index.html
+
+H2 Console: \
+http://localhost:8080/h2-console
+
+JDBC URL: jdbc:h2:file:./data \
+User Name: sa \
+Password: password
+
+Почитать:
+
+- Односторонние и двусторонние связи https://www.baeldung.com/jpa-hibernate-associations
+- Getters и Setters для двусторонних связей https://en.wikibooks.org/wiki/Java_Persistence/OneToMany#Getters_and_Setters
+- Многие-ко-многим с доп. атрибутами https://thorben-janssen.com/hibernate-tip-many-to-many-association-with-additional-attributes/
+- Многие-ко-многим с доп. атрибутами https://www.baeldung.com/jpa-many-to-many
+- Каскадное удаление сущностей со связями многие-ко-многим https://www.baeldung.com/jpa-remove-entity-many-to-many
+- Выбор типа коллекции для отношений вида ко-многим в JPA https://thorben-janssen.com/association-mappings-bag-list-set/

3 lab/settings.gradle

@@ -0,0 +1 @@
+rootProject.name = 'demo'

3 lab/src/main/java/com/example/demo/DemoApplication.java

@@ -0,0 +1,87 @@
+package com.example.demo;
+
+import java.sql.Time;
+import java.util.ArrayList;
+import java.util.Objects;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.boot.CommandLineRunner;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+import java.util.List;
+
+import com.example.demo.comments.model.CommentEntity;
+import com.example.demo.comments.service.CommentService;
+import com.example.demo.messages.model.MessageEntity;
+import com.example.demo.messages.service.MessageService;
+import com.example.demo.posts.model.PostEntity;
+import com.example.demo.posts.service.PostService;
+import com.example.demo.users.model.UserEntity;
+import com.example.demo.users.service.UserService;
+
+@SpringBootApplication
+public class DemoApplication implements CommandLineRunner {
+    private final Logger log = LoggerFactory.getLogger(DemoApplication.class);
+
+    private final UserService userService;
+    private final PostService postService;
+    private final CommentService commentService;
+    private final MessageService messageService;
+
+    public DemoApplication(UserService userService, PostService postService, CommentService commentService,
+            MessageService messageService) {
+        this.userService = userService;
+        this.postService = postService;
+        this.commentService = commentService;
+        this.messageService = messageService;
+    }
+
+    public static void main(String[] args) {
+        SpringApplication.run(DemoApplication.class, args);
+    }
+
+    @Override
+    public void run(String... args) throws Exception {
+        if (args.length > 0 && Objects.equals("--populate", args[0])) {
+
+            log.info("Create default items values");
+            final List<UserEntity> blank = new ArrayList<UserEntity>();
+            final var user1 = userService.create(new UserEntity("sardq", "aasd@asd", "asdsd", null));
+            final var user2 = userService.create(new UserEntity("sardasdq", "aasdsad@asd", "123", blank));
+            final List<UserEntity> friends = new ArrayList<>();
+            friends.add(user1);
+            friends.add(user2);
+            userService.addFriend(user1.getId(), user2);
+
+            final var user3 = userService.create(new UserEntity("sxzcvardq", "aaxsd@asd", "asfgd", friends));
+            final var user4 = userService.create(new UserEntity("sarbvljdq", "aacbxcsd@asd", "zxvb", blank));
+            log.info("Create default posts values");
+            final var post1 = postService.create(
+                    new PostEntity(user1, new Time(System.currentTimeMillis()), "test", Long.valueOf(0),
+                            Long.valueOf(0)));
+            final var post2 = postService.create(
+                    new PostEntity(user3, new Time(System.currentTimeMillis()), "test", Long.valueOf(11),
+                            Long.valueOf(2)));
+            final var post3 = postService.create(
+                    new PostEntity(user4, new Time(System.currentTimeMillis()), "test", Long.valueOf(40),
+                            Long.valueOf(15)));
+
+            log.info("Create default comments values");
+            commentService
+                    .create(new CommentEntity(user1, post2, new Time(System.currentTimeMillis()), "my comment"));
+            commentService
+                    .create(new CommentEntity(user3, post1, new Time(System.currentTimeMillis()), "my comment2"));
+            commentService
+                    .create(new CommentEntity(user4, post3, new Time(System.currentTimeMillis()), "my comment3"));
+
+            log.info("Create default messages values");
+            messageService.create(new MessageEntity(user1, user2, new Time(System.currentTimeMillis()), "hello"));
+            messageService
+                    .create(new MessageEntity(user1, user2, new Time(System.currentTimeMillis()), "how are you"));
+            messageService
+                    .create(new MessageEntity(user2, user1, new Time(System.currentTimeMillis()), "I'm ok"));
+        }
+    }
+}

3 lab/src/main/java/com/example/demo/comments/api/CommentController.java

@@ -0,0 +1,81 @@
+package com.example.demo.comments.api;
+
+import org.modelmapper.ModelMapper;
+import org.springframework.web.bind.annotation.DeleteMapping;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.PutMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+
+import com.example.demo.comments.model.CommentEntity;
+import com.example.demo.comments.service.CommentService;
+import com.example.demo.core.convert;
+import com.example.demo.core.api.PageDto;
+import com.example.demo.core.api.PageDtoMapper;
+import com.example.demo.core.configuration.Constants;
+import com.example.demo.posts.service.PostService;
+import com.example.demo.users.service.UserService;
+
+import jakarta.validation.Valid;
+
+@RestController
+@RequestMapping(Constants.API_URL + "/comment")
+public class CommentController {
+    private final UserService userService;
+    private final PostService postService;
+    private final CommentService commentService;
+    private final ModelMapper modelMapper;
+
+    public CommentController(CommentService commentService, UserService userService, PostService postService,
+            ModelMapper modelMapper) {
+        this.userService = userService;
+        this.commentService = commentService;
+        this.postService = postService;
+        this.modelMapper = modelMapper;
+    }
+
+    private CommentDto toDto(CommentEntity entity) {
+        var model = modelMapper.map(entity, CommentDto.class);
+        convert time = new convert();
+        model.setTime(time.dateToString(entity.getTime()));
+        return model;
+    }
+
+    private CommentEntity toEntity(CommentDto dto) {
+        final CommentEntity entity = modelMapper.map(dto, CommentEntity.class);
+        entity.setperson(userService.get(dto.getUserId()));
+        entity.setPost(postService.get(dto.getPostId()));
+        return entity;
+    }
+
+    @GetMapping
+    public PageDto<CommentDto> getAll(
+            @RequestParam(name = "page", defaultValue = "0") int page,
+            @RequestParam(name = "size", defaultValue = Constants.DEFAULT_PAGE_SIZE) int size) {
+        return PageDtoMapper.toDto(commentService.getAll(page, size), this::toDto);
+    }
+
+    @GetMapping("/{id}")
+    public CommentDto get(@PathVariable(name = "id") Long id) {
+        return toDto(commentService.get(id));
+    }
+
+    @PostMapping
+    public CommentDto create(@RequestBody @Valid CommentDto dto) {
+        return toDto(commentService.create(toEntity(dto)));
+    }
+
+    @PutMapping("/{id}")
+    public CommentDto update(@PathVariable(name = "id") Long id, @RequestBody CommentDto dto) {
+        return toDto(commentService.update(id, toEntity(dto)));
+    }
+
+    @DeleteMapping("/{id}")
+    public CommentDto delete(@PathVariable(name = "id") Long id) {
+        return toDto(commentService.delete(id));
+    }
+}

3 lab/src/main/java/com/example/demo/comments/api/CommentDto.java

@@ -0,0 +1,62 @@
+package com.example.demo.comments.api;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+import jakarta.validation.constraints.Min;
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
+
+public class CommentDto {
+    private Long id;
+    @NotNull
+    @Min(1)
+    private Long userId;
+    @NotBlank
+    private String text;
+    @NotNull
+    @Min(1)
+    private Long postId;
+    @NotBlank
+    private String time;
+
+    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public Long getUserId() {
+        return userId;
+    }
+
+    public void setUserId(Long userId) {
+        this.userId = userId;
+    }
+
+    public Long getPostId() {
+        return postId;
+    }
+
+    public void setPostId(Long postId) {
+        this.postId = postId;
+    }
+
+    public String getText() {
+        return text;
+    }
+
+    public void setText(String text) {
+        this.text = text;
+    }
+
+    public String getTime() {
+        return time;
+    }
+
+    public void setTime(String time) {
+        this.time = time;
+    }
+}

3 lab/src/main/java/com/example/demo/comments/model/CommentEntity.java

@@ -0,0 +1,90 @@
+package com.example.demo.comments.model;
+
+import java.util.Date;
+import java.util.Objects;
+
+import com.example.demo.core.model.BaseEntity;
+import com.example.demo.posts.model.PostEntity;
+import com.example.demo.users.model.UserEntity;
+
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.Table;
+
+@Entity
+@Table(name = "comments")
+public class CommentEntity extends BaseEntity {
+    @ManyToOne
+    @JoinColumn(name = "personEntity", nullable = false)
+    private UserEntity person;
+    @ManyToOne
+    @JoinColumn(name = "postEntity", nullable = false)
+    private PostEntity post;
+    @Column(nullable = false)
+    private Date time;
+    @Column(length = 100)
+    private String text;
+
+    public CommentEntity() {
+    }
+
+    public CommentEntity(UserEntity person, PostEntity post, Date time, String text) {
+        this.person = person;
+        this.post = post;
+        this.time = time;
+        this.text = text;
+    }
+
+    public UserEntity getperson() {
+        return person;
+    }
+
+    public void setperson(UserEntity person) {
+        this.person = person;
+    }
+
+    public PostEntity getPost() {
+        return post;
+    }
+
+    public void setPost(PostEntity post) {
+        this.post = post;
+    }
+
+    public Date getTime() {
+        return time;
+    }
+
+    public void setTime(Date time) {
+        this.time = time;
+    }
+
+    public String getText() {
+        return text;
+    }
+
+    public void setText(String text) {
+        this.text = text;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, person, post, text, time);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null || getClass() != obj.getClass())
+            return false;
+        final CommentEntity other = (CommentEntity) obj;
+        return Objects.equals(other.getId(), id)
+                && Objects.equals(other.getperson(), person)
+                && Objects.equals(other.getPost(), post)
+                && Objects.equals(other.getText(), text)
+                && Objects.equals(other.getTime(), time);
+    }
+}

3 lab/src/main/java/com/example/demo/comments/repository/CommentRepository.java

@@ -0,0 +1,14 @@
+package com.example.demo.comments.repository;
+
+import java.util.Optional;
+
+import org.springframework.data.repository.CrudRepository;
+import org.springframework.data.repository.PagingAndSortingRepository;
+
+import com.example.demo.comments.model.CommentEntity;
+
+public interface CommentRepository
+        extends CrudRepository<CommentEntity, Long>, PagingAndSortingRepository<CommentEntity, Long> {
+
+    Optional<CommentEntity> findById(Long Id);
+}

3 lab/src/main/java/com/example/demo/comments/service/CommentService.java

@@ -0,0 +1,63 @@
+package com.example.demo.comments.service;
+
+import java.util.List;
+import java.util.stream.StreamSupport;
+
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.PageRequest;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+import com.example.demo.comments.model.CommentEntity;
+import com.example.demo.comments.repository.CommentRepository;
+import com.example.demo.core.error.NotFoundException;
+
+@Service
+public class CommentService {
+    private final CommentRepository repository;
+
+    public CommentService(CommentRepository repository) {
+        this.repository = repository;
+    }
+
+    @Transactional(readOnly = true)
+    public List<CommentEntity> getAll() {
+        return StreamSupport.stream(repository.findAll().spliterator(), false).toList();
+
+    }
+
+    @Transactional(readOnly = true)
+    public Page<CommentEntity> getAll(int page, int size) {
+        return repository.findAll(PageRequest.of(page, size));
+    }
+
+    @Transactional(readOnly = true)
+    public CommentEntity get(Long id) {
+        return repository.findById(id)
+                .orElseThrow(() -> new NotFoundException(CommentEntity.class, id));
+    }
+
+    @Transactional
+    public CommentEntity create(CommentEntity entity) {
+        if (entity == null) {
+            throw new IllegalArgumentException("Entity is null");
+        }
+        repository.save(entity);
+        return repository.save(entity);
+    }
+
+    @Transactional
+    public CommentEntity update(Long id, CommentEntity entity) {
+        final CommentEntity existsEntity = get(id);
+        existsEntity.setText(entity.getText());
+        repository.save(existsEntity);
+        return existsEntity;
+    }
+
+    @Transactional
+    public CommentEntity delete(Long id) {
+        final CommentEntity existsEntity = get(id);
+        repository.delete(existsEntity);
+        return existsEntity;
+    }
+}

3 lab/src/main/java/com/example/demo/core/api/PageDto.java

@@ -0,0 +1,97 @@
+package com.example.demo.core.api;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class PageDto<D> {
+    private List<D> items = new ArrayList<>();
+    private int itemsCount;
+    private int currentPage;
+    private int currentSize;
+    private int totalPages;
+    private long totalItems;
+    private boolean isFirst;
+    private boolean isLast;
+    private boolean hasNext;
+    private boolean hasPrevious;
+
+    public List<D> getItems() {
+        return items;
+    }
+
+    public void setItems(List<D> items) {
+        this.items = items;
+    }
+
+    public int getItemsCount() {
+        return itemsCount;
+    }
+
+    public void setItemsCount(int itemsCount) {
+        this.itemsCount = itemsCount;
+    }
+
+    public int getCurrentPage() {
+        return currentPage;
+    }
+
+    public void setCurrentPage(int currentPage) {
+        this.currentPage = currentPage;
+    }
+
+    public int getCurrentSize() {
+        return currentSize;
+    }
+
+    public void setCurrentSize(int currentSize) {
+        this.currentSize = currentSize;
+    }
+
+    public int getTotalPages() {
+        return totalPages;
+    }
+
+    public void setTotalPages(int totalPages) {
+        this.totalPages = totalPages;
+    }
+
+    public long getTotalItems() {
+        return totalItems;
+    }
+
+    public void setTotalItems(long totalItems) {
+        this.totalItems = totalItems;
+    }
+
+    public boolean isFirst() {
+        return isFirst;
+    }
+
+    public void setFirst(boolean isFirst) {
+        this.isFirst = isFirst;
+    }
+
+    public boolean isLast() {
+        return isLast;
+    }
+
+    public void setLast(boolean isLast) {
+        this.isLast = isLast;
+    }
+
+    public boolean isHasNext() {
+        return hasNext;
+    }
+
+    public void setHasNext(boolean hasNext) {
+        this.hasNext = hasNext;
+    }
+
+    public boolean isHasPrevious() {
+        return hasPrevious;
+    }
+
+    public void setHasPrevious(boolean hasPrevious) {
+        this.hasPrevious = hasPrevious;
+    }
+}

3 lab/src/main/java/com/example/demo/core/api/PageDtoMapper.java

@@ -0,0 +1,25 @@
+package com.example.demo.core.api;
+
+import java.util.function.Function;
+
+import org.springframework.data.domain.Page;
+
+public class PageDtoMapper {
+    private PageDtoMapper() {
+    }
+
+    public static <D, E> PageDto<D> toDto(Page<E> page, Function<E, D> mapper) {
+        final PageDto<D> dto = new PageDto<>();
+        dto.setItems(page.getContent().stream().map(mapper::apply).toList());
+        dto.setItemsCount(page.getNumberOfElements());
+        dto.setCurrentPage(page.getNumber());
+        dto.setCurrentSize(page.getSize());
+        dto.setTotalPages(page.getTotalPages());
+        dto.setTotalItems(page.getTotalElements());
+        dto.setFirst(page.isFirst());
+        dto.setLast(page.isLast());
+        dto.setHasNext(page.hasNext());
+        dto.setHasPrevious(page.hasPrevious());
+        return dto;
+    }
+}

3 lab/src/main/java/com/example/demo/core/configuration/Constants.java

@@ -0,0 +1,10 @@
+package com.example.demo.core.configuration;
+
+public class Constants {
+    public static final String API_URL = "/api/1.0";
+    public static final String SEQUENCE_NAME = "hibernate_sequence";
+    public static final String DEFAULT_PAGE_SIZE = "5";
+
+    private Constants() {
+    }
+}

3 lab/src/main/java/com/example/demo/core/configuration/MapperConfiguration.java

@@ -0,0 +1,13 @@
+package com.example.demo.core.configuration;
+
+import org.modelmapper.ModelMapper;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+public class MapperConfiguration {
+    @Bean
+    ModelMapper modelMapper() {
+        return new ModelMapper();
+    }
+}

3 lab/src/main/java/com/example/demo/core/configuration/WebConfiguration.java

@@ -0,0 +1,15 @@
+package com.example.demo.core.configuration;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.lang.NonNull;
+import org.springframework.web.servlet.config.annotation.CorsRegistry;
+import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
+
+@Configuration
+public class WebConfiguration implements WebMvcConfigurer {
+    @Override
+    public void addCorsMappings(@NonNull CorsRegistry registry) {
+        registry.addMapping("/**")
+                .allowedMethods("GET", "POST", "PUT", "DELETE");
+    }
+}

3 lab/src/main/java/com/example/demo/core/convert.java

@@ -0,0 +1,17 @@
+package com.example.demo.core;
+
+import java.text.DateFormat;
+import java.text.SimpleDateFormat;
+import java.util.Date;
+
+public class convert {
+    public Date stringToDate(String string) throws Exception {
+        DateFormat format = new SimpleDateFormat("HH:mm:ss");
+        return (Date) format.parse(string);
+    }
+
+    public String dateToString(Date date) {
+        DateFormat dateFormat = new SimpleDateFormat("dd.MM.YYYY hh:mm:ss");
+        return dateFormat.format(date);
+    }
+}

3 lab/src/main/java/com/example/demo/core/error/NotFoundException.java

@@ -0,0 +1,7 @@
+package com.example.demo.core.error;
+
+public class NotFoundException extends RuntimeException {
+    public <T> NotFoundException(Class<T> clazz, Long id) {
+        super(String.format("%s with id [%s] is not found or not exists", clazz.getSimpleName(), id));
+    }
+}

3 lab/src/main/java/com/example/demo/core/model/BaseEntity.java

@@ -0,0 +1,32 @@
+package com.example.demo.core.model;
+
+import com.example.demo.core.configuration.Constants;
+
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import jakarta.persistence.MappedSuperclass;
+import jakarta.persistence.SequenceGenerator;
+
+@MappedSuperclass
+public abstract class BaseEntity {
+    @Id
+    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = Constants.SEQUENCE_NAME)
+    @SequenceGenerator(name = Constants.SEQUENCE_NAME, sequenceName = Constants.SEQUENCE_NAME, allocationSize = 1)
+    protected Long id;
+
+    protected BaseEntity() {
+    }
+
+    protected BaseEntity(Long id) {
+        this.id = id;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+}

3 lab/src/main/java/com/example/demo/messages/api/MessageController.java

@@ -0,0 +1,79 @@
+package com.example.demo.messages.api;
+
+import org.modelmapper.ModelMapper;
+import org.springframework.web.bind.annotation.DeleteMapping;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.PutMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+
+import com.example.demo.core.convert;
+import com.example.demo.core.api.PageDto;
+import com.example.demo.core.api.PageDtoMapper;
+import com.example.demo.core.configuration.Constants;
+import com.example.demo.messages.model.MessageEntity;
+import com.example.demo.messages.service.MessageService;
+import com.example.demo.users.service.UserService;
+
+import jakarta.validation.Valid;
+
+@RestController
+@RequestMapping(Constants.API_URL + "/message")
+public class MessageController {
+    private final UserService userService;
+    private final MessageService messageService;
+    private final ModelMapper modelMapper;
+
+    public MessageController(MessageService messageService, UserService userService, ModelMapper modelMapper) {
+        this.messageService = messageService;
+        this.userService = userService;
+        this.modelMapper = modelMapper;
+    }
+
+    private MessageDto toDto(MessageEntity entity) {
+        var model = modelMapper.map(entity, MessageDto.class);
+        convert time = new convert();
+        model.setTime(time.dateToString(entity.getTime()));
+        return model;
+    }
+
+    private MessageEntity toEntity(MessageDto dto) {
+        final MessageEntity entity = modelMapper.map(dto, MessageEntity.class);
+        entity.setFriend(userService.get(dto.getFriendId()));
+        entity.setPerson(userService.get(dto.getPersonId()));
+        return entity;
+
+    }
+
+    @GetMapping
+    public PageDto<MessageDto> getAll(
+            @RequestParam(name = "personId", defaultValue = "0") Long personId,
+            @RequestParam(name = "page", defaultValue = "0") int page,
+            @RequestParam(name = "size", defaultValue = Constants.DEFAULT_PAGE_SIZE) int size) {
+        return PageDtoMapper.toDto(messageService.getAll(personId, page, size), this::toDto);
+    }
+
+    @GetMapping("/{id}")
+    public MessageDto get(@PathVariable(name = "id") Long id) {
+        return toDto(messageService.get(id));
+    }
+
+    @PostMapping
+    public MessageDto create(@RequestBody @Valid MessageDto dto) {
+        return toDto(messageService.create(toEntity(dto)));
+    }
+
+    @PutMapping("/{id}")
+    public MessageDto update(@PathVariable(name = "id") Long id, @RequestBody MessageDto dto) {
+        return toDto(messageService.update(id, toEntity(dto)));
+    }
+
+    @DeleteMapping("/{id}")
+    public MessageDto delete(@PathVariable(name = "id") Long id) {
+        return toDto(messageService.delete(id));
+    }
+}

3 lab/src/main/java/com/example/demo/messages/api/MessageDto.java

@@ -0,0 +1,62 @@
+package com.example.demo.messages.api;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+import jakarta.validation.constraints.Min;
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
+
+public class MessageDto {
+    private Long id;
+    @NotNull
+    @Min(1)
+    private Long friendId;
+    @NotNull
+    @Min(1)
+    private Long personId;
+    @NotBlank
+    private String text;
+    @NotBlank
+    private String time;
+
+    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public Long getPersonId() {
+        return personId;
+    }
+
+    public void setPersonId(Long personId) {
+        this.personId = personId;
+    }
+
+    public Long getFriendId() {
+        return friendId;
+    }
+
+    public void setFriendId(Long friendId) {
+        this.friendId = friendId;
+    }
+
+    public String getTime() {
+        return time;
+    }
+
+    public void setTime(String time) {
+        this.time = time;
+    }
+
+    public String getText() {
+        return text;
+    }
+
+    public void setText(String text) {
+        this.text = text;
+    }
+}

3 lab/src/main/java/com/example/demo/messages/model/MessageEntity.java

@@ -0,0 +1,91 @@
+package com.example.demo.messages.model;
+
+import java.util.Date;
+import java.util.Objects;
+
+import com.example.demo.core.model.BaseEntity;
+import com.example.demo.users.model.UserEntity;
+
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.Table;
+
+@Entity
+@Table(name = "messages")
+public class MessageEntity extends BaseEntity {
+
+    @ManyToOne
+    @JoinColumn(name = "userEntity", nullable = false)
+    private UserEntity person;
+    @ManyToOne
+    @JoinColumn(name = "dialogFriend", nullable = false)
+    private UserEntity friend;
+    @Column(nullable = false)
+    private Date time;
+    @Column(length = 100)
+    private String text;
+
+    public MessageEntity() {
+    }
+
+    public MessageEntity(UserEntity person, UserEntity friend, Date time, String text) {
+        this.person = person;
+        this.friend = friend;
+        this.text = text;
+        this.time = time;
+    }
+
+    public UserEntity getFriend() {
+        return friend;
+    }
+
+    public void setFriend(UserEntity friend) {
+        this.friend = friend;
+    }
+
+    public UserEntity getPerson() {
+        return person;
+    }
+
+    public void setPerson(UserEntity person) {
+        this.person = person;
+    }
+
+    public Date getTime() {
+        return time;
+    }
+
+    public void setTime(Date time) {
+        this.time = time;
+    }
+
+    public String getText() {
+        return text;
+    }
+
+    public void setText(String text) {
+        this.text = text;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, friend, person, time, text);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null || getClass() != obj.getClass())
+            return false;
+        final MessageEntity other = (MessageEntity) obj;
+        return Objects.equals(other.getId(), id)
+                && Objects.equals(other.getPerson(), person)
+                && Objects.equals(other.getFriend(), friend)
+                && Objects.equals(other.getText(), text)
+                && Objects.equals(other.getTime(), time);
+    }
+
+}

3 lab/src/main/java/com/example/demo/messages/repository/MessageRepository.java

@@ -0,0 +1,21 @@
+package com.example.demo.messages.repository;
+
+import java.util.List;
+import java.util.Optional;
+
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.data.repository.CrudRepository;
+import org.springframework.data.repository.PagingAndSortingRepository;
+
+import com.example.demo.messages.model.MessageEntity;
+
+public interface MessageRepository
+        extends CrudRepository<MessageEntity, Long>, PagingAndSortingRepository<MessageEntity, Long> {
+    List<MessageEntity> findByPersonId(Long personId);
+
+    Page<MessageEntity> findByPersonId(Long personId, Pageable pageable);
+
+    Optional<MessageEntity> findById(Long Id);
+
+}

3 lab/src/main/java/com/example/demo/messages/service/MessageService.java

@@ -0,0 +1,72 @@
+package com.example.demo.messages.service;
+
+import java.util.List;
+import java.util.stream.StreamSupport;
+
+import org.springframework.transaction.annotation.Transactional;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.PageRequest;
+import org.springframework.data.domain.Pageable;
+import org.springframework.stereotype.Service;
+
+import com.example.demo.core.error.NotFoundException;
+import com.example.demo.messages.model.MessageEntity;
+import com.example.demo.messages.repository.MessageRepository;
+
+@Service
+public class MessageService {
+    private final MessageRepository repository;
+
+    public MessageService(MessageRepository repository) {
+        this.repository = repository;
+    }
+
+    @Transactional(readOnly = true)
+    public List<MessageEntity> getAll(long personId) {
+        if (personId <= 0L) {
+            return StreamSupport.stream(repository.findAll().spliterator(), false).toList();
+        } else {
+            return repository.findByPersonId(personId);
+        }
+
+    }
+
+    @Transactional(readOnly = true)
+    public Page<MessageEntity> getAll(long personId, int page, int size) {
+        final Pageable pageRequest = PageRequest.of(page, size);
+        if (personId <= 0L) {
+            return repository.findAll(pageRequest);
+        }
+        return repository.findByPersonId(personId, pageRequest);
+    }
+
+    @Transactional
+    public MessageEntity get(Long id) {
+        return repository.findById(id)
+                .orElseThrow(() -> new NotFoundException(MessageEntity.class, id));
+    }
+
+    @Transactional
+    public MessageEntity create(MessageEntity entity) {
+        if (entity == null) {
+            throw new IllegalArgumentException("Entity is null");
+        }
+        repository.save(entity);
+        return repository.save(entity);
+    }
+
+    @Transactional
+    public MessageEntity update(Long id, MessageEntity entity) {
+        final MessageEntity existsEntity = get(id);
+        existsEntity.setText(entity.getText());
+        repository.save(existsEntity);
+        return existsEntity;
+    }
+
+    @Transactional
+    public MessageEntity delete(Long id) {
+        final MessageEntity existsEntity = get(id);
+        repository.delete(existsEntity);
+        return existsEntity;
+    }
+}

3 lab/src/main/java/com/example/demo/posts/api/PostController.java

@@ -0,0 +1,92 @@
+package com.example.demo.posts.api;
+
+import org.modelmapper.ModelMapper;
+import org.springframework.web.bind.annotation.DeleteMapping;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.PutMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+
+import com.example.demo.core.convert;
+import com.example.demo.core.api.PageDto;
+import com.example.demo.core.api.PageDtoMapper;
+import com.example.demo.core.configuration.Constants;
+import com.example.demo.posts.model.PostEntity;
+import com.example.demo.posts.service.PostService;
+import com.example.demo.users.service.UserService;
+
+import jakarta.validation.Valid;
+
+@RestController
+@RequestMapping(Constants.API_URL + "/post")
+public class PostController {
+    private final UserService userService;
+    private final PostService postService;
+    private final ModelMapper modelMapper;
+
+    public PostController(PostService postService, UserService userService, ModelMapper modelMapper) {
+        this.postService = postService;
+        this.userService = userService;
+        this.modelMapper = modelMapper;
+    }
+
+    private PostDto toDto(PostEntity entity) {
+        var model = modelMapper.map(entity, PostDto.class);
+        convert time = new convert();
+        model.setTime(time.dateToString(entity.getTime()));
+        return model;
+    }
+
+    private PostEntity toEntity(PostDto dto) {
+        final PostEntity entity = modelMapper.map(dto, PostEntity.class);
+        entity.setPerson(userService.get(dto.getPersonId()));
+        return entity;
+
+    }
+
+    @GetMapping
+    public PageDto<PostDto> getAll(
+            @RequestParam(name = "page", defaultValue = "0") int page,
+            @RequestParam(name = "size", defaultValue = Constants.DEFAULT_PAGE_SIZE) int size) {
+        return PageDtoMapper.toDto(postService.getAll(page, size), this::toDto);
+    }
+
+    @GetMapping("/{id}")
+    public PostDto get(@PathVariable(name = "id") Long id) {
+        return toDto(postService.get(id));
+    }
+
+    @PostMapping
+    public PostDto create(@RequestBody @Valid PostDto dto) {
+        return toDto(postService.create(toEntity(dto)));
+    }
+
+    @PostMapping("/like/{id}")
+    public PostDto addLike(@PathVariable(name = "id") Long id) {
+        return toDto(postService.addLike(id));
+    }
+
+    @DeleteMapping("/like/{id}")
+    public PostDto removeLike(@PathVariable(name = "id") Long id) {
+        return toDto(postService.removeLiked(id));
+    }
+
+    @PostMapping("/view/{id}")
+    public PostDto addView(@PathVariable(name = "id") Long id) {
+        return toDto(postService.addView(id));
+    }
+
+    @PutMapping("/{id}")
+    public PostDto update(@PathVariable(name = "id") Long id, @RequestBody PostDto dto) {
+        return toDto(postService.update(id, toEntity(dto)));
+    }
+
+    @DeleteMapping("/{id}")
+    public PostDto delete(@PathVariable(name = "id") Long id) {
+        return toDto(postService.delete(id));
+    }
+}

3 lab/src/main/java/com/example/demo/posts/api/PostDto.java

@@ -0,0 +1,76 @@
+package com.example.demo.posts.api;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+import com.fasterxml.jackson.annotation.JsonProperty.Access;
+
+import jakarta.validation.constraints.Min;
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
+
+public class PostDto {
+    @JsonProperty(access = Access.READ_ONLY)
+    private Long id;
+    @NotNull
+    @Min(1)
+    private Long personId;
+    @NotBlank
+    private String time;
+    @NotBlank
+    private String text;
+    @NotNull
+    @Min(0)
+    private Long viewed;
+    @NotNull
+    @Min(0)
+    private Long liked;
+
+    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public Long getPersonId() {
+        return personId;
+    }
+
+    public void setPersonId(Long personId) {
+        this.personId = personId;
+    }
+
+    public String getText() {
+        return text;
+    }
+
+    public void setText(String text) {
+        this.text = text;
+    }
+
+    public String getTime() {
+        return time;
+    }
+
+    public void setTime(String time) {
+        this.time = time;
+    }
+
+    public Long getViewed() {
+        return viewed;
+    }
+
+    public void setViewed(Long viewed) {
+        this.viewed = viewed;
+    }
+
+    public Long getLiked() {
+        return liked;
+    }
+
+    public void setLiked(Long liked) {
+        this.liked = liked;
+    }
+}

3 lab/src/main/java/com/example/demo/posts/model/PostEntity.java

@@ -0,0 +1,102 @@
+package com.example.demo.posts.model;
+
+import java.util.Date;
+import java.util.Objects;
+
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.Table;
+
+import com.example.demo.core.model.BaseEntity;
+import com.example.demo.users.model.UserEntity;
+
+@Entity
+@Table(name = "posts")
+public class PostEntity extends BaseEntity {
+    @ManyToOne
+    @JoinColumn(name = "user_Id", nullable = false)
+    private UserEntity person;
+    @Column(nullable = false)
+    private Date time;
+    @Column(length = 100)
+    private String text;
+    @Column
+    private Long viewed;
+    @Column
+    private Long liked;
+
+    public PostEntity() {
+        super();
+    }
+
+    public PostEntity(UserEntity person, Date time, String text, Long viewed, Long liked) {
+        this.person = person;
+        this.text = text;
+        this.time = time;
+        this.viewed = viewed;
+        this.liked = liked;
+    }
+
+    public UserEntity getPerson() {
+        return person;
+    }
+
+    public void setPerson(UserEntity person) {
+        this.person = person;
+    }
+
+    public Date getTime() {
+        return time;
+    }
+
+    public void setTime(Date time) {
+        this.time = time;
+    }
+
+    public String getText() {
+        return text;
+    }
+
+    public void setText(String text) {
+        this.text = text;
+    }
+
+    public Long getViewed() {
+        return viewed;
+    }
+
+    public void setViewed(Long viewed) {
+        this.viewed = viewed;
+    }
+
+    public Long getLiked() {
+        return liked;
+    }
+
+    public void setLiked(Long liked) {
+        this.liked = liked;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, person, time, text, viewed, liked);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null || getClass() != obj.getClass())
+            return false;
+        final PostEntity other = (PostEntity) obj;
+        return Objects.equals(other.getId(), id)
+                && Objects.equals(other.getPerson(), person)
+                && Objects.equals(other.getText(), text)
+                && Objects.equals(other.getTime(), time)
+                && Objects.equals(other.getLiked(), liked)
+                && Objects.equals(other.getViewed(), viewed);
+    }
+
+}

3 lab/src/main/java/com/example/demo/posts/repository/PostRepository.java

@@ -0,0 +1,14 @@
+package com.example.demo.posts.repository;
+
+import java.util.Optional;
+import org.springframework.data.repository.CrudRepository;
+import org.springframework.data.repository.PagingAndSortingRepository;
+
+import com.example.demo.posts.model.PostEntity;
+
+public interface PostRepository
+        extends CrudRepository<PostEntity, Long>, PagingAndSortingRepository<PostEntity, Long> {
+
+    Optional<PostEntity> findById(Long Id);
+
+}

3 lab/src/main/java/com/example/demo/posts/service/PostService.java

@@ -0,0 +1,86 @@
+package com.example.demo.posts.service;
+
+import java.util.List;
+import java.util.stream.StreamSupport;
+
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.PageRequest;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+import com.example.demo.core.error.NotFoundException;
+import com.example.demo.posts.model.PostEntity;
+import com.example.demo.posts.repository.PostRepository;
+
+@Service
+public class PostService {
+    private final PostRepository repository;
+
+    public PostService(PostRepository repository) {
+        this.repository = repository;
+    }
+
+    @Transactional(readOnly = true)
+    public List<PostEntity> getAll() {
+        return StreamSupport.stream(repository.findAll().spliterator(), false).toList();
+    }
+
+    @Transactional(readOnly = true)
+    public Page<PostEntity> getAll(int page, int size) {
+        return repository.findAll(PageRequest.of(page, size));
+    }
+
+    @Transactional(readOnly = true)
+    public PostEntity get(Long id) {
+        return repository.findById(id)
+                .orElseThrow(() -> new NotFoundException(PostEntity.class, id));
+    }
+
+    @Transactional
+    public PostEntity create(PostEntity entity) {
+        if (entity == null) {
+            throw new IllegalArgumentException("Entity is null");
+        }
+        repository.save(entity);
+        return repository.save(entity);
+    }
+
+    @Transactional
+    public PostEntity addLike(Long id) {
+        final PostEntity existsEntity = get(id);
+        existsEntity.setLiked((existsEntity.getLiked() + 1));
+        repository.save(existsEntity);
+        return existsEntity;
+    }
+
+    @Transactional
+    public PostEntity removeLiked(Long id) {
+        final PostEntity existsEntity = get(id);
+        existsEntity.setLiked((existsEntity.getLiked() - 1));
+        repository.save(existsEntity);
+        return existsEntity;
+    }
+
+    @Transactional
+    public PostEntity addView(Long id) {
+        final PostEntity existsEntity = get(id);
+        existsEntity.setViewed((existsEntity.getViewed() + 1));
+        repository.save(existsEntity);
+        return existsEntity;
+    }
+
+    @Transactional
+    public PostEntity update(Long id, PostEntity entity) {
+        final PostEntity existsEntity = get(id);
+        existsEntity.setText(entity.getText());
+        repository.save(existsEntity);
+        return existsEntity;
+    }
+
+    @Transactional
+    public PostEntity delete(Long id) {
+        final PostEntity existsEntity = get(id);
+        repository.delete(existsEntity);
+        return existsEntity;
+    }
+}

3 lab/src/main/java/com/example/demo/users/api/UserController.java

@@ -0,0 +1,94 @@
+package com.example.demo.users.api;
+
+import java.util.List;
+
+import org.modelmapper.ModelMapper;
+import org.springframework.web.bind.annotation.DeleteMapping;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.PutMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import com.example.demo.core.configuration.Constants;
+import com.example.demo.users.model.UserEntity;
+import com.example.demo.users.model.UserTop;
+import com.example.demo.users.service.UserService;
+
+import jakarta.validation.Valid;
+
+@RestController
+@RequestMapping(Constants.API_URL + "/user")
+public class UserController {
+    private final UserService userService;
+    private final ModelMapper modelMapper;
+
+    public UserController(UserService userService, ModelMapper modelMapper) {
+        this.userService = userService;
+        this.modelMapper = modelMapper;
+    }
+
+    private UserDto toDto(UserEntity entity) {
+        var model = modelMapper.map(entity, UserDto.class);
+        if (entity.getFriends() != null) {
+            for (UserEntity user : entity.getFriends()) {
+                model.addFriendId(user.getId());
+            }
+        }
+        return model;
+
+    }
+
+    public UserTopDto toTopDto(UserTop user) {
+        return modelMapper.map(user, UserTopDto.class);
+
+    }
+
+    private UserEntity toEntity(UserDto dto) {
+        return modelMapper.map(dto, UserEntity.class);
+    }
+
+    @GetMapping
+    public List<UserDto> getAll() {
+        return userService.getAll().stream().map(this::toDto).toList();
+    }
+
+    @GetMapping("/{id}")
+    public UserDto get(@PathVariable(name = "id") Long id) {
+        return toDto(userService.get(id));
+    }
+
+    @PostMapping
+    public UserDto create(@RequestBody @Valid UserDto dto) {
+        return toDto(userService.create(toEntity(dto)));
+    }
+
+    @PostMapping("/friends/{id}")
+    public UserDto addFriend(@PathVariable(name = "id") Long id, @RequestBody UserDto dto) {
+        return toDto(userService.addFriend(id, toEntity(dto)));
+    }
+
+    @DeleteMapping("/friends/{id}")
+    public UserDto removeFriend(@PathVariable(name = "id") Long id, @RequestBody UserDto dto) {
+        return toDto(userService.removeFriend(id, toEntity(dto)));
+    }
+
+    @PutMapping("/{id}")
+    public UserDto update(@PathVariable(name = "id") Long id, @RequestBody UserDto dto) {
+        return toDto(userService.update(id, toEntity(dto)));
+    }
+
+    @DeleteMapping("/{id}")
+    public UserDto delete(@PathVariable(name = "id") Long id) {
+        return toDto(userService.delete(id));
+    }
+
+    @GetMapping("/topFriends")
+    public List<UserTopDto> getMethod() {
+        return userService.getTop(0, 5).getContent().stream()
+                .map(this::toTopDto)
+                .toList();
+    }
+}

3 lab/src/main/java/com/example/demo/users/api/UserDto.java

@@ -0,0 +1,68 @@
+package com.example.demo.users.api;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.annotation.JsonProperty.Access;
+
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.Size;
+
+public class UserDto {
+    @JsonProperty(access = Access.READ_ONLY)
+    private Long id;
+    @NotBlank
+    @Size(min = 3, max = 20)
+    private String nickname;
+    @NotBlank
+    @Size(min = 3, max = 20)
+    private String email;
+    @NotBlank
+    @Size(min = 3, max = 20)
+    private String password;
+    private List<Long> friendsId = new ArrayList<>();
+
+    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getNickname() {
+        return nickname;
+    }
+
+    public void setNickname(String nickname) {
+        this.nickname = nickname;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public void setPassword(String password) {
+        this.password = password;
+    }
+
+    @JsonProperty(access = JsonProperty.Access.READ_ONLY)
+    public List<Long> getFriendsId() {
+        return friendsId;
+    }
+
+    public void addFriendId(long Id) {
+        friendsId.add(Id);
+    }
+
+}

3 lab/src/main/java/com/example/demo/users/api/UserTopDto.java

@@ -0,0 +1,26 @@
+package com.example.demo.users.api;
+
+public class UserTopDto {
+    private String user;
+    private int count;
+
+    public UserTopDto() {
+    }
+
+    public String getUser() {
+        return user;
+    }
+
+    public void setUser(String user) {
+        this.user = user;
+    }
+
+    public int getCount() {
+        return count;
+    }
+
+    public void setCount(int count) {
+        this.count = count;
+    }
+
+}

3 lab/src/main/java/com/example/demo/users/model/UserEntity.java

@@ -0,0 +1,92 @@
+package com.example.demo.users.model;
+
+import java.util.ArrayList;
+import java.util.Objects;
+
+import java.util.List;
+import com.example.demo.core.model.BaseEntity;
+
+import jakarta.persistence.CascadeType;
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.FetchType;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.JoinTable;
+import jakarta.persistence.ManyToMany;
+import jakarta.persistence.Table;
+
+@Entity
+@Table(name = "users")
+public class UserEntity extends BaseEntity {
+    @Column(nullable = false, length = 20)
+    private String nickname;
+    @Column(nullable = false, unique = true, length = 20)
+    private String email;
+    @Column(nullable = false, length = 20)
+    private String password;
+    @ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.REFRESH)
+    @JoinTable(name = "user_friendship", joinColumns = @JoinColumn(name = "first_user_id", referencedColumnName = "Id", nullable = false), inverseJoinColumns = @JoinColumn(name = "second_user_id", referencedColumnName = "Id", nullable = false))
+    private List<UserEntity> friends = new ArrayList<UserEntity>();
+
+    public UserEntity() {
+    }
+
+    public UserEntity(String nickname, String email, String password, List<UserEntity> friends) {
+
+        this.nickname = nickname;
+        this.email = email;
+        this.password = password;
+        this.friends = friends;
+    }
+
+    public String getNickname() {
+        return nickname;
+    }
+
+    public void setNickname(String nickname) {
+        this.nickname = nickname;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public void setPassword(String password) {
+        this.password = password;
+    }
+
+    public List<UserEntity> getFriends() {
+        return friends;
+    }
+
+    public void setFriends(List<UserEntity> friends) {
+        this.friends = friends;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, nickname, email, password, friends);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null || getClass() != obj.getClass())
+            return false;
+        final UserEntity other = (UserEntity) obj;
+        return Objects.equals(other.getId(), id)
+                && Objects.equals(other.getFriends(), friends)
+                && Objects.equals(other.getNickname(), nickname)
+                && Objects.equals(other.getEmail(), email)
+                && Objects.equals(other.getPassword(), password);
+    }
+}