Лабораторная работа №4: Сдана

app/build.gradle

@@ -4,6 +4,9 @@ plugins {
     id 'kotlin-kapt'
 }
 
+apply plugin: 'com.android.application'
+apply plugin: 'com.google.dagger.hilt.android'
+
 android {
     namespace 'com.example.dtf'
     compileSdk 34
@@ -71,4 +74,16 @@ dependencies {
     implementation 'androidx.room:room-runtime:2.5.0' // Библиотека "Room"
     kapt "androidx.room:room-compiler:2.5.0" // Кодогенератор
     implementation 'androidx.room:room-ktx:2.5.0'
+
+    implementation "com.google.dagger:hilt-android:2.42"
+    kapt "com.google.dagger:hilt-android-compiler:2.42"
+    implementation("androidx.hilt:hilt-navigation-compose:1.0.0")
+    implementation 'androidx.compose.runtime:runtime-livedata:1.0.0-beta01'
+    implementation "androidx.datastore:datastore-preferences:1.0.0"
+
+    def paging_version = "3.2.1"
+
+    implementation "androidx.paging:paging-runtime-ktx:$paging_version"
+    implementation "androidx.paging:paging-compose:$paging_version"
+    implementation("androidx.room:room-paging:2.5.0")
 }

app/src/main/AndroidManifest.xml

@@ -3,6 +3,7 @@
     xmlns:tools="http://schemas.android.com/tools">
 
     <application
+        android:name=".DTFApp"
         android:allowBackup="true"
         android:dataExtractionRules="@xml/data_extraction_rules"
         android:fullBackupContent="@xml/backup_rules"
@@ -12,7 +13,7 @@
         android:theme="@style/Theme.DTF"
         tools:targetApi="31">
         <activity
-            android:name="com.example.dtf.MainActivity"
+            android:name=".MainActivity"
             android:windowSoftInputMode="adjustResize"
             android:exported="true"
             android:theme="@style/Theme.DTF">

app/src/main/java/com/example/dtf/AppModule.kt

@@ -0,0 +1,52 @@
+package com.example.dtf
+
+import android.app.Application
+import androidx.room.*
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
+import androidx.sqlite.db.SupportSQLiteDatabase
+import com.example.dtf.db.AppDatabase
+import com.example.dtf.models.User
+import com.example.dtf.repositories.*
+import dagger.Module
+import dagger.Provides
+import dagger.hilt.InstallIn
+import dagger.hilt.components.SingletonComponent
+import javax.inject.Singleton
+
+@Module
+@InstallIn(SingletonComponent::class)
+object AppModule {
+    @Provides
+    @Singleton
+    fun provideDatabase(app: Application) : AppDatabase {
+        return Room.databaseBuilder(
+            app,
+            AppDatabase::class.java,
+            AppDatabase.DB_NAME
+        )
+        .fallbackToDestructiveMigration()
+        .build()
+    }
+
+    @Provides
+    @Singleton
+    fun provideCategoryRepository(db: AppDatabase) = CategoryRepository(db.categoryDao())
+
+    @Provides
+    @Singleton
+    fun provideCommentRepository(db: AppDatabase) = CommentRepository(db.commentDao())
+
+    @Provides
+    @Singleton
+    fun provideLikeRepository(db: AppDatabase) = LikeRepository(db.likeDao())
+
+    @Provides
+    @Singleton
+    fun providePostRepository(db: AppDatabase) = PostRepository(db.postDao())
+
+    @Provides
+    @Singleton
+    fun proviveUserRepository(db: AppDatabase) = UserRepository(db.userDao())
+}

app/src/main/java/com/example/dtf/DTFApp.kt

@@ -0,0 +1,11 @@
+package com.example.dtf
+
+import android.app.Application
+import dagger.hilt.android.HiltAndroidApp
+
+@HiltAndroidApp
+class DTFApp : Application() {
+    override fun onCreate() {
+        super.onCreate()
+    }
+}

app/src/main/java/com/example/dtf/MainActivity.kt

@@ -33,7 +33,9 @@ import com.example.dtf.screens.ProfileScreen
 import com.example.dtf.screens.RegisterScreen
 import com.example.dtf.utils.ScreenPaths
 import com.example.dtf.widgets.BottomNavBar
+import dagger.hilt.android.AndroidEntryPoint
 
+@AndroidEntryPoint
 class MainActivity : ComponentActivity() {
     @SuppressLint("UnusedMaterial3ScaffoldPaddingParameter",
         "UnusedMaterialScaffoldPaddingParameter"
@@ -100,7 +102,7 @@ class MainActivity : ComponentActivity() {
                         }
                         composable(ScreenPaths.NewPost.route) {
                             includeBackButton.value = true
-                            NewPostScreen()
+                            NewPostScreen(navController)
                         }
                         composable(ScreenPaths.Post.route) { navBackStackEntry ->
                             includeBackButton.value = true
@@ -115,6 +117,7 @@ class MainActivity : ComponentActivity() {
                             includeBackButton.value = true
                             navBackStackEntry.arguments?.getString("post")?.let { postId ->
                                 EditPostScreen(
+                                    navController,
                                     postId.toInt()
                                 )
                             }

app/src/main/java/com/example/dtf/PreferencesManager.kt

@@ -0,0 +1,23 @@
+package com.example.dtf
+
+import android.content.Context
+import android.content.SharedPreferences
+
+class PreferencesManager(context: Context) {
+    private val sharedPreferences: SharedPreferences =
+        context.getSharedPreferences("MyPrefs", Context.MODE_PRIVATE)
+
+    fun saveData(key: String, value: String) {
+        val editor = sharedPreferences.edit()
+        editor.putString(key, value)
+        editor.apply()
+    }
+
+    fun getData(key: String, defaultValue: String): String {
+        return sharedPreferences.getString(key, defaultValue) ?: defaultValue
+    }
+
+    fun deleteData(key: String) {
+        sharedPreferences.edit().remove(key).apply()
+    }
+}

app/src/main/java/com/example/dtf/dao/CategoryDao.kt

@@ -20,7 +20,4 @@ interface CategoryDao {
 
     @Query("select * from category where category.id = :id")
     fun getById(id: Int) : Flow<Category>
-
-    @Query("select * from category where category.name = :name")
-    fun getByName(name: String) : Flow<CategoryWithPosts>
 }

app/src/main/java/com/example/dtf/dao/CommentDao.kt

@@ -1,5 +1,6 @@
 package com.example.dtf.dao
 
+import androidx.paging.PagingSource
 import androidx.room.*
 import com.example.dtf.models.*
 import kotlinx.coroutines.flow.Flow
@@ -21,6 +22,6 @@ interface CommentDao {
     @Query("select * from comment where comment.id = :id")
     fun getById(id: Int) : Flow<Comment>
 
-    @Query("select * from comment where comment.post_id = :postId")
+    @Query("select * from comment where comment.post_id = :postId ORDER BY date DESC")
-    fun getByPost(postId: Int) : Flow<List<Comment>>
+    fun getByPost(postId: Int) : PagingSource<Int, Comment>
 }

app/src/main/java/com/example/dtf/dao/LikeDao.kt

@@ -0,0 +1,20 @@
+package com.example.dtf.dao
+
+import androidx.room.*
+import com.example.dtf.models.Like
+import kotlinx.coroutines.flow.Flow
+
+@Dao
+interface LikeDao {
+    @Insert
+    suspend fun insert(like: Like)
+
+    @Delete
+    suspend fun delete(like: Like)
+
+    @Query("SELECT COUNT(*) FROM likes WHERE post_id = :postId")
+    fun countByPost(postId: Int) : Flow<Int>
+
+    @Query("SELECT COUNT(*) = 1 FROM likes WHERE post_id = :postId AND user_id = :userId")
+    fun isLikedByUser(userId: Int, postId: Int) : Flow<Boolean>
+}

app/src/main/java/com/example/dtf/dao/PostDao.kt

@@ -1,5 +1,6 @@
 package com.example.dtf.dao
 
+import androidx.paging.PagingSource
 import androidx.room.*
 import com.example.dtf.models.*
 import kotlinx.coroutines.flow.Flow
@@ -19,8 +20,8 @@ interface PostDao {
     fun getAll() : Flow<List<Post>>
 
     @Query("select * from post where post.id = :id")
-    fun getById(id: Int) : Flow<PostWithComments>
+    fun getById(id: Int) : Flow<Post>
 
-    @Query("select * from post where post.category_id = :categoryId")
+    @Query("select * from post where post.category_id = :categoryId ORDER BY date DESC")
-    fun getByCategory(categoryId: String) : Flow<Post>
+    fun getByCategory(categoryId: String) : PagingSource<Int, Post>
 }

app/src/main/java/com/example/dtf/dao/UserDao.kt

@@ -19,5 +19,8 @@ interface UserDao {
     fun getAll() : Flow<List<User>>
 
     @Query("select * from user where user.id = :id")
-    fun getById(id: Int): User
+    fun getById(id: Int): Flow<User>
+
+    @Query("select * from user where user.username = :username and user.password = :password")
+    fun getByUsernameAndPassword(username: String, password: String): Flow<User?>
 }

app/src/main/java/com/example/dtf/db/AppDatabase.kt

@@ -11,6 +11,7 @@ import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
 import androidx.sqlite.db.SupportSQLiteDatabase
 import com.example.dtf.dao.*
+import com.example.dtf.models.Like
 import java.util.Date
 
 @Database(
@@ -18,9 +19,10 @@ import java.util.Date
         User::class,
         Category::class,
         Post::class,
+        Like::class,
         Comment::class
     ],
-    version = 1,
+    version = 2,
     exportSchema = false
 )
 @TypeConverters(Converter::class)
@@ -29,119 +31,9 @@ abstract class AppDatabase : RoomDatabase() {
     abstract fun categoryDao() : CategoryDao
     abstract fun commentDao() : CommentDao
     abstract fun postDao() : PostDao
+    abstract fun likeDao() : LikeDao
 
     companion object {
-        private const val DB_NAME: String = "news-db"
+        public const val DB_NAME: String = "news-db"
-
-        @Volatile
-        private var INSTANCE: AppDatabase? = null
-
-        private suspend fun populateDatabase() {
-            INSTANCE?.let { database ->
-                val userDao = database.userDao()
-
-                userDao.insert(User(1, "Sheriff", "123456", true))
-                userDao.insert(User(2, "Человек", "123456", true))
-
-                val categoryDao = database.categoryDao()
-
-                categoryDao.insert(Category(1, "Игры"))
-                categoryDao.insert(Category(2, "Кино"))
-                categoryDao.insert(Category(3, "Аниме"))
-
-                val postDao = database.postDao()
-
-                postDao.insert(
-                    Post(
-                        1,
-                        "Что не так с half-life 2",
-                        "Да всё не так",
-                        Date(2023, 10, 22),
-                        1,
-                        1
-                    )
-                )
-                postDao.insert(
-                    Post(
-                        2,
-                        "Я действительно ненавижу фильм про титаник",
-                        "Пруфов не будет",
-                        Date(2023, 9, 22),
-                        1,
-                        2
-                    )
-                )
-                postDao.insert(
-                    Post(
-                        3,
-                        "\"Госпожа Кагуя\" это переоценённый тайтл",
-                        "Я, конечно, не смотрел, но мне так кажется. А всё потому, что там происходит такое, что даже Аристотелю не снилось. А может даже Платону. Об этом можно рассуждать тысячи лет, но я смогу уложиться всего в пару слов. И первое слово - этот тайтл полное днище. Ладно, не слово",
-                        Date(2023, 9, 22),
-                        1,
-                        3
-                    )
-                )
-                postDao.insert(
-                    Post(
-                        4,
-                        "\"Восхождение в тени\" это переоценённый тайтл",
-                        "Я, конечно, не смотрел, но мне так кажется. А всё потому, что там происходит такое, что даже Аристотелю не снилось. А может даже Платону. Об этом можно рассуждать тысячи лет, но я смогу уложиться всего в пару слов. И первое слово - этот тайтл полное днище. Ладно, не слово",
-                        Date(2023, 9, 22),
-                        1,
-                        3
-                    )
-                )
-                postDao.insert(
-                    Post(
-                        5,
-                        "\"Наруто\" это переоценённый тайтл",
-                        "Я, конечно, не смотрел, но мне так кажется. А всё потому, что там происходит такое, что даже Аристотелю не снилось. А может даже Платону. Об этом можно рассуждать тысячи лет, но я смогу уложиться всего в пару слов. И первое слово - этот тайтл полное днище. Ладно, не слово",
-                        Date(2023, 9, 22),
-                        1,
-                        3
-                    )
-                )
-                postDao.insert(
-                    Post(
-                        6,
-                        "\"Блич\" это переоценённый тайтл",
-                        "Я, конечно, не смотрел, но мне так кажется. А всё потому, что там происходит такое, что даже Аристотелю не снилось. А может даже Платону. Об этом можно рассуждать тысячи лет, но я смогу уложиться всего в пару слов. И первое слово - этот тайтл полное днище. Ладно, не слово",
-                        Date(2023, 9, 22),
-                        1,
-                        3
-                    )
-                )
-
-                val commentDao = database.commentDao()
-
-                commentDao.insert(Comment(1, 2, 1, "Пост бред. Начнём с того, что вот эта твоя манера речи клоунская...", Date(2023, 10, 20)))
-                commentDao.insert(Comment(2, 1, 1, "Да какой бред, чел, я всё по факту сказал", Date(2023, 10, 20)))
-                commentDao.insert(Comment(3, 2, 3,"Автора на увольнение", Date(2023, 9, 20)))
-                commentDao.insert(Comment(4, 2, 4,"Автора на увольнение дважды", Date(2023, 9, 20)))
-                commentDao.insert(Comment(5, 2, 5,"Автора на увольнение трижды", Date(2023, 9, 20)))
-                commentDao.insert(Comment(6, 2, 6,"Автора на увольнение четырежды", Date(2023, 9, 20)))
     }
-        }
-
-        fun getInstance(appContext: Context): AppDatabase {
-            return INSTANCE ?: synchronized(this) {
-                Room.databaseBuilder(
-                    appContext,
-                    AppDatabase::class.java,
-                    DB_NAME
-                )
-                    .addCallback(object : Callback() {
-                        override fun onCreate(db: SupportSQLiteDatabase) {
-                            super.onCreate(db)
-                            CoroutineScope(Dispatchers.IO).launch {
-                                populateDatabase()
-                            }
-                        }
-                    })
-                    .build()
-                    .also { INSTANCE = it }
-            }
-        }
-    }
-
 }

app/src/main/java/com/example/dtf/models/Like.kt

@@ -0,0 +1,11 @@
+package com.example.dtf.models
+
+import androidx.room.*
+
+@Entity(tableName = "likes", primaryKeys = ["user_id", "post_id"])
+data class Like (
+    @ColumnInfo(name = "user_id", index = true)
+    val userId: Int,
+    @ColumnInfo(name = "post_id", index = true)
+    val postId: Int
+)

app/src/main/java/com/example/dtf/repositories/CategoryRepository.kt

@@ -0,0 +1,19 @@
+package com.example.dtf.repositories
+
+import com.example.dtf.dao.CategoryDao
+import com.example.dtf.models.Category
+import javax.inject.Inject
+
+class CategoryRepository @Inject constructor(
+    private val categoryDao: CategoryDao
+) {
+    suspend fun insert(category: Category) = categoryDao.insert(category)
+
+    suspend fun update(category: Category) = categoryDao.update(category)
+
+    suspend fun delete(category: Category) = categoryDao.delete(category)
+
+    fun getAll() = categoryDao.getAll()
+
+    fun getById(id: Int) = categoryDao.getById(id)
+}

app/src/main/java/com/example/dtf/repositories/CommentRepository.kt

@@ -0,0 +1,28 @@
+package com.example.dtf.repositories
+
+import androidx.paging.*
+import com.example.dtf.dao.CommentDao
+import com.example.dtf.models.Comment
+import javax.inject.Inject
+
+class CommentRepository @Inject constructor(
+    private val commentDao: CommentDao
+) {
+    suspend fun insert(comment: Comment) = commentDao.insert(comment)
+
+    suspend fun update(comment: Comment) = commentDao.update(comment)
+
+    suspend fun delete(comment: Comment) = commentDao.delete(comment)
+
+    fun getAll() = commentDao.getAll()
+
+    fun getById(id: Int) = commentDao.getById(id)
+
+    fun getByPost(postId: Int) = Pager(
+        PagingConfig(
+            pageSize = 5,
+            enablePlaceholders = false
+        ),
+        pagingSourceFactory = { commentDao.getByPost(postId) }
+    ).flow
+}

app/src/main/java/com/example/dtf/repositories/LikeRepository.kt

@@ -0,0 +1,17 @@
+package com.example.dtf.repositories
+
+import com.example.dtf.dao.LikeDao
+import com.example.dtf.models.Like
+import javax.inject.Inject
+
+class LikeRepository @Inject constructor(
+    private val likeDao: LikeDao
+) {
+    suspend fun insert(like: Like) = likeDao.insert(like)
+
+    suspend fun delete(like: Like) = likeDao.delete(like)
+
+    fun countByPost(postId: Int) = likeDao.countByPost(postId)
+
+    fun isLikedByUser(userId: Int, postId: Int) = likeDao.isLikedByUser(userId, postId)
+}

app/src/main/java/com/example/dtf/repositories/PostRepository.kt

@@ -0,0 +1,29 @@
+package com.example.dtf.repositories
+
+import androidx.paging.*
+import com.example.dtf.dao.PostDao
+import com.example.dtf.models.Post
+import kotlinx.coroutines.flow.Flow
+import javax.inject.Inject
+
+class PostRepository @Inject constructor(
+    private val postDao: PostDao
+) {
+    suspend fun insert(post: Post) = postDao.insert(post)
+
+    suspend fun update(post: Post) = postDao.update(post)
+
+    suspend fun delete(post: Post) = postDao.delete(post)
+
+    fun getAll() = postDao.getAll()
+
+    fun getById(id: Int) = postDao.getById(id)
+
+    fun getByCategory(categoryId: Int) = Pager(
+        PagingConfig(
+            pageSize = 3,
+            enablePlaceholders = false
+        ),
+        pagingSourceFactory = { postDao.getByCategory(categoryId.toString()) }
+    ).flow
+}

app/src/main/java/com/example/dtf/repositories/UserRepository.kt

@@ -0,0 +1,22 @@
+package com.example.dtf.repositories
+
+import com.example.dtf.dao.UserDao
+import com.example.dtf.models.User
+import kotlinx.coroutines.flow.Flow
+import javax.inject.Inject
+
+class UserRepository @Inject constructor(
+    private val userDao: UserDao
+)  {
+    suspend fun insert(user: User) = userDao.insert(user)
+
+    suspend fun update(user: User) = userDao.update(user)
+
+    suspend fun delete(user: User) = userDao.delete(user)
+
+    fun getAll() = userDao.getAll()
+
+    fun getById(id: Int) = userDao.getById(id)
+
+    fun getByUsernameAndPassword(username: String, password: String) = userDao.getByUsernameAndPassword(username, password)
+}

app/src/main/java/com/example/dtf/screens/EditPostScreen.kt

@@ -7,6 +7,7 @@ import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.foundation.verticalScroll
 import androidx.compose.material.*
 import androidx.compose.runtime.*
+import androidx.compose.runtime.livedata.observeAsState
 import androidx.compose.ui.*
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.platform.LocalContext
@@ -14,27 +15,72 @@ import androidx.compose.ui.text.TextStyle
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.input.TextFieldValue
 import androidx.compose.ui.unit.*
-import com.example.dtf.db.AppDatabase
+import androidx.hilt.navigation.compose.hiltViewModel
+import androidx.navigation.NavHostController
+import com.example.dtf.PreferencesManager
+import com.example.dtf.utils.ScreenPaths
+import com.example.dtf.viewmodels.EditPostViewModel
 import com.example.dtf.widgets.MyTextField
-import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.withContext
 
 @Composable
-fun EditPostScreen(postId: Int) {
+fun EditPostScreen(navController: NavHostController, postId: Int) {
-    val context = LocalContext.current
+    val sharedPref = PreferencesManager(LocalContext.current)
 
     val title = remember { mutableStateOf(TextFieldValue("")) }
     val content = remember { mutableStateOf(TextFieldValue("")) }
 
-    LaunchedEffect(Unit) {
+    val viewModel = hiltViewModel<EditPostViewModel>()
-        withContext(Dispatchers.IO) {
+
-            AppDatabase.getInstance(context).postDao().getById(postId).collect { data ->
+    val post = viewModel.post.observeAsState().value
-                title.value = TextFieldValue(data.post.title)
+
-                content.value = TextFieldValue(data.post.content)
+    val success = viewModel.editingPostState.observeAsState().value
+
+    viewModel.retrievePost(postId)
+
+    if (post != null) {
+        title.value = TextFieldValue(post.title)
+        content.value = TextFieldValue(post.content)
+    }
+
+    if (success == true) {
+        navController.navigate(ScreenPaths.Post.route.replace("{post}", postId.toString())) {
+            popUpTo(ScreenPaths.Post.route.replace("{post}", postId.toString())) {
+                inclusive = true
             }
         }
     }
 
+    if (success == false) {
+        AlertDialog(
+            title = {
+                Text(
+                    text = "Ошибка",
+                    fontWeight = FontWeight.Bold,
+                    fontSize = 20.sp
+                )
+            },
+            text = {
+                Text(
+                    text = "Нельзя сохранить новость с пустым заголовком или содержанием",
+                    fontWeight = FontWeight.Normal,
+                    fontSize = 16.sp
+                )
+            },
+            onDismissRequest = {
+                viewModel.calmEditingState()
+            },
+            buttons = {
+                TextButton(
+                    onClick = {
+                        viewModel.calmEditingState()
+                    }
+                ) {
+                    Text("ОК")
+                }
+            }
+        )
+    }
+
     Column(
         modifier = Modifier.verticalScroll(rememberScrollState()),
         verticalArrangement = Arrangement.spacedBy(10.dp),
@@ -57,7 +103,7 @@ fun EditPostScreen(postId: Int) {
         )
         Button(
             {
-
+                viewModel.editPost(sharedPref, postId, title.value.text, content.value.text)
             },
             colors = ButtonDefaults.buttonColors(Color(0xFF388DF2)),
             border = BorderStroke(1.dp, Color(0xFF0085FF)),

app/src/main/java/com/example/dtf/screens/LoginScreen.kt

@@ -1,33 +1,77 @@
 package com.example.dtf.screens
 
 import androidx.compose.foundation.BorderStroke
-import androidx.compose.foundation.border
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.*
 import androidx.compose.foundation.shape.RoundedCornerShape
-import androidx.compose.material.Button
+import androidx.compose.material.*
-import androidx.compose.material.ButtonDefaults
+import androidx.compose.runtime.*
-import androidx.compose.material.Text
+import androidx.compose.runtime.livedata.observeAsState
-import androidx.compose.runtime.Composable
-import androidx.compose.runtime.mutableStateOf
-import androidx.compose.runtime.remember
 import androidx.compose.ui.*
 import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.text.TextStyle
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.input.TextFieldValue
-import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.*
-import androidx.compose.ui.unit.dp
+import androidx.hilt.navigation.compose.hiltViewModel
-import androidx.compose.ui.unit.sp
-import androidx.navigation.NavController
 import androidx.navigation.NavHostController
+import com.example.dtf.PreferencesManager
 import com.example.dtf.utils.ScreenPaths
+import com.example.dtf.viewmodels.LoginViewModel
 import com.example.dtf.widgets.MyTextField
 
 @Composable
 fun LoginScreen(navController: NavHostController) {
+    val sharedPref = PreferencesManager(LocalContext.current)
+
     val login = remember { mutableStateOf(TextFieldValue(""))}
     val password = remember { mutableStateOf(TextFieldValue(""))}
+
+    val viewModel = hiltViewModel<LoginViewModel>()
+
+    val success = viewModel.successState.observeAsState().value
+
+    if (success == true) {
+        navController.navigate(ScreenPaths.Posts.route) {
+            popUpTo(ScreenPaths.Posts.route) {
+                inclusive = true
+            }
+        }
+    }
+
+    if (success == false) {
+        AlertDialog(
+            title = {
+                Text(
+                    text = "Ошибка авторизации",
+                    fontWeight = FontWeight.Bold,
+                    fontSize = 20.sp
+                )
+            },
+            text = {
+                Text(
+                    text = "Неверный логин или пароль",
+                    fontWeight = FontWeight.Normal,
+                    fontSize = 16.sp
+                )
+            },
+            onDismissRequest = {
+                viewModel.calmSuccessState()
+            },
+            buttons = {
+                TextButton(
+                    onClick = {
+                        viewModel.calmSuccessState()
+                    }
+                ) {
+                    Text("ОК")
+                }
+
+            }
+        )
+    }
+
     Row(
         horizontalArrangement = Arrangement.Center,
         modifier = Modifier.fillMaxSize()
@@ -65,7 +109,7 @@ fun LoginScreen(navController: NavHostController) {
             )
             Button(
                 {
-                    navController.navigate(ScreenPaths.Posts.route)
+                    viewModel.login(sharedPref, login.value.text, password.value.text)
                 },
                 colors = ButtonDefaults.buttonColors(Color(0xFF388DF2)),
                 border = BorderStroke(1.dp, Color(0xFF0085FF)),

app/src/main/java/com/example/dtf/screens/NewPostScreen.kt

@@ -7,6 +7,7 @@ import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.foundation.verticalScroll
 import androidx.compose.material.*
 import androidx.compose.runtime.*
+import androidx.compose.runtime.livedata.observeAsState
 import androidx.compose.ui.*
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.platform.LocalContext
@@ -15,32 +16,69 @@ import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.input.TextFieldValue
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.unit.*
-import com.example.dtf.db.AppDatabase
+import androidx.hilt.navigation.compose.hiltViewModel
+import androidx.navigation.NavHostController
+import com.example.dtf.PreferencesManager
 import com.example.dtf.models.Category
+import com.example.dtf.utils.ScreenPaths
+import com.example.dtf.viewmodels.NewPostViewModel
 import com.example.dtf.widgets.MyTextField
-import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.withContext
 
 @Composable
-fun NewPostScreen() {
+fun NewPostScreen(navController: NavHostController) {
-    val categories = remember { mutableStateListOf<Category>() }
+    val sharedPref = PreferencesManager(LocalContext.current)
-    val context = LocalContext.current
 
-    LaunchedEffect(Unit) {
+    val selectedCategory = remember { mutableStateOf(Category(null, "")) }
-        withContext(Dispatchers.IO) {
-            AppDatabase.getInstance(context).categoryDao().getAll().collect {data ->
-                categories.clear()
-                categories.addAll(data)
-            }
-        }
-    }
-
-    val selectedCategory = remember { mutableStateOf("") }
     val expanded = remember { mutableStateOf(false) }
 
     val title = remember { mutableStateOf(TextFieldValue()) }
     val content = remember { mutableStateOf(TextFieldValue()) }
 
+    val viewModel = hiltViewModel<NewPostViewModel>()
+    val success = viewModel.addingPostState.observeAsState().value
+    val categories = viewModel.categories.observeAsState().value
+
+    viewModel.retrieveCategories()
+
+    if (success == true) {
+        navController.navigate(ScreenPaths.Posts.route) {
+            popUpTo(ScreenPaths.Posts.route) {
+                inclusive = true
+            }
+        }
+    }
+
+    if (success == false) {
+        AlertDialog(
+            title = {
+                Text(
+                    text = "Ошибка",
+                    fontWeight = FontWeight.Bold,
+                    fontSize = 20.sp
+                )
+            },
+            text = {
+                Text(
+                    text = "Нельзя создать новость с пустым заголовком или содержанием",
+                    fontWeight = FontWeight.Normal,
+                    fontSize = 16.sp
+                )
+            },
+            onDismissRequest = {
+                viewModel.calmAddingState()
+            },
+            buttons = {
+                TextButton(
+                    onClick = {
+                        viewModel.calmAddingState()
+                    }
+                ) {
+                    Text("ОК")
+                }
+            }
+        )
+    }
+
     Column(
         modifier = Modifier.verticalScroll(rememberScrollState()),
         verticalArrangement = Arrangement.spacedBy(10.dp),
@@ -56,7 +94,7 @@ fun NewPostScreen() {
             modifier = Modifier.fillMaxWidth().padding(15.dp, 10.dp, 15.dp, 0.dp)
         ) {
             Text(
-                text = selectedCategory.value,
+                text = selectedCategory.value.name,
                 style = TextStyle(
                     fontSize = 24.sp,
                     fontWeight = FontWeight(400),
@@ -68,10 +106,10 @@ fun NewPostScreen() {
                 expanded = expanded.value,
                 onDismissRequest = {expanded.value = false}
             ) {
-                categories.forEach {category ->
+                categories?.forEach { category ->
                     DropdownMenuItem(
                         onClick = {
-                            selectedCategory.value = category.name
+                            selectedCategory.value = category
                             expanded.value = false
                         },
                     ) {
@@ -101,7 +139,9 @@ fun NewPostScreen() {
         )
         Button(
             {
-
+                if (selectedCategory.value.id != null) {
+                    viewModel.addPost(sharedPref, selectedCategory.value.id!!, title.value.text, content.value.text)
+                }
             },
             colors = ButtonDefaults.buttonColors(Color(0xFF388DF2)),
             border = BorderStroke(1.dp, Color(0xFF0085FF)),

app/src/main/java/com/example/dtf/screens/PostScreen.kt

@@ -2,6 +2,7 @@ package com.example.dtf.screens
 
 import androidx.compose.foundation.layout.*
 import androidx.compose.foundation.*
+import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material.*
 import androidx.compose.material.icons.Icons
@@ -9,6 +10,7 @@ import androidx.compose.material.icons.filled.AddCircle
 import androidx.compose.material.icons.filled.ThumbUp
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.*
+import androidx.compose.runtime.livedata.observeAsState
 import androidx.compose.ui.*
 import androidx.compose.ui.draw.*
 import androidx.compose.ui.graphics.*
@@ -16,52 +18,68 @@ import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.text.input.TextFieldValue
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.unit.*
+import androidx.hilt.navigation.compose.hiltViewModel
+import androidx.lifecycle.viewModelScope
 import androidx.navigation.NavHostController
+import androidx.paging.compose.collectAsLazyPagingItems
+import androidx.paging.compose.itemKey
+import com.example.dtf.PreferencesManager
 import com.example.dtf.db.AppDatabase
 import com.example.dtf.models.Comment
 import com.example.dtf.models.Post
 import com.example.dtf.models.PostWithComments
 import com.example.dtf.models.User
 import com.example.dtf.utils.ScreenPaths
+import com.example.dtf.viewmodels.PostViewModel
 import com.example.dtf.widgets.MyTextField
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 import java.util.Date
 
 @Composable
 fun PostScreen(postId: Int, navController: NavHostController) {
-    val post = remember { mutableStateOf(PostWithComments(Post(null, "", "", Date(), -1, -1), listOf())) }
+    val sharedPref = PreferencesManager(LocalContext.current)
 
-    val user = remember { mutableStateOf(User(-1, "", "", false)) }
+    val viewModel = hiltViewModel<PostViewModel>()
-    val context = LocalContext.current
+    val post = viewModel.post.observeAsState().value
+    val comments = viewModel.getCommentsListUiState(postId).collectAsLazyPagingItems()
+
+    val likes = remember { mutableIntStateOf(0) }
+    val isLiked = remember { mutableStateOf(false) }
 
     LaunchedEffect(Unit) {
-        withContext(Dispatchers.IO) {
+        viewModel.getLikes(postId).collect {
-            user.value = AppDatabase.getInstance(context).userDao().getById(1)
+            likes.intValue = it
-            AppDatabase.getInstance(context).postDao().getById(postId).collect {data ->
-                post.value = data
         }
     }
+
+    LaunchedEffect(Unit) {
+        viewModel.isLiked(sharedPref, postId).collect {
+            isLiked.value = it
         }
+    }
+
+    viewModel.retrievePost(postId)
 
     val content = remember { mutableStateOf(TextFieldValue("")) }
 
-    Column(
+    LazyColumn(
         modifier = Modifier
-            .fillMaxSize()
+            .fillMaxWidth()
-            .background(Color.White)
+            .background(Color.White),
-            .verticalScroll(rememberScrollState()),
         verticalArrangement = Arrangement.spacedBy(5.dp),
         horizontalAlignment = Alignment.Start
     ) {
+        item {
             Text(
                 modifier = Modifier.padding(10.dp),
-            text = post.value.post.title,
+                text = post?.title ?: "Loading...",
                 fontSize = 26.sp
             )
             Text(
                 modifier = Modifier.fillMaxHeight().padding(10.dp, 0.dp, 10.dp, 0.dp),
-            text = post.value.post.content,
+                text = post?.content ?: "Loading...",
                 fontSize = 20.sp
             )
             Row(
@@ -69,21 +87,24 @@ fun PostScreen(postId: Int, navController: NavHostController) {
                 verticalAlignment = Alignment.Bottom,
                 horizontalArrangement = Arrangement.SpaceBetween
             ) {
+                if (post != null) {
                     Text(
                         text = "day.month.year".replace(
                             "day",
-                    post.value.post.date.day.toString()
+                            post.date.day.toString()
                         ).replace(
                             "month",
-                    post.value.post.date.month.toString()
+                            post.date.month.toString()
                         ).replace(
                             "year",
-                    post.value.post.date.year.toString()
+                            post.date.year.toString()
                         ),
                         fontSize = 14.sp,
                         color = Color(0xFFCECCCC)
                     )
-            if (user.value.isModerator) {
+                }
+
+                if (sharedPref.getData("isModerator", "false").toBooleanStrict()) {
                     Text(
                         modifier = Modifier.clickable {
                             navController.navigate(ScreenPaths.EditPost.route.replace("{post}", postId.toString()))
@@ -94,18 +115,28 @@ fun PostScreen(postId: Int, navController: NavHostController) {
                     )
                 }
                 Row (
-                modifier = Modifier,
+                    modifier = Modifier.clickable {
+                        if (isLiked.value) {
+                            viewModel.unlikePost(sharedPref, postId)
+                            likes.intValue--
+                        } else {
+                            viewModel.likePost(sharedPref, postId)
+                            likes.intValue++
+                        }
+                        isLiked.value = !isLiked.value
+                    },
                     horizontalArrangement = Arrangement.End
                 ) {
                     Text(
-                    text = "0",
+                        text = likes.intValue.toString(),
                         fontSize = 16.sp,
                         color = Color.Green
                     )
                     Icon(
                         modifier = Modifier.padding(start = 8.dp),
                         imageVector = Icons.Default.ThumbUp,
-                    contentDescription = null
+                        contentDescription = null,
+                        tint = if (isLiked.value) { Color(40, 200, 40, 255) } else {Color.Black}
                     )
                 }
             }
@@ -129,7 +160,10 @@ fun PostScreen(postId: Int, navController: NavHostController) {
                 )
                 IconButton(
                     modifier = Modifier.fillMaxWidth().scale(1.5f),
-                onClick = {},
+                    onClick = {
+                        viewModel.addComment(sharedPref, postId, content.value.text)
+                        content.value = TextFieldValue("")
+                    },
                 ) {
                     Icon(
                         imageVector = Icons.Default.AddCircle,
@@ -137,23 +171,23 @@ fun PostScreen(postId: Int, navController: NavHostController) {
                     )
                 }
             }
-        post.value.comments.reversed().forEach() {comment ->
-            Comment(comment)
         }
+        items(
+            comments.itemCount,
+            key = comments.itemKey()
+        ) {
+            Comment(comments[it]!!)
+        }
+        item {
             Spacer(modifier = Modifier.height(60.dp))
         }
+    }
 }
 
 @Composable
 private fun Comment(comment: Comment) {
-    val user = remember { mutableStateOf(User(-1, "", "", false)) }
+    val viewModel = hiltViewModel<PostViewModel>()
-    val context = LocalContext.current
+    val user = viewModel.getCommentsAuthor(comment).collectAsState(null).value
-
-    LaunchedEffect(Unit) {
-        withContext(Dispatchers.IO) {
-            user.value = AppDatabase.getInstance(context).userDao().getById(comment.userId)
-        }
-    }
 
     Column(
         modifier = Modifier
@@ -168,7 +202,7 @@ private fun Comment(comment: Comment) {
             horizontalArrangement = Arrangement.SpaceBetween
         ) {
             Text(
-                text = user.value.username,
+                text = user?.username ?: "Loading...",
                 fontSize = 20.sp
             )
             Text(

app/src/main/java/com/example/dtf/screens/PostsScreen.kt

@@ -2,6 +2,7 @@ package com.example.dtf.screens
 
 import androidx.compose.foundation.layout.*
 import androidx.compose.foundation.*
+import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.material.*
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.ThumbUp
@@ -14,36 +15,33 @@ import androidx.compose.ui.graphics.*
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.unit.*
+import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.navigation.NavHostController
+import androidx.paging.PagingData
+import androidx.paging.compose.LazyPagingItems
+import androidx.paging.compose.collectAsLazyPagingItems
+import androidx.paging.compose.itemKey
+import com.example.dtf.PreferencesManager
 import com.example.dtf.db.AppDatabase
 import com.example.dtf.models.Category
 import com.example.dtf.models.CategoryWithPosts
+import com.example.dtf.models.Post
 import com.example.dtf.utils.ScreenPaths
+import com.example.dtf.viewmodels.PostsViewModel
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 
 @Composable
 fun PostsScreen(navController: NavHostController) {
-    val currentCategory = remember { mutableStateOf("") }
+    val sharedPref = PreferencesManager(LocalContext.current)
-    val categories = remember { mutableListOf<Category> () }
-    val categoryWithPosts = remember { mutableStateOf(CategoryWithPosts(Category(-1, ""), listOf()))}
-    val context = LocalContext.current
-    val scope = rememberCoroutineScope()
 
-    LaunchedEffect(Unit) {
+    val currentCategory = remember { mutableStateOf<Category?>(null) }
-        withContext(Dispatchers.IO) {
+
-            AppDatabase.getInstance(context).categoryDao().getAll().collect {data ->
+    val viewModel = hiltViewModel<PostsViewModel>()
-                currentCategory.value = data.first().name
+    val posts = remember { mutableStateOf<Flow<PagingData<Post>>?>(null) }
-                categories.clear()
-                categories.addAll(data)
-                AppDatabase.getInstance(context).categoryDao().getByName(currentCategory.value).collect {data ->
-                    categoryWithPosts.value = data
-                }
-            }
-        }
-    }
 
     Column(
         modifier = Modifier.fillMaxSize(),
@@ -60,42 +58,37 @@ fun PostsScreen(navController: NavHostController) {
             horizontalArrangement = Arrangement.spacedBy(25.dp),
             verticalAlignment = Alignment.CenterVertically
         ) {
-            Categories(scope, categoryWithPosts, currentCategory, categories)
+            Categories(viewModel, currentCategory, posts)
         }
         Row(
             modifier = Modifier.fillMaxSize()
         ) {
-            Column(
+            if (currentCategory.value != null && posts.value != null) {
-                modifier = Modifier.fillMaxSize().verticalScroll(rememberScrollState()),
+                PostsByCategory(viewModel, navController, posts)
-                verticalArrangement = Arrangement.spacedBy(10.dp)
-            ) {
-                if (currentCategory.value.isNotEmpty()) {
-                    PostsByCategory(navController, categoryWithPosts)
-                }
-                Spacer(modifier = Modifier.height(60.dp))
             }
         }
     }
 }
 
 @Composable
-private fun Categories(scope: CoroutineScope, categoryWithPosts: MutableState<CategoryWithPosts>, categoryState: MutableState<String>, categories: MutableList<Category>) {
+private fun Categories(viewModel: PostsViewModel, currentCategory: MutableState<Category?>, posts: MutableState<Flow<PagingData<Post>>?>) {
-    val context = LocalContext.current
+    val categories = viewModel.getCategories().collectAsState(listOf()).value
+
+    if (categories.isNotEmpty() && currentCategory.value == null) {
+        currentCategory.value = categories[0]
+        posts.value = viewModel.getPostsListUiState(currentCategory.value!!.id!!)
+    }
 
     Spacer(modifier = Modifier.width(5.dp))
     categories.forEach {category ->
         Text(
             modifier = Modifier
                 .clickable {
-                    categoryState.value = category.name
+                    currentCategory.value = category
-                    scope.launch {
+                    posts.value = viewModel.getPostsListUiState(category.id!!)
-                        AppDatabase.getInstance(context).categoryDao().getByName(categoryState.value).collect { data ->
-                            categoryWithPosts.value = data
-                        }
-                    }
                 }
                 .drawBehind {
-                    if (category.name == categoryState.value) {
+                    if (category.name == currentCategory.value?.name) {
                         val strokeWidthPx = 2.dp.toPx()
                         val verticalOffset = size.height + 2.sp.toPx()
                         drawLine(
@@ -113,8 +106,44 @@ private fun Categories(scope: CoroutineScope, categoryWithPosts: MutableState<Ca
 }
 
 @Composable
-private fun PostsByCategory(navController: NavHostController, categoryWithPosts: MutableState<CategoryWithPosts>) {
+private fun PostsByCategory(viewModel: PostsViewModel, navController: NavHostController, posts: MutableState<Flow<PagingData<Post>>?>) {
-    categoryWithPosts.value.posts.forEach { post ->
+    val postsItems = posts.value!!.collectAsLazyPagingItems()
+
+    LazyColumn(
+        modifier = Modifier.fillMaxSize(),
+        verticalArrangement = Arrangement.spacedBy(10.dp)
+    ) {
+        items(
+            count = postsItems.itemCount,
+            key = postsItems.itemKey()
+        ) {
+            Post(viewModel, navController, postsItems[it]!!)
+        }
+        item {
+            Spacer(modifier = Modifier.height(60.dp))
+        }
+    }
+}
+
+@Composable
+private fun Post(viewModel: PostsViewModel, navController: NavHostController, post: Post) {
+    val sharedPref = PreferencesManager(LocalContext.current)
+
+    val likes = remember { mutableIntStateOf(0) }
+    val isLiked = remember { mutableStateOf(false) }
+
+    LaunchedEffect(Unit) {
+        viewModel.getLikes(post.id!!).collect {
+            likes.intValue = it
+        }
+    }
+
+    LaunchedEffect(Unit) {
+        viewModel.isLiked(sharedPref, post.id!!).collect {
+            isLiked.value = it
+        }
+    }
+
     Column(
         modifier = Modifier
             .fillMaxHeight(0.3f)
@@ -158,21 +187,30 @@ private fun PostsByCategory(navController: NavHostController, categoryWithPosts:
                 color = Color(0xFFCECCCC)
             )
             Row (
-                    modifier = Modifier.fillMaxWidth(),
+                modifier = Modifier.fillMaxWidth().clickable {
+                    if (isLiked.value) {
+                        viewModel.unlikePost(sharedPref, post.id!!)
+                        likes.intValue--
+                    } else {
+                        viewModel.likePost(sharedPref, post.id!!)
+                        likes.intValue++
+                    }
+                    isLiked.value = !isLiked.value
+                },
                 horizontalArrangement = Arrangement.End
             ) {
                 Text(
-                        text = "0",
+                    text = likes.intValue.toString(),
                     fontSize = 16.sp,
                     color = Color.Green
                 )
                 Icon(
                     modifier = Modifier.padding(start = 8.dp),
                     imageVector = Icons.Default.ThumbUp,
-                        contentDescription = null
+                    contentDescription = null,
+                    tint = if (isLiked.value) { Color(40, 200, 40, 255) } else {Color.Black}
                 )
             }
         }
     }
-    }
 }

app/src/main/java/com/example/dtf/screens/ProfileScreen.kt

@@ -5,30 +5,25 @@ import androidx.compose.foundation.layout.*
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material.*
 import androidx.compose.runtime.Composable
-import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.livedata.observeAsState
-import androidx.compose.runtime.mutableStateOf
-import androidx.compose.runtime.remember
 import androidx.compose.ui.*
 import androidx.compose.ui.graphics.*
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.unit.*
+import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.navigation.NavHostController
-import com.example.dtf.db.AppDatabase
+import com.example.dtf.PreferencesManager
-import com.example.dtf.models.User
 import com.example.dtf.utils.ScreenPaths
-import kotlinx.coroutines.Dispatchers
+import com.example.dtf.viewmodels.ProfileViewModel
-import kotlinx.coroutines.withContext
 
 @Composable
 fun ProfileScreen(navController: NavHostController) {
-    val user = remember { mutableStateOf(User(-1, "", "", false)) }
+    val sharedPref = PreferencesManager(LocalContext.current)
-    val context = LocalContext.current
 
-    LaunchedEffect(Unit) {
+    val viewModel = hiltViewModel<ProfileViewModel>()
-        withContext(Dispatchers.IO) {
+    val user = viewModel.user.observeAsState().value
-            user.value = AppDatabase.getInstance(context).userDao().getById(1)
+
-        }
+    viewModel.retrieveUser(sharedPref)
-    }
 
     Column(
         modifier = Modifier.fillMaxSize()
@@ -52,14 +47,14 @@ fun ProfileScreen(navController: NavHostController) {
                         contentAlignment = Alignment.Center
                     ) {
                         Text(
-                            text = if (user.value.username.isNotEmpty()) { user.value.username[0].toString() } else {""},
+                            text = if (user != null) { user.username[0].toString() } else {""},
                             fontSize = 30.sp,
                         )
                     }
                 }
                 Spacer(modifier = Modifier.fillMaxHeight(0.1f))
                 Text(
-                    text = user.value.username,
+                    text = user?.username ?: "",
                     fontSize = 30.sp,
                     color = Color.White
                 )
@@ -84,6 +79,7 @@ fun ProfileScreen(navController: NavHostController) {
 
                     Text(
                         modifier = Modifier.clickable {
+                            viewModel.logout(sharedPref)
                             navController.navigate(ScreenPaths.Login.route)
                         },
                         text = "Выйти",

app/src/main/java/com/example/dtf/screens/RegisterScreen.kt

@@ -7,10 +7,13 @@ import androidx.compose.foundation.border
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.*
 import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material.AlertDialog
 import androidx.compose.material.Button
 import androidx.compose.material.ButtonDefaults
 import androidx.compose.material.Text
+import androidx.compose.material.TextButton
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.livedata.observeAsState
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.ui.*
@@ -23,9 +26,11 @@ import androidx.compose.ui.text.input.TextFieldValue
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
+import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.navigation.NavController
 import androidx.navigation.NavHostController
 import com.example.dtf.utils.ScreenPaths
+import com.example.dtf.viewmodels.RegisterViewModel
 import com.example.dtf.widgets.MyTextField
 
 @Composable
@@ -33,6 +38,49 @@ fun RegisterScreen(navController: NavHostController) {
     val login = remember { mutableStateOf(TextFieldValue(""))}
     val password = remember { mutableStateOf(TextFieldValue(""))}
     val confirmPassword = remember { mutableStateOf(TextFieldValue(""))}
+
+    val viewModel = hiltViewModel<RegisterViewModel>()
+    val success = viewModel.successState.observeAsState().value
+
+    if (success == true) {
+        navController.navigate(ScreenPaths.Login.route) {
+            popUpTo(ScreenPaths.Login.route) {
+                inclusive = true
+            }
+        }
+    }
+
+    if (success == false) {
+        AlertDialog(
+            title = {
+                Text(
+                    text = "Ошибка регистрации",
+                    fontWeight = FontWeight.Bold,
+                    fontSize = 20.sp
+                )
+            },
+            text = {
+                Text(
+                    text = "Проверьте корректность введенных данных",
+                    fontWeight = FontWeight.Normal,
+                    fontSize = 16.sp
+                )
+            },
+            onDismissRequest = {
+                viewModel.calmSuccessState()
+            },
+            buttons = {
+                TextButton(
+                    onClick = {
+                        viewModel.calmSuccessState()
+                    }
+                ) {
+                    Text("ОК")
+                }
+            }
+        )
+    }
+
     Row(
         horizontalArrangement = Arrangement.Center,
         modifier = Modifier.fillMaxSize()
@@ -78,7 +126,9 @@ fun RegisterScreen(navController: NavHostController) {
                     .heightIn(max=55.dp)
             )
             Button(
-                {},
+                {
+                    viewModel.register(login.value.text, password.value.text, confirmPassword.value.text)
+                },
                 colors = ButtonDefaults.buttonColors(Color(0xFF388DF2)),
                 border = BorderStroke(1.dp, Color(0xFF0085FF)),
                 shape = RoundedCornerShape(15.dp),

app/src/main/java/com/example/dtf/viewmodels/EditPostViewModel.kt

@@ -0,0 +1,52 @@
+package com.example.dtf.viewmodels
+
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import com.example.dtf.PreferencesManager
+import com.example.dtf.models.Post
+import com.example.dtf.repositories.PostRepository
+import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.launch
+import javax.inject.Inject
+
+@HiltViewModel
+class EditPostViewModel @Inject constructor(
+    private val postRepository: PostRepository
+) : ViewModel() {
+    private val _editingPostState = MutableLiveData<Boolean?>(null)
+    val editingPostState: LiveData<Boolean?>
+        get() = _editingPostState
+
+    private val _post = MutableLiveData<Post>()
+    val post: LiveData<Post>
+        get() = _post
+
+    fun retrievePost(postId: Int) {
+        viewModelScope.launch {
+            postRepository.getById(postId).collect {
+                _post.postValue(it)
+            }
+        }
+    }
+
+    fun calmEditingState() {
+        _editingPostState.value = null
+    }
+
+    fun editPost(sharedPref: PreferencesManager, postId: Int, title: String, content: String) {
+        if (!sharedPref.getData("isModerator", "false").toBooleanStrict()) return
+
+        viewModelScope.launch {
+            if (title.isNotEmpty() && content.isNotEmpty()) {
+                postRepository.getById(postId).collect {
+                    postRepository.update(Post(postId, title, content, it.date, it.userId, it.categoryId))
+                    _editingPostState.postValue(true)
+                }
+            } else {
+                _editingPostState.postValue(false)
+            }
+        }
+    }
+}

app/src/main/java/com/example/dtf/viewmodels/LoginViewModel.kt

@@ -0,0 +1,59 @@
+package com.example.dtf.viewmodels
+
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import com.example.dtf.PreferencesManager
+import com.example.dtf.models.Category
+import com.example.dtf.models.User
+import com.example.dtf.repositories.CategoryRepository
+import com.example.dtf.repositories.UserRepository
+import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.launch
+import javax.inject.Inject
+
+@HiltViewModel
+class LoginViewModel @Inject constructor(
+    private val userRepository: UserRepository,
+    private val categoryRepository: CategoryRepository
+) : ViewModel() {
+    private val _successState = MutableLiveData<Boolean?>()
+    val successState: LiveData<Boolean?>
+        get() = _successState
+
+    init {
+        addAdmin()
+    }
+
+    fun calmSuccessState() {
+        _successState.postValue(null)
+    }
+
+    fun login(sharedPref: PreferencesManager, username: String, password: String) {
+        viewModelScope.launch {
+            userRepository.getByUsernameAndPassword(username, password).collect {
+                if (it == null) {
+                    _successState.postValue(false)
+                } else {
+                    sharedPref.saveData("userId", it.id.toString())
+                    sharedPref.saveData("isModerator", it.isModerator.toString())
+                    _successState.postValue(true)
+                }
+            }
+        }
+    }
+
+    private fun addAdmin() {
+        viewModelScope.launch {
+            userRepository.getAll().collect {
+                if (it.size == 0) {
+                    userRepository.insert(User(1, "admin", "admin", true))
+                    categoryRepository.insert(Category(1, "Аниме"))
+                    categoryRepository.insert(Category(2, "Игры"))
+                    categoryRepository.insert(Category(3, "Фильмы"))
+                }
+            }
+        }
+    }
+}

app/src/main/java/com/example/dtf/viewmodels/NewPostViewModel.kt

@@ -0,0 +1,65 @@
+package com.example.dtf.viewmodels
+
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import com.example.dtf.PreferencesManager
+import com.example.dtf.models.Category
+import com.example.dtf.models.Post
+import com.example.dtf.repositories.CategoryRepository
+import com.example.dtf.repositories.PostRepository
+import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.launch
+import java.time.LocalDate
+import java.util.Date
+import javax.inject.Inject
+
+@HiltViewModel
+class NewPostViewModel @Inject constructor(
+    private val postRepository: PostRepository,
+    private val categoryRepository: CategoryRepository
+) : ViewModel() {
+    private val _addingPostState = MutableLiveData<Boolean?>(null)
+    val addingPostState: LiveData<Boolean?>
+        get() = _addingPostState
+
+    private val _categories = MutableLiveData<List<Category>>(listOf())
+    val categories: LiveData<List<Category>>
+        get() = _categories
+
+    fun retrieveCategories() {
+        viewModelScope.launch {
+            categoryRepository.getAll().collect {
+                _categories.postValue(it)
+            }
+        }
+    }
+
+    fun calmAddingState() {
+        _addingPostState.value = null
+    }
+
+    fun addPost(sharedPref: PreferencesManager, categoryId: Int, title: String, content: String) {
+        if (!sharedPref.getData("isModerator", "false").toBooleanStrict()) return
+
+        viewModelScope.launch {
+            if (title.isNotEmpty() && content.isNotEmpty()) {
+                postRepository.insert(
+                    Post(
+                        null,
+                        title,
+                        content,
+                        Date(),
+                        sharedPref.getData("userId", "0").toInt(),
+                        categoryId
+                    )
+                )
+
+                _addingPostState.postValue(true)
+            } else {
+                _addingPostState.postValue(false)
+            }
+        }
+    }
+}

app/src/main/java/com/example/dtf/viewmodels/PostViewModel.kt

@@ -0,0 +1,91 @@
+package com.example.dtf.viewmodels
+
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import androidx.lifecycle.viewmodel.compose.viewModel
+import androidx.paging.PagingData
+import com.example.dtf.PreferencesManager
+import com.example.dtf.models.Comment
+import com.example.dtf.models.Like
+import com.example.dtf.models.Post
+import com.example.dtf.repositories.CommentRepository
+import com.example.dtf.repositories.LikeRepository
+import com.example.dtf.repositories.PostRepository
+import com.example.dtf.repositories.UserRepository
+import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.launch
+import java.util.Date
+import javax.inject.Inject
+
+@HiltViewModel
+class PostViewModel @Inject constructor(
+    private val postRepository: PostRepository,
+    private val commentRepository: CommentRepository,
+    private val likeRepository: LikeRepository,
+    private val userRepository: UserRepository
+) : ViewModel() {
+    private val _post = MutableLiveData<Post>()
+    val post: LiveData<Post>
+        get() = _post
+
+    fun retrievePost(postId: Int) {
+        viewModelScope.launch {
+            postRepository.getById(postId).collect {
+                _post.postValue(it)
+            }
+        }
+    }
+
+    fun getLikes(postId: Int) = likeRepository.countByPost(postId)
+
+    fun likePost(sharedPref: PreferencesManager, postId: Int) {
+        val userId = sharedPref.getData("userId", "-1").toInt()
+
+        if (userId == -1) return
+
+        viewModelScope.launch {
+            likeRepository.insert(Like(userId, postId))
+        }
+    }
+
+    fun unlikePost(sharedPref: PreferencesManager, postId: Int) {
+        val userId = sharedPref.getData("userId", "-1").toInt()
+
+        if (userId == -1) return
+
+        viewModelScope.launch {
+            likeRepository.delete(Like(userId, postId))
+        }
+    }
+
+    fun isLiked(sharedPref: PreferencesManager, postId: Int)
+        = likeRepository.isLikedByUser(
+            sharedPref.getData("userId", "-1").toInt(),
+            postId
+        )
+
+    fun addComment(sharedPref: PreferencesManager, postId: Int, content: String) {
+        val userId = sharedPref.getData("userId", "-1").toInt()
+
+        if (userId == -1 || content.trim().isEmpty()) return
+
+        viewModelScope.launch {
+            commentRepository.insert(
+                Comment(
+                    null,
+                    userId,
+                    postId,
+                    content,
+                    Date()
+                )
+            )
+        }
+    }
+
+    fun getCommentsAuthor(comment: Comment) = userRepository.getById(comment.userId)
+
+    fun getCommentsListUiState(postId: Int): Flow<PagingData<Comment>> = commentRepository.getByPost(postId)
+}

app/src/main/java/com/example/dtf/viewmodels/PostsViewModel.kt

@@ -0,0 +1,51 @@
+package com.example.dtf.viewmodels
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import com.example.dtf.PreferencesManager
+import com.example.dtf.models.Like
+import com.example.dtf.repositories.CategoryRepository
+import com.example.dtf.repositories.LikeRepository
+import com.example.dtf.repositories.PostRepository
+import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.launch
+import javax.inject.Inject
+
+@HiltViewModel
+class PostsViewModel @Inject constructor(
+    private val postRepository: PostRepository,
+    private val categoryRepository: CategoryRepository,
+    private val likeRepository: LikeRepository
+) : ViewModel() {
+    fun getLikes(postId: Int) = likeRepository.countByPost(postId)
+
+    fun likePost(sharedPref: PreferencesManager, postId: Int) {
+        val userId = sharedPref.getData("userId", "-1").toInt()
+
+        if (userId == -1) return
+
+        viewModelScope.launch {
+            likeRepository.insert(Like(userId, postId))
+        }
+    }
+
+    fun unlikePost(sharedPref: PreferencesManager, postId: Int) {
+        val userId = sharedPref.getData("userId", "-1").toInt()
+
+        if (userId == -1) return
+
+        viewModelScope.launch {
+            likeRepository.delete(Like(userId, postId))
+        }
+    }
+
+    fun isLiked(sharedPref: PreferencesManager, postId: Int)
+            = likeRepository.isLikedByUser(
+        sharedPref.getData("userId", "-1").toInt(),
+        postId
+    )
+
+    fun getCategories() = categoryRepository.getAll()
+
+    fun getPostsListUiState(categoryId: Int) = postRepository.getByCategory(categoryId)
+}

app/src/main/java/com/example/dtf/viewmodels/ProfileViewModel.kt

@@ -0,0 +1,38 @@
+package com.example.dtf.viewmodels
+
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import com.example.dtf.PreferencesManager
+import com.example.dtf.models.User
+import com.example.dtf.repositories.UserRepository
+import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.launch
+import javax.inject.Inject
+
+@HiltViewModel
+class ProfileViewModel @Inject constructor(
+    private val userRepository: UserRepository
+) : ViewModel() {
+    private val _user = MutableLiveData<User>()
+    val user: LiveData<User>
+        get() = _user
+
+    fun retrieveUser(sharedPref: PreferencesManager) {
+        val userId = sharedPref.getData("userId", "-1").toInt()
+
+        if (userId == -1) return
+
+        viewModelScope.launch {
+            userRepository.getById(userId).collect {
+                _user.postValue(it)
+            }
+        }
+    }
+
+    fun logout(sharedPref: PreferencesManager) {
+        sharedPref.deleteData("userId")
+        sharedPref.deleteData("isModerator")
+    }
+}

app/src/main/java/com/example/dtf/viewmodels/RegisterViewModel.kt

@@ -0,0 +1,53 @@
+package com.example.dtf.viewmodels
+
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import com.example.dtf.PreferencesManager
+import com.example.dtf.models.User
+import com.example.dtf.repositories.UserRepository
+import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.launch
+import javax.inject.Inject
+
+@HiltViewModel
+class RegisterViewModel @Inject constructor(
+    private val userRepository: UserRepository
+) : ViewModel() {
+    private val _successState = MutableLiveData<Boolean?>()
+    val successState: LiveData<Boolean?>
+        get() = _successState
+
+    fun calmSuccessState() {
+        _successState.postValue(null)
+    }
+
+    fun register(username: String, password: String, confirmPassword: String) {
+        if (username.length < 5 || username.length > 20) {
+            _successState.postValue(false)
+            return
+        }
+
+        if (password.length < 8 || password.length > 30) {
+            _successState.postValue(false)
+            return
+        }
+
+        if (password != confirmPassword) {
+            _successState.postValue(false)
+            return
+        }
+
+        viewModelScope.launch {
+            userRepository.getByUsernameAndPassword(username, password).collect {
+                if (it != null) {
+                    _successState.postValue(false)
+                } else {
+                    userRepository.insert(User(null, username, password, false))
+                    _successState.postValue(true)
+                }
+            }
+        }
+    }
+}

app/src/main/java/com/example/dtf/widgets/BottomNavBar.kt

@@ -29,6 +29,7 @@ import androidx.compose.ui.res.painterResource
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
 import androidx.navigation.compose.currentBackStackEntryAsState
+import com.example.dtf.PreferencesManager
 import com.example.dtf.db.AppDatabase
 import com.example.dtf.models.User
 import com.example.dtf.utils.ScreenPaths
@@ -37,28 +38,7 @@ import kotlinx.coroutines.withContext
 
 @Composable
 fun BottomNavBar(navController: NavController) {
-    val user = remember { mutableStateOf(User(-1, "", "", false)) }
+    val sharedPref = PreferencesManager(LocalContext.current)
-    val buttons = remember { mutableListOf(
-        Triple(ScreenPaths.Posts.route, Icons.Default.Home, "Новости"),
-        Triple(ScreenPaths.Profile.route, Icons.Default.Person, "Профиль")
-    ) }
-    val context = LocalContext.current
-
-    LaunchedEffect(Unit) {
-        withContext(Dispatchers.IO) {
-            user.value = AppDatabase.getInstance(context).userDao().getById(1)
-            if (user.value.isModerator) {
-                buttons.clear()
-                buttons.addAll(
-                    listOf(
-                        Triple(ScreenPaths.Posts.route, Icons.Default.Home, "Новости"),
-                        Triple(ScreenPaths.NewPost.route, Icons.Default.Edit, "Создать"),
-                        Triple(ScreenPaths.Profile.route, Icons.Default.Person, "Профиль")
-                    )
-                )
-            }
-        }
-    }
 
     BottomNavigation(
         modifier = Modifier.height(70.dp),
@@ -69,7 +49,7 @@ fun BottomNavBar(navController: NavController) {
         val currentRoute = navBackStackEntry?.destination?.route
         listOfNotNull(
             Triple(ScreenPaths.Posts.route, Icons.Default.Home, "Новости"),
-            if (user.value.isModerator) {
+            if (sharedPref.getData("isModerator", "false").toBooleanStrict()) {
                 Triple(ScreenPaths.NewPost.route, Icons.Default.Edit, "Создать")
             } else { null },
             Triple(ScreenPaths.Profile.route, Icons.Default.Person, "Профиль")

build.gradle

@@ -7,6 +7,7 @@ buildscript {
     }
     dependencies {
         classpath 'com.android.tools.build:gradle:4.0.0'
+        classpath 'com.google.dagger:hilt-android-gradle-plugin:2.42'
     }
 }// Top-level build file where you can add configuration options common to all sub-projects/modules.
 plugins {