using Npgsql;
using System;
using System.Collections.Generic;
using System.Diagnostics.Contracts;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace DepartmentStaffDatabase
{
    public class Implements: Abstracts
    {
        private NpgsqlConnection GetConnect()
        {
            return new NpgsqlConnection("Host=192.168.56.103;Username=postgres;Password=postgres;Database=TestLab3");
        }
        public override void CreateDepartment(Department department)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand
                ("INSERT INTO department VALUES (nextval('Department_seq'), @Name, @Head)", conn);
            cmd.Parameters.AddWithValue("@name", department.DepartmentName);
            cmd.Parameters.AddWithValue("@head", department.Head);
            cmd.ExecuteNonQuery();
        }
        public override void UpdateDepartment(Department department)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"UPDATE department SET name = @name, head = @head WHERE id = @Id", conn);
            cmd.Parameters.AddWithValue("@Id", department.Id);
            cmd.Parameters.AddWithValue("@name", department.DepartmentName);
            cmd.Parameters.AddWithValue("@head", department.Head);
            cmd.ExecuteNonQuery();
        }
        public override void DeleteDepartment(int id)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"DELETE FROM department WHERE id = @Id", conn);
            cmd.Parameters.AddWithValue("@Id", id);
            cmd.ExecuteNonQuery();
        }
        public override Department GetDepartment(int id)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"SELECT * FROM department WHERE id = {id}", conn);
            using var reader = cmd.ExecuteReader();
            if (reader.Read())
            {
                return new Department
                {
                    Id = reader.GetInt32(0),
                    DepartmentName = reader.GetString(1),
                    Head = reader.GetString(2),
                };
            }
            return null;
        }
        public override Department GetDepartment(string departmentName)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"SELECT * FROM department WHERE name = '{departmentName}'", conn);
            using var reader = cmd.ExecuteReader();
            if (reader.Read())
            {
                return new Department
                {
                    Id = reader.GetInt32(0),
                    DepartmentName = reader.GetString(1),
                    Head = reader.GetString(2),
                };
            }
            return null;
        }
        public override List<Department> GetDepartments()
        {
            List<Department> departments = new List<Department>();
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand("SELECT * FROM department", conn);
            using var reader = cmd.ExecuteReader();
            while (reader.Read())
            {
                departments.Add(new Department
                {
                    Id = reader.GetInt32(0),
                    DepartmentName = reader.GetString(1),
                    Head = reader.GetString(2),
                });
            }
            return departments;
        }
        public override void DeleteDepartments()
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"DELETE FROM department", conn);
            cmd.ExecuteNonQuery();
        }

        //=======================================================================

        public override void CreatePosition(Position position)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand
                ("INSERT INTO position VALUES (nextval('Position_seq'), @Name, @Salary, @DepartmentId)", conn);
            cmd.Parameters.AddWithValue("@name", position.PositionName);
            cmd.Parameters.AddWithValue("@salary", position.Salary);
            cmd.Parameters.AddWithValue("@departmentId", position.DepartmentId);
            cmd.ExecuteNonQuery();
        }
        public override void UpdatePosition(Position position)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"UPDATE position SET name = @name, salary = @salary, departmentId = @departmentId WHERE id = @Id", conn);
            cmd.Parameters.AddWithValue("@Id", position.Id);
            cmd.Parameters.AddWithValue("@name", position.PositionName);
            cmd.Parameters.AddWithValue("@salary", position.Salary);
            cmd.Parameters.AddWithValue("@departmentId", position.DepartmentId);
            cmd.ExecuteNonQuery();
        }
        public override void DeletePosition(int id)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"DELETE FROM position WHERE id = @Id", conn);
            cmd.Parameters.AddWithValue("@Id", id);
            cmd.ExecuteNonQuery();
        }
        public override Position GetPosition(int id)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"SELECT * FROM position WHERE id = {id}", conn);
            using var reader = cmd.ExecuteReader();
            if (reader.Read())
            {
                return new Position
                {
                    Id = reader.GetInt32(0),
                    PositionName = reader.GetString(1),
                    Salary = reader.GetDouble(2),
                    DepartmentId = reader.GetInt32(3),
                };
            }
            return null;
        }
        public override Position GetPosition(string positionName)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"SELECT * FROM position WHERE name = '{positionName}'", conn);
            using var reader = cmd.ExecuteReader();
            if (reader.Read())
            {
                return new Position
                {
                    Id = reader.GetInt32(0),
                    PositionName = reader.GetString(1),
                    Salary = reader.GetDouble(2),
                    DepartmentId = reader.GetInt32(3),
                };
            }
            return null;
        }
        public override List<Position> GetPositions()
        {
            List<Position> positions = new List<Position>();
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand("SELECT * FROM position", conn);
            using var reader = cmd.ExecuteReader();
            while (reader.Read())
            {
                positions.Add(new Position
                {
                    Id = reader.GetInt32(0),
                    PositionName = reader.GetString(1),
                    Salary = reader.GetDouble(2),
                    DepartmentId = reader.GetInt32(3),
                });
            }
            return positions;
        }
        public override void Deletepositions()
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"DELETE FROM position", conn);
            cmd.ExecuteNonQuery();
        }

        //=======================================================================

        public override void CreateEmployee(Employee employee)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand
                ("INSERT INTO employee VALUES (nextval('Employee_seq'), @Name, @Birthdate, @Address, @PhoneNumber, @Email, @PositionId)", conn);
            cmd.Parameters.AddWithValue("@name", employee.EmployeeName);
            cmd.Parameters.AddWithValue("@Birthdate", employee.Birthdate);
            cmd.Parameters.AddWithValue("@Address", employee.Address);
            cmd.Parameters.AddWithValue("@PhoneNumber", employee.PhoneNumber);
            cmd.Parameters.AddWithValue("@Email", employee.Email);
            cmd.Parameters.AddWithValue("@PositionId", employee.PositionId);
            cmd.ExecuteNonQuery();
        }
        public override void UpdateEmployee(Employee employee)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"UPDATE employee SET name = @name, birthdate = @birthdate, " +
                $"address = @address, phoneNumber = @phoneNumber, email = @email, positionId = @positionId WHERE id = @Id", conn);
            cmd.Parameters.AddWithValue("@Id", employee.Id);
            cmd.Parameters.AddWithValue("@name", employee.EmployeeName);
            cmd.Parameters.AddWithValue("@Birthdate", employee.Birthdate);
            cmd.Parameters.AddWithValue("@Address", employee.Address);
            cmd.Parameters.AddWithValue("@PhoneNumber", employee.PhoneNumber);
            cmd.Parameters.AddWithValue("@Email", employee.Email);
            cmd.Parameters.AddWithValue("@PositionId", employee.PositionId);
            cmd.ExecuteNonQuery();
        }
        public override void DeleteEmployee(int id)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"DELETE FROM employee WHERE id = @Id", conn);
            cmd.Parameters.AddWithValue("@Id", id);
            cmd.ExecuteNonQuery();
        }
        public override Employee GetEmployee(int id)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"SELECT * FROM employee WHERE id = {id}", conn);
            using var reader = cmd.ExecuteReader();
            if (reader.Read())
            {
                return new Employee
                {
                    Id = reader.GetInt32(0),
                    EmployeeName = reader.GetString(1),
                    Birthdate = reader.GetDateTime(2),
                    Address = reader.GetString(3),
                    PhoneNumber = reader.GetString(4),
                    Email = reader.GetString(5),
                    PositionId = reader.GetInt32(6),
                };
            }
            return null;
        }
        public override Employee GetEmployee(string employeeName)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"SELECT * FROM employee WHERE name = '{employeeName}'", conn);
            using var reader = cmd.ExecuteReader();
            if (reader.Read())
            {
                return new Employee
                {
                    Id = reader.GetInt32(0),
                    EmployeeName = reader.GetString(1),
                    Birthdate = reader.GetDateTime(2),
                    Address = reader.GetString(3),
                    PhoneNumber = reader.GetString(4),
                    Email = reader.GetString(5),
                    PositionId = reader.GetInt32(6),
                };
            }
            return null;
        }
        public override List<Employee> GetEmployees()
        {
            List<Employee> employees = new List<Employee>();
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand("SELECT * FROM employee", conn);
            using var reader = cmd.ExecuteReader();
            while (reader.Read())
            {
                employees.Add(new Employee
                {
                    Id = reader.GetInt32(0),
                    EmployeeName = reader.GetString(1),
                    Birthdate = reader.GetDateTime(2),
                    Address = reader.GetString(3),
                    PhoneNumber = reader.GetString(4),
                    Email = reader.GetString(5),
                    PositionId = reader.GetInt32(6),
                });
            }
            return employees;
        }
        public override void DeleteEmployees()
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"DELETE FROM employee", conn);
            cmd.ExecuteNonQuery();
        }

        //=======================================================================

        public override void CreateContract(Contract contract)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand
                ("INSERT INTO contract VALUES (nextval('Contract_seq'), @DateOfConclusin, @Duration, @EmployeeId)", conn);
            cmd.Parameters.AddWithValue("@dateOfConclusin", contract.DateOfConclusion);
            cmd.Parameters.AddWithValue("@duration", contract.Duration);
            cmd.Parameters.AddWithValue("@employeeId", contract.EmployeeId);
            cmd.ExecuteNonQuery();
        }
        public override void UpdateContract(Contract contract)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"UPDATE contract SET dateOfConclusion = @dateOfConclusion, duration = @duration, employeeId = @employeeId WHERE id = @Id", conn);
            cmd.Parameters.AddWithValue("@Id", contract.Id);
            cmd.Parameters.AddWithValue("@dateOfConclusion", contract.DateOfConclusion);
            cmd.Parameters.AddWithValue("@duration", contract.Duration);
            cmd.Parameters.AddWithValue("@employeeId", contract.EmployeeId);
            cmd.ExecuteNonQuery();
        }
        public override void DeleteContract(int id)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"DELETE FROM contract WHERE id = @Id", conn);
            cmd.Parameters.AddWithValue("@Id", id);
            cmd.ExecuteNonQuery();
        }
        public override Contract GetContract(int id)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"SELECT * FROM contract WHERE id = {id}", conn);
            using var reader = cmd.ExecuteReader();
            if (reader.Read())
            {
                return new Contract
                {
                    Id = reader.GetInt32(0),
                    DateOfConclusion = reader.GetDateTime(1),
                    Duration = reader.GetInt32(2),
                    EmployeeId = reader.GetInt32(3),
                };
            }
            return null;
        }
        public override List<Contract> GetContracts()
        {
            List<Contract> contracts = new List<Contract>();
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand("SELECT * FROM contract", conn);
            using var reader = cmd.ExecuteReader();
            while (reader.Read())
            {
                contracts.Add(new Contract
                {
                    Id = reader.GetInt32(0),
                    DateOfConclusion = reader.GetDateTime(1),
                    Duration = reader.GetInt32(2),
                    EmployeeId = reader.GetInt32(3),
                });
            }
            return contracts;
        }
        public override void DeleteContracts()
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"DELETE FROM contract", conn);
            cmd.ExecuteNonQuery();
        }

        //=======================================================================

        public override void CreateCourse(Course course)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand
                ("INSERT INTO course VALUES (nextval('Course_seq'), @EventDateb, @HoursNumber, @Result)", conn);
            cmd.Parameters.AddWithValue("@EventDateb", course.DateOfEvent);
            cmd.Parameters.AddWithValue("@HoursNumber", course.HoursNumber);
            cmd.Parameters.AddWithValue("@Result", course.Result);
            cmd.ExecuteNonQuery();
        }
        public override void UpdateCourse(Course course)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"UPDATE course SET eventDateb = @eventDateb, hoursNumber = @hoursNumber, result = @result WHERE id = @Id", conn);
            cmd.Parameters.AddWithValue("@Id", course.Id);
            cmd.Parameters.AddWithValue("@EventDateb", course.DateOfEvent);
            cmd.Parameters.AddWithValue("@HoursNumber", course.HoursNumber);
            cmd.Parameters.AddWithValue("@Result", course.Result);
            cmd.ExecuteNonQuery();
        }
        public override void DeleteCourse(int id)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"DELETE FROM course WHERE id = @Id", conn);
            cmd.Parameters.AddWithValue("@Id", id);
            cmd.ExecuteNonQuery();
        }
        public override Course GetCourse(int id)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"SELECT * FROM course WHERE id = {id}", conn);
            using var reader = cmd.ExecuteReader();
            if (reader.Read())
            {
                return new Course
                {
                    Id = reader.GetInt32(0),
                    DateOfEvent = reader.GetDateTime(1),
                    HoursNumber = reader.GetInt32(2),
                    Result = reader.GetString(3),
                };
            }
            return null;
        }
        public override List<Course> GetCourses()
        {
            List<Course> contracts = new List<Course>();
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand("SELECT * FROM course", conn);
            using var reader = cmd.ExecuteReader();
            while (reader.Read())
            {
                contracts.Add(new Course
                {
                    Id = reader.GetInt32(0),
                    DateOfEvent = reader.GetDateTime(1),
                    HoursNumber = reader.GetInt32(2),
                    Result = reader.GetString(3),
                });
            }
            return contracts;
        }
        public override void DeleteCourses()
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"DELETE FROM course", conn);
            cmd.ExecuteNonQuery();
        }

        //=======================================================================

        public override void CreateEmployee_Course(Employee_Course employee_course)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand
                ("INSERT INTO employee_course VALUES (@EmployeeId, @CourseId)", conn);
            cmd.Parameters.AddWithValue("@EmployeeId", employee_course.EmployeeId);
            cmd.Parameters.AddWithValue("@CourseId", employee_course.CourseId);
            cmd.ExecuteNonQuery();
        }
        public override void DeleteEmployee_Course(int empId, int courseId)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"DELETE FROM employee_course WHERE EmployeeId = @EmployeeId AND CourseId = @CourseId", conn);
            cmd.Parameters.AddWithValue("@EmployeeId", empId);
            cmd.Parameters.AddWithValue("@CourseId", courseId);
            cmd.ExecuteNonQuery();
        }
        public override Employee_Course GetEmployee_Course(int empId, int courseId)
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"SELECT * FROM employee_course WHERE EmployeeId = {empId} AND CourseId = {courseId}", conn);
            using var reader = cmd.ExecuteReader();
            if (reader.Read())
            {
                return new Employee_Course
                {
                    EmployeeId = reader.GetInt32(0),
                    CourseId = reader.GetInt32(1),
                };
            }
            return null;
        }
        public override List<Employee_Course> GetEmployee_Courses()
        {
            List<Employee_Course> employee_course = new List<Employee_Course>();
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand("SELECT * FROM employee_course", conn);
            using var reader = cmd.ExecuteReader();
            while (reader.Read())
            {
                employee_course.Add(new Employee_Course
                {
                    EmployeeId = reader.GetInt32(0),
                    CourseId = reader.GetInt32(1),
                });
            }
            return employee_course;
        }
        public override void DeleteEmployee_Courses()
        {
            using var conn = GetConnect();
            conn.Open();
            using var cmd = new NpgsqlCommand($"DELETE FROM employee_course", conn);
            cmd.ExecuteNonQuery();
        }
    }
}