Zimogorov_Arseniy_OrdersManager/ReaderMainForm.cs

using Npgsql;
using System;
using System.Configuration;
using System.Data;
using System.Windows.Forms;

namespace WindowsFormsApp4
{
    public partial class ReaderMainForm : Form
    {
        private readonly string connStr = ConfigurationManager.ConnectionStrings["PostgreSQL"].ConnectionString;

        public ReaderMainForm()
        {
            InitializeComponent();
        }

        private void ReaderMainForm_Load(object sender, EventArgs e)
        {
            LoadLibraryName();
            labelWelcome.Text = $"Читатель: {Session.UserFullName}";
            LoadMyLoans();
            tabControl.SelectedIndex = 0;
        }

        private void LoadLibraryName()
        {
            string query = "SELECT name FROM libraries WHERE id = @libId";
            using (var conn = new NpgsqlConnection(connStr))
            using (var cmd = new NpgsqlCommand(query, conn))
            {
                cmd.Parameters.AddWithValue("libId", Session.LibraryId);
                conn.Open();
                var result = cmd.ExecuteScalar();
                labelLibraryName.Text = result != null ? "Библиотека: " + result.ToString() : "Библиотека: Неизвестно";
            }
        }

        private void btnSearch_Click(object sender, EventArgs e)
        {
            string searchTerm = txtSearch.Text.Trim();
            if (string.IsNullOrEmpty(searchTerm) || searchTerm == "Введите название или автора")
            {
                MessageBox.Show("Введите название книги или фамилию автора");
                return;
            }

            string query = "SELECT * FROM search_books(@search)";
            DataTable dt = new DataTable();
            using (var conn = new NpgsqlConnection(connStr))
            using (var cmd = new NpgsqlCommand(query, conn))
            {
                cmd.Parameters.AddWithValue("search", searchTerm);
                conn.Open();
                using (var adapter = new NpgsqlDataAdapter(cmd))
                {
                    adapter.Fill(dt);
                }
            }
            dataGridViewBooks.DataSource = dt;
        }

        private void LoadMyLoans()
        {
            string query = @"
                SELECT 
                    o.d AS order_id,
                    b.title AS Название,
                    a.name || ' ' || a.lastname AS Автор,
                    o.give_date AS Дата_выдачи,
                    o.return_date AS План_возврата,
                    CASE WHEN o.return_date < CURRENT_DATE THEN 'Просрочена' ELSE 'Активна' END AS Статус
                FROM orders o
                JOIN book_exemplar be ON o.book_exemplar = be.isbn
                JOIN book b ON be.book_id = b.id
                JOIN authors a ON b.author_id = a.id
                WHERE o.user_id = @userId AND o.fact_return_date IS NULL
                ORDER BY o.return_date";
            DataTable dt = new DataTable();
            using (var conn = new NpgsqlConnection(connStr))
            using (var cmd = new NpgsqlCommand(query, conn))
            {
                cmd.Parameters.AddWithValue("userId", Session.UserId);
                conn.Open();
                using (var adapter = new NpgsqlDataAdapter(cmd))
                {
                    adapter.Fill(dt);
                }
            }
            dataGridViewMyLoans.DataSource = dt;
            if (dataGridViewMyLoans.Columns["order_id"] != null)
                dataGridViewMyLoans.Columns["order_id"].Visible = false;
        }

        private void btnExtend_Click(object sender, EventArgs e)
        {
            if (dataGridViewMyLoans.CurrentRow == null)
            {
                MessageBox.Show("Выберите книгу для продления", "Ошибка");
                return;
            }
            int orderId = Convert.ToInt32(dataGridViewMyLoans.CurrentRow.Cells["order_id"].Value);
            string status = dataGridViewMyLoans.CurrentRow.Cells["Статус"].Value.ToString();
            if (status == "Просрочена")
            {
                MessageBox.Show("Нельзя продлить просроченную книгу. Обратитесь в библиотеку.", "Ошибка");
                return;
            }

            try
            {
                using (var conn = new NpgsqlConnection(connStr))
                {
                    conn.Open();
                    string sql = @"
                        UPDATE orders 
                        SET return_date = return_date + 14,
                            extended = true
                        WHERE d = @orderId AND fact_return_date IS NULL";
                    using (var cmd = new NpgsqlCommand(sql, conn))
                    {
                        cmd.Parameters.AddWithValue("orderId", orderId);
                        int rows = cmd.ExecuteNonQuery();
                        if (rows > 0)
                        {
                            MessageBox.Show("Книга продлена на 14 дней", "Успех");
                            LoadMyLoans(); 
                        }
                        else
                        {
                            MessageBox.Show("Не удалось продлить книгу", "Ошибка");
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Ошибка: {ex.Message}", "Ошибка");
            }
        }

        private void btnLogout_Click(object sender, EventArgs e)
        {
            Session.UserId = 0;
            Session.UserRole = null;
            Session.UserFullName = null;
            Session.LibraryId = null;

            this.Close();  
        }

        private void labelWelcome_Click(object sender, EventArgs e)
        {

        }
    }
}