Zimogorov_Arseniy_OrdersManager/ReturnBookForm .cs

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

namespace WindowsFormsApp4
{
    public partial class ReturnBookForm : Form
    {
        private readonly string connStr = ConfigurationManager.ConnectionStrings["PostgreSQL"].ConnectionString;
        private int selectedOrderId = 0;
        private bool isLoading = false;  

        public ReturnBookForm()
        {
            InitializeComponent();
            this.dataGridViewReaders.SelectionChanged += dataGridViewReaders_SelectionChanged;
            this.dataGridViewLoans.SelectionChanged += dataGridViewLoans_SelectionChanged;
        }

        private void ReturnBookForm_Load(object sender, EventArgs e)
        {
            LoadLibraryName();
        }

        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 searchText = txtReaderSearch.Text.Trim();
            if (string.IsNullOrEmpty(searchText) || searchText == "Введите фамилию или телефон")
            {
                MessageBox.Show("Введите фамилию, имя или телефон читателя");
                return;
            }

            string query = @"
                SELECT id, name, lastname, phone, email, 
                       (SELECT COUNT(*) FROM orders WHERE user_id = u.id AND fact_return_date IS NULL) AS active_loans
                FROM users u
                WHERE role_name = 'reader'
                  AND (name ILIKE @search OR lastname ILIKE @search OR phone ILIKE @search OR email ILIKE @search)
                ORDER BY lastname, name";

            DataTable dt = new DataTable();
            using (var conn = new NpgsqlConnection(connStr))
            using (var cmd = new NpgsqlCommand(query, conn))
            {
                cmd.Parameters.AddWithValue("search", $"%{searchText}%");
                conn.Open();
                using (var adapter = new NpgsqlDataAdapter(cmd))
                {
                    adapter.Fill(dt);
                }
            }

            dataGridViewReaders.DataSource = dt;
            if (dataGridViewReaders.Columns["id"] != null)
                dataGridViewReaders.Columns["id"].Visible = false;
            dataGridViewLoans.DataSource = null;
            selectedOrderId = 0;
        }

        private void dataGridViewReaders_SelectionChanged(object sender, EventArgs e)
        {
            if (isLoading) return;
            if (dataGridViewReaders.CurrentRow == null) return;

            int readerId = Convert.ToInt32(dataGridViewReaders.CurrentRow.Cells["id"].Value);
            LoadActiveLoans(readerId);
        }

        private void LoadActiveLoans(int readerId)
        {
            isLoading = true;
            string query = @"
        SELECT 
            o.d AS order_id,
            b.title || ' (инв. ' || be.isbn || ')' AS book_display,
            o.give_date,
            o.return_date
        FROM orders o
        JOIN book_exemplar be ON o.book_exemplar = be.isbn
        JOIN book b ON be.book_id = b.id
        WHERE o.user_id = @readerId
          AND o.fact_return_date IS NULL
          AND be.library_id = @libId   -- фильтр по библиотеке экземпляра
        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("readerId", readerId);
                cmd.Parameters.AddWithValue("libId", Session.LibraryId); 
                conn.Open();
                using (var adapter = new NpgsqlDataAdapter(cmd))
                {
                    adapter.Fill(dt);
                }
            }

            dataGridViewLoans.DataSource = dt;
            if (dataGridViewLoans.Columns["order_id"] != null)
                dataGridViewLoans.Columns["order_id"].Visible = false;
            isLoading = false;
        }

        private void dataGridViewLoans_SelectionChanged(object sender, EventArgs e)
        {
            if (dataGridViewLoans.CurrentRow == null)
            {
                selectedOrderId = 0;
                return;
            }
            selectedOrderId = Convert.ToInt32(dataGridViewLoans.CurrentRow.Cells["order_id"].Value);
        }

        private void buttonReturn_Click(object sender, EventArgs e)
        {
            if (selectedOrderId == 0)
            {
                MessageBox.Show("Выберите книгу для возврата", "Ошибка", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                return;
            }

            try
            {
                using (var conn = new NpgsqlConnection(connStr))
                {
                    conn.Open();
                    string sql = "SELECT return_book(@orderId, @condition)";
                    using (var cmd = new NpgsqlCommand(sql, conn))
                    {
                        cmd.Parameters.AddWithValue("orderId", selectedOrderId);
                        cmd.Parameters.AddWithValue("condition", "good");
                        cmd.ExecuteNonQuery();
                        MessageBox.Show("Книга успешно возвращена", "Успех", MessageBoxButtons.OK, MessageBoxIcon.Information);

                        txtReaderSearch.Text = "Введите фамилию или телефон";
                        txtReaderSearch.ForeColor = System.Drawing.Color.Gray;
                        dataGridViewReaders.DataSource = null;
                        dataGridViewLoans.DataSource = null;
                        selectedOrderId = 0;
                    }
                }
            }
            catch (PostgresException ex)
            {
                MessageBox.Show($"Ошибка БД: {ex.MessageText}", "Ошибка", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Ошибка: {ex.Message}", "Ошибка", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void txtReaderSearch_Enter(object sender, EventArgs e)
        {
            if (txtReaderSearch.Text == "Введите фамилию или телефон")
            {
                txtReaderSearch.Text = "";
                txtReaderSearch.ForeColor = System.Drawing.Color.Black;
            }
        }

        private void txtReaderSearch_Leave(object sender, EventArgs e)
        {
            if (string.IsNullOrWhiteSpace(txtReaderSearch.Text))
            {
                txtReaderSearch.Text = "Введите фамилию или телефон";
                txtReaderSearch.ForeColor = System.Drawing.Color.Gray;
            }
        }
    }
}