using Npgsql;
using System;
using System.Configuration;
using System.Security.Cryptography;
using System.Text;
using System.Windows.Forms;

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

        public Register()
        {
            InitializeComponent();
        }

        private void Register_Load(object sender, EventArgs e)
        {
            LoadLibraries();
        }

        private void LoadLibraries()
        {
            using (var conn = new NpgsqlConnection(connStr))
            {
                conn.Open();
                string query = "SELECT id, name FROM libraries ORDER BY name";
                using (var cmd = new NpgsqlCommand(query, conn))
                using (var reader = cmd.ExecuteReader())
                {
                    comboBox1.Items.Clear();
                    while (reader.Read())
                    {
                        string item = $"{reader["id"]} - {reader["name"]}";
                        comboBox1.Items.Add(item);
                    }
                }
            }
        }

        private bool IsValidEmail(string email)
        {
            if (string.IsNullOrWhiteSpace(email)) return false;
            try
            {
                var addr = new System.Net.Mail.MailAddress(email);
                return addr.Address == email;
            }
            catch
            {
                return false;
            }
        }

        private void button2_Click_1(object sender, EventArgs e)
        {
            if (!CheckFields())
                return;

            if (!IsValidEmail(textBox9.Text))
            {
                MessageBox.Show("Неверный формат Email", "Ошибка", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                return;
            }

            RegisterUser();
        }

        private bool CheckFields()
        {
            if (textBox5.Text != textBox6.Text)
            {
                MessageBox.Show("Пароли не совпадают", "Ошибка", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                return false;
            }
            if (string.IsNullOrWhiteSpace(textBox1.Text) ||
                string.IsNullOrWhiteSpace(textBox2.Text) ||
                string.IsNullOrWhiteSpace(textBox7.Text) ||
                string.IsNullOrWhiteSpace(maskedTextBox1.Text) ||
                string.IsNullOrWhiteSpace(textBox5.Text) ||
                string.IsNullOrWhiteSpace(textBox9.Text))
            {
                MessageBox.Show("Заполните все обязательные поля", "Ошибка", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                return false;
            }
            if (comboBox1.SelectedItem == null)
            {
                MessageBox.Show("Выберите библиотеку", "Ошибка", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                return false;
            }
            return true;
        }

        private void RegisterUser()
        {
            try
            {
                string selected = comboBox1.SelectedItem.ToString();
                int libraryId = int.Parse(selected.Split('-')[0].Trim());

                string login = textBox1.Text.Trim();
                string rawPassword = textBox5.Text;
                string name = textBox2.Text.Trim();
                string lastname = textBox7.Text.Trim();
                string phone = maskedTextBox1.Text.Replace(" ", "").Replace("-", "").Replace("(", "").Replace(")", "");
                string email = textBox9.Text.Trim();
                string address = textBox4.Text.Trim();

                string salt = GenerateSalt();
                string hashedPassword = HashPassword(rawPassword, salt);

                int userId = CallRegisterFunction(libraryId, name, lastname, phone, email, address, login, hashedPassword, salt);

                if (userId > 0)
                {
                    MessageBox.Show("Регистрация успешна! Теперь вы можете войти.", "Успех", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    this.Close();
                }
                else
                {
                    MessageBox.Show("Не удалось зарегистрировать пользователя", "Ошибка", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
            catch (PostgresException ex)
            {
                MessageBox.Show($"Ошибка базы данных: {ex.MessageText}", "Ошибка", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Ошибка: {ex.Message}", "Ошибка", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private string GenerateSalt()
        {
            byte[] saltBytes = new byte[16];
            using (var rng = new RNGCryptoServiceProvider())
            {
                rng.GetBytes(saltBytes);
            }
            return Convert.ToBase64String(saltBytes);
        }

        private string HashPassword(string password, string salt)
        {
            byte[] combined = Encoding.UTF8.GetBytes(password + salt);
            using (SHA256 sha256 = SHA256.Create())
            {
                byte[] hashBytes = sha256.ComputeHash(combined);
                return Convert.ToBase64String(hashBytes);
            }
        }

        private int CallRegisterFunction(int libraryId, string name, string lastname, string phone, string email, string address, string login, string hashedPassword, string salt)
        {
            using (var conn = new NpgsqlConnection(connStr))
            {
                conn.Open();
                string sql = "SELECT register_reader(@libId, @name, @lastname, @phone, @email, @address, @login, @password_hash, @salt)";
                using (var cmd = new NpgsqlCommand(sql, conn))
                {
                    cmd.Parameters.AddWithValue("libId", libraryId);
                    cmd.Parameters.AddWithValue("name", name);
                    cmd.Parameters.AddWithValue("lastname", lastname);
                    cmd.Parameters.AddWithValue("phone", phone);
                    cmd.Parameters.AddWithValue("email", email);
                    cmd.Parameters.AddWithValue("address", address ?? (object)DBNull.Value);
                    cmd.Parameters.AddWithValue("login", login);
                    cmd.Parameters.AddWithValue("password_hash", hashedPassword);
                    cmd.Parameters.AddWithValue("salt", salt);

                    object result = cmd.ExecuteScalar();
                    return result != null ? Convert.ToInt32(result) : 0;
                }
            }
        }
    }
}