using System;
using System.Collections;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using MySql.Data.MySqlClient;
using GTANetworkAPI;

namespace DatabaseAPI
{
    public class API : Script
    {
        #region Settings
        public static readonly string HOST = "localhost"; //altis.liveyourlife.cc
        public static readonly int PORT = 3306; //3306
        public static readonly string DATABASE = "gta_dev"; //gta_dev
        public static readonly string USERNAME = "root"; //gta_dev
        public static readonly string PASSWORD = ""; //X7x25a4iLo266arA4E7aHuH8feJaji
        public static readonly string SSLMODE = "none";

        // Die Anzahl an Verbindungen, die gleichzeitig offen sind.
        public static readonly int POOL_SIZE = 4;

        // Der Interval (in Minuten) in dem die Verbindungen erneuert werden.
        public static readonly int RECONNECT_INTERVAL = 180;
        #endregion

        private static API instance;

        private List<MySqlConnection> availableConnections;

        public API()
        {
            this.availableConnections = new List<MySqlConnection>();

            PopulatePool();
            StartReconnectThread();

            instance = this;
        }

        public static API GetInstance()
        {
            return instance;
        }

        public MySqlConnection GetConnection()
        {
            MySqlConnection connection = null;

            do
            {
                Monitor.Enter(availableConnections);

                bool sleep = false;

                if (availableConnections.Count > 0)
                {
                    connection = availableConnections[0];

                    availableConnections.RemoveAt(0);
                }
                else
                {
                    sleep = true;
                }

                Monitor.Exit(availableConnections);

                if (sleep)
                {
                    Task.Delay(1).Wait();
                }
            } while (connection == null);

            return connection;
        }

        public void FreeConnection(MySqlConnection connection)
        {
            Monitor.Enter(availableConnections);

            availableConnections.Add(connection);

            Monitor.Exit(availableConnections);
        }

        private bool PopulatePool()
        {
            string connectionDescription = "Server=" + HOST + ";Database=" + DATABASE + ";Port=" + PORT + ";User Id=" + USERNAME + ";Password=" + PASSWORD + ";SSLMODE=" + SSLMODE;

            /*for (int i = 0; i < POOL_SIZE; i++)
            {
                MySqlConnection connection = new MySqlConnection(connectionDescription);

                connection.Open();

                availableConnections.Add(connection);
            }*/

            MySqlConnection conn = null;
            try
            {
                conn = new MySqlConnection(connectionDescription);
                conn.Open();
                availableConnections.Add(conn);
                Console.WriteLine("_______________________________________\n");
                Console.ForegroundColor = ConsoleColor.Green;
                Console.WriteLine("\n[MySQL] Verbindung hergestellt!");
                Console.ForegroundColor = ConsoleColor.White;
                Console.WriteLine("\n[MySQL] Host: {0}", DatabaseAPI.API.HOST);
                Console.WriteLine("_______________________________________\n");
                return true;
            }
            catch (MySqlException ex)
            {
                switch (ex.Number)
                {
                    case 0: //Zugriff verweigert (Überprüfe DATABASE, USERNAME, PASSWORD)
                        MySQLError("Zugriff verweigert! überprüfe: DATABASE, USERNAME und PASSWORD!");
                        break;
                    case 1042: //Verbindung zum Server kann nicht hergestellt werden
                        MySQLError("Keine Verbindung zum Server");
                        break;
                    case 1045: //USERNAME oder PASWORD falsch
                        MySQLError("USERNAME oder PASSWORD falsch!");
                        break;
                    default: //Ein unbekannter Fehler
                        MySQLError("Irgendetwas ist schief gelaufen!");
                        break;
                }
            }
            finally
            {
                if (conn != null)
                {
                    conn.Close();
                }
            }
            return false;
        }

        public static void MySQLError(string fehler)
        {
            Console.WriteLine("_______________________________________\n");
            Console.ForegroundColor = ConsoleColor.Red;
            Console.WriteLine("\n[MySQL] Verbindung fehlgeschlagen!");
            Console.ForegroundColor = ConsoleColor.White;
            Console.WriteLine("\nFehler: {0}", fehler);
            Console.WriteLine("_______________________________________\n");
        }

        private void StartReconnectThread()
        {
            Task.Run(() =>
            {
                while (true)
                {
                    Task.Delay(1000 * 60 * RECONNECT_INTERVAL).Wait();

                    int connectionsClosed = 0;

                    do
                    {
                        Monitor.Enter(availableConnections);

                        bool sleep = false;

                        if (availableConnections.Count > 0)
                        {
                            MySqlConnection connection = availableConnections[0];

                            availableConnections.RemoveAt(0);

                            connection.Close();
                            connectionsClosed++;
                        }
                        else
                        {
                            sleep = true;
                        }

                        Monitor.Exit(availableConnections);

                        if (sleep)
                        {
                            Task.Delay(1).Wait();
                        }
                    } while (connectionsClosed < POOL_SIZE);

                    Monitor.Enter(availableConnections);

                    PopulatePool();

                    Monitor.Exit(availableConnections);
                }
            });
        }
    }
}