/*
 * Source: Main.cs
 * Project: DBUtil
 * Description: Stores mostly abstract classes and classes that
 * need to be invoked at runtime (for example the MySQL connector).
 * Author: Kane Holbrook (4/May/2011)
 */

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using MySql.Data.MySqlClient;
using System.Timers;

namespace DBUtil
{
    // -- ----
    // DBUtil.MySQL <: Permissable
    // public static class
    //
    // Provides a set of methods and variables that store the MySQL
    // runtime environment. All variables are constant.
    public static class MySQL
    {
        public const string hostname = "192.168.12.50";     // Host of the MySQL hostname.
        public const string username = "dbutil";            // Username to use.
        public const string password = "Pa55word1";         // Password.
        public const string database = "dbutil";            // The database itself.

        // DBUtil.MySQL.IsAlive
        // static public bool (property)
        // Returns the state of the MySQL connection. "False" if not connected or connection is lost, otherwise true.
        static public bool IsAlive = false;

        // DBUtil.MySQL.Connection
        // static public MySqlConnection
        // Returns the MySQL connection. Should be used in conjunction with IsAlive to avoid returning a null value.
        static public MySqlConnection Connection;

        // This timer is used to call MaintainConnection.
        static private Timer Timer;


        // -- ----
        // DBUtil.MySQL.Connect
        // static public bool method
        // Builds the connection string and connects to MySQL.

        static public bool Connect()
        {
            // Build the connection string.
            Connection = new MySqlConnection(@"Server=" + hostname + "; Database=" + database + "; Uid=" + username + "; Pwd=" + password + ";");

            try
            {
                // OPEN THOU CONNECTION.
                Connection.Open();

                // If we get to here, we can assume MySQL connected successfully; so we start a timer to ping it every 15 seconds
                // in order to maintain connectivity.
                Timer.Elapsed += new ElapsedEventHandler(MaintainConnection);
                Timer.Interval = 15000;
                Timer.Start();

                IsAlive = true;

                // THOU IS CONNECTIF'.
                return true;
            }
            catch (MySqlException E)
            {
                // aww fuck. :(
                Console.WriteLine("[DBUtil.DLL] Failed to connect to MySQL database. Reason specified:\r\n\t" + E.ToString());
                Console.WriteLine("[DBUtil.DLL] Layman's terms: you probably entered the wrong details. Dumb fuck.");
                return false;
            }
        }

        // This function is hooked to a timer; its purpose is to maintain the MySQL connection even when it goes down.
        // If it detects that connectivity has been lost it will attempt to reestablish it.
        static private void MaintainConnection(object sender, ElapsedEventArgs e)
        {
            // Ping return false if the connection is lost.
            if (!Connection.Ping())
            {
                // So we stop the timer to stop us getting ten thousand instances of it while we try to reconnect.
                Timer.Stop();

                // And let other applications know that the SQL has died.
                IsAlive = false;

                // And we try the reconnection sequence five times.
                for (int i = 0; i < 5; i++)
                {
                    // We inform the user and close the broken connection, ready to be restarted..
                    Console.WriteLine("[DBUtil.DLL] Connection lost to MySQL database. Attempting to reconnect ... attempt " + i);
                    Connection.Close();

                    try
                    {
                        // And we then try to reconnect.
                        Connection.Open();

                        // If no exception has been thrown by now you can assume we are connected. So we
                        // restart the ping timer (that coincidently calls this function) and inform the user

                        Timer.Start();
                        IsAlive = true;
                        Console.WriteLine("[DBUtil.DLL] Connection re-established.");
                        return;
                    }
                    catch (Exception E)
                    {
                        // Throw an exception and try again.
                        Console.WriteLine("[DBUtil.DLL] Failed to reconnect; reason specified: " + E.ToString());
                    }

                    // Then sleep for a second then try again.
                    System.Threading.Thread.Sleep(1000);
                }
            }
        }
    }
}