// ClassicalSharp copyright 2014-2016 UnknownShadow200 | Licensed under MIT
using System;
using System.Drawing;
using System.IO;
using System.Net;
using System.Net.Sockets;
using ClassicalSharp.Entities;
using ClassicalSharp.Events;
using ClassicalSharp.Gui;
using ClassicalSharp.Network;
using ClassicalSharp.TexturePack;
using ClassicalSharp.Network.Protocols;

namespace ClassicalSharp.Network {

	public partial class NetworkProcessor : IServerConnection {
		
		public NetworkProcessor( Game window ) {
			game = window;
			cpeData = game.AddComponent( new CPESupport() );
		}
		
		public override bool IsSinglePlayer { get { return false; } }
		
		Socket socket;
		DateTime lastPacket;
		Opcode lastOpcode;
		internal NetReader reader;
		internal NetWriter writer;
		
		internal ClassicProtocol classic;
		internal CPEProtocol cpe;
		internal CPEProtocolBlockDefs cpeBlockDefs;
		internal WoMProtocol wom;

		internal CPESupport cpeData;
		internal ScheduledTask task;
		internal bool receivedFirstPosition;
		internal byte[] needRemoveNames = new byte[256 >> 3];
		
		public override void Connect( IPAddress address, int port ) {
			socket = new Socket( address.AddressFamily, SocketType.Stream, ProtocolType.Tcp );
			try {
				socket.Connect( address, port );
			} catch( SocketException ex ) {
				ErrorHandler.LogError( "connecting to server", ex );
				game.Disconnect( "&eUnable to reach " + address + ":" + port,
				                "Unable to establish an underlying connection" );
				Dispose();
				return;
			}
			
			reader = new NetReader( socket );
			writer = new NetWriter( socket );
			
			classic = new ClassicProtocol( game );
			classic.Init();
			cpe = new CPEProtocol( game );
			cpe.Init();
			cpeBlockDefs = new CPEProtocolBlockDefs( game );
			cpeBlockDefs.Init();
			wom = new WoMProtocol( game );
			wom.Init();
			
			Disconnected = false;
			receivedFirstPosition = false;
			lastPacket = DateTime.UtcNow;
			game.WorldEvents.OnNewMap += OnNewMap;
			game.UserEvents.BlockChanged += BlockChanged;

			classic.SendLogin( game.Username, game.Mppass );
			lastPacket = DateTime.UtcNow;
		}
		
		public override void Dispose() {
			game.WorldEvents.OnNewMap -= OnNewMap;
			game.UserEvents.BlockChanged -= BlockChanged;
			socket.Close();
			Disconnected = true;
		}
		
		public override void Tick( ScheduledTask task ) {
			if( Disconnected ) return;
			if( (DateTime.UtcNow - lastPacket).TotalSeconds >= 30 ) {
				CheckDisconnection( task.Interval );
			}
			if( Disconnected ) return;
			
			LocalPlayer player = game.LocalPlayer;
			this.task = task;
			
			try {
				reader.ReadPendingData();
			} catch( SocketException ex ) {
				ErrorHandler.LogError( "reading packets", ex );
				game.Disconnect( "&eLost connection to the server", "I/O error when reading packets" );
				Dispose();
				return;
			}
			
			while( (reader.size - reader.index) > 0 ) {
				byte opcode = reader.buffer[reader.index];
				// Workaround for older D3 servers which wrote one byte too many for HackControl packets.
				if( cpeData.needD3Fix && lastOpcode == Opcode.CpeHackControl && (opcode == 0x00 || opcode == 0xFF) ) {
					Utils.LogDebug( "Skipping invalid HackControl byte from D3 server." );
					reader.Skip( 1 );
					player.physics.jumpVel = 0.42f; // assume default jump height
					player.physics.serverJumpVel = player.physics.jumpVel;
					continue;
				}
				
				if( opcode > maxHandledPacket ) {
					ErrorHandler.LogError( "NetworkProcessor.Tick",
					                      "received an invalid opcode of " + opcode );
					reader.Skip( 1 );
					continue;
				}
				
				if( (reader.size - reader.index) < packetSizes[opcode] ) break;
				ReadPacket( opcode );
			}
			
			reader.RemoveProcessed();
			if( receivedFirstPosition ) {
				SendPosition( player.Position, player.HeadYawDegrees, player.PitchDegrees );
			}
			CheckAsyncResources();
			wom.Tick();
		}
		
		/// <summary> Sets the incoming packet handler for the given packet id. </summary>
		public void Set( Opcode opcode, Action handler, int packetSize ) {
			handlers[(byte)opcode] = handler;
			packetSizes[(byte)opcode] = (ushort)packetSize;
			maxHandledPacket = Math.Max( (byte)opcode, maxHandledPacket );
		}
		
		internal void SendPacket() {
			if( Disconnected ) {
				writer.index = 0;
				return;
			}
			try {
				writer.Send();
			} catch( SocketException ) {
				// NOTE: Not immediately disconnecting, as otherwise we sometimes miss out on kick messages
				writer.index = 0;
			}
		}
		
		void ReadPacket( byte opcode ) {
			reader.Skip( 1 ); // remove opcode
			lastOpcode = (Opcode)opcode;
			Action handler = handlers[opcode];
			lastPacket = DateTime.UtcNow;
			
			if( handler == null )
				throw new NotImplementedException( "Unsupported packet:" + (Opcode)opcode );
			handler();
		}
		
		internal void SkipPacketData( Opcode opcode ) {
			reader.Skip( packetSizes[(byte)opcode] - 1 );
		}
		
		internal void ResetProtocols() {
			UsingExtPlayerList = false;
			UsingPlayerClick = false;
			SupportsPartialMessages = false;
			SupportsFullCP437 = false;
			
			for( int i = 0; i < handlers.Length; i++ )
				handlers[i] = null;
			
			packetSizes[(byte)Opcode.CpeEnvSetMapApperance] = 69;
			packetSizes[(byte)Opcode.CpeDefineBlockExt] = 85;
		}
		
		internal Action[] handlers = new Action[256];
		internal ushort[] packetSizes = new ushort[256];
		int maxHandledPacket = 0;
		
		void BlockChanged( object sender, BlockChangedEventArgs e ) {
			Vector3I p = e.Coords;
			byte block = game.Inventory.HeldBlock;
			
			if( e.Block == 0 ) {
				classic.SendSetBlock( p.X, p.Y, p.Z, false, block );
			} else {
				classic.SendSetBlock( p.X, p.Y, p.Z, true, e.Block );
			}
		}
		
		void OnNewMap( object sender, EventArgs e ) {
			// wipe all existing entity states
			for( int i = 0; i < 256; i++ )
				RemoveEntity( (byte)i );
		}
		
		double testAcc = 0;
		void CheckDisconnection( double delta ) {
			testAcc += delta;
			if( testAcc < 1 ) return;
			testAcc = 0;
			
			if( !socket.Connected || ( socket.Poll( 1000, SelectMode.SelectRead ) && socket.Available == 0 ) ) {
				game.Disconnect( "&eDisconnected from the server", "Connection timed out" );
				Dispose();
			}
		}
	}
}