using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Threading;
using System.Threading.Tasks;

namespace Model
{
	[ObjectSystem]
	public class SessionSystem : ObjectSystem<Session>, IAwake<NetworkComponent, AChannel>, IStart
	{
		public void Awake(NetworkComponent network, AChannel channel)
		{
			this.Get().Awake(network, channel);
		}

		public void Start()
		{
			this.Get().Start();
		}
	}

	public sealed class Session : Entity
	{
		private static uint RpcId { get; set; }
		public NetworkComponent network;
		private AChannel channel;
		
		private readonly Dictionary<uint, Action<PacketInfo>> requestCallback = new Dictionary<uint, Action<PacketInfo>>();
		
		private readonly List<byte[]> byteses = new List<byte[]>() {new byte[0], new byte[0], new byte[0]};

		public void Awake(NetworkComponent net, AChannel c)
		{
			this.network = net;
			this.channel = c;
			this.requestCallback.Clear();
		}

		public void Start()
		{
			this.StartRecv();
		}

		public override void Dispose()
		{
			if (this.Id == 0)
			{
				return;
			}

			long id = this.Id;

			base.Dispose();

			foreach (Action<PacketInfo> action in this.requestCallback.Values.ToArray())
			{
				action.Invoke(new PacketInfo());
			}

			this.channel.Dispose();
			this.network.Remove(id);
			this.requestCallback.Clear();
		}

		public IPEndPoint RemoteAddress
		{
			get
			{
				return this.channel.RemoteAddress;
			}
		}

		public ChannelType ChannelType
		{
			get
			{
				return this.channel.ChannelType;
			}
		}

		private async void StartRecv()
		{
			while (true)
			{
				if (this.Id == 0)
				{
					return;
				}

				Packet packet;
				try
				{
					packet = await this.channel.Recv();
					if (this.Id == 0)
					{
						return;
					}
				}
				catch (Exception e)
				{
					Log.Error(e.ToString());
					continue;
				}
				
				try
				{
					this.Run(packet);
				}
				catch (Exception e)
				{
					Log.Error(e.ToString());
				}
			}
		}

		private void Run(Packet packet)
		{
			if (packet.Length < Packet.MinSize)
			{
				Log.Error($"message error length < {Packet.MinSize}, ip: {this.RemoteAddress}");
				this.network.Remove(this.Id);
				return;
			}

			ushort headerSize = BitConverter.ToUInt16(packet.Bytes, 0);
			Header header = this.network.MessagePacker.DeserializeFrom<Header>(packet.Bytes, 2, headerSize);
			byte flag = header.Flag;
			PacketInfo packetInfo = new PacketInfo
			{
				Header = header,
				Index = (ushort)(headerSize + 2),
				Bytes = packet.Bytes,
				Length = (ushort)(packet.Length - 2 - headerSize)
			};

			// flag第2位表示这是rpc返回消息
			if ((flag & 0x40) > 0)
			{
				uint rpcId = header.RpcId;
				Action<PacketInfo> action;
				if (!this.requestCallback.TryGetValue(rpcId, out action))
				{
					return;
				}
				this.requestCallback.Remove(rpcId);
				action(packetInfo);
				return;
			}

			this.network.MessageDispatcher.Dispatch(this, packetInfo);
		}

		public Task<PacketInfo> Call(ushort opcode, byte[] bytes)
		{
			uint rpcId = ++RpcId;
			var tcs = new TaskCompletionSource<PacketInfo>();
			this.requestCallback[rpcId] = (packetInfo) =>
			{
				try
				{
					tcs.SetResult(packetInfo);
				}
				catch (Exception e)
				{
					tcs.SetException(new Exception($"Rpc Error: {opcode}", e));
				}
			};

			const byte flag = 0x80;
			this.SendMessage(flag, opcode, rpcId, bytes);
			return tcs.Task;
		}

		public Task<PacketInfo> Call(ushort opcode, byte[] bytes, CancellationToken cancellationToken)
		{
			uint rpcId = ++RpcId;
			var tcs = new TaskCompletionSource<PacketInfo>();
			this.requestCallback[rpcId] = (packetInfo) =>
			{
				try
				{
					tcs.SetResult(packetInfo);
				}
				catch (Exception e)
				{
					tcs.SetException(new Exception($"Rpc Error: {opcode}", e));
				}
			};

			cancellationToken.Register(() => { this.requestCallback.Remove(rpcId); });

			const byte flag = 0x80;
			this.SendMessage(flag, opcode, rpcId, bytes);
			return tcs.Task;
		}

		public void Send(ushort opcode, byte[] bytes)
		{
			if (this.Id == 0)
			{
				throw new Exception("session已经被Dispose了");
			}
			const byte flag = 0x00;
			this.SendMessage(flag, opcode, 0, bytes);
		}

		public void Reply(ushort opcode, uint rpcId, byte[] bytes)
		{
			if (this.Id == 0)
			{
				throw new Exception("session已经被Dispose了");
			}

			const byte flag = 0x40;
			this.SendMessage(flag, opcode, rpcId, bytes);
		}

		private void SendMessage(byte flag, ushort opcode, uint rpcId, byte[] bytes)
		{
			Header header = new Header
			{
				Opcode = opcode,
				RpcId = rpcId,
				Flag = flag
			};

			byte[] headerBytes = this.network.MessagePacker.SerializeToByteArray(header);
			byte[] headerLength = BitConverter.GetBytes((ushort)headerBytes.Length);

			this.byteses[0] = headerLength;
			this.byteses[1] = headerBytes;
			this.byteses[2] = bytes;
			channel.Send(this.byteses);
		}
	}
}