using System;
using System.Collections.Concurrent;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading.Tasks;
using Newtonsoft.Json;
using TeamAAS.Communication.Attributes;
using TeamAAS.Communication.Base;
using TeamAAS.Communication.Interfaces;

namespace TeamAAS.Communication.Devices
{
    /// <summary>
    /// UDP 通讯（数据报协议，无连接，广播/多播支持）。
    /// </summary>
    [Communication("UDP", "基础通讯", "UDP 数据报通讯")]
    public class UdpCommunication : BindableCommunicationBase
    {
        [JsonIgnore]
        private UdpClient _udpClient;
        private readonly ConcurrentQueue<string> _received = new ConcurrentQueue<string>();

        private string _localIp = "0.0.0.0";
        public string LocalIp
        {
            get { return _localIp; }
            set { if (SetProperty(ref _localIp, value)) Notify(nameof(EndpointUrl)); }
        }

        private int _localPort = 8888;
        public int LocalPort
        {
            get { return _localPort; }
            set { if (SetProperty(ref _localPort, value)) Notify(nameof(EndpointUrl)); }
        }

        private string _remoteIp = "127.0.0.1";
        public string RemoteIp
        {
            get { return _remoteIp; }
            set { if (SetProperty(ref _remoteIp, value)) Notify(nameof(EndpointUrl)); }
        }

        private int _remotePort = 9999;
        public int RemotePort
        {
            get { return _remotePort; }
            set { if (SetProperty(ref _remotePort, value)) Notify(nameof(EndpointUrl)); }
        }

        public override string EndpointUrl
        {
            get { return $"udp://{LocalIp}:{LocalPort} -> {RemoteIp}:{RemotePort}"; }
            set
            {
                if (!string.IsNullOrWhiteSpace(value) && value.StartsWith("udp://"))
                {
                    var uri = new Uri(value);
                    if (!string.IsNullOrWhiteSpace(uri.Host)) LocalIp = uri.Host;
                    if (uri.Port > 0) LocalPort = uri.Port;
                }
            }
        }

        [JsonIgnore]
        public override bool IsConnected => _udpClient != null;

        public override event Action<object, bool> ConnectChangedEvent;
        public override event Action<object, string> DataReceivedEvent;

        public override void Connect()
        {
            Disconnect();
            IPAddress bindIp = IPAddress.Any;
            if (!string.IsNullOrWhiteSpace(LocalIp))
            {
                try { bindIp = IPAddress.Parse(LocalIp.Trim()); }
                catch { bindIp = IPAddress.Any; }
            }

            _udpClient = new UdpClient(LocalPort)
            {
                ExclusiveAddressUse = false
            };

            try
            {
                _udpClient.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
            }
            catch { }

            _ = Task.Run(ReceiveLoop);
            ConnectChangedEvent?.Invoke(this, true);
            Notify(nameof(IsConnected));
        }

        public override Task ConnectAsync()
        {
            return Task.Run(() => Connect());
        }

        private async Task ReceiveLoop()
        {
            try
            {
                while (_udpClient != null)
                {
                    var result = await _udpClient.ReceiveAsync();
                    var text = Encoding.UTF8.GetString(result.Buffer, 0, result.Buffer.Length);
                    _received.Enqueue(text);
                    DataReceivedEvent?.Invoke(this, text);
                }
            }
            catch
            {
            }
        }

        public void Send(string text)
        {
            if (_udpClient == null)
                throw new InvalidOperationException("UDP 未连接。");

            var data = Encoding.UTF8.GetBytes(text ?? string.Empty);
            var endPoint = new IPEndPoint(IPAddress.Parse(RemoteIp), RemotePort);
            _udpClient.Send(data, data.Length, endPoint);
        }

        public void Send(byte[] data)
        {
            if (_udpClient == null)
                throw new InvalidOperationException("UDP 未连接。");

            var endPoint = new IPEndPoint(IPAddress.Parse(RemoteIp), RemotePort);
            _udpClient.Send(data, data.Length, endPoint);
        }

        public override object ReadValue(string address)
        {
            _received.TryDequeue(out var text);
            return text;
        }

        public override Task<object> ReadValueAsync(string address)
        {
            return Task.FromResult(ReadValue(address));
        }

        public override void WriteValue(string address, object value)
        {
            Send(value?.ToString() ?? string.Empty);
        }

        public override Task WriteValueAsync(string address, object value)
        {
            Send(value?.ToString() ?? string.Empty);
            return Task.CompletedTask;
        }

        public override void Disconnect()
        {
            if (_udpClient != null)
            {
                try { _udpClient.Close(); } catch { }
                _udpClient.Dispose();
                _udpClient = null;
            }

            ConnectChangedEvent?.Invoke(this, false);
            Notify(nameof(IsConnected));
        }

        public override void Dispose()
        {
            Disconnect();
        }
    }
}