using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Primitives;
using OCPPServer.Protocol;
using SuperSocket.SocketBase;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.WebSockets;
using System.ServiceModel.Channels;
using System.Text;
using System.Threading.Tasks;
using static OCPPServer.Protocol.ClientData;

namespace EVCB_OCPP.WSServer.Service;

public static class AppExtention
{
    public static void MapWsService(this WebApplication webApplication)
    {
        var protocals = new List<string>() { "", "ocpp1.6", "ocpp2.0" };

        webApplication.UseWebSockets(new WebSocketOptions()
        {
            KeepAliveInterval = TimeSpan.FromSeconds(10)
        });

        webApplication.Use(async (HttpContext context, RequestDelegate next) => {
            if (context.WebSockets.IsWebSocketRequest)
            {
                var matched = context.WebSockets.WebSocketRequestedProtocols.Intersect(protocals);
                if (matched is null || !matched.Any())
                {
                    await context.Response.WriteAsync("Protocol not matched");
                    return;
                }
                using WebSocket webSocket = await context.WebSockets.AcceptWebSocketAsync(matched.First());
                var servcie = context.RequestServices.GetService<WebsocketService<WsClientData>>();
                await servcie.AddWebSocket(webSocket, context);
                return;
            }
            else
            {
                await next(context);
            }
        });
    }
}

public interface IWebsocketService
{
    public Task AddWebSocket(WebSocket webSocket, HttpContext context);
}

public class WebsocketService<T> : IWebsocketService where T: WsSession
{
    public WebsocketService() { }

    public Func<T,  Task<bool>> ValidateHandshake;

    public event EventHandler<T> NewSessionConnected;

    public async Task AddWebSocket(WebSocket webSocket, HttpContext context)
    {
        T data = Activator.CreateInstance<T>();
        data.ClientWebSocket = webSocket;
        data.Path = context?.Request?.Path;
        data.UriScheme = context?.Request?.Scheme;
        data.AuthHeader = context?.Request?.Headers?.Authorization;
        data.SessionID = context.TraceIdentifier;
        data.Endpoint = null;
        data.Origin = context.Request.Headers.Origin;

        var validated = await ValidateHandshake(data);

        if (!validated)
        {
            return;
        }

        NewSessionConnected?.Invoke(this, data);
        await data.EndConnSemaphore.WaitAsync();
        return;
    }
}

public class WsSession
{
    public WsSession()
    {

    }

    public PathString? Path { get; set; }
    public string UriScheme { get; set; }
    public string AuthHeader { get; set; }
    public string SessionID { get; set; }
    public Endpoint Endpoint { get; internal set; }
    public StringValues Origin { get; internal set; }
    public DateTime LastActiveTime { get; set; }


    public WebSocket _WebSocket { get; internal set; }
    public WebSocket ClientWebSocket {
        get => _WebSocket;
        set
        {
            Init(value);
        }
    }

    public WebSocketState State => ClientWebSocket.State;
    public string SecWebSocketProtocol => ClientWebSocket.SubProtocol;

    public SemaphoreSlim EndConnSemaphore { get; } = new SemaphoreSlim(0);

    //public event OCPPClientDataEventHandler<WsSession, String> m_ReceiveData;

    public event EventHandler SessionClosed;

    private Task ReceiveLoopTask;

    private void Init(WebSocket webSocket)
    {
        _WebSocket = webSocket;
        ReceiveLoopTask = StartReceivd(webSocket);
    }

    private async Task StartReceivd(WebSocket webSocket)
    {
        while (true)
        {
            var buffer = new byte[1024 * 4];
            var result = await webSocket.ReceiveAsync(new ArraySegment<byte>(buffer), default);
            if (result.CloseStatus.HasValue)
            {
                Close(CloseReason.ClientClosing);
                break;
            }
            string received = Encoding.UTF8.GetString(buffer, 0, result.Count);
            //m_ReceiveData?.Invoke(this, received);
            this.LastActiveTime = DateTime.UtcNow;
            HandleReceivedData(received);
        }
    }

    internal virtual void HandleReceivedData(string data)
    {

    }

    internal void Send(string dataString)
    {
        var data = Encoding.UTF8.GetBytes(dataString);
        ClientWebSocket.SendAsync(data, WebSocketMessageType.Text, endOfMessage: true, cancellationToken: default);
    }

    internal void Send(byte[] data, int offset, int length)
    {
        ClientWebSocket.SendAsync(data, WebSocketMessageType.Text, endOfMessage: true, cancellationToken: default);
    }

    internal void Close(CloseReason closeReason)
    {
        SessionClosed?.Invoke(this, null);
        _WebSocket.Dispose();
        EndConnSemaphore.Release();
    }
}