using System.Net;
using System.Net.WebSockets;
using System.Text;
using System.Text.Json;
using System.Text.RegularExpressions;

namespace CollabVM.Server
{
    // https://github.com/paulbatum/WebSocket-Samples/blob/master/HttpListenerWebSocketEcho/Server/Server.cs
    public class CollabVMHttpServer
    {
        private HttpListener _listener = new();
        private Dictionary<String, CollabVMv1_2GuacamoleServer> _servers = new();
        private readonly IPEndPoint _serverEndPoint;
        private readonly Boolean _allowList = false;

        public CollabVMHttpServer(IPEndPoint endPoint, Boolean allowServerList = false)
        {
            this._serverEndPoint = endPoint;
            this._allowList = allowServerList;
        }
        public CollabVMHttpServer(IPAddress address, UInt16 port = 6004, Boolean allowList = false) : this(new(address, port), allowList) { }

        public CollabVMHttpServer(CollabVMv1_2GuacamoleServer server, IPEndPoint endPoint)
        {
            this._serverEndPoint = endPoint;
            this._addServer("/", server);
        }
        public CollabVMHttpServer(CollabVMv1_2GuacamoleServer server, IPAddress address, UInt16 port = 6004) : this(server, new(address, port)) { }

        private void ListenPath(String path)
        {
            String tmp = $"http://{this._serverEndPoint.Address}:{this._serverEndPoint.Port}{path}";
            //String tmp = $"http://+:{this._serverEndPoint.Port}/{path}";
            Console.Error.WriteLine($"Listen: {tmp}");
            this._listener.Prefixes.Add(tmp);
        }

        private void _addServer(String path, CollabVMv1_2GuacamoleServer server)
        {
            this._servers[path] = server;
            //this.ListenPath(path);
        }

        public void AddServer(String name, CollabVMv1_2GuacamoleServer server)
        {
            Regex nameRegex = new Regex(@"^[a-zA-Z0-9_-]+$");
            if (this._servers.ContainsKey("/"))
            {
                throw new InvalidOperationException("Cannot add servers to a single-server instance");
            }
            if (name.Contains("/"))
            {
                throw new ArgumentException("Server name must only include latin letters, numbers, underscores and hyphens", nameof(name));
            }
            this._addServer($"/{name}", server);
        }

        public async void Start()
        {
            this.ListenPath("/");
            this._listener.Start();
            while (true)
            {
                HttpListenerContext context = await this._listener.GetContextAsync();
                Console.Error.WriteLine($"<< {context.Request.HttpMethod} {context.Request.UserHostAddress} {context.Request.UserHostName} {context.Request.RawUrl}");
                if (context.Request.RawUrl is not null)
                {
                    if (context.Request.IsWebSocketRequest)
                    {
                        if (this._servers.TryGetValue(context.Request.RawUrl, out CollabVMv1_2GuacamoleServer? server))
                        {
                            WebSocketContext wsc;
                            try
                            {
                                wsc = await context.AcceptWebSocketAsync(subProtocol: "guacamole");
                            } catch (Exception)
                            {
                                context.Response.StatusCode = (Int32)HttpStatusCode.InternalServerError;
                                context.Response.Close();
                                continue;
                            }
                            this.HandleWebSocket(wsc, server, context.Request.RemoteEndPoint);
                            continue;
                        } else
                        {
                            context.Response.StatusCode = (Int32)HttpStatusCode.NotFound;
                            context.Response.Close();
                            continue;
                        }
                    } else if (this._allowList && context.Request.RawUrl == "/")
                    {
                        context.Response.StatusCode = (Int32)HttpStatusCode.OK;
                        context.Response.ContentType = "application/json";
                        context.Response.Close(Encoding.UTF8.GetBytes(JsonSerializer.Serialize(this._servers.Keys.Select((path) => $"ws://{context.Request.UserHostAddress}{path}").ToList())), false);
                        continue;
                    }
                }
                context.Response.StatusCode = (Int32)HttpStatusCode.BadRequest;
                context.Response.Close();
            }
        }

        private async void HandleWebSocket(WebSocketContext wsc, CollabVMv1_2GuacamoleServer server, IPEndPoint remote)
        {
            server.HandleSocket(wsc.WebSocket, remote);
        }
    }
}