/*
 
Copyright (c) 2017 Ahmed Kh. Zamil

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

*/

using System;
using System.Diagnostics;
using System.IO;
using System.Net.Sockets;
using System.Text;
using System.Threading;
using System.Net;
using System.Collections;
using System.Collections.Generic;
using Esiur.Net.Sockets;
using Esiur.Data;
using Esiur.Misc;
using Esiur.Core;
using System.Security.Cryptography.X509Certificates;
using Esiur.Resource;
using System.Text.RegularExpressions;
using System.Linq;
using System.Reflection;
using Esiur.Net.Packets.Http;
using Esiur.Net.Packets.WebSocket;

namespace Esiur.Net.Http;
public class HttpServer : NetworkServer<HttpConnection>, IResource
{
    Dictionary<string, HttpSession> sessions = new Dictionary<string, HttpSession>();
    readonly object sessionsLock = new object();
    HttpFilter[] filters = new HttpFilter[0];

    Dictionary<Packets.Http.HttpMethod, List<RouteInfo>> routes = new()
    {
        [Packets.Http.HttpMethod.GET] = new List<RouteInfo>(),
        [Packets.Http.HttpMethod.POST] = new List<RouteInfo>(),
        [Packets.Http.HttpMethod.HEAD] = new List<RouteInfo>(),
        [Packets.Http.HttpMethod.OPTIONS] = new List<RouteInfo>(),
        [Packets.Http.HttpMethod.UNKNOWN] = new List<RouteInfo>(),
        [Packets.Http.HttpMethod.DELETE] = new List<RouteInfo>(),
        [Packets.Http.HttpMethod.TRACE] = new List<RouteInfo>(),
        [Packets.Http.HttpMethod.CONNECT] = new List<RouteInfo>(),
        [Packets.Http.HttpMethod.PUT] = new List<RouteInfo>()
    };

    //List<RouteInfo> GetRoutes = new List<RouteInfo>();
    //List<RouteInfo> PostRoutes = new List<RouteInfo>();


    class RouteInfo
    {
        public Delegate Handler;
        public Regex Pattern;
        Dictionary<string, ParameterInfo> ParameterIndex = new();
        int? SenderIndex;
        //bool HasSender;
        int ArgumentsCount;

        public RouteInfo(Delegate handler, Regex pattern)
        {

            Pattern = pattern;
            Handler = handler;

            var ps = handler.Method.GetParameters();

            ArgumentsCount = ps.Length;

            var last = ps.LastOrDefault();

            if (last != null && last.ParameterType == typeof(HttpConnection))
            {

                SenderIndex = ps.Length - 1;
                for (var i = 0; i < ps.Length - 1; i++)
                    ParameterIndex[ps[i].Name] = ps[i];
            }
            else
            {
                for (var i = 0; i < ps.Length; i++)
                    ParameterIndex[ps[i].Name] = ps[i];
            }
        }


        public bool Invoke(HttpConnection sender)
        {
            var match = Pattern.Match(sender.Request.URL);

            if (!match.Success)
                return false;

            var args = new object[ArgumentsCount];

            foreach (var kv in ParameterIndex)
            {
                var g = match.Groups[kv.Key];
                args[kv.Value.Position] = RuntimeCaster.Cast(g.Value, kv.Value.ParameterType);
            }

            if (SenderIndex != null)
                args[(int)SenderIndex] = sender;

            var rt = Handler.DynamicInvoke(args);

            if (rt is bool)
                return (bool)rt;

            return true;
        }
    }






    public Instance Instance
    {
        get;
        set;
    }

    //[Attribute]
    public virtual string IP
    {
        get;
        set;
    }

    //[Attribute]
    public virtual ushort Port
    {
        get;
        set;
    }

 
    //[Attribute]
    public virtual uint MaxPost
    {
        get;
        set;
    } = HttpPacketHelpers.DefaultMaximumContentLength;

    public virtual uint MaximumHeaderLength
    {
        get;
        set;
    } = HttpPacketHelpers.DefaultMaximumHeaderLength;

    public virtual int MaximumHeaderCount
    {
        get;
        set;
    } = HttpPacketHelpers.DefaultMaximumHeaderCount;

    public virtual int MaximumFormFields
    {
        get;
        set;
    } = HttpPacketHelpers.DefaultMaximumFormFields;

    public virtual int MaximumFormKeyLength
    {
        get;
        set;
    } = HttpPacketHelpers.DefaultMaximumFormKeyLength;

    public virtual int MaximumFormValueLength
    {
        get;
        set;
    } = HttpPacketHelpers.DefaultMaximumFormValueLength;

    public virtual int MaximumMultipartPartLength
    {
        get;
        set;
    } = HttpPacketHelpers.DefaultMaximumMultipartPartLength;

    /// <summary>
    /// Maximum payload accumulated for one WebSocket application message, including
    /// all of its fragments. Set to zero to disable the configured limit.
    /// </summary>
    public virtual ulong MaximumWebSocketMessageLength
    {
        get;
        set;
    } = WebsocketPacket.DefaultMaximumPayloadLength;

    /// <summary>
    /// WebSocket subprotocols supported by this server, in server preference order.
    /// A protocol is returned to the client only when it was also requested.
    /// </summary>
    public virtual string[] WebSocketSubprotocols
    {
        get;
        set;
    } = Array.Empty<string>();

    /// <summary>
    /// Whether HTTP 500 responses may include exception messages. Disabled by default
    /// to avoid disclosing implementation details to remote clients.
    /// </summary>
    public virtual bool ExposeExceptionDetails
    {
        get;
        set;
    }

    //[Attribute]
    public virtual bool SSL
    {
        get;
        set;
    }

    //[Attribute]
    public virtual string Certificate
    {
        get;
        set;
    }


    public HttpSession CreateSession(string id, int timeout)
    {
        var s = new HttpSession();
        s.OnEnd += SessionEnded;
        s.OnDestroy += SessionDestroyed;

        lock (sessionsLock)
            sessions.Add(id, s);

        try
        {
            s.Set(id, timeout);
        }
        catch
        {
            lock (sessionsLock)
                sessions.Remove(id);
            s.Destroy();
            throw;
        }

        return s;
    }

    /// <summary>
    /// Looks up a live HTTP session by its cookie identifier.
    /// </summary>
    public bool TryGetSession(string id, out HttpSession session)
    {
        session = null;
        if (string.IsNullOrEmpty(id))
            return false;

        lock (sessionsLock)
        {
            if (!sessions.TryGetValue(id, out var candidate) || candidate.IsDestroyed)
                return false;

            session = candidate;
            return true;
        }
    }

    private void SessionEnded(HttpSession session)
    {
        RemoveSession(session);
        session.Destroy();
    }

    private void SessionDestroyed(object sender)
    {
        if (sender is HttpSession session)
            RemoveSession(session);
    }

    private void RemoveSession(HttpSession session)
    {
        lock (sessionsLock)
        {
            if (session.Id != null &&
                sessions.TryGetValue(session.Id, out var current) &&
                ReferenceEquals(current, session))
                sessions.Remove(session.Id);
        }
    }

    public static string MakeCookie(string Item, string Value, DateTime Expires, string Domain, string Path, bool HttpOnly)
        => MakeCookie(
            Item,
            Value,
            Expires,
            Domain,
            Path,
            HttpOnly,
            false,
            HttpCookieSameSite.Unspecified);

    public static string MakeCookie(
        string Item,
        string Value,
        DateTime Expires,
        string Domain,
        string Path,
        bool HttpOnly,
        bool Secure,
        HttpCookieSameSite SameSite)
    {
        return new HttpCookie(Item, Value)
        {
            Expires = Expires,
            Domain = Domain,
            Path = Path,
            HttpOnly = HttpOnly,
            Secure = Secure,
            SameSite = SameSite,
        }.ToString();
    }

    protected override void ClientDisconnected(HttpConnection connection)
    {
        foreach (var filter in filters)
            filter.ClientDisconnected(connection);
    }



    internal bool Execute(HttpConnection sender)
    {
        if (!sender.WSMode)
            foreach (var route in routes[sender.Request.Method])
                if (route.Invoke(sender))
                    return true;


        foreach (var resource in filters)
            if (resource.Execute(sender).Wait(30000))
                return true;



        return false;
    }

    
    public void MapGet(string pattern, Delegate handler)
    {
        var regex = Global.GetRouteRegex(pattern);
        var list = routes[Packets.Http.HttpMethod.GET];
        list.Add(new RouteInfo(handler, regex));
    }

    public void MapPost(string pattern, Delegate handler)
    {
        var regex = Global.GetRouteRegex(pattern);
        var list = routes[Packets.Http.HttpMethod.POST];
        list.Add(new RouteInfo(handler, regex));
    }

    /*
    protected override void SessionEnded(NetworkSession session)
    {
        // verify wether there are no active connections related to the session

        foreach (HTTPConnection c in Connections)//.Values)
        {
            if (c.Session == session)
            {
                session.Refresh();
                return;
            }
        }

        foreach (Instance instance in Instance.Children)
        {
            var f = (HTTPFilter)instance.Resource;
            f.SessionExpired((HTTPSession)session);
        }

        base.SessionEnded((HTTPSession)session);
        //Sessions.Remove(Session.ID);
        //Session.Dispose();
    }
    */

    /*
    public int TTL
    {
        get
        {
            return Timeout;// mTimeout;
        }
    }
     */


    public async AsyncReply<bool> Handle(ResourceOperation operation, IResourceContext context = null)
    {

        if (operation == ResourceOperation.Initialize)
        {
            //var ip = (IPAddress)Instance.Attributes["ip"];
            //var port = (int)Instance.Attributes["port"];
            //var ssl = (bool)Instance.Attributes["ssl"];
            //var cert = (string)Instance.Attributes["certificate"];

            //if (ip == null) ip = IPAddress.Any;

            Sockets.ISocket listener;
            IPAddress ipAdd;

            if (IP == null)
                ipAdd = IPAddress.Any;
            else
                ipAdd = IPAddress.Parse(IP);

            if (SSL)
                listener = new SSLSocket(new IPEndPoint(ipAdd, Port), new X509Certificate2(Certificate));
            else
                listener = new TcpSocket(new IPEndPoint(ipAdd, Port));

            Start(listener);
        }
        else if (operation == ResourceOperation.Terminate)
        {
            Stop();
            DisposeSessions();
        }
        else if (operation == ResourceOperation.SystemReloading)
        {
            await Handle(ResourceOperation.Terminate);
            await Handle(ResourceOperation.Initialize);
        }
        else if (operation == ResourceOperation.SystemReady)
        {
            filters = await Instance.Children<HttpFilter>();
        }

        return true;

    }

    private void DisposeSessions()
    {
        HttpSession[] activeSessions;
        lock (sessionsLock)
        {
            activeSessions = sessions.Values.ToArray();
            sessions.Clear();
        }

        foreach (var activeSession in activeSessions)
            activeSession.Destroy();
    }


    public override void Add(HttpConnection connection)
    {
        connection.Server = this;
        base.Add(connection);
    }

    public override void Remove(HttpConnection connection)
    {
        connection.Server = null;
        base.Remove(connection);
    }

    protected override void ClientConnected(HttpConnection connection)
    {
        //if (filters.Length == 0 && routes.)
        //{
        //    connection.Close();
        //    return;
        //}

        foreach (var resource in filters)
        {
            resource.ClientConnected(connection);
        }
    }


    /*
    public int LocalPort
    {
        get 
        {
            return cServer.LocalPort;
        }
    }
     */

    /* 
    public HTTPServer(int Port)
    {
        cServer = new TServer();
        cServer.LocalPort = Port;
        cServer.StartServer();
        cServer.ClientConnected += new TServer.eClientConnected(ClientConnected);
        cServer.ClientDisConnected += new TServer.eClientDisConnected(ClientDisConnected);
        cServer.ClientIsSwitching += new TServer.eClientIsSwitching(ClientIsSwitching);
        cServer.DataReceived += new TServer.eDataReceived(DataReceived);

    }*/

    //~HTTPServer()
    //{
    //    cServer.StopServer();
    //}
}