#region License
/*
 * WebSocketServiceHostManager.cs
 *
 * The MIT License
 *
 * Copyright (c) 2012-2014 sta.blockhead
 *
 * 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.
 */
#endregion

using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Threading;
using WebSocketSharp.Net;

namespace WebSocketSharp.Server
{
  /// <summary>
  /// Manages the WebSocket services provided by the <see cref="HttpServer"/> or
  /// <see cref="WebSocketServer"/>.
  /// </summary>
  public class WebSocketServiceHostManager
  {
    #region Private Fields

    private Dictionary<string, WebSocketServiceHost> _hosts;
    private volatile bool                            _keepClean;
    private Logger                                   _logger;
    private volatile ServerState                     _state;
    private object                                   _sync;

    #endregion

    #region Internal Constructors

    internal WebSocketServiceHostManager ()
      : this (new Logger ())
    {
    }

    internal WebSocketServiceHostManager (Logger logger)
    {
      _logger = logger;
      _hosts = new Dictionary<string, WebSocketServiceHost> ();
      _keepClean = true;
      _state = ServerState.READY;
      _sync = new object ();
    }

    #endregion

    #region Public Properties

    /// <summary>
    /// Gets the number of the WebSocket services provided by the server.
    /// </summary>
    /// <value>
    /// An <see cref="int"/> that represents the number of the WebSocket services.
    /// </value>
    public int Count {
      get {
        lock (_sync) {
          return _hosts.Count;
        }
      }
    }

    /// <summary>
    /// Gets the collection of the WebSocket service hosts.
    /// </summary>
    /// <value>
    /// An IEnumerable&lt;WebSocketServiceHost&gt; that contains the collection of the WebSocket
    /// service hosts.
    /// </value>
    public IEnumerable<WebSocketServiceHost> Hosts {
      get {
        return copyHosts ().Values;
      }
    }

    /// <summary>
    /// Gets a WebSocket service host with the specified <paramref name="path"/>.
    /// </summary>
    /// <value>
    /// A <see cref="WebSocketServiceHost"/> instance that represents the WebSocket service host if
    /// it's successfully found; otherwise, <see langword="null"/>.
    /// </value>
    /// <param name="path">
    /// A <see cref="string"/> that represents the absolute path to the WebSocket service to find.
    /// </param>
    public WebSocketServiceHost this [string path] {
      get {
        WebSocketServiceHost host;
        TryGetServiceHost (path, out host);

        return host;
      }
    }

    /// <summary>
    /// Gets a value indicating whether the manager cleans up periodically the inactive sessions in
    /// the WebSocket services provided by the server.
    /// </summary>
    /// <value>
    /// <c>true</c> if the manager cleans up the inactive sessions every 60 seconds; otherwise,
    /// <c>false</c>.
    /// </value>
    public bool KeepClean {
      get {
        return _keepClean;
      }

      internal set {
        lock (_sync) {
          if (!(value ^ _keepClean))
            return;

          _keepClean = value;
          foreach (var host in _hosts.Values)
            host.KeepClean = value;
        }
      }
    }

    /// <summary>
    /// Gets the collection of every path to the WebSocket services provided by the server.
    /// </summary>
    /// <value>
    /// An IEnumerable&lt;string&gt; that contains the collection of every path to the WebSocket
    /// services.
    /// </value>
    public IEnumerable<string> Paths {
      get {
        return copyHosts ().Keys;
      }
    }

    /// <summary>
    /// Gets the number of the WebSocket sessions in the server.
    /// </summary>
    /// <value>
    /// An <see cref="int"/> that represents the number of the sessions in the server.
    /// </value>
    public int SessionCount {
      get {
        var count = 0;
        foreach (var host in Hosts) {
          if (_state != ServerState.START)
            break;

          count += host.SessionCount;
        }

        return count;
      }
    }

    #endregion

    #region Private Methods

    private void broadcast (Opcode opcode, byte [] data, Action completed)
    {
      var cache = new Dictionary<CompressionMethod, byte []> ();
      try {
        foreach (var host in Hosts) {
          if (_state != ServerState.START)
            break;

          host.Sessions.Broadcast (opcode, data, cache);
        }

        if (completed != null)
          completed ();
      }
      catch (Exception ex) {
        _logger.Fatal (ex.ToString ());
      }
      finally {
        cache.Clear ();
      }
    }

    private void broadcast (Opcode opcode, Stream stream, Action completed)
    {
      var cache = new Dictionary<CompressionMethod, Stream> ();
      try {
        foreach (var host in Hosts) {
          if (_state != ServerState.START)
            break;

          host.Sessions.Broadcast (opcode, stream, cache);
        }

        if (completed != null)
          completed ();
      }
      catch (Exception ex) {
        _logger.Fatal (ex.ToString ());
      }
      finally {
        foreach (var cached in cache.Values)
          cached.Dispose ();

        cache.Clear ();
      }
    }

    private void broadcastAsync (Opcode opcode, byte [] data, Action completed)
    {
      ThreadPool.QueueUserWorkItem (
        state => broadcast (opcode, data, completed));
    }

    private void broadcastAsync (Opcode opcode, Stream stream, Action completed)
    {
      ThreadPool.QueueUserWorkItem (
        state => broadcast (opcode, stream, completed));
    }

    private Dictionary<string, Dictionary<string, bool>> broadping (
      byte [] frame, int millisecondsTimeout)
    {
      var result = new Dictionary<string, Dictionary<string, bool>> ();
      foreach (var host in Hosts) {
        if (_state != ServerState.START)
          break;

        result.Add (host.ServicePath, host.Sessions.Broadping (frame, millisecondsTimeout));
      }

      return result;
    }

    private Dictionary<string, WebSocketServiceHost> copyHosts ()
    {
      lock (_sync) {
        return new Dictionary<string, WebSocketServiceHost> (_hosts);
      }
    }

    #endregion

    #region Internal Methods

    internal void Add (string path, WebSocketServiceHost host)
    {
      lock (_sync) {
        WebSocketServiceHost find;
        if (_hosts.TryGetValue (path, out find)) {
          _logger.Error (
            "A WebSocket service with the specified path already exists.\npath: " + path);

          return;
        }

        if (_state == ServerState.START)
          host.Sessions.Start ();

        _hosts.Add (path, host);
      }
    }

    internal bool Remove (string path)
    {
      path = HttpUtility.UrlDecode (path).TrimEndSlash ();

      WebSocketServiceHost host;
      lock (_sync) {
        if (!_hosts.TryGetValue (path, out host)) {
          _logger.Error ("A WebSocket service with the specified path not found.\npath: " + path);
          return false;
        }

        _hosts.Remove (path);
      }

      if (host.Sessions.State == ServerState.START)
        host.Sessions.Stop (
          ((ushort) CloseStatusCode.AWAY).ToByteArrayInternally (ByteOrder.BIG), true);

      return true;
    }

    internal void Start ()
    {
      lock (_sync) {
        foreach (var host in _hosts.Values)
          host.Sessions.Start ();

        _state = ServerState.START;
      }
    }

    internal void Stop (byte [] data, bool send)
    {
      lock (_sync) {
        _state = ServerState.SHUTDOWN;

        var payload = new PayloadData (data);
        var args = new CloseEventArgs (payload);
        var frameAsBytes = send
                         ? WsFrame.CreateCloseFrame (Mask.UNMASK, payload).ToByteArray ()
                         : null;

        foreach (var host in _hosts.Values)
          host.Sessions.Stop (args, frameAsBytes);

        _hosts.Clear ();

        _state = ServerState.STOP;
      }
    }

    internal bool TryGetServiceHostInternally (string path, out WebSocketServiceHost host)
    {
      path = HttpUtility.UrlDecode (path).TrimEndSlash ();

      bool result;
      lock (_sync) {
        result = _hosts.TryGetValue (path, out host);
      }

      if (!result)
        _logger.Error ("A WebSocket service with the specified path not found.\npath: " + path);

      return result;
    }

    #endregion

    #region Public Methods

    /// <summary>
    /// Broadcasts a binary <paramref name="data"/> to every client in the WebSocket services
    /// provided by the server.
    /// </summary>
    /// <param name="data">
    /// An array of <see cref="byte"/> that represents the binary data to broadcast.
    /// </param>
    public void Broadcast (byte [] data)
    {
      var msg = _state.CheckIfStart () ?? data.CheckIfValidSendData ();
      if (msg != null) {
        _logger.Error (msg);
        return;
      }

      if (data.LongLength <= WebSocket.FragmentLength)
        broadcast (Opcode.BINARY, data, null);
      else
        broadcast (Opcode.BINARY, new MemoryStream (data), null);
    }

    /// <summary>
    /// Broadcasts a text <paramref name="data"/> to every client in the WebSocket services
    /// provided by the server.
    /// </summary>
    /// <param name="data">
    /// A <see cref="string"/> that represents the text data to broadcast.
    /// </param>
    public void Broadcast (string data)
    {
      var msg = _state.CheckIfStart () ?? data.CheckIfValidSendData ();
      if (msg != null) {
        _logger.Error (msg);
        return;
      }

      var rawData = Encoding.UTF8.GetBytes (data);
      if (rawData.LongLength <= WebSocket.FragmentLength)
        broadcast (Opcode.TEXT, rawData, null);
      else
        broadcast (Opcode.TEXT, new MemoryStream (rawData), null);
    }

    /// <summary>
    /// Broadcasts a binary <paramref name="data"/> asynchronously to every client in the WebSocket
    /// services provided by the server.
    /// </summary>
    /// <remarks>
    /// This method doesn't wait for the broadcast to be complete.
    /// </remarks>
    /// <param name="data">
    /// An array of <see cref="byte"/> that represents the binary data to broadcast.
    /// </param>
    /// <param name="completed">
    /// A <see cref="Action"/> delegate that references the method(s) called when the broadcast is
    /// complete.
    /// </param>
    public void BroadcastAsync (byte [] data, Action completed)
    {
      var msg = _state.CheckIfStart () ?? data.CheckIfValidSendData ();
      if (msg != null) {
        _logger.Error (msg);
        return;
      }

      if (data.LongLength <= WebSocket.FragmentLength)
        broadcastAsync (Opcode.BINARY, data, completed);
      else
        broadcastAsync (Opcode.BINARY, new MemoryStream (data), completed);
    }

    /// <summary>
    /// Broadcasts a text <paramref name="data"/> asynchronously to every client in the WebSocket
    /// services provided by the server.
    /// </summary>
    /// <remarks>
    /// This method doesn't wait for the broadcast to be complete.
    /// </remarks>
    /// <param name="data">
    /// A <see cref="string"/> that represents the text data to broadcast.
    /// </param>
    /// <param name="completed">
    /// A <see cref="Action"/> delegate that references the method(s) called when the broadcast is
    /// complete.
    /// </param>
    public void BroadcastAsync (string data, Action completed)
    {
      var msg = _state.CheckIfStart () ?? data.CheckIfValidSendData ();
      if (msg != null) {
        _logger.Error (msg);
        return;
      }

      var rawData = Encoding.UTF8.GetBytes (data);
      if (rawData.LongLength <= WebSocket.FragmentLength)
        broadcastAsync (Opcode.TEXT, rawData, completed);
      else
        broadcastAsync (Opcode.TEXT, new MemoryStream (rawData), completed);
    }

    /// <summary>
    /// Broadcasts a binary data from the specified <see cref="Stream"/> asynchronously to every
    /// client in the WebSocket services provided by the server.
    /// </summary>
    /// <remarks>
    /// This method doesn't wait for the broadcast to be complete.
    /// </remarks>
    /// <param name="stream">
    /// A <see cref="Stream"/> from which contains the binary data to broadcast.
    /// </param>
    /// <param name="length">
    /// An <see cref="int"/> that represents the number of bytes to broadcast.
    /// </param>
    /// <param name="completed">
    /// A <see cref="Action"/> delegate that references the method(s) called when the broadcast is
    /// complete.
    /// </param>
    public void BroadcastAsync (Stream stream, int length, Action completed)
    {
      var msg = _state.CheckIfStart () ??
                stream.CheckIfCanRead () ??
                (length < 1 ? "'length' must be greater than 0." : null);

      if (msg != null) {
        _logger.Error (msg);
        return;
      }

      stream.ReadBytesAsync (
        length,
        data => {
          var len = data.Length;
          if (len == 0) {
            _logger.Error ("A data cannot be read from 'stream'.");
            return;
          }

          if (len < length)
            _logger.Warn (
              String.Format (
                "A data with 'length' cannot be read from 'stream'.\nexpected: {0} actual: {1}",
                length,
                len));

          if (len <= WebSocket.FragmentLength)
            broadcast (Opcode.BINARY, data, completed);
          else
            broadcast (Opcode.BINARY, new MemoryStream (data), completed);
        },
        ex => _logger.Fatal (ex.ToString ()));
    }

    /// <summary>
    /// Sends a Ping to every client in the WebSocket services provided by the server.
    /// </summary>
    /// <returns>
    /// A Dictionary&lt;string, Dictionary&lt;string, bool&gt;&gt; that contains the collection of
    /// pairs of service path and collection of pairs of session ID and value indicating whether
    /// the manager received a Pong from every client in a time. If this method isn't available,
    /// returns <see langword="null"/>.
    /// </returns>
    public Dictionary<string, Dictionary<string, bool>> Broadping ()
    {
      var msg = _state.CheckIfStart ();
      if (msg != null) {
        _logger.Error (msg);
        return null;
      }

      return broadping (WsFrame.EmptyUnmaskPingData, 1000);
    }

    /// <summary>
    /// Sends a Ping with the specified <paramref name="message"/> to every client in the WebSocket
    /// services provided by the server.
    /// </summary>
    /// <returns>
    /// A Dictionary&lt;string, Dictionary&lt;string, bool&gt;&gt; that contains the collection of
    /// pairs of service path and collection of pairs of session ID and value indicating whether
    /// the manager received a Pong from every client in a time. If this method isn't available or
    /// <paramref name="message"/> is invalid, returns <see langword="null"/>.
    /// </returns>
    /// <param name="message">
    /// A <see cref="string"/> that represents the message to send.
    /// </param>
    public Dictionary<string, Dictionary<string, bool>> Broadping (string message)
    {
      if (message == null || message.Length == 0)
        return Broadping ();

      byte [] data = null;
      var msg = _state.CheckIfStart () ??
                (data = Encoding.UTF8.GetBytes (message)).CheckIfValidControlData ("message");

      if (msg != null) {
        _logger.Error (msg);
        return null;
      }

      return broadping (WsFrame.CreatePingFrame (Mask.UNMASK, data).ToByteArray (), 1000);
    }

    /// <summary>
    /// Tries to get a WebSocket service host with the specified <paramref name="path"/>.
    /// </summary>
    /// <returns>
    /// <c>true</c> if the WebSocket service is successfully found; otherwise, <c>false</c>.
    /// </returns>
    /// <param name="path">
    /// A <see cref="string"/> that represents the absolute path to the WebSocket service to find.
    /// </param>
    /// <param name="host">
    /// When this method returns, a <see cref="WebSocketServiceHost"/> instance that represents the
    /// WebSocket service host if it's successfully found; otherwise, <see langword="null"/>. This
    /// parameter is passed uninitialized.
    /// </param>
    public bool TryGetServiceHost (string path, out WebSocketServiceHost host)
    {
      var msg = _state.CheckIfStart () ?? path.CheckIfValidServicePath ();
      if (msg != null) {
        _logger.Error (msg);
        host = null;

        return false;
      }

      return TryGetServiceHostInternally (path, out host);
    }

    #endregion
  }
}