#region License
/*
 * WebSocketServiceManager.cs
 *
 * The MIT License
 *
 * Copyright (c) 2012-2015 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;
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 WebSocketServiceManager
  {
    #region Private Fields

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

    #endregion

    #region Internal Constructors

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

    internal WebSocketServiceManager (Logger logger)
    {
      _logger = logger;

      _clean = true;
      _hosts = new Dictionary<string, WebSocketServiceHost> ();
      _state = ServerState.Ready;
      _sync = ((ICollection) _hosts).SyncRoot;
      _waitTime = TimeSpan.FromSeconds (1);
    }

    #endregion

    #region Public Properties

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

    /// <summary>
    /// Gets the host instances for the Websocket services.
    /// </summary>
    /// <value>
    /// An <c>IEnumerable&lt;WebSocketServiceHost&gt;</c> instance that provides an enumerator
    /// which supports the iteration over the collection of the host instances for the services.
    /// </value>
    public IEnumerable<WebSocketServiceHost> Hosts {
      get {
        lock (_sync)
          return _hosts.Values.ToList ();
      }
    }

    /// <summary>
    /// Gets the WebSocket service host with the specified <paramref name="path"/>.
    /// </summary>
    /// <value>
    /// A <see cref="WebSocketServiceHost"/> instance that provides the access to
    /// the information in the service, or <see langword="null"/> if it's not found.
    /// </value>
    /// <param name="path">
    /// A <see cref="string"/> that represents the absolute path to the 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 the inactive sessions
    /// in the WebSocket services periodically.
    /// </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 _clean;
      }

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

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

    /// <summary>
    /// Gets the paths for the WebSocket services.
    /// </summary>
    /// <value>
    /// An <c>IEnumerable&lt;string&gt;</c> instance that provides an enumerator which supports
    /// the iteration over the collection of the paths for the services.
    /// </value>
    public IEnumerable<string> Paths {
      get {
        lock (_sync)
          return _hosts.Keys.ToList ();
      }
    }

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

          cnt += host.Sessions.Count;
        }

        return cnt;
      }
    }

    /// <summary>
    /// Gets the wait time for the response to the WebSocket Ping or Close.
    /// </summary>
    /// <value>
    /// A <see cref="TimeSpan"/> that represents the wait time.
    /// </value>
    public TimeSpan WaitTime {
      get {
        return _waitTime;
      }

      internal set {
        lock (_sync) {
          if (value == _waitTime)
            return;

          _waitTime = value;
          foreach (var host in _hosts.Values)
            host.WaitTime = value;
        }
      }
    }

    #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[] frameAsBytes, TimeSpan timeout)
    {
      var ret = new Dictionary<string, Dictionary<string, bool>> ();
      foreach (var host in Hosts) {
        if (_state != ServerState.Start)
          break;

        ret.Add (host.Path, host.Sessions.Broadping (frameAsBytes, timeout));
      }

      return ret;
    }

    #endregion

    #region Internal Methods

    internal void Add<TBehavior> (string path, Func<TBehavior> initializer)
      where TBehavior : WebSocketBehavior
    {
      lock (_sync) {
        path = HttpUtility.UrlDecode (path).TrimEndSlash ();

        WebSocketServiceHost host;
        if (_hosts.TryGetValue (path, out host)) {
          _logger.Error (
            "A WebSocket service with the specified path already exists:\n  path: " + path);

          return;
        }

        host = new WebSocketServiceHost<TBehavior> (path, initializer, _logger);
        if (!_clean)
          host.KeepClean = false;

        if (_waitTime != host.WaitTime)
          host.WaitTime = _waitTime;

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

        _hosts.Add (path, host);
      }
    }

    internal bool InternalTryGetServiceHost (string path, out WebSocketServiceHost host)
    {
      bool ret;
      lock (_sync) {
        path = HttpUtility.UrlDecode (path).TrimEndSlash ();
        ret = _hosts.TryGetValue (path, out host);
      }

      if (!ret)
        _logger.Error (
          "A WebSocket service with the specified path isn't found:\n  path: " + path);

      return ret;
    }

    internal bool Remove (string path)
    {
      WebSocketServiceHost host;
      lock (_sync) {
        path = HttpUtility.UrlDecode (path).TrimEndSlash ();
        if (!_hosts.TryGetValue (path, out host)) {
          _logger.Error (
            "A WebSocket service with the specified path isn't found:\n  path: " + path);

          return false;
        }

        _hosts.Remove (path);
      }

      if (host.State == ServerState.Start)
        host.Stop ((ushort) CloseStatusCode.Away, null);

      return true;
    }

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

        _state = ServerState.Start;
      }
    }

    internal void Stop (CloseEventArgs e, bool send, bool wait)
    {
      lock (_sync) {
        _state = ServerState.ShuttingDown;
        var bytes = send
                    ? WebSocketFrame.CreateCloseFrame (e.PayloadData, false).ToByteArray ()
                    : null;

        var timeout = wait ? _waitTime : TimeSpan.Zero;
        foreach (var host in _hosts.Values)
          host.Sessions.Stop (e, bytes, timeout);

        _hosts.Clear ();
        _state = ServerState.Stop;
      }
    }

    #endregion

    #region Public Methods

    /// <summary>
    /// Sends binary <paramref name="data"/> to every client in the WebSocket services.
    /// </summary>
    /// <param name="data">
    /// An array of <see cref="byte"/> that represents the binary data to send.
    /// </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>
    /// Sends text <paramref name="data"/> to every client in the WebSocket services.
    /// </summary>
    /// <param name="data">
    /// A <see cref="string"/> that represents the text data to send.
    /// </param>
    public void Broadcast (string data)
    {
      var msg = _state.CheckIfStart () ?? data.CheckIfValidSendData ();
      if (msg != null) {
        _logger.Error (msg);
        return;
      }

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

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

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

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

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

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

          if (len < length)
            _logger.Warn (
              String.Format (
                "The data with 'length' cannot be read from 'stream':\n  expected: {0}\n  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.
    /// </summary>
    /// <returns>
    /// A <c>Dictionary&lt;string, Dictionary&lt;string, bool&gt;&gt;</c> that contains
    /// a collection of pairs of a service path and a collection of pairs of a session ID
    /// and a value indicating whether the manager received a Pong from each client in a time,
    /// or <see langword="null"/> if this method isn't available.
    /// </returns>
    public Dictionary<string, Dictionary<string, bool>> Broadping ()
    {
      var msg = _state.CheckIfStart ();
      if (msg != null) {
        _logger.Error (msg);
        return null;
      }

      return broadping (WebSocketFrame.EmptyUnmaskPingBytes, _waitTime);
    }

    /// <summary>
    /// Sends a Ping with the specified <paramref name="message"/> to every client in
    /// the WebSocket services.
    /// </summary>
    /// <returns>
    /// A <c>Dictionary&lt;string, Dictionary&lt;string, bool&gt;&gt;</c> that contains
    /// a collection of pairs of a service path and a collection of pairs of a session ID
    /// and a value indicating whether the manager received a Pong from each client in a time,
    /// or <see langword="null"/> if this method isn't available or <paramref name="message"/>
    /// is invalid.
    /// </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 () ?? WebSocket.CheckPingParameter (message, out data);
      if (msg != null) {
        _logger.Error (msg);
        return null;
      }

      return broadping (WebSocketFrame.CreatePingFrame (data, false).ToByteArray (), _waitTime);
    }

    /// <summary>
    /// Tries to get the WebSocket service host with the specified <paramref name="path"/>.
    /// </summary>
    /// <returns>
    /// <c>true</c> if the service is successfully found; otherwise, <c>false</c>.
    /// </returns>
    /// <param name="path">
    /// A <see cref="string"/> that represents the absolute path to the service to find.
    /// </param>
    /// <param name="host">
    /// When this method returns, a <see cref="WebSocketServiceHost"/> instance that
    /// provides the access to the information in the service, or <see langword="null"/>
    /// if it's not found. 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 InternalTryGetServiceHost (path, out host);
    }

    #endregion
  }
}