#region MIT License
/*
 * WebSocketServiceManager.cs
 *
 * The MIT License
 *
 * Copyright (c) 2012-2013 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.Linq;
using System.Timers;

namespace WebSocketSharp.Server {

  /// <summary>
  /// Manages the collection of <see cref="WebSocketService"/> objects.
  /// </summary>
  public class WebSocketServiceManager {

    #region Fields

    private object                               _forSweep;
    private volatile bool                        _isStopped;
    private volatile bool                        _isSweeping;
    private Dictionary<string, WebSocketService> _services;
    private Timer                                _sweepTimer;
    private object                               _syncRoot;

    #endregion

    #region Constructor

    internal WebSocketServiceManager()
    {
      _forSweep   = new object();
      _isStopped  = false;
      _isSweeping = false;
      _services   = new Dictionary<string, WebSocketService>();
      _syncRoot   = new object();

      setSweepTimer();
      startSweepTimer();
    }

    #endregion

    #region Properties

    /// <summary>
    /// Gets the collection of IDs of active <see cref="WebSocketService"/> objects
    /// managed by the <see cref="WebSocketServiceManager"/>.
    /// </summary>
    /// <value>
    /// An IEnumerable&lt;string&gt; that contains the collection of IDs of active <see cref="WebSocketService"/> objects.
    /// </value>
    public IEnumerable<string> ActiveIDs {
      get {
        return from result in Broadping(String.Empty)
               where result.Value
               select result.Key;
      }
    }

    /// <summary>
    /// Gets the number of <see cref="WebSocketService"/> objects
    /// managed by the <see cref="WebSocketServiceManager"/>.
    /// </summary>
    /// <value>
    /// An <see cref="int"/> that contains the number of <see cref="WebSocketService"/> objects
    /// managed by the <see cref="WebSocketServiceManager"/>.
    /// </value>
    public int Count {
      get {
        lock (_syncRoot)
        {
          return _services.Count;
        }
      }
    } 

    /// <summary>
    /// Gets the collection of IDs of inactive <see cref="WebSocketService"/> objects
    /// managed by the <see cref="WebSocketServiceManager"/>.
    /// </summary>
    /// <value>
    /// An IEnumerable&lt;string&gt; that contains the collection of IDs of inactive <see cref="WebSocketService"/> objects.
    /// </value>
    public IEnumerable<string> InactiveIDs {
      get {
        return from result in Broadping(String.Empty)
               where !result.Value
               select result.Key;
      }
    }

    /// <summary>
    /// Gets the collection of IDs of <see cref="WebSocketService"/> objects
    /// managed by the <see cref="WebSocketServiceManager"/>.
    /// </summary>
    /// <value>
    /// An IEnumerable&lt;string&gt; that contains the collection of IDs of <see cref="WebSocketService"/> objects.
    /// </value>
    public IEnumerable<string> IDs {
      get {
        lock (_syncRoot)
        {
          return _services.Keys;
        }
      }
    }

    /// <summary>
    /// Gets a value indicating whether the <see cref="WebSocketServiceManager"/> cleans up
    /// the inactive <see cref="WebSocketService"/> objects periodically.
    /// </summary>
    /// <value>
    /// <c>true</c> if the <see cref="WebSocketServiceManager"/> cleans up the inactive <see cref="WebSocketService"/> objects
    /// every 60 seconds; otherwise, <c>false</c>.
    /// </value>
    public bool Sweeped {
      get {
        return _sweepTimer.Enabled;
      }

      internal set {
        if (value && !_isStopped)
          startSweepTimer();

        if (!value)
          stopSweepTimer();
      }
    }

    #endregion

    #region Private Methods

    private void broadcast(byte[] data)
    {
      lock (_syncRoot)
      {
        foreach (var service in _services.Values)
          service.Send(data);
      }
    }

    private void broadcast(string data)
    {
      lock (_syncRoot)
      {
        foreach (var service in _services.Values)
          service.Send(data);
      }
    }

    private void broadcastAsync(byte[] data)
    {
      var copied   = copy();
      var services = copied.Values.GetEnumerator();

      Action completed = null;
      completed = () =>
      {
        if (services.MoveNext())
          services.Current.SendAsync(data, completed);
      };

      if (services.MoveNext())
        services.Current.SendAsync(data, completed);
    }

    private void broadcastAsync(string data)
    {
      var copied   = copy();
      var services = copied.Values.GetEnumerator();

      Action completed = null;
      completed = () =>
      {
        if (services.MoveNext())
          services.Current.SendAsync(data, completed);
      };

      if (services.MoveNext())
        services.Current.SendAsync(data, completed);
    }

    private Dictionary<string, WebSocketService> copy()
    {
      lock (_syncRoot)
      {
        return new Dictionary<string, WebSocketService>(_services);
      }
    }

    private string createID()
    {
      return Guid.NewGuid().ToString("N");
    }

    private void setSweepTimer()
    {
      _sweepTimer = new Timer(60 * 1000);
      _sweepTimer.Elapsed += (sender, e) =>
      {
        Sweep();
      };
    }

    private void startSweepTimer()
    {
      if (!Sweeped)
        _sweepTimer.Start();
    }

    private void stop(ushort code, string reason, bool ignoreArgs)
    {
      stopSweepTimer();
      lock (_syncRoot)
      {
        if (_isStopped)
          return;

        _isStopped = true;
        foreach (var service in copy().Values)
          if (ignoreArgs)
            service.Stop();
          else
            service.Stop(code, reason);
      }
    }

    private void stopSweepTimer()
    {
      if (Sweeped)
        _sweepTimer.Stop();
    }

    #endregion

    #region Internal Methods

    internal string Add(WebSocketService service)
    {
      lock (_syncRoot)
      {
        if (_isStopped)
          return null;

        var id = createID();
        _services.Add(id, service);

        return id;
      }
    }

    internal bool Remove(string id)
    {
      lock (_syncRoot)
      {
        return _services.Remove(id);
      }
    }

    internal void Stop()
    {
      stop(0, null, true);
    }

    internal void Stop(ushort code, string reason)
    {
      stop(code, reason, false);
    }

    internal void Stop(CloseStatusCode code, string reason)
    {
      Stop((ushort)code, reason);
    }

    #endregion

    #region Public Methods

    /// <summary>
    /// Broadcasts the specified array of <see cref="byte"/> to the clients of every <see cref="WebSocketService"/>
    /// managed by the <see cref="WebSocketServiceManager"/>.
    /// </summary>
    /// <param name="data">
    /// An array of <see cref="byte"/> to broadcast.
    /// </param>
    public void Broadcast(byte[] data)
    {
      if (_isStopped)
        broadcast(data);
      else
        broadcastAsync(data);
    }

    /// <summary>
    /// Broadcasts the specified <see cref="string"/> to the clients of every <see cref="WebSocketService"/>
    /// managed by the <see cref="WebSocketServiceManager"/>.
    /// </summary>
    /// <param name="data">
    /// A <see cref="string"/> to broadcast.
    /// </param>
    public void Broadcast(string data)
    {
      if (_isStopped)
        broadcast(data);
      else
        broadcastAsync(data);
    }

    /// <summary>
    /// Pings with the specified <see cref="string"/> to the clients of every <see cref="WebSocketService"/>
    /// managed by the <see cref="WebSocketServiceManager"/>.
    /// </summary>
    /// <returns>
    /// A Dictionary&lt;string, bool&gt; that contains the collection of IDs and values
    /// indicating whether each <see cref="WebSocketService"/> received a Pong in a time.
    /// </returns>
    /// <param name="message">
    /// A <see cref="string"/> that contains a message.
    /// </param>
    public Dictionary<string, bool> Broadping(string message)
    {
      var result = new Dictionary<string, bool>();
      foreach (var session in copy())
        result.Add(session.Key, session.Value.Ping(message));

      return result;
    }

    /// <summary>
    /// Cleans up the inactive <see cref="WebSocketService"/> objects.
    /// </summary>
    public void Sweep()
    {
      if (_isStopped || _isSweeping || Count == 0)
        return;

      lock (_forSweep)
      {
        _isSweeping = true;
        foreach (var id in InactiveIDs)
        {
          lock (_syncRoot)
          {
            if (_isStopped)
            {
              _isSweeping = false;
              return;
            }

            WebSocketService service;
            if (TryGetWebSocketService(id, out service))
              service.Stop(CloseStatusCode.ABNORMAL, String.Empty);
          }
        }

        _isSweeping = false;
      }
    }

    /// <summary>
    /// Tries to get the <see cref="WebSocketService"/> associated with the specified <paramref name="id"/>.
    /// </summary>
    /// <returns>
    /// <c>true</c> if the <see cref="WebSocketServiceManager"/> manages the <see cref="WebSocketService"/> with the specified <paramref name="id"/>; otherwise, <c>false</c>.
    /// </returns>
    /// <param name="id">
    /// A <see cref="string"/> that contains the ID to find.
    /// </param>
    /// <param name="service">
    /// When this method returns, contains the <see cref="WebSocketService"/> with the specified <paramref name="id"/>, if the <paramref name="id"/> is found; otherwise, <see langword="null"/>.
    /// </param>
    public bool TryGetWebSocketService(string id, out WebSocketService service)
    {
      lock (_syncRoot)
      {
        return _services.TryGetValue(id, out service);
      }
    }

    #endregion
  }
}