#region License
/*
 * WebSocketServiceManager.cs
 *
 * The MIT License
 *
 * Copyright (c) 2012-2021 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>
  /// Provides the management function for the WebSocket services.
  /// </summary>
  /// <remarks>
  /// This class manages the WebSocket services provided by
  /// the <see cref="WebSocketServer"/> or <see cref="HttpServer"/> class.
  /// </remarks>
  public class WebSocketServiceManager
  {
    #region Private Fields

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

    #endregion

    #region Internal Constructors

    internal WebSocketServiceManager (Logger log)
    {
      _log = log;

      _hosts = new Dictionary<string, WebSocketServiceHost> ();
      _keepClean = true;
      _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 service host instances for the WebSocket services.
    /// </summary>
    /// <value>
    ///   <para>
    ///   An <c>IEnumerable&lt;WebSocketServiceHost&gt;</c> instance.
    ///   </para>
    ///   <para>
    ///   It provides an enumerator which supports the iteration over
    ///   the collection of the service host instances.
    ///   </para>
    /// </value>
    public IEnumerable<WebSocketServiceHost> Hosts {
      get {
        lock (_sync)
          return _hosts.Values.ToList ();
      }
    }

    /// <summary>
    /// Gets the service host instance for a WebSocket service with
    /// the specified path.
    /// </summary>
    /// <value>
    ///   <para>
    ///   A <see cref="WebSocketServiceHost"/> instance or
    ///   <see langword="null"/> if not found.
    ///   </para>
    ///   <para>
    ///   The service host instance provides the function to access
    ///   the information in the service.
    ///   </para>
    /// </value>
    /// <param name="path">
    ///   <para>
    ///   A <see cref="string"/> that specifies an absolute path to
    ///   the service to find.
    ///   </para>
    ///   <para>
    ///   / is trimmed from the end of the string if present.
    ///   </para>
    /// </param>
    /// <exception cref="ArgumentNullException">
    /// <paramref name="path"/> is <see langword="null"/>.
    /// </exception>
    /// <exception cref="ArgumentException">
    ///   <para>
    ///   <paramref name="path"/> is an empty string.
    ///   </para>
    ///   <para>
    ///   -or-
    ///   </para>
    ///   <para>
    ///   <paramref name="path"/> is not an absolute path.
    ///   </para>
    ///   <para>
    ///   -or-
    ///   </para>
    ///   <para>
    ///   <paramref name="path"/> includes either or both
    ///   query and fragment components.
    ///   </para>
    /// </exception>
    public WebSocketServiceHost this[string path] {
      get {
        if (path == null)
          throw new ArgumentNullException ("path");

        if (path.Length == 0)
          throw new ArgumentException ("An empty string.", "path");

        if (path[0] != '/') {
          var msg = "It is not an absolute path.";

          throw new ArgumentException (msg, "path");
        }

        if (path.IndexOfAny (new[] { '?', '#' }) > -1) {
          var msg = "It includes either or both query and fragment components.";

          throw new ArgumentException (msg, "path");
        }

        WebSocketServiceHost host;

        InternalTryGetServiceHost (path, out host);

        return host;
      }
    }

    /// <summary>
    /// Gets or sets a value indicating whether the inactive sessions in
    /// the WebSocket services are cleaned up periodically.
    /// </summary>
    /// <remarks>
    /// The set operation does nothing if the server has already started or
    /// it is shutting down.
    /// </remarks>
    /// <value>
    ///   <para>
    ///   <c>true</c> if the inactive sessions are cleaned up every 60
    ///   seconds; otherwise, <c>false</c>.
    ///   </para>
    ///   <para>
    ///   The default value is <c>true</c>.
    ///   </para>
    /// </value>
    public bool KeepClean {
      get {
        return _keepClean;
      }

      set {
        lock (_sync) {
          if (!canSet ())
            return;

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

          _keepClean = value;
        }
      }
    }

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

    /// <summary>
    /// Gets or sets the time to wait for the response to the WebSocket Ping
    /// or Close.
    /// </summary>
    /// <remarks>
    /// The set operation does nothing if the server has already started or
    /// it is shutting down.
    /// </remarks>
    /// <value>
    ///   <para>
    ///   A <see cref="TimeSpan"/> to wait for the response.
    ///   </para>
    ///   <para>
    ///   The default value is the same as 1 second.
    ///   </para>
    /// </value>
    /// <exception cref="ArgumentOutOfRangeException">
    /// The value specified for a set operation is zero or less.
    /// </exception>
    public TimeSpan WaitTime {
      get {
        return _waitTime;
      }

      set {
        if (value <= TimeSpan.Zero) {
          var msg = "It is zero or less.";

          throw new ArgumentOutOfRangeException ("value", msg);
        }

        lock (_sync) {
          if (!canSet ())
            return;

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

          _waitTime = value;
        }
      }
    }

    #endregion

    #region Private Methods

    private bool canSet ()
    {
      return _state == ServerState.Ready || _state == ServerState.Stop;
    }

    #endregion

    #region Internal Methods

    internal bool InternalTryGetServiceHost (
      string path, out WebSocketServiceHost host
    )
    {
      path = path.TrimSlashFromEnd ();

      lock (_sync)
        return _hosts.TryGetValue (path, out host);
    }

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

        _state = ServerState.Start;
      }
    }

    internal void Stop (ushort code, string reason)
    {
      lock (_sync) {
        _state = ServerState.ShuttingDown;

        foreach (var host in _hosts.Values)
          host.Stop (code, reason);

        _state = ServerState.Stop;
      }
    }

    #endregion

    #region Public Methods

    /// <summary>
    /// Adds a WebSocket service with the specified behavior, path,
    /// and delegate.
    /// </summary>
    /// <param name="path">
    ///   <para>
    ///   A <see cref="string"/> that specifies an absolute path to
    ///   the service to add.
    ///   </para>
    ///   <para>
    ///   / is trimmed from the end of the string if present.
    ///   </para>
    /// </param>
    /// <param name="initializer">
    ///   <para>
    ///   An <c>Action&lt;TBehavior&gt;</c> delegate or
    ///   <see langword="null"/> if not needed.
    ///   </para>
    ///   <para>
    ///   The delegate invokes the method called when initializing
    ///   a new session instance for the service.
    ///   </para>
    /// </param>
    /// <typeparam name="TBehavior">
    ///   <para>
    ///   The type of the behavior for the service.
    ///   </para>
    ///   <para>
    ///   It must inherit the <see cref="WebSocketBehavior"/> class.
    ///   </para>
    ///   <para>
    ///   And also, it must have a public parameterless constructor.
    ///   </para>
    /// </typeparam>
    /// <exception cref="ArgumentNullException">
    /// <paramref name="path"/> is <see langword="null"/>.
    /// </exception>
    /// <exception cref="ArgumentException">
    ///   <para>
    ///   <paramref name="path"/> is an empty string.
    ///   </para>
    ///   <para>
    ///   -or-
    ///   </para>
    ///   <para>
    ///   <paramref name="path"/> is not an absolute path.
    ///   </para>
    ///   <para>
    ///   -or-
    ///   </para>
    ///   <para>
    ///   <paramref name="path"/> includes either or both
    ///   query and fragment components.
    ///   </para>
    ///   <para>
    ///   -or-
    ///   </para>
    ///   <para>
    ///   <paramref name="path"/> is already in use.
    ///   </para>
    /// </exception>
    public void AddService<TBehavior> (
      string path, Action<TBehavior> initializer
    )
      where TBehavior : WebSocketBehavior, new ()
    {
      if (path == null)
        throw new ArgumentNullException ("path");

      if (path.Length == 0)
        throw new ArgumentException ("An empty string.", "path");

      if (path[0] != '/') {
        var msg = "It is not an absolute path.";

        throw new ArgumentException (msg, "path");
      }

      if (path.IndexOfAny (new[] { '?', '#' }) > -1) {
        var msg = "It includes either or both query and fragment components.";

        throw new ArgumentException (msg, "path");
      }

      path = path.TrimSlashFromEnd ();

      lock (_sync) {
        WebSocketServiceHost host;

        if (_hosts.TryGetValue (path, out host)) {
          var msg = "It is already in use.";

          throw new ArgumentException (msg, "path");
        }

        host = new WebSocketServiceHost<TBehavior> (path, initializer, _log);

        if (!_keepClean)
          host.KeepClean = false;

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

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

        _hosts.Add (path, host);
      }
    }

    /// <summary>
    /// Removes all WebSocket services managed by the manager.
    /// </summary>
    /// <remarks>
    /// A service is stopped with close status 1001 (going away)
    /// if it has already started.
    /// </remarks>
    public void Clear ()
    {
      List<WebSocketServiceHost> hosts = null;

      lock (_sync) {
        hosts = _hosts.Values.ToList ();

        _hosts.Clear ();
      }

      foreach (var host in hosts) {
        if (host.State == ServerState.Start)
          host.Stop (1001, String.Empty);
      }
    }

    /// <summary>
    /// Removes a WebSocket service with the specified path.
    /// </summary>
    /// <remarks>
    /// The service is stopped with close status 1001 (going away)
    /// if it has already started.
    /// </remarks>
    /// <returns>
    /// <c>true</c> if the service is successfully found and removed;
    /// otherwise, <c>false</c>.
    /// </returns>
    /// <param name="path">
    ///   <para>
    ///   A <see cref="string"/> that specifies an absolute path to
    ///   the service to remove.
    ///   </para>
    ///   <para>
    ///   / is trimmed from the end of the string if present.
    ///   </para>
    /// </param>
    /// <exception cref="ArgumentNullException">
    /// <paramref name="path"/> is <see langword="null"/>.
    /// </exception>
    /// <exception cref="ArgumentException">
    ///   <para>
    ///   <paramref name="path"/> is an empty string.
    ///   </para>
    ///   <para>
    ///   -or-
    ///   </para>
    ///   <para>
    ///   <paramref name="path"/> is not an absolute path.
    ///   </para>
    ///   <para>
    ///   -or-
    ///   </para>
    ///   <para>
    ///   <paramref name="path"/> includes either or both
    ///   query and fragment components.
    ///   </para>
    /// </exception>
    public bool RemoveService (string path)
    {
      if (path == null)
        throw new ArgumentNullException ("path");

      if (path.Length == 0)
        throw new ArgumentException ("An empty string.", "path");

      if (path[0] != '/') {
        var msg = "It is not an absolute path.";

        throw new ArgumentException (msg, "path");
      }

      if (path.IndexOfAny (new[] { '?', '#' }) > -1) {
        var msg = "It includes either or both query and fragment components.";

        throw new ArgumentException (msg, "path");
      }

      path = path.TrimSlashFromEnd ();
      WebSocketServiceHost host;

      lock (_sync) {
        if (!_hosts.TryGetValue (path, out host))
          return false;

        _hosts.Remove (path);
      }

      if (host.State == ServerState.Start)
        host.Stop (1001, String.Empty);

      return true;
    }

    /// <summary>
    /// Tries to get the service host instance for a WebSocket service with
    /// the specified path.
    /// </summary>
    /// <returns>
    /// <c>true</c> if the service is successfully found; otherwise,
    /// <c>false</c>.
    /// </returns>
    /// <param name="path">
    ///   <para>
    ///   A <see cref="string"/> that specifies an absolute path to
    ///   the service to find.
    ///   </para>
    ///   <para>
    ///   / is trimmed from the end of the string if present.
    ///   </para>
    /// </param>
    /// <param name="host">
    ///   <para>
    ///   When this method returns, a <see cref="WebSocketServiceHost"/>
    ///   instance or <see langword="null"/> if not found.
    ///   </para>
    ///   <para>
    ///   The service host instance provides the function to access
    ///   the information in the service.
    ///   </para>
    /// </param>
    /// <exception cref="ArgumentNullException">
    /// <paramref name="path"/> is <see langword="null"/>.
    /// </exception>
    /// <exception cref="ArgumentException">
    ///   <para>
    ///   <paramref name="path"/> is an empty string.
    ///   </para>
    ///   <para>
    ///   -or-
    ///   </para>
    ///   <para>
    ///   <paramref name="path"/> is not an absolute path.
    ///   </para>
    ///   <para>
    ///   -or-
    ///   </para>
    ///   <para>
    ///   <paramref name="path"/> includes either or both
    ///   query and fragment components.
    ///   </para>
    /// </exception>
    public bool TryGetServiceHost (string path, out WebSocketServiceHost host)
    {
      if (path == null)
        throw new ArgumentNullException ("path");

      if (path.Length == 0)
        throw new ArgumentException ("An empty string.", "path");

      if (path[0] != '/') {
        var msg = "It is not an absolute path.";

        throw new ArgumentException (msg, "path");
      }

      if (path.IndexOfAny (new[] { '?', '#' }) > -1) {
        var msg = "It includes either or both query and fragment components.";

        throw new ArgumentException (msg, "path");
      }

      return InternalTryGetServiceHost (path, out host);
    }

    #endregion
  }
}