#region License
/*
 * QueryStringCollection.cs
 *
 * This code is derived from HttpUtility.cs (System.Net) of Mono
 * (http://www.mono-project.com).
 *
 * The MIT License
 *
 * Copyright (c) 2005-2009 Novell, Inc. (http://www.novell.com)
 * Copyright (c) 2018 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

#region Authors
/*
 * Authors:
 * - Patrik Torstensson <Patrik.Torstensson@labs2.com>
 * - Wictor Wilén (decode/encode functions) <wictor@ibizkit.se>
 * - Tim Coleman <tim@timcoleman.com>
 * - Gonzalo Paniagua Javier <gonzalo@ximian.com>
 */
#endregion

using System;
using System.Collections.Specialized;
using System.Text;

namespace WebSocketSharp.Net
{
  internal sealed class QueryStringCollection : NameValueCollection
  {
    #region Public Constructors

    public QueryStringCollection ()
    {
    }

    public QueryStringCollection (int capacity)
      : base (capacity)
    {
    }

    #endregion

    #region Private Methods

    private static string urlDecode (string s, Encoding encoding)
    {
      return s.IndexOfAny (new[] { '%', '+' }) > -1
             ? HttpUtility.UrlDecode (s, encoding)
             : s;
    }

    #endregion

    #region Public Methods

    public static QueryStringCollection Parse (string query)
    {
      return Parse (query, Encoding.UTF8);
    }

    public static QueryStringCollection Parse (string query, Encoding encoding)
    {
      if (query == null)
        return new QueryStringCollection (1);

      var len = query.Length;
      if (len == 0)
        return new QueryStringCollection (1);

      if (query == "?")
        return new QueryStringCollection (1);

      if (query[0] == '?')
        query = query.Substring (1);

      if (encoding == null)
        encoding = Encoding.UTF8;

      var ret = new QueryStringCollection ();

      var components = query.Split ('&');
      foreach (var component in components) {
        len = component.Length;
        if (len == 0)
          continue;

        if (component == "=")
          continue;

        var i = component.IndexOf ('=');
        if (i < 0) {
          ret.Add (null, urlDecode (component, encoding));
          continue;
        }

        if (i == 0) {
          ret.Add (null, urlDecode (component.Substring (1), encoding));
          continue;
        }

        var name = urlDecode (component.Substring (0, i), encoding);

        var start = i + 1;
        var val = start < len
                  ? urlDecode (component.Substring (start), encoding)
                  : String.Empty;

        ret.Add (name, val);
      }

      return ret;
    }

    public override string ToString ()
    {
      var buff = new StringBuilder ();

      foreach (var key in AllKeys)
        buff.AppendFormat ("{0}={1}&", key, this[key]);

      if (buff.Length > 0)
        buff.Length--;

      return buff.ToString ();
    }

    #endregion
  }
}