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

#region Authors
/*
 * Authors:
 * - Gonzalo Paniagua Javier <gonzalo@novell.com>
 */
#endregion

using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Globalization;
using System.IO;
using System.Security.Cryptography.X509Certificates;
using System.Text;

namespace WebSocketSharp.Net
{
  /// <summary>
  /// Provides the access to a request to the <see cref="HttpListener"/>.
  /// </summary>
  /// <remarks>
  /// The HttpListenerRequest class cannot be inherited.
  /// </remarks>
  public sealed class HttpListenerRequest
  {
    #region Private Fields

    private static readonly byte[] _100continue;
    private string[]               _acceptTypes;
    private bool                   _chunked;
    private Encoding               _contentEncoding;
    private long                   _contentLength;
    private bool                   _contentLengthWasSet;
    private HttpListenerContext    _context;
    private CookieCollection       _cookies;
    private WebHeaderCollection    _headers;
    private Guid                   _identifier;
    private Stream                 _inputStream;
    private bool                   _keepAlive;
    private bool                   _keepAliveWasSet;
    private string                 _method;
    private NameValueCollection    _queryString;
    private Uri                    _referer;
    private string                 _uri;
    private Uri                    _url;
    private string[]               _userLanguages;
    private Version                _version;
    private bool                   _websocketRequest;
    private bool                   _websocketRequestWasSet;

    #endregion

    #region Static Constructor

    static HttpListenerRequest ()
    {
      _100continue = Encoding.ASCII.GetBytes ("HTTP/1.1 100 Continue\r\n\r\n");
    }

    #endregion

    #region Internal Constructors

    internal HttpListenerRequest (HttpListenerContext context)
    {
      _context = context;
      _contentLength = -1;
      _headers = new WebHeaderCollection ();
      _identifier = Guid.NewGuid ();
    }

    #endregion

    #region Public Properties

    /// <summary>
    /// Gets the media types which are acceptable for the response.
    /// </summary>
    /// <value>
    /// An array of <see cref="string"/> that contains the media type names in the Accept
    /// request-header, or <see langword="null"/> if the request didn't include an Accept header.
    /// </value>
    public string[] AcceptTypes {
      get {
        return _acceptTypes;
      }
    }

    /// <summary>
    /// Gets an error code that identifies a problem with the client's certificate.
    /// </summary>
    /// <value>
    /// Always returns <c>0</c>.
    /// </value>
    public int ClientCertificateError {
      get {
        return 0; // TODO: Always returns 0.
      }
    }

    /// <summary>
    /// Gets the encoding for the entity body data included in the request.
    /// </summary>
    /// <value>
    /// A <see cref="Encoding"/> that represents the encoding for the entity body data,
    /// or <see cref="Encoding.Default"/> if the request didn't include the information
    /// about the encoding.
    /// </value>
    public Encoding ContentEncoding {
      get {
        return _contentEncoding ?? (_contentEncoding = Encoding.Default);
      }
    }

    /// <summary>
    /// Gets the size of the entity body data included in the request.
    /// </summary>
    /// <value>
    /// A <see cref="long"/> that represents the value of the Content-Length entity-header. The
    /// value is a number of bytes in the entity body data. <c>-1</c> if the size isn't known.
    /// </value>
    public long ContentLength64 {
      get {
        return _contentLength;
      }
    }

    /// <summary>
    /// Gets the media type of the entity body included in the request.
    /// </summary>
    /// <value>
    /// A <see cref="string"/> that represents the value of the Content-Type entity-header.
    /// </value>
    public string ContentType {
      get {
        return _headers["Content-Type"];
      }
    }

    /// <summary>
    /// Gets the cookies included in the request.
    /// </summary>
    /// <value>
    /// A <see cref="CookieCollection"/> that contains the cookies included in the request.
    /// </value>
    public CookieCollection Cookies {
      get {
        return _cookies ?? (_cookies = _headers.GetCookies (false));
      }
    }

    /// <summary>
    /// Gets a value indicating whether the request has the entity body.
    /// </summary>
    /// <value>
    /// <c>true</c> if the request has the entity body; otherwise, <c>false</c>.
    /// </value>
    public bool HasEntityBody {
      get {
        return _contentLength > 0 || _chunked;
      }
    }

    /// <summary>
    /// Gets the HTTP headers used in the request.
    /// </summary>
    /// <value>
    /// A <see cref="NameValueCollection"/> that contains the HTTP headers used in the request.
    /// </value>
    public NameValueCollection Headers {
      get {
        return _headers;
      }
    }

    /// <summary>
    /// Gets the HTTP method used in the request.
    /// </summary>
    /// <value>
    /// A <see cref="string"/> that represents the HTTP method used in the request.
    /// </value>
    public string HttpMethod {
      get {
        return _method;
      }
    }

    /// <summary>
    /// Gets a <see cref="Stream"/> that contains the entity body data included in the request.
    /// </summary>
    /// <value>
    /// A <see cref="Stream"/> that contains the entity body data included in the request.
    /// </value>
    public Stream InputStream {
      get {
        return _inputStream ??
               (_inputStream = HasEntityBody
                               ? _context.Connection.GetRequestStream (_chunked, _contentLength)
                               : Stream.Null);
      }
    }

    /// <summary>
    /// Gets a value indicating whether the client that sent the request is authenticated.
    /// </summary>
    /// <value>
    /// <c>true</c> if the client is authenticated; otherwise, <c>false</c>.
    /// </value>
    public bool IsAuthenticated {
      get {
        return _context.User != null;
      }
    }

    /// <summary>
    /// Gets a value indicating whether the request is sent from the local computer.
    /// </summary>
    /// <value>
    /// <c>true</c> if the request is sent from the local computer; otherwise, <c>false</c>.
    /// </value>
    public bool IsLocal {
      get {
        return RemoteEndPoint.Address.IsLocal ();
      }
    }

    /// <summary>
    /// Gets a value indicating whether the HTTP connection is secured using the SSL protocol.
    /// </summary>
    /// <value>
    /// <c>true</c> if the HTTP connection is secured; otherwise, <c>false</c>.
    /// </value>
    public bool IsSecureConnection {
      get {
        return _context.Connection.IsSecure;
      }
    }

    /// <summary>
    /// Gets a value indicating whether the request is a WebSocket connection request.
    /// </summary>
    /// <value>
    /// <c>true</c> if the request is a WebSocket connection request; otherwise, <c>false</c>.
    /// </value>
    public bool IsWebSocketRequest {
      get {
        if (!_websocketRequestWasSet) {
          _websocketRequest = _method == "GET" &&
                              _version > HttpVersion.Version10 &&
                              _headers.Contains ("Upgrade", "websocket") &&
                              _headers.Contains ("Connection", "Upgrade");

          _websocketRequestWasSet = true;
        }

        return _websocketRequest;
      }
    }

    /// <summary>
    /// Gets a value indicating whether the client requests a persistent connection.
    /// </summary>
    /// <value>
    /// <c>true</c> if the client requests a persistent connection; otherwise, <c>false</c>.
    /// </value>
    public bool KeepAlive {
      get {
        if (!_keepAliveWasSet) {
          string keepAlive;
          _keepAlive = _version > HttpVersion.Version10 ||
                       _headers.Contains ("Connection", "keep-alive") ||
                       ((keepAlive = _headers["Keep-Alive"]) != null && keepAlive != "closed");

          _keepAliveWasSet = true;
        }

        return _keepAlive;
      }
    }

    /// <summary>
    /// Gets the server endpoint as an IP address and a port number.
    /// </summary>
    /// <value>
    /// A <see cref="System.Net.IPEndPoint"/> that represents the server endpoint.
    /// </value>
    public System.Net.IPEndPoint LocalEndPoint {
      get {
        return _context.Connection.LocalEndPoint;
      }
    }

    /// <summary>
    /// Gets the HTTP version used in the request.
    /// </summary>
    /// <value>
    /// A <see cref="Version"/> that represents the HTTP version used in the request.
    /// </value>
    public Version ProtocolVersion {
      get {
        return _version;
      }
    }

    /// <summary>
    /// Gets the query string included in the request.
    /// </summary>
    /// <value>
    /// A <see cref="NameValueCollection"/> that contains the query string parameters.
    /// </value>
    public NameValueCollection QueryString {
      get {
        return _queryString ??
               (_queryString = HttpUtility.InternalParseQueryString (_url.Query, Encoding.UTF8));
      }
    }

    /// <summary>
    /// Gets the raw URL (without the scheme, host, and port) requested by the client.
    /// </summary>
    /// <value>
    /// A <see cref="string"/> that represents the raw URL requested by the client.
    /// </value>
    public string RawUrl {
      get {
        return _url.PathAndQuery; // TODO: Should decode?
      }
    }

    /// <summary>
    /// Gets the client endpoint as an IP address and a port number.
    /// </summary>
    /// <value>
    /// A <see cref="System.Net.IPEndPoint"/> that represents the client endpoint.
    /// </value>
    public System.Net.IPEndPoint RemoteEndPoint {
      get {
        return _context.Connection.RemoteEndPoint;
      }
    }

    /// <summary>
    /// Gets the request identifier of a incoming HTTP request.
    /// </summary>
    /// <value>
    /// A <see cref="Guid"/> that represents the identifier of a request.
    /// </value>
    public Guid RequestTraceIdentifier {
      get {
        return _identifier;
      }
    }

    /// <summary>
    /// Gets the URL requested by the client.
    /// </summary>
    /// <value>
    /// A <see cref="Uri"/> that represents the URL requested by the client.
    /// </value>
    public Uri Url {
      get {
        return _url;
      }
    }

    /// <summary>
    /// Gets the URL of the resource from which the requested URL was obtained.
    /// </summary>
    /// <value>
    /// A <see cref="Uri"/> that represents the value of the Referer request-header,
    /// or <see langword="null"/> if the request didn't include an Referer header.
    /// </value>
    public Uri UrlReferrer {
      get {
        return _referer;
      }
    }

    /// <summary>
    /// Gets the information about the user agent originating the request.
    /// </summary>
    /// <value>
    /// A <see cref="string"/> that represents the value of the User-Agent request-header.
    /// </value>
    public string UserAgent {
      get {
        return _headers["User-Agent"];
      }
    }

    /// <summary>
    /// Gets the server endpoint as an IP address and a port number.
    /// </summary>
    /// <value>
    /// A <see cref="string"/> that represents the server endpoint.
    /// </value>
    public string UserHostAddress {
      get {
        return LocalEndPoint.ToString ();
      }
    }

    /// <summary>
    /// Gets the internet host name and port number (if present) specified by the client.
    /// </summary>
    /// <value>
    /// A <see cref="string"/> that represents the value of the Host request-header.
    /// </value>
    public string UserHostName {
      get {
        return _headers["Host"];
      }
    }

    /// <summary>
    /// Gets the natural languages which are preferred for the response.
    /// </summary>
    /// <value>
    /// An array of <see cref="string"/> that contains the natural language names in
    /// the Accept-Language request-header, or <see langword="null"/> if the request
    /// didn't include an Accept-Language header.
    /// </value>
    public string[] UserLanguages {
      get {
        return _userLanguages;
      }
    }

    #endregion

    #region Private Methods

    private static bool tryCreateVersion (string version, out Version result)
    {
      try {
        result = new Version (version);
        return true;
      }
      catch {
        result = null;
        return false;
      }
    }

    #endregion

    #region Internal Methods

    internal void AddHeader (string header)
    {
      var colon = header.IndexOf (':');
      if (colon == -1) {
        _context.ErrorMessage = "Invalid header";
        return;
      }

      var name = header.Substring (0, colon).Trim ();
      var val = header.Substring (colon + 1).Trim ();
      _headers.InternalSet (name, val, false);

      var lower = name.ToLower (CultureInfo.InvariantCulture);
      if (lower == "accept") {
        _acceptTypes = new List<string> (val.SplitHeaderValue (',')).ToArray ();
        return;
      }

      if (lower == "accept-language") {
        _userLanguages = val.Split (',');
        return;
      }

      if (lower == "content-length") {
        long len;
        if (Int64.TryParse (val, out len) && len >= 0) {
          _contentLength = len;
          _contentLengthWasSet = true;
        }
        else {
          _context.ErrorMessage = "Invalid Content-Length header";
        }

        return;
      }

      if (lower == "content-type") {
        try {
          _contentEncoding = HttpUtility.GetEncoding (val);
        }
        catch {
          _context.ErrorMessage = "Invalid Content-Type header";
        }

        return;
      }

      if (lower == "referer")
        _referer = val.ToUri ();
    }

    internal void FinishInitialization ()
    {
      var host = _headers["Host"];
      var nohost = host == null || host.Length == 0;
      if (_version > HttpVersion.Version10 && nohost) {
        _context.ErrorMessage = "Invalid Host header";
        return;
      }

      if (nohost)
        host = UserHostAddress;

      _url = HttpUtility.CreateRequestUrl (_uri, host, IsWebSocketRequest, IsSecureConnection);
      if (_url == null) {
        _context.ErrorMessage = "Invalid request url";
        return;
      }

      var enc = Headers["Transfer-Encoding"];
      if (_version > HttpVersion.Version10 && enc != null && enc.Length > 0) {
        _chunked = enc.ToLower () == "chunked";
        if (!_chunked) {
          _context.ErrorMessage = String.Empty;
          _context.ErrorStatus = 501;

          return;
        }
      }

      if (!_chunked && !_contentLengthWasSet) {
        var method = _method.ToLower ();
        if (method == "post" || method == "put") {
          _context.ErrorMessage = String.Empty;
          _context.ErrorStatus = 411;

          return;
        }
      }

      var expect = Headers["Expect"];
      if (expect != null && expect.Length > 0 && expect.ToLower () == "100-continue") {
        var output = _context.Connection.GetResponseStream ();
        output.WriteInternally (_100continue, 0, _100continue.Length);
      }
    }

    // Returns true is the stream could be reused.
    internal bool FlushInput ()
    {
      if (!HasEntityBody)
        return true;

      var len = 2048;
      if (_contentLength > 0)
        len = (int) Math.Min (_contentLength, (long) len);

      var buff = new byte[len];
      while (true) {
        // TODO: Test if MS has a timeout when doing this.
        try {
          var ares = InputStream.BeginRead (buff, 0, len, null, null);
          if (!ares.IsCompleted && !ares.AsyncWaitHandle.WaitOne (100))
            return false;

          if (InputStream.EndRead (ares) <= 0)
            return true;
        }
        catch {
          return false;
        }
      }
    }

    internal void SetRequestLine (string requestLine)
    {
      var parts = requestLine.Split (new[] { ' ' }, 3);
      if (parts.Length != 3) {
        _context.ErrorMessage = "Invalid request line (parts)";
        return;
      }

      _method = parts[0];
      if (!_method.IsToken ()) {
        _context.ErrorMessage = "Invalid request line (method)";
        return;
      }

      _uri = parts[1];

      var ver = parts[2];
      if (ver.Length != 8 ||
          !ver.StartsWith ("HTTP/") ||
          !tryCreateVersion (ver.Substring (5), out _version) ||
          _version.Major < 1)
        _context.ErrorMessage = "Invalid request line (version)";
    }

    #endregion

    #region Public Methods

    /// <summary>
    /// Begins getting the client's X.509 v.3 certificate asynchronously.
    /// </summary>
    /// <remarks>
    /// This asynchronous operation must be completed by calling the
    /// <see cref="EndGetClientCertificate"/> method. Typically, that method is invoked by the
    /// <paramref name="requestCallback"/> delegate.
    /// </remarks>
    /// <returns>
    /// An <see cref="IAsyncResult"/> that contains the status of the asynchronous operation.
    /// </returns>
    /// <param name="requestCallback">
    /// An <see cref="AsyncCallback"/> delegate that references the method(s) called when the
    /// asynchronous operation completes.
    /// </param>
    /// <param name="state">
    /// An <see cref="object"/> that contains a user defined object to pass to the
    /// <paramref name="requestCallback"/> delegate.
    /// </param>
    /// <exception cref="NotImplementedException">
    /// This method isn't implemented.
    /// </exception>
    public IAsyncResult BeginGetClientCertificate (AsyncCallback requestCallback, object state)
    {
      // TODO: Not Implemented.
      throw new NotImplementedException ();
    }

    /// <summary>
    /// Ends an asynchronous operation to get the client's X.509 v.3 certificate.
    /// </summary>
    /// <remarks>
    /// This method completes an asynchronous operation started by calling the
    /// <see cref="BeginGetClientCertificate"/> method.
    /// </remarks>
    /// <returns>
    /// A <see cref="X509Certificate2"/> that contains the client's X.509 v.3 certificate.
    /// </returns>
    /// <param name="asyncResult">
    /// An <see cref="IAsyncResult"/> obtained by calling the
    /// <see cref="BeginGetClientCertificate"/> method.
    /// </param>
    /// <exception cref="NotImplementedException">
    /// This method isn't implemented.
    /// </exception>
    public X509Certificate2 EndGetClientCertificate (IAsyncResult asyncResult)
    {
      // TODO: Not Implemented.
      throw new NotImplementedException ();
    }

    /// <summary>
    /// Gets the client's X.509 v.3 certificate.
    /// </summary>
    /// <returns>
    /// A <see cref="X509Certificate2"/> that contains the client's X.509 v.3 certificate.
    /// </returns>
    /// <exception cref="NotImplementedException">
    /// This method isn't implemented.
    /// </exception>
    public X509Certificate2 GetClientCertificate ()
    {
      // TODO: Not Implemented.
      throw new NotImplementedException ();
    }

    /// <summary>
    /// Returns a <see cref="string"/> that represents the current
    /// <see cref="HttpListenerRequest"/>.
    /// </summary>
    /// <returns>
    /// A <see cref="string"/> that represents the current <see cref="HttpListenerRequest"/>.
    /// </returns>
    public override string ToString ()
    {
      var output = new StringBuilder (64);
      output.AppendFormat ("{0} {1} HTTP/{2}\r\n", _method, _uri, _version);
      output.Append (_headers.ToString ());

      return output.ToString ();
    }

    #endregion
  }
}