//
// System.Net.HttpListenerRequest
//
// Authors:
//	Gonzalo Paniagua Javier (gonzalo.mono@gmail.com)
//	Marek Safar (marek.safar@gmail.com)
//
// Copyright (c) 2005 Novell, Inc. (http://www.novell.com)
// Copyright (c) 2011-2012 Xamarin, Inc. (http://xamarin.com)
//
// 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.
//

using System.Collections;
using System.Collections.Specialized;
using System.Globalization;
using System.IO;
using System.Security.Cryptography.X509Certificates;
using System.Text;
using System.Security.Authentication.ExtendedProtection;
using System.Threading.Tasks;
using System.Net;

namespace System.Net {
	public sealed class HttpListenerRequest
	{
		class Context : TransportContext
		{
			public override ChannelBinding GetChannelBinding (ChannelBindingKind kind)
			{
				throw new NotImplementedException ();
			}
		}

		string [] accept_types;
		Encoding content_encoding;
		long content_length;
		bool cl_set;
		CookieCollection cookies;
		WebHeaderCollection headers;
		string method;
		Stream input_stream;
		Version version;
		NameValueCollection query_string; // check if null is ok, check if read-only, check case-sensitiveness
		string raw_url;
		Uri url;
		Uri referrer;
		string [] user_languages;
		HttpListenerContext context;
		bool is_chunked;
		bool ka_set;
		bool keep_alive;
		delegate X509Certificate2 GCCDelegate ();
		GCCDelegate gcc_delegate;

		static byte [] _100continue = Encoding.ASCII.GetBytes ("HTTP/1.1 100 Continue\r\n\r\n");

		internal HttpListenerRequest (HttpListenerContext context)
		{
			this.context = context;
			headers = new WebHeaderCollection ();
			version = HttpVersion.Version10;
		}

		static char [] separators = new char [] { ' ' };

		internal void SetRequestLine (string req)
		{
			string [] parts = req.Split (separators, 3);
			if (parts.Length != 3) {
				context.ErrorMessage = "Invalid request line (parts).";
				return;
			}

			method = parts [0];
			foreach (char c in method){
				int ic = (int) c;

				if ((ic >= 'A' && ic <= 'Z') ||
				    (ic > 32 && c < 127 && c != '(' && c != ')' && c != '<' &&
				     c != '<' && c != '>' && c != '@' && c != ',' && c != ';' &&
				     c != ':' && c != '\\' && c != '"' && c != '/' && c != '[' &&
				     c != ']' && c != '?' && c != '=' && c != '{' && c != '}'))
					continue;

				context.ErrorMessage = "(Invalid verb)";
				return;
			}

			raw_url = parts [1];
			if (parts [2].Length != 8 || !parts [2].StartsWith ("HTTP/")) {
				context.ErrorMessage = "Invalid request line (version).";
				return;
			}

			try {
				version = new Version (parts [2].Substring (5));
				if (version.Major < 1)
					throw new Exception ();
			} catch {
				context.ErrorMessage = "Invalid request line (version).";
				return;
			}
		}

		void CreateQueryString (string query)
		{
			if (query == null || query.Length == 0) {
				query_string = new NameValueCollection (1);
				return;
			}

			query_string = new NameValueCollection ();
			if (query [0] == '?')
				query = query.Substring (1);
			string [] components = query.Split ('&');
			foreach (string kv in components) {
				int pos = kv.IndexOf ('=');
				if (pos == -1) {
					query_string.Add (null, WebUtility.UrlDecode (kv));
				} else {
					string key = WebUtility.UrlDecode (kv.Substring (0, pos));
					string val = WebUtility.UrlDecode (kv.Substring (pos + 1));
					
					query_string.Add (key, val);
				}
			}
		}

		static bool MaybeUri (string s)
		{
			int p = s.IndexOf (':');
			if (p == -1)
				return false;

			if (p >= 10)
				return false;

			return IsPredefinedScheme (s.Substring (0, p));
		}

		//
		// Using a simple block of if's is twice as slow as the compiler generated
		// switch statement.   But using this tuned code is faster than the
		// compiler generated code, with a million loops on x86-64:
		//
		// With "http": .10 vs .51 (first check)
		// with "https": .16 vs .51 (second check)
		// with "foo": .22 vs .31 (never found)
		// with "mailto": .12 vs .51  (last check)
		//
		//
		static bool IsPredefinedScheme (string scheme)
		{
			if (scheme == null || scheme.Length < 3)
				return false;
			
			char c = scheme [0];
			if (c == 'h')
				return (scheme == "http" || scheme == "https");
			if (c == 'f')
				return (scheme == "file" || scheme == "ftp");
				
			if (c == 'n'){
				c = scheme [1];
				if (c == 'e')
					return (scheme == "news" || scheme == "net.pipe" || scheme == "net.tcp");
				if (scheme == "nntp")
					return true;
				return false;
			}
			if ((c == 'g' && scheme == "gopher") || (c == 'm' && scheme == "mailto"))
				return true;

			return false;
		}

		internal void FinishInitialization ()
		{
			string host = UserHostName;
			if (version > HttpVersion.Version10 && (host == null || host.Length == 0)) {
				context.ErrorMessage = "Invalid host name";
				return;
			}

			string path;
			Uri raw_uri = null;
			if (MaybeUri (raw_url.ToLowerInvariant ()) && Uri.TryCreate (raw_url, UriKind.Absolute, out raw_uri))
				path = raw_uri.PathAndQuery;
			else
				path = raw_url;

			if ((host == null || host.Length == 0))
				host = UserHostAddress;

			if (raw_uri != null)
				host = raw_uri.Host;
	
			int colon = host.IndexOf (':');
			if (colon >= 0)
				host = host.Substring (0, colon);

			string base_uri = String.Format ("{0}://{1}:{2}",
								(IsSecureConnection) ? "https" : "http",
								host, LocalEndPoint.Port);

			if (!Uri.TryCreate (base_uri + path, UriKind.Absolute, out url)){
				context.ErrorMessage = WebUtility.HtmlEncode ("Invalid url: " + base_uri + path);
				return;
			}

			CreateQueryString (url.Query);

			// Use reference source HttpListenerRequestUriBuilder to process url.
			// Fixes #29927
			url = HttpListenerRequestUriBuilder.GetRequestUri (raw_url, url.Scheme,
								url.Authority, url.LocalPath, url.Query);

			if (version >= HttpVersion.Version11) {
				string t_encoding = Headers ["Transfer-Encoding"];
				is_chunked = (t_encoding != null && String.Compare (t_encoding, "chunked", StringComparison.OrdinalIgnoreCase) == 0);
				// 'identity' is not valid!
				if (t_encoding != null && !is_chunked) {
					context.Connection.SendError (null, 501);
					return;
				}
			}

			if (!is_chunked && !cl_set) {
				if (String.Compare (method, "POST", StringComparison.OrdinalIgnoreCase) == 0 ||
				    String.Compare (method, "PUT", StringComparison.OrdinalIgnoreCase) == 0) {
					context.Connection.SendError (null, 411);
					return;
				}
			}

			if (String.Compare (Headers ["Expect"], "100-continue", StringComparison.OrdinalIgnoreCase) == 0) {
				ResponseStream output = context.Connection.GetResponseStream ();
				output.InternalWrite (_100continue, 0, _100continue.Length);
			}
		}

		internal static string Unquote (String str) {
			int start = str.IndexOf ('\"');
			int end = str.LastIndexOf ('\"');
			if (start >= 0 && end >=0)
				str = str.Substring (start + 1, end - 1);
			return str.Trim ();
		}

		internal void AddHeader (string header)
		{
			int colon = header.IndexOf (':');
			if (colon == -1 || colon == 0) {
				context.ErrorMessage = "Bad Request";
				context.ErrorStatus = 400;
				return;
			}

			string name = header.Substring (0, colon).Trim ();
			string val = header.Substring (colon + 1).Trim ();
			string lower = name.ToLower (CultureInfo.InvariantCulture);
			headers.SetInternal (name, val);
			switch (lower) {
				case "accept-language":
					user_languages = val.Split (','); // yes, only split with a ','
					break;
				case "accept":
					accept_types = val.Split (','); // yes, only split with a ','
					break;
				case "content-length":
					try {
						//TODO: max. content_length?
						content_length = Int64.Parse (val.Trim ());
						if (content_length < 0)
							context.ErrorMessage = "Invalid Content-Length.";
						cl_set = true;
					} catch {
						context.ErrorMessage = "Invalid Content-Length.";
					}

					break;
				case "referer":
					try {
						referrer = new Uri (val);
					} catch {
						referrer = new Uri ("http://someone.is.screwing.with.the.headers.com/");
					}
					break;
				case "cookie":
					if (cookies == null)
						cookies = new CookieCollection();

					string[] cookieStrings = val.Split(new char[] {',', ';'});
					Cookie current = null;
					int version = 0;
					foreach (string cookieString in cookieStrings) {
						string str = cookieString.Trim ();
						if (str.Length == 0)
							continue;
						if (str.StartsWith ("$Version")) {
							version = Int32.Parse (Unquote (str.Substring (str.IndexOf ('=') + 1)));
						} else if (str.StartsWith ("$Path")) {
							if (current != null)
								current.Path = str.Substring (str.IndexOf ('=') + 1).Trim ();
						} else if (str.StartsWith ("$Domain")) {
							if (current != null)
								current.Domain = str.Substring (str.IndexOf ('=') + 1).Trim ();
						} else if (str.StartsWith ("$Port")) {
							if (current != null)
								current.Port = str.Substring (str.IndexOf ('=') + 1).Trim ();
						} else {
							if (current != null) {
								cookies.Add (current);
							}
							try {
								current = new Cookie ();
								int idx = str.IndexOf ('=');
								if (idx > 0) {
									current.Name = str.Substring (0, idx).Trim ();
									current.Value =  str.Substring (idx + 1).Trim ();
								} else {
									current.Name = str.Trim ();
									current.Value = String.Empty;
								}
								current.Version = version;
							} catch (CookieException) {
								current = null;
							}
						}
					}
					if (current != null) {
						cookies.Add (current);
					}
					break;
			}
		}

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

			int length = 2048;
			if (content_length > 0)
				length = (int) Math.Min (content_length, (long) length);

			byte [] bytes = new byte [length];
			while (true) {
				// TODO: test if MS has a timeout when doing this
				try {
					IAsyncResult ares = InputStream.BeginRead (bytes, 0, length, null, null);
					if (!ares.IsCompleted && !ares.AsyncWaitHandle.WaitOne (1000))
						return false;
					if (InputStream.EndRead (ares) <= 0)
						return true;
				} catch (ObjectDisposedException) {
					input_stream = null;
					return true;
				} catch {
					return false;
				}
			}
		}

		public string [] AcceptTypes {
			get { return accept_types; }
		}

		public int ClientCertificateError {
			get {
				HttpConnection cnc = context.Connection;
				if (cnc.ClientCertificate == null)
					throw new InvalidOperationException ("No client certificate");
				int [] errors = cnc.ClientCertificateErrors;
				if (errors != null && errors.Length > 0)
					return errors [0];
				return 0;
			}
		}

		public Encoding ContentEncoding {
			get {
				if (content_encoding == null)
					content_encoding = Encoding.Default;
				return content_encoding;
			}
		}

		public long ContentLength64 {
			get { return is_chunked ? -1 : content_length; }
		}

		public string ContentType {
			get { return headers ["content-type"]; }
		}

		public CookieCollection Cookies {
			get {
				// TODO: check if the collection is read-only
				if (cookies == null)
					cookies = new CookieCollection ();
				return cookies;
			}
		}

		public bool HasEntityBody {
			get { return (content_length > 0 || is_chunked); }
		}

		public NameValueCollection Headers {
			get { return headers; }
		}

		public string HttpMethod {
			get { return method; }
		}

		public Stream InputStream {
			get {
				if (input_stream == null) {
					if (is_chunked || content_length > 0)
						input_stream = context.Connection.GetRequestStream (is_chunked, content_length);
					else
						input_stream = Stream.Null;
				}

				return input_stream;
			}
		}

		[MonoTODO ("Always returns false")]
		public bool IsAuthenticated {
			get { return false; }
		}

		public bool IsLocal {
			get { return LocalEndPoint.Address.Equals (RemoteEndPoint.Address); }
		}

		public bool IsSecureConnection {
			get { return context.Connection.IsSecure; } 
		}

		public bool KeepAlive {
			get {
				if (ka_set)
					return keep_alive;

				ka_set = true;
				// 1. Connection header
				// 2. Protocol (1.1 == keep-alive by default)
				// 3. Keep-Alive header
				string cnc = headers ["Connection"];
				if (!String.IsNullOrEmpty (cnc)) {
					keep_alive = (0 == String.Compare (cnc, "keep-alive", StringComparison.OrdinalIgnoreCase));
				} else if (version == HttpVersion.Version11) {
					keep_alive = true;
				} else {
					cnc = headers ["keep-alive"];
					if (!String.IsNullOrEmpty (cnc))
						keep_alive = (0 != String.Compare (cnc, "closed", StringComparison.OrdinalIgnoreCase));
				}
				return keep_alive;
			}
		}

		public IPEndPoint LocalEndPoint {
			get { return context.Connection.LocalEndPoint; }
		}

		public Version ProtocolVersion {
			get { return version; }
		}

		public NameValueCollection QueryString {
			get { return query_string; }
		}

		public string RawUrl {
			get { return raw_url; }
		}

		public IPEndPoint RemoteEndPoint {
			get { return context.Connection.RemoteEndPoint; }
		}

		[MonoTODO ("Always returns Guid.Empty")]
		public Guid RequestTraceIdentifier {
			get { return Guid.Empty; }
		}

		public Uri Url {
			get { return url; }
		}

		public Uri UrlReferrer {
			get { return referrer; }
		}

		public string UserAgent {
			get { return headers ["user-agent"]; }
		}

		public string UserHostAddress {
			get { return LocalEndPoint.ToString (); }
		}

		public string UserHostName {
			get { return headers ["host"]; }
		}

		public string [] UserLanguages {
			get { return user_languages; }
		}

		public IAsyncResult BeginGetClientCertificate (AsyncCallback requestCallback, object state)
		{
			if (gcc_delegate == null)
				gcc_delegate = new GCCDelegate (GetClientCertificate);
			return gcc_delegate.BeginInvoke (requestCallback, state);
		}

		public X509Certificate2 EndGetClientCertificate (IAsyncResult asyncResult)
		{
			if (asyncResult == null)
				throw new ArgumentNullException ("asyncResult");

			if (gcc_delegate == null)
				throw new InvalidOperationException ();

			return gcc_delegate.EndInvoke (asyncResult);
		}

		public X509Certificate2 GetClientCertificate ()
		{
			return context.Connection.ClientCertificate;
		}

		[MonoTODO]
		public string ServiceName {
			get {
				return null;
			}
		}
		
		public TransportContext TransportContext {
			get {
				return new Context ();
			}
		}
		
		[MonoTODO]
		public bool IsWebSocketRequest {
			get {
				return false;
			}
		}

		public Task<X509Certificate2> GetClientCertificateAsync ()
		{
			return Task<X509Certificate2>.Factory.FromAsync (BeginGetClientCertificate, EndGetClientCertificate, null);
		}
	}
}