//
// ContentDispositionHeaderValue.cs
//
// Authors:
//	Marek Safar  <marek.safar@gmail.com>
//
// Copyright (C) 2012 Xamarin Inc (http://www.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.Generic;
using System.Text;
using System.Globalization;

namespace System.Net.Http.Headers
{
	public class ContentDispositionHeaderValue : ICloneable
	{
		string dispositionType;
		List<NameValueHeaderValue> parameters;

		private ContentDispositionHeaderValue ()
		{
		}

		public ContentDispositionHeaderValue (string dispositionType)
		{
			DispositionType = dispositionType;
		}

		protected ContentDispositionHeaderValue (ContentDispositionHeaderValue source)
		{
			if (source == null)
				throw new ArgumentNullException ("source");

			dispositionType = source.dispositionType;
			if (source.parameters != null) {
				foreach (var item in source.parameters)
					Parameters.Add (new NameValueHeaderValue (item));
			}
		}

		public DateTimeOffset? CreationDate {
			get {
				return GetDateValue ("creation-date");
			}
			set {
				SetDateValue ("creation-date", value);
			}
		}
		
		public string DispositionType {
			get {
				return dispositionType;
			}
			set {
				Parser.Token.Check (value);
				dispositionType = value;
			}
		}

		public string FileName {
			get {
				var value = FindParameter ("filename");
				if (value == null)
					return null;

				return DecodeValue (value, false);
			}
			set {
				if (value != null)
					value = EncodeBase64Value (value);

				SetValue ("filename", value);
			}
		}

		public string FileNameStar {
			get {
				var value = FindParameter ("filename*");
				if (value == null)
					return null;

				return DecodeValue (value, true);
			}
			set {
				if (value != null)
					value = EncodeRFC5987 (value);

				SetValue ("filename*", value);
			}
		}

		public DateTimeOffset? ModificationDate {
			get {
				return GetDateValue ("modification-date");
			}
			set {
				SetDateValue ("modification-date", value);
			}
		}

		public string Name {
			get {
				return FindParameter ("name");
			}
			set {
				SetValue ("name", value);
			}
		}

		public ICollection<NameValueHeaderValue> Parameters {
			get {
				return parameters ?? (parameters = new List<NameValueHeaderValue> ());
			}
		}

		public DateTimeOffset? ReadDate {
			get {
				return GetDateValue ("read-date");
			}
			set {
				SetDateValue ("read-date", value);
			}
		}

		public long? Size {
			get {
				var found = FindParameter ("size");
				long result;
				if (Parser.Long.TryParse (found, out result))
					return result;

				return null;
			}
			set {
				if (value == null) {
					SetValue ("size", null);
					return;
				}

				if (value < 0)
					throw new ArgumentOutOfRangeException ("value");

				SetValue ("size", value.Value.ToString (CultureInfo.InvariantCulture));
			}
		}

		object ICloneable.Clone ()
		{
			return new ContentDispositionHeaderValue (this);
		}

		public override bool Equals (object obj)
		{
			var source = obj as ContentDispositionHeaderValue;
			return source != null &&
				string.Equals (source.dispositionType, dispositionType, StringComparison.OrdinalIgnoreCase) &&
				source.parameters.SequenceEqual (parameters);
		}

		string FindParameter (string name)
		{
			if (parameters == null)
				return null;

			foreach (var entry in parameters) {
				if (string.Equals (entry.Name, name, StringComparison.OrdinalIgnoreCase))
					return entry.Value;
			}

			return null;
		}

		DateTimeOffset? GetDateValue (string name)
		{
			var value = FindParameter (name);
			if (value == null || value == null)
				return null;

			if (value.Length < 3)
				return null;

			if (value[0] == '\"')
				value = value.Substring (1, value.Length - 2);

			DateTimeOffset offset;
			if (Lexer.TryGetDateValue (value, out offset))
				return offset;

			return null;
		}

		static string EncodeBase64Value (string value)
		{
			for (int i = 0; i < value.Length; ++i) {
				var ch = value[i];
				if (ch > 127) {
					var encoding = Encoding.UTF8;
					return string.Format ("\"=?{0}?B?{1}?=\"",
						encoding.WebName, Convert.ToBase64String (encoding.GetBytes (value)));
				}
			}

			if (!Lexer.IsValidToken (value))
				return "\"" + value + "\"";

			return value;
		}

		static string EncodeRFC5987 (string value)
		{
			var encoding = Encoding.UTF8;
			StringBuilder sb = new StringBuilder (value.Length + 11);
			sb.Append (encoding.WebName);
			sb.Append ('\'');
			sb.Append ('\'');

			for (int i = 0; i < value.Length; ++i) {
				var ch = value[i];
				if (ch > 127) {
					foreach (var b in encoding.GetBytes (new[] { ch })) {
						sb.Append ('%');
						sb.Append (b.ToString ("X2"));
					}

					continue;
				}

				sb.Append (ch);
			}

			return sb.ToString ();
		}

		static string DecodeValue (string value, bool extendedNotation)
		{
			//
			// A short (length <= 78 characters)
			// parameter value containing only non-`tspecials' characters SHOULD be
			// represented as a single `token'.  A short parameter value containing
			// only ASCII characters, but including `tspecials' characters, SHOULD
			// be represented as `quoted-string'.  Parameter values longer than 78
			// characters, or which contain non-ASCII characters, MUST be encoded as
			// specified in [RFC 2184].
			//
			if (value.Length < 2)
				return value;

			string[] sep;
			Encoding encoding;

			// Quoted string
			if (value[0] == '\"') {
				//
				// Is Base64 encoded ?
				// encoded-word := "=?" charset "?" encoding "?" encoded-text "?="
				//
				sep = value.Split ('?');
				if (sep.Length != 5 || sep[0] != "\"=" || sep[4] != "=\"" || (sep[2] != "B" && sep[2] != "b"))
					return value;

				try {
					encoding = Encoding.GetEncoding (sep[1]);
					return encoding.GetString (Convert.FromBase64String (sep[3]));
				} catch {
					return value;
				}
			}

			if (!extendedNotation)
				return value;

			//
			// RFC 5987: Charset/Language Encoding
			//
			sep = value.Split ('\'');
			if (sep.Length != 3)
				return null;

			try {
				encoding = Encoding.GetEncoding (sep[0]);
			} catch {
				return null;
			}

			// TODO: What to do with sep[1] language

			value = sep[2];

			int pct_encoded = value.IndexOf ('%');
			if (pct_encoded < 0)
				return value;

			StringBuilder sb = new StringBuilder ();
			byte[] buffer = null;
			int buffer_pos = 0;

			for (int i = 0; i < value.Length;) {
				var ch = value[i];
				if (ch == '%') {
					var unescaped = ch;
					ch = Uri.HexUnescape (value, ref i);
					if (ch != unescaped) {
						if (buffer == null)
							buffer = new byte[value.Length - i + 1];

						buffer[buffer_pos++] = (byte) ch;
						continue;
					}
				} else {
					++i;
				}

				if (buffer_pos != 0) {
					sb.Append (encoding.GetChars (buffer, 0, buffer_pos));
					buffer_pos = 0;
				}

				sb.Append (ch);
			}

			if (buffer_pos != 0) {
				sb.Append (encoding.GetChars (buffer, 0, buffer_pos));
			}

			return sb.ToString ();
		}

		public override int GetHashCode ()
		{
			return dispositionType.ToLowerInvariant ().GetHashCode () ^
				HashCodeCalculator.Calculate (parameters);
		}

		public static ContentDispositionHeaderValue Parse (string input)
		{
			ContentDispositionHeaderValue value;
			if (TryParse (input, out value))
				return value;

			throw new FormatException (input);
		}

		void SetDateValue (string key, DateTimeOffset? value)
		{
			SetValue (key, value == null ? null : ("\"" + value.Value.ToString ("r", CultureInfo.InvariantCulture)) + "\"");
		}

		void SetValue (string key, string value)
		{
			if (parameters == null)
				parameters = new List<NameValueHeaderValue> ();

			parameters.SetValue (key, value);
		}

		public override string ToString ()
		{
			return dispositionType + CollectionExtensions.ToString (parameters);
		}

		public static bool TryParse (string input, out ContentDispositionHeaderValue parsedValue)
		{
			parsedValue = null;

			var lexer = new Lexer (input);
			var t = lexer.Scan ();
			if (t.Kind != Token.Type.Token)
				return false;

			List<NameValueHeaderValue> parameters = null;
			var type = lexer.GetStringValue (t);

			t = lexer.Scan ();

			switch (t.Kind) {
			case Token.Type.SeparatorSemicolon:
				if (!NameValueHeaderValue.TryParseParameters (lexer, out parameters, out t) || t != Token.Type.End)
					return false;
				break;
			case Token.Type.End:
				break;
			default:
				return false;
			}

			parsedValue = new ContentDispositionHeaderValue () {
				dispositionType = type,
				parameters = parameters
			};

			return true;
		}
	}
}