//
// X501Name.cs: X.501 Distinguished Names stuff 
//
// Author:
//	Sebastien Pouliot <sebastien@ximian.com>
//
// (C) 2002, 2003 Motus Technologies Inc. (http://www.motus.com)
// Copyright (C) 2004-2006 Novell, Inc (http://www.novell.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;
using System.Globalization;
using System.Text;

using Mono.Security;
using Mono.Security.Cryptography;

namespace Mono.Security.X509 {

	// References:
	// 1.	Information technology - Open Systems Interconnection - The Directory: Models
	//	http://www.itu.int/rec/recommendation.asp?type=items&lang=e&parent=T-REC-X.501-200102-I
	// 2.	RFC2253: Lightweight Directory Access Protocol (v3): UTF-8 String Representation of Distinguished Names
	//	http://www.ietf.org/rfc/rfc2253.txt

	/*
	 * Name ::= CHOICE { RDNSequence }
	 * 
	 * RDNSequence ::= SEQUENCE OF RelativeDistinguishedName
	 * 
	 * RelativeDistinguishedName ::= SET OF AttributeTypeAndValue
	 */
#if INSIDE_CORLIB || INSIDE_SYSTEM
	internal
#else
	public 
#endif
	sealed class X501 {

		static byte[] countryName = { 0x55, 0x04, 0x06 };
		static byte[] organizationName = { 0x55, 0x04, 0x0A };
		static byte[] organizationalUnitName = { 0x55, 0x04, 0x0B };
		static byte[] commonName = { 0x55, 0x04, 0x03 };
		static byte[] localityName = { 0x55, 0x04, 0x07 };
		static byte[] stateOrProvinceName = { 0x55, 0x04, 0x08 };
		static byte[] streetAddress = { 0x55, 0x04, 0x09 };
		static byte[] serialNumber = { 0x55, 0x04, 0x05 };
		static byte[] domainComponent = { 0x09, 0x92, 0x26, 0x89, 0x93, 0xF2, 0x2C, 0x64, 0x01, 0x19 };
		static byte[] userid = { 0x09, 0x92, 0x26, 0x89, 0x93, 0xF2, 0x2C, 0x64, 0x01, 0x01 };
		static byte[] email = { 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x09, 0x01 };
		static byte[] dnQualifier = { 0x55, 0x04, 0x2E };
		static byte[] title = { 0x55, 0x04, 0x0C };
		static byte[] surname = { 0x55, 0x04, 0x04 };
		static byte[] givenName = { 0x55, 0x04, 0x2A };
		static byte[] initial = { 0x55, 0x04, 0x2B };

		private X501 () 
		{
		}

		static public string ToString (ASN1 seq) 
		{
			StringBuilder sb = new StringBuilder ();
			for (int i = 0; i < seq.Count; i++) {
				ASN1 entry = seq [i];
				AppendEntry (sb, entry, true);

				// separator (not on last iteration)
				if (i < seq.Count - 1)
					sb.Append (", ");
			}
			return sb.ToString ();
		}

		static public string ToString (ASN1 seq, bool reversed, string separator, bool quotes)
		{
			StringBuilder sb = new StringBuilder ();

			if (reversed) {
				for (int i = seq.Count - 1; i >= 0; i--) {
					ASN1 entry = seq [i];
					AppendEntry (sb, entry, quotes);

					// separator (not on last iteration)
					if (i > 0)
						sb.Append (separator);
				}
			} else {
				for (int i = 0; i < seq.Count; i++) {
					ASN1 entry = seq [i];
					AppendEntry (sb, entry, quotes);

					// separator (not on last iteration)
					if (i < seq.Count - 1)
						sb.Append (separator);
				}
			}
			return sb.ToString ();
		}

		static private void AppendEntry (StringBuilder sb, ASN1 entry, bool quotes)
		{
			// multiple entries are valid
			for (int k = 0; k < entry.Count; k++) {
				ASN1 pair = entry [k];
				ASN1 s = pair [1];
				if (s == null)
					continue;

				ASN1 poid = pair [0];
				if (poid == null)
					continue;

				if (poid.CompareValue (countryName))
					sb.Append ("C=");
				else if (poid.CompareValue (organizationName))
					sb.Append ("O=");
				else if (poid.CompareValue (organizationalUnitName))
					sb.Append ("OU=");
				else if (poid.CompareValue (commonName))
					sb.Append ("CN=");
				else if (poid.CompareValue (localityName))
					sb.Append ("L=");
				else if (poid.CompareValue (stateOrProvinceName))
					sb.Append ("S=");	// NOTE: RFC2253 uses ST=
				else if (poid.CompareValue (streetAddress))
					sb.Append ("STREET=");
				else if (poid.CompareValue (domainComponent))
					sb.Append ("DC=");
				else if (poid.CompareValue (userid))
					sb.Append ("UID=");
				else if (poid.CompareValue (email))
					sb.Append ("E=");	// NOTE: Not part of RFC2253
				else if (poid.CompareValue (dnQualifier))
					sb.Append ("dnQualifier=");
				else if (poid.CompareValue (title))
					sb.Append ("T=");
				else if (poid.CompareValue (surname))
					sb.Append ("SN=");
				else if (poid.CompareValue (givenName))
					sb.Append ("G=");
				else if (poid.CompareValue (initial))
					sb.Append ("I=");
				else if (poid.CompareValue (serialNumber))
					sb.Append ("SERIALNUMBER=");					
				else {
					// unknown OID
					sb.Append ("OID.");	// NOTE: Not present as RFC2253
					sb.Append (ASN1Convert.ToOid (poid));
					sb.Append ("=");
				}

				string sValue = null;
				// 16bits or 8bits string ? TODO not complete (+special chars!)
				if (s.Tag == 0x1E) {
					// BMPSTRING
					StringBuilder sb2 = new StringBuilder ();
					for (int j = 1; j < s.Value.Length; j += 2)
						sb2.Append ((char)s.Value[j]);
					sValue = sb2.ToString ();
				} else {
					if (s.Tag == 0x14)
						sValue = Encoding.UTF7.GetString (s.Value);
					else
						sValue = Encoding.UTF8.GetString (s.Value);
				}

				// in some cases we must quote (") the value
				// Note: this doesn't seems to conform to RFC2253
				// Set of characters that need quoting is taken from s_quoteNeedingChars
				// in corefx/src/System.Security.Cryptography.X509Certificates/src/Internal/Cryptography/Pal.Unix/X500NameEncoder.cs
				char[] specials = { ',', '+', '"', '=', '<', '>', ';', '#', '\n' };
				if (quotes) {
					if ((sValue.IndexOfAny (specials, 0, sValue.Length) > 0) ||
					    sValue.StartsWith (" ") || (sValue.EndsWith (" ")))
						sValue = "\"" + sValue.Replace ("\"", "") + "\"";
				}

				sb.Append (sValue);

				// separator (not on last iteration)
				if (k < entry.Count - 1)
					sb.Append (", ");
			}
		}

		static private X520.AttributeTypeAndValue GetAttributeFromOid (string attributeType) 
		{
			string s = attributeType.ToUpper (CultureInfo.InvariantCulture).Trim ();
			switch (s) {
				case "C":
					return new X520.CountryName ();
				case "O":
					return new X520.OrganizationName ();
				case "OU":
					return new X520.OrganizationalUnitName ();
				case "CN":
					return new X520.CommonName ();
				case "L":
					return new X520.LocalityName ();
				case "S":	// Microsoft
				case "ST":	// RFC2253
					return new X520.StateOrProvinceName ();
				case "E":	// NOTE: Not part of RFC2253
					return new X520.EmailAddress ();
				case "DC":	// RFC2247
					return new X520.DomainComponent ();
				case "UID":	// RFC1274
					return new X520.UserId ();
				case "DNQUALIFIER":
					return new X520.DnQualifier ();
				case "T":
					return new X520.Title ();
				case "SN":
					return new X520.Surname ();
				case "G":
					return new X520.GivenName ();
				case "I":
					return new X520.Initial ();
				case "SERIALNUMBER":
					return new X520.SerialNumber ();
				default:
					if (s.StartsWith ("OID.")) {
						// MUST support it but it OID may be without it
						return new X520.Oid (s.Substring (4));
					} else {
						if (IsOid (s))
							return new X520.Oid (s);
						else
							return null;
					}
			}
		}

		static private bool IsOid (string oid)
		{
			try {
				ASN1 asn = ASN1Convert.FromOid (oid);
				return (asn.Tag == 0x06);
			}
			catch {
				return false;
			}
		}

		// no quote processing
		static private X520.AttributeTypeAndValue ReadAttribute (string value, ref int pos)
		{
			while ((value[pos] == ' ') && (pos < value.Length))
				pos++;

			// get '=' position in substring
			int equal = value.IndexOf ('=', pos);
			if (equal == -1) {
				string msg = Locale.GetText ("No attribute found.");
				throw new FormatException (msg);
			}

			string s = value.Substring (pos, equal - pos);
			X520.AttributeTypeAndValue atv = GetAttributeFromOid (s);
			if (atv == null) {
				string msg = Locale.GetText ("Unknown attribute '{0}'.");
				throw new FormatException (String.Format (msg, s));
			}
			pos = equal + 1; // skip the '='
			return atv;
		}

		static private bool IsHex (char c)
		{
			if (Char.IsDigit (c))
				return true;
			char up = Char.ToUpper (c, CultureInfo.InvariantCulture);
			return ((up >= 'A') && (up <= 'F'));
		}

		static string ReadHex (string value, ref int pos)
		{
			StringBuilder sb = new StringBuilder ();
			// it is (at least an) 8 bits char
			sb.Append (value[pos++]);
			sb.Append (value[pos]);
			// look ahead for a 16 bits char
			if ((pos < value.Length - 4) && (value[pos+1] == '\\') && IsHex (value[pos+2])) {
				pos += 2; // pass last char and skip \
				sb.Append (value[pos++]);
				sb.Append (value[pos]);
			}
			byte[] data = CryptoConvert.FromHex (sb.ToString ());
			return Encoding.UTF8.GetString (data);
		}

		static private int ReadEscaped (StringBuilder sb, string value, int pos)
		{
			switch (value[pos]) {
			case '\\':
			case '"':
			case '=':
			case ';':
			case '<':
			case '>':
			case '+':
			case '#':
			case ',':
				sb.Append (value[pos]);
				return pos;
			default:
				if (pos >= value.Length - 2) {
					string msg = Locale.GetText ("Malformed escaped value '{0}'.");
					throw new FormatException (string.Format (msg, value.Substring (pos)));
				}
				// it's either a 8 bits or 16 bits char
				sb.Append (ReadHex (value, ref pos));
				return pos;
			}
		}

		static private int ReadQuoted (StringBuilder sb, string value, int pos)
		{
			int original = pos;
			while (pos <= value.Length) {
				switch (value[pos]) {
				case '"':
					return pos;
				case '\\':
					return ReadEscaped (sb, value, pos);
				default:
					sb.Append (value[pos]);
					pos++;
					break;
				}
			}
			string msg = Locale.GetText ("Malformed quoted value '{0}'.");
			throw new FormatException (string.Format (msg, value.Substring (original)));
		}

		static private string ReadValue (string value, ref int pos)
		{
			int original = pos;
			StringBuilder sb = new StringBuilder ();
			while (pos < value.Length) {
				switch (value [pos]) {
				case '\\':
					pos = ReadEscaped (sb, value, ++pos);
					break;
				case '"':
					pos = ReadQuoted (sb, value, ++pos);
					break;
				case '=':
				case ';':
				case '<':
				case '>':
					string msg = Locale.GetText ("Malformed value '{0}' contains '{1}' outside quotes.");
					throw new FormatException (string.Format (msg, value.Substring (original), value[pos]));
				case '+':
				case '#':
					throw new NotImplementedException ();
				case ',':
					pos++;
					return sb.ToString ();
				default:
					sb.Append (value[pos]);
					break;
				}
				pos++;
			}
			return sb.ToString ();
		}

		static public ASN1 FromString (string rdn) 
		{
			if (rdn == null)
				throw new ArgumentNullException ("rdn");

			int pos = 0;
			ASN1 asn1 = new ASN1 (0x30);
			while (pos < rdn.Length) {
				X520.AttributeTypeAndValue atv = ReadAttribute (rdn, ref pos);
				atv.Value = ReadValue (rdn, ref pos);

				ASN1 sequence = new ASN1 (0x31);
				sequence.Add (atv.GetASN1 ());
				asn1.Add (sequence); 
			}
			return asn1;
		}
	}
}