//
// System.Security.AccessControl.ObjectAce implementation
//
// Authors:
//	Dick Porter  <dick@ximian.com>
//	Atsushi Enomoto  <atsushi@ximian.com>
//	Kenneth Bell
//	James Bellinger  <jfb@zer7.com>
//
// Copyright (C) 2006-2007 Novell, Inc (http://www.novell.com)
// Copyright (C) 2012      James Bellinger
//
// 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.Security.Principal;
using System.Globalization;

namespace System.Security.AccessControl
{
	public sealed class ObjectAce : QualifiedAce
	{
		private Guid object_ace_type;
		private Guid inherited_object_type;
		private ObjectAceFlags object_ace_flags;

		public ObjectAce (AceFlags aceFlags, AceQualifier qualifier,
				  int accessMask, SecurityIdentifier sid,
				  ObjectAceFlags flags, Guid type,
				  Guid inheritedType, bool isCallback,
				  byte[] opaque)
			: base (ConvertType(qualifier, isCallback), aceFlags, opaque)
		{
			AccessMask = accessMask;
			SecurityIdentifier = sid;
			ObjectAceFlags = flags;
			ObjectAceType = type;
			InheritedObjectAceType = inheritedType;
		}

		internal ObjectAce (AceType type, AceFlags flags, int accessMask,
		                    SecurityIdentifier sid, ObjectAceFlags objFlags,
		                    Guid objType, Guid inheritedType, byte[] opaque)
			: base(type, flags, opaque)
		{
			AccessMask = accessMask;
			SecurityIdentifier = sid;
			ObjectAceFlags = objFlags;
			ObjectAceType = objType;
			InheritedObjectAceType = inheritedType;
		}
		
		internal ObjectAce(byte[] binaryForm, int offset)
			: base(binaryForm, offset)
		{
			int len = ReadUShort(binaryForm, offset + 2);
			int lenMinimum = 12 + SecurityIdentifier.MinBinaryLength;
			
			if (offset > binaryForm.Length - len)
				throw new ArgumentException("Invalid ACE - truncated", "binaryForm");
			if (len < lenMinimum)
				throw new ArgumentException("Invalid ACE", "binaryForm");
			
			AccessMask = ReadInt(binaryForm, offset + 4);
			ObjectAceFlags = (ObjectAceFlags)ReadInt(binaryForm, offset + 8);
			
			if (ObjectAceTypePresent) lenMinimum += 16;
			if (InheritedObjectAceTypePresent) lenMinimum += 16;
			if (len < lenMinimum)
				throw new ArgumentException("Invalid ACE", "binaryForm");

			int pos = 12;
			if (ObjectAceTypePresent) {
				ObjectAceType = ReadGuid(binaryForm, offset + pos); pos += 16;
			}
			if (InheritedObjectAceTypePresent) {
				InheritedObjectAceType = ReadGuid(binaryForm, offset + pos); pos += 16;
			}
			
			SecurityIdentifier = new SecurityIdentifier(binaryForm, offset + pos);
			pos += SecurityIdentifier.BinaryLength;
			
			int opaqueLen = len - pos;
			if (opaqueLen > 0) {
				byte[] opaque = new byte[opaqueLen];
				Array.Copy(binaryForm, offset + pos, opaque, 0, opaqueLen);
				SetOpaque (opaque);
			}
		}

		public override int BinaryLength
		{
			get {
				int length = 12 + SecurityIdentifier.BinaryLength + OpaqueLength;
				if (ObjectAceTypePresent) length += 16;
				if (InheritedObjectAceTypePresent) length += 16;
				return length;
			}
		}

		public Guid InheritedObjectAceType {
			get { return inherited_object_type; }
			set { inherited_object_type = value; }
		}
		
		bool InheritedObjectAceTypePresent {
			get { return 0 != (ObjectAceFlags & ObjectAceFlags.InheritedObjectAceTypePresent); }
		}
		
		public ObjectAceFlags ObjectAceFlags {
			get { return object_ace_flags; }
			set { object_ace_flags = value; }
		}
		
		public Guid ObjectAceType {
			get { return object_ace_type; }
			set { object_ace_type = value; }
		}

		bool ObjectAceTypePresent {
			get { return 0 != (ObjectAceFlags & ObjectAceFlags.ObjectAceTypePresent); }
		}
		
		public override void GetBinaryForm (byte[] binaryForm, int offset)
		{
			int len = BinaryLength;
			binaryForm[offset++] = (byte)this.AceType;
			binaryForm[offset++] = (byte)this.AceFlags;
			WriteUShort ((ushort)len, binaryForm, offset); offset += 2;
			WriteInt (AccessMask, binaryForm, offset); offset += 4;
			WriteInt ((int)ObjectAceFlags, binaryForm, offset); offset += 4;
			
			if (0 != (ObjectAceFlags & ObjectAceFlags.ObjectAceTypePresent)) {
				WriteGuid (ObjectAceType, binaryForm, offset); offset += 16;
			}
			if (0 != (ObjectAceFlags & ObjectAceFlags.InheritedObjectAceTypePresent)) {
				WriteGuid (InheritedObjectAceType, binaryForm, offset); offset += 16;
			}
			
			SecurityIdentifier.GetBinaryForm (binaryForm, offset);
			offset += SecurityIdentifier.BinaryLength;
			
			byte[] opaque = GetOpaque ();
			if (opaque != null) {
				Array.Copy (opaque, 0, binaryForm, offset, opaque.Length);
				offset += opaque.Length;
			}
		}
		
		public static int MaxOpaqueLength (bool isCallback)
		{
			// Varies by platform?
			return 65423;
		}
		
		internal override string GetSddlForm()
		{
			if (OpaqueLength != 0)
				throw new NotImplementedException (
					"Unable to convert conditional ACEs to SDDL");
			
			string objType = "";
			if ((ObjectAceFlags & ObjectAceFlags.ObjectAceTypePresent) != 0)
				objType = object_ace_type.ToString("D");
			
			string inhObjType = "";
			if ((ObjectAceFlags & ObjectAceFlags.InheritedObjectAceTypePresent) != 0)
				inhObjType = inherited_object_type.ToString("D");
			
			return string.Format (CultureInfo.InvariantCulture,
			                      "({0};{1};{2};{3};{4};{5})",
			                      GetSddlAceType (AceType),
			                      GetSddlAceFlags (AceFlags),
			                      GetSddlAccessRights (AccessMask),
			                      objType,
			                      inhObjType,
			                      SecurityIdentifier.GetSddlForm ());
		}
		
		private static AceType ConvertType(AceQualifier qualifier, bool isCallback)
		{
			switch(qualifier)
			{
			case AceQualifier.AccessAllowed:
				if (isCallback)
					return AceType.AccessAllowedCallbackObject;
				else
					return AceType.AccessAllowedObject;
				
			case AceQualifier.AccessDenied:
				if (isCallback)
					return AceType.AccessDeniedCallbackObject;
				else
					return AceType.AccessDeniedObject;
				
			case AceQualifier.SystemAlarm:
				if (isCallback)
					return AceType.SystemAlarmCallbackObject;
				else
					return AceType.SystemAlarmObject;
				
			case AceQualifier.SystemAudit:
				if (isCallback)
					return AceType.SystemAuditCallbackObject;
				else
					return AceType.SystemAuditObject;
				
			default:
				throw new ArgumentException("Unrecognized ACE qualifier: " + qualifier, "qualifier");
			}
		}
		
		private void WriteGuid (Guid val, byte[] buffer,
		                        int offset)
		{
			byte[] guidData = val.ToByteArray();
			Array.Copy(guidData, 0, buffer, offset, 16);
		}
		
		private Guid ReadGuid(byte[] buffer, int offset)
		{
			byte[] temp = new byte[16];
			Array.Copy(buffer, offset, temp, 0, 16);
			return new Guid(temp);
		}
	}
}