/* ****************************************************************************

 *

 * Copyright (c) Microsoft Corporation. 

 *

 * This source code is subject to terms and conditions of the Microsoft Public License. A 

 * copy of the license can be found in the License.html file at the root of this distribution. If 

 * you cannot locate the  Microsoft Public License, please send an email to 

 * dlr@microsoft.com. By using this source code in any fashion, you are agreeing to be bound 

 * by the terms of the Microsoft Public License.

 *

 * You must not remove this notice, or any other, from this software.

 *

 *

 * ***************************************************************************/

using System; using Microsoft;





#if !SILVERLIGHT // ComObject



#if CODEPLEX_40

using System.Linq.Expressions;

#else

using Microsoft.Linq.Expressions;

#endif

using System.Runtime.CompilerServices;

#if !CODEPLEX_40
using Microsoft.Runtime.CompilerServices;
#endif




#if CODEPLEX_40

namespace System.Dynamic {

#else

namespace Microsoft.Scripting {

#endif

    internal sealed class BoundDispEvent : DynamicObject {

        private object _rcw;

        private Guid _sourceIid;

        private int _dispid;



        internal BoundDispEvent(object rcw, Guid sourceIid, int dispid) {

            _rcw = rcw;

            _sourceIid = sourceIid;

            _dispid = dispid;

        }



        /// <summary>

        /// Provides the implementation of performing AddAssign and SubtractAssign binary operations.

        /// </summary>

        /// <param name="binder">The binder provided by the call site.</param>

        /// <param name="handler">The handler for the operation.</param>

        /// <param name="result">The result of the operation.</param>

        /// <returns>true if the operation is complete, false if the call site should determine behavior.</returns>

        public override bool TryBinaryOperation(BinaryOperationBinder binder, object handler, out object result) {

            if (binder.Operation == ExpressionType.AddAssign) {

                result = InPlaceAdd(handler);

                return true;

            }



            if (binder.Operation == ExpressionType.SubtractAssign) {

                result = InPlaceSubtract(handler);

                return true;

            }



            result = null;

            return false;

        }



        private static void VerifyHandler(object handler) {

            if (handler is Delegate && handler.GetType() != typeof(Delegate)) {

                return; // delegate

            }



            if (handler is IDynamicMetaObjectProvider) {

                return; // IDMOP

            }



            throw Error.UnsupportedHandlerType();

        }



        /// <summary>

        /// Adds a handler to an event.

        /// </summary>

        /// <param name="handler">The handler to be added.</param>

        /// <returns>The original event with handler added.</returns>

        [SpecialName]

        public object InPlaceAdd(object handler) {

            ContractUtils.RequiresNotNull(handler, "handler");

            VerifyHandler(handler);



            ComEventSink comEventSink = ComEventSink.FromRuntimeCallableWrapper(_rcw, _sourceIid, true);

            comEventSink.AddHandler(_dispid, handler);

            return this;

        }



        /// <summary>

        /// Removes handler from the event.

        /// </summary>

        /// <param name="handler">The handler to be removed.</param>

        /// <returns>The original event with handler removed.</returns>

        [SpecialName]

        public object InPlaceSubtract(object handler) {

            ContractUtils.RequiresNotNull(handler, "handler");

            VerifyHandler(handler);



            ComEventSink comEventSink = ComEventSink.FromRuntimeCallableWrapper(_rcw, _sourceIid, false);

            if (comEventSink != null) {

                comEventSink.RemoveHandler(_dispid, handler);

            }



            return this;

        }

    }

}



#endif