SystemContextExtensions.cs

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// 
//  Copyright 2010-2015 Deveel
// 
//    Licensed under the Apache License, Version 2.0 (the "License");
//    you may not use this file except in compliance with the License.
//    You may obtain a copy of the License at
// 
//        http://www.apache.org/licenses/LICENSE-2.0
// 
//    Unless required by applicable law or agreed to in writing, software
//    distributed under the License is distributed on an "AS IS" BASIS,
//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//    See the License for the specific language governing permissions and
//    limitations under the License.
//

using System;

using Deveel.Data.Diagnostics;
using Deveel.Data.Services;

namespace Deveel.Data.Sql.Triggers {
    public static class SystemContextExtensions {
        public static void UseTriggerListener(this ISystemContext context, ITriggerListener listener) {
            var router = context.ResolveService<TriggerEventRouter>();
            if (router == null)
                context.RegisterService<TriggerEventRouter>();

            context.RegisterInstance(listener);
        }

        public static void ListenTriggers(this ISystemContext context, Action<TriggerEvent> listener) {
            context.UseTriggerListener(new DelegatedTriggerListener(context, listener));
        }

        #region DelegatedTriggerListener

        private class DelegatedTriggerListener : ITriggerListener, IDisposable {
            private Action<TriggerEvent> listener;
            private ISystemContext systemContext;

            public DelegatedTriggerListener(ISystemContext systemContext, Action<TriggerEvent> listener) {
                this.systemContext = systemContext;
                this.listener = listener;
            }

            public void OnTriggerEvent(TriggerEvent trigger) {
                try {
                    if (listener != null)
                        listener(trigger);
                } catch (Exception ex) {
                    // TODO: form a source...
                    // TODO: systemContext.EventRegistry.Error(null, ex);
                }
            }

            public void Dispose() {
                listener = null;
                systemContext = null;
            }
        }

        #endregion
    }
}