Event.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 System.Collections.Generic;

namespace Deveel.Data.Diagnostics {
    public abstract class Event : IEvent {
        private IDictionary<string, object> metadata;
        private IEventSource source;

        protected Event() 
            : this(DateTimeOffset.UtcNow) {
        }

        protected Event(DateTimeOffset timeStamp) {
            TimeStamp = timeStamp;
        }

        private IDictionary<string, object> GenerateEventData() {
            var dictionary = new Dictionary<string, object>();
            GetEventData(dictionary);
            return dictionary;
        }

        protected virtual void GetEventData(Dictionary<string, object> data) {
        }

        public IEventSource EventSource {
            get {
                if (source == null)
                    return null;

                return OnSourceGet(source);
            }
            set { source = OnSourceSet(value); }
        }

        public DateTimeOffset TimeStamp { get; private set; }

        protected virtual IEventSource OnSourceGet(IEventSource eventSource) {
            return eventSource;
        }

        protected virtual IEventSource OnSourceSet(IEventSource eventSource) {
            return eventSource;
        }

        IDictionary<string, object> IEvent.EventData {
            get {
                if (metadata == null)
                    metadata = GenerateEventData();

                return metadata;
            }
        }
    }
}