Trigger.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;

namespace Deveel.Data.Sql.Triggers {
    public class Trigger : IDbObject {
        public Trigger(TriggerInfo triggerInfo) {
            if (triggerInfo == null)
                throw new ArgumentNullException("triggerInfo");

            TriggerInfo = triggerInfo;
        }

        public TriggerInfo TriggerInfo { get; private set; }

        public ObjectName TriggerName {
            get { return TriggerInfo.TriggerName; }
        }

        public TriggerType TriggerType {
            get { return TriggerInfo.TriggerType; }
        }

        DbObjectType IDbObject.ObjectType {
            get { return DbObjectType.Trigger; }
        }

        ObjectName IDbObject.FullName {
            get { return TriggerInfo.TriggerName; }
        }

        private void FireTrigger(IQuery context, TableEvent tableEvent) {
            if (TriggerType == TriggerType.Callback) {
                NotifyTriggerEvent(context, tableEvent);
            } else {
                ExecuteProcedure(context);
            }
        }

        private void ExecuteProcedure(IQuery context) {
            throw new NotImplementedException();
        }

        private void NotifyTriggerEvent(IQuery context, TableEvent tableEvent) {
            var tableName = tableEvent.Table.FullName;
            var eventType = tableEvent.EventType;

            var triggerEvent = new TriggerEvent(context.Session, TriggerName, tableName, eventType, tableEvent.OldRowId,
                tableEvent.NewRow);
            // TODO: context.RegisterEvent(triggerEvent);
        }

        public bool CanInvoke(TableEvent context) {
            if ((TriggerInfo.EventType & context.EventType) == 0)
                return false;

            var tableName = context.Table.TableInfo.TableName;
            return TriggerInfo.TableName == null ||
                   TriggerInfo.TableName.Equals(tableName, true);
        }

        public void Invoke(IQuery context, TableEvent tableEvent) {
            var isBefore = (tableEvent.EventType & TriggerEventType.Before) != 0;

            var transaction = context.Session.Transaction;
            if (transaction is ITableStateHandler) {
                var stateHandler = (ITableStateHandler) transaction;
                var oldState = stateHandler.TableState;
                var newState = new OldNewTableState(tableEvent.Table.FullName, tableEvent.OldRowId.RowNumber, tableEvent.NewRow,
                    isBefore);

                stateHandler.SetTableState(newState);

                try {
                    FireTrigger(context, tableEvent);
                } finally {
                    stateHandler.SetTableState(oldState);
                }
            } else {
                FireTrigger(context, tableEvent);
            }
        }
    }
}