/*
 ***************************************************************************************
 *  Copyright (C) 2006 EsperTech, Inc. All rights reserved.                            *
 *  http://www.espertech.com/esper                                                     *
 *  http://www.espertech.com                                                           *
 *  ---------------------------------------------------------------------------------- *
 *  The software in this package is published under the terms of the GPL license       *
 *  a copy of which has been included with this distribution in the license.txt file.  *
 ***************************************************************************************
 */
package com.espertech.esper.epl.view;

import com.espertech.esper.core.context.util.AgentInstanceContext;

/**
 * An output condition that is satisfied at the first event
 * of either a time-based or count-based batch.
 */
public class OutputConditionFirst extends OutputConditionBase implements OutputCondition {
    private final OutputCondition innerCondition;
    private boolean witnessedFirst;

    public OutputConditionFirst(OutputCallback outputCallback, AgentInstanceContext agentInstanceContext, OutputConditionFactory innerConditionFactory) {
        super(outputCallback);
        OutputCallback localCallback = createCallbackToLocal();
        this.innerCondition = innerConditionFactory.make(agentInstanceContext, localCallback);
        this.witnessedFirst = false;
    }

    public void updateOutputCondition(int newEventsCount, int oldEventsCount) {
        if (!witnessedFirst) {
            witnessedFirst = true;
            boolean doOutput = true;
            boolean forceUpdate = false;
            outputCallback.continueOutputProcessing(doOutput, forceUpdate);
        }
        innerCondition.updateOutputCondition(newEventsCount, oldEventsCount);
    }

    private OutputCallback createCallbackToLocal() {
        return new OutputCallback() {
            public void continueOutputProcessing(boolean doOutput, boolean forceUpdate) {
                OutputConditionFirst.this.continueOutputProcessing(forceUpdate);
            }
        };
    }

    public void terminated() {
        outputCallback.continueOutputProcessing(true, true);
    }

    public void stop() {
        // no action required
    }

    private void continueOutputProcessing(boolean forceUpdate) {
        boolean doOutput = !witnessedFirst;
        outputCallback.continueOutputProcessing(doOutput, forceUpdate);
        witnessedFirst = false;
    }
}