/*
 * *************************************************************************************
 *  Copyright (C) 2008 EsperTech, Inc. All rights reserved.                            *
 *  http://esper.codehaus.org                                                          *
 *  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.regression.client;

import com.espertech.esper.epl.expression.ExprNode;
import com.espertech.esper.pattern.*;
import com.espertech.esper.pattern.observer.*;
import com.espertech.esper.client.EPException;

import java.util.List;

public class MyFileExistsObserverFactory extends ObserverFactorySupport
{
    protected ExprNode filenameExpression;
    protected MatchedEventConvertor convertor;

    public void setObserverParameters(List<ExprNode> expressionParameters, MatchedEventConvertor convertor) throws ObserverParameterException
    {
        String message = "File exists observer takes a single string filename parameter";
        if (expressionParameters.size() != 1)
        {
            throw new ObserverParameterException(message);
        }
        if (!(expressionParameters.get(0).getExprEvaluator().getType() == String.class))
        {
            throw new ObserverParameterException(message);
        }

        this.filenameExpression = expressionParameters.get(0);
        this.convertor = convertor;
    }

    public EventObserver makeObserver(PatternAgentInstanceContext context, MatchedEventMap beginState, ObserverEventEvaluator observerEventEvaluator, EvalStateNodeNumber stateNodeId, Object observerState)
    {
        Object filename = PatternExpressionUtil.evaluate("File-exists observer ", beginState, filenameExpression, convertor, null);
        if (filename == null)
        {
            throw new EPException("Filename evaluated to null");
        }

        return new MyFileExistsObserver(beginState, observerEventEvaluator, filename.toString());
    }
}