/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 *
 */

package org.apache.jmeter.functions;


import java.util.Collection;
import java.util.LinkedList;
import java.util.List;

import org.apache.jmeter.engine.util.CompoundVariable;
import org.apache.jmeter.samplers.SampleResult;
import org.apache.jmeter.samplers.Sampler;
import org.apache.jmeter.util.JMeterUtils;

/**
 * Function to get a JMeter Variable
 *
 * Parameters:
 * - variable name
 * - default value
 *
 * Returns:
 * - the variable value, but if not found
 * - the default value if set, and if not the variable name itself
 * @since 2.3RC3
 */
public class Variable extends AbstractFunction {

    private static final List<String> desc = new LinkedList<>();

    private static final String KEY = "__V"; //$NON-NLS-1$

    // Number of parameters expected - used to reject invalid calls
    private static final int MIN_PARAMETER_COUNT = 1;
    private static final int MAX_PARAMETER_COUNT = 2;

    static {
        desc.add(JMeterUtils.getResString("variable_name_param")); //$NON-NLS-1$
        desc.add(JMeterUtils.getResString("property_default_param")); //$NON-NLS-1$
    }

    private Object[] values;

    public Variable() {
        //used for test
    }

    /** {@inheritDoc} */
    @Override
    public String execute(SampleResult previousResult, Sampler currentSampler) throws InvalidVariableException {
        String variableName = ((CompoundVariable) values[0]).execute();
        String variableDefault = variableName;
        if (values.length > 1) {
            variableDefault = ((CompoundVariable) values[1]).execute();
        }
        String variableValue = getVariables().get(variableName);
        return variableValue == null ? variableDefault : variableValue;
    }

    /** {@inheritDoc} */
    @Override
    public void setParameters(Collection<CompoundVariable> parameters) throws InvalidVariableException {
        checkParameterCount(parameters, MIN_PARAMETER_COUNT, MAX_PARAMETER_COUNT);
        values = parameters.toArray();
    }

    /** {@inheritDoc} */
    @Override
    public String getReferenceKey() {
        return KEY;
    }

    /** {@inheritDoc} */
    @Override
    public List<String> getArgumentDesc() {
        return desc;
    }

}
