/*
 *  Copyright 2004-2006 Stefan Reuter
 *
 *  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.
 *
 */
package org.asteriskjava.fastagi;

import java.lang.reflect.Constructor;

import org.asteriskjava.util.Log;
import org.asteriskjava.util.LogFactory;

/**
 * Abstract base class for common mapping strategies.
 * <p>
 * If you implement your own mapping strategy you can derive from this class.
 * 
 * @author srt
 * @since 0.3
 */
public abstract class AbstractMappingStrategy implements MappingStrategy
{
    /**
     * Reference to Asterisk-Java's logging subsystem.
     */
    protected Log logger = LogFactory.getLog(getClass());

    /**
     * Creates a new instance of an AGI script.
     * 
     * @param className Class name of the AGI script. The class must implement
     *            {@link AgiScript}.
     * @return the created instance of the AGI script class. If the instance
     *         can't be created an error is logged and <code>null</code> is
     *         returned.
     */
    @SuppressWarnings("unchecked")
    protected AgiScript createAgiScriptInstance(String className)
    {
        Class tmpClass;
        Class<AgiScript> agiScriptClass;
        Constructor<AgiScript> constructor;
        AgiScript agiScript;

        agiScript = null;

        try
        {
            tmpClass = Class.forName(className);
        }
        catch (ClassNotFoundException e1)
        {
            logger.error("Unable to create AgiScript instance of type " + className
                    + ": Class not found, make sure the class exists and is available on the CLASSPATH");
            return null;
        }

        if (!AgiScript.class.isAssignableFrom(tmpClass))
        {
            logger.error("Unable to create AgiScript instance of type " + className
                    + ": Class does not implement the AgiScript interface");
            return null;
        }

        agiScriptClass = (Class<AgiScript>) tmpClass;
        try
        {
            constructor = agiScriptClass.getConstructor();
            agiScript = constructor.newInstance();
        }
        catch (Exception e)
        {
            logger.error("Unable to create AgiScript instance of type " + className, e);
        }

        return agiScript;
    }
}