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/*
 * Copyright (c) 2006 Pyxis Technologies inc.
 *
 * This is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA,
 * or see the FSF site: http://www.fsf.org.
 */

package com.greenpepper.runner;

import java.lang.reflect.Constructor;
import java.util.List;

import com.greenpepper.util.ClassUtils;
import static com.greenpepper.util.CollectionUtil.shift;
import static com.greenpepper.util.CollectionUtil.toList;
import com.greenpepper.util.StringUtil;
import com.greenpepper.util.cli.Converter;

/**
 * A converter which creates a new instance of an object. This converter expects
 * a semi-colon comma separated list of values. The first value is the class name of the
 * object to instantiate. Following values represent a list of parameters. Any semi-colon special character
 * %3B
 found inside an actual parameter will be converted to ; (way to keep semi-colon as parameter)
 * 
 * The target class must abide to the following rules:
 * 

 * When no parameter is expected, it must provide a default constructor
 * Otherwise, if parameters are expected, it must provide a constructor accepting
 * an array of string.
 * 
 * 
 * Note: it could be interesting to see if we can make
 * {@link com.greenpepper.util.ClassUtils#findBestTypedConstructor(Class,java.lang.Object...)}
 * smarter and use it.
 *
 * @author oaouattara
 * @version $Id: $Id
 */
public class FactoryConverter implements Converter
{
    private Class expectedType;

    /**
     * 
Constructor for FactoryConverter.
     */
    public FactoryConverter()
    {
        this(null);
    }

    /**
     * Constructor for FactoryConverter.
     *
     * @param expectedType a {@link java.lang.Class} object.
     */
    public FactoryConverter(Class expectedType)
    {
        this.expectedType = expectedType;
    }

    /** {@inheritDoc} */
    @SuppressWarnings("unchecked")
    public Object convert( String value ) throws Exception
    {
        List parameters = toList( escapeValues( value.split( ";" ) ) );
        Class klass = ClassUtils.loadClass( shift( parameters ) );

        if (expectedType != null && !expectedType.isAssignableFrom(klass))
        {
            throw new IllegalArgumentException("Class " + expectedType.getName() + " is not assignable from"  + klass.getName() );
        }

        if (parameters.size() == 0) return klass.newInstance();

        String[] args = parameters.toArray( new String[parameters.size()] );
        Constructor constructor = klass.getConstructor( args.getClass() );
        return constructor.newInstance( new Object[]{args} );
    }

    private String[] escapeValues(String[] values)
    {
        for (int index = 0; index < values.length; index++)
        {
            values[index] = StringUtil.unescapeSemiColon( values[index] );
        }

        return values;
    }
}