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/**
 * MVEL 2.0
 * Copyright (C) 2007 The Codehaus
 * Mike Brock, Dhanji Prasanna, John Graham, Mark Proctor
 *
 * 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.mvel2.conversion;

import static java.lang.reflect.Array.get;
import static java.lang.reflect.Array.getLength;
import static java.lang.reflect.Array.newInstance;
import static java.lang.reflect.Array.set;
import static org.mvel2.DataConversion.convert;

import java.lang.reflect.Array;
import java.util.Collection;

import org.mvel2.ConversionHandler;

public class ArrayHandler implements ConversionHandler {

    private final Class type;

    public ArrayHandler(Class type) {
        this.type = type;
    }

    /**
     * Messy method to handle primitive boxing for conversion. If someone can re-write this more
     * elegantly, be my guest.
     *
     * @param sourceType
     * @param input
     * @param targetType
     * @return
     */
    private static Object handleLooseTypeConversion(Class sourceType, Object input, Class targetType) {
        Class targType = targetType.getComponentType();
        if (Collection.class.isAssignableFrom(sourceType)) {
            Object newArray = newInstance(targType, ((Collection) input).size());

            int i = 0;
            for (Object o : ((Collection) input)) {
                Array.set(newArray, i++, convert(o, targType));
            }

            return newArray;
        }

        if (!input.getClass().isArray()) {
            // if the input isn't an array converts it in an array with lenght = 1 having has its single item the input itself
            Object target = newInstance(targType, 1);
            set(target, 0, input);
            return target;
        }

        int len = getLength(input);
        Object target = newInstance(targType, len);

        for (int i = 0; i < len; i++) {
            set(target, i, convert(get(input, i), targType));
        }

        return target;
    }

    public Object convertFrom(Object in) {
        return handleLooseTypeConversion(in.getClass(), in, type);
    }

    public boolean canConvertFrom(Class cls) {
        return cls.isArray() || Collection.class.isAssignableFrom(cls);
    }
}