/***
 * Copyright (c) 2009 Caelum - www.caelum.com.br/opensource
 * All rights reserved.
 *
 * 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 br.com.caelum.vraptor.http.ognl;

import java.lang.reflect.Array;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Collection;
import java.util.GregorianCalendar;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Queue;
import java.util.Set;
import java.util.SortedSet;
import java.util.TreeSet;

import net.vidageek.mirror.dsl.Mirror;

/**
 * Capable of instantiating generic interfaces and custom types.
 *
 * @author Guilherme Silveira
 */
public class GenericNullHandler implements NullHandler {

	private static final Map<Class<?>, Class<?>> CONCRETE_TYPES = new HashMap<Class<?>, Class<?>>();
	private final EmptyElementsRemoval removal;

	static {
	CONCRETE_TYPES.put(List.class, ArrayList.class);
	CONCRETE_TYPES.put(Calendar.class, GregorianCalendar.class);
	CONCRETE_TYPES.put(Collection.class, ArrayList.class);
	CONCRETE_TYPES.put(Set.class, HashSet.class);
	CONCRETE_TYPES.put(SortedSet.class, TreeSet.class);
	CONCRETE_TYPES.put(Queue.class, LinkedList.class);
	}

	public GenericNullHandler(EmptyElementsRemoval removal) {
		this.removal = removal;
	}

	public <T> T instantiate(Class<T> baseType) {
		if (baseType.isArray()) {
			return baseType.cast(Array.newInstance(baseType.getComponentType(), 0));
		}
	Class<?> typeToInstantiate = baseType;
	if (baseType.isInterface() || Modifier.isAbstract(baseType.getModifiers())) {
		if (!CONCRETE_TYPES.containsKey(baseType)) {
		// TODO better
		throw new IllegalArgumentException("Vraptor does not support this interface or abstract type: "
			+ typeToInstantiate.getName());
		}
		typeToInstantiate = CONCRETE_TYPES.get(baseType);
	}
	Object instance = new Mirror().on(typeToInstantiate).invoke().constructor().withoutArgs();

	if(Collection.class.isAssignableFrom(typeToInstantiate)) {
		removal.add((Collection)instance);
	}

	return baseType.cast(instance);
	}

}