/***
 * 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.core;

import static com.google.common.collect.Maps.newLinkedHashMap;

import java.util.Map;
import java.util.Map.Entry;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import br.com.caelum.vraptor.Result;
import br.com.caelum.vraptor.interceptor.ExceptionHandlerInterceptor;
import br.com.caelum.vraptor.ioc.Component;
import br.com.caelum.vraptor.proxy.Proxifier;

/**
 * Default implementation of {@link ExceptionMapper}.
 *
 * <p>This class is a part of Exception Handling Feature.</p>
 *
 * @author Otávio Scherer Garcia
 * @see ExceptionRecorder
 * @see ExceptionRecorderParameter
 * @see ExceptionMapper
 * @see ExceptionHandlerInterceptor
 * @since 3.2
 */
@Component
public class DefaultExceptionMapper
	implements ExceptionMapper {

	private static final Logger logger = LoggerFactory.getLogger(DefaultExceptionMapper.class);

	private final Map<Class<? extends Exception>, ExceptionRecorder<Result>> exceptions;
	private final Proxifier proxifier;

	public DefaultExceptionMapper(Proxifier proxifier) {
		this.proxifier = proxifier;
		this.exceptions = newLinkedHashMap();
	}

	public Result record(Class<? extends Exception> exception) {
		if (exception == null) {
			throw new NullPointerException("Exception cannot be null.");
		}
	
		ExceptionRecorder<Result> instance = new ExceptionRecorder<Result>(proxifier);
		exceptions.put(exception, instance);
	
		return proxifier.proxify(Result.class, instance);
	}

	public ExceptionRecorder<Result> findByException(Exception e) {
		logger.debug("find for exception {}", e.getClass());
	
		for (Entry<Class<? extends Exception>, ExceptionRecorder<Result>> entry : exceptions.entrySet()) {
			if (entry.getKey().isInstance(e)) {
			logger.debug("found exception mapping: {} -> {}", entry.getKey(), entry.getValue());
	
			return entry.getValue();
			}
		}
	
		return hasExceptionCause(e) ? findByException((Exception) e.getCause()) : null;
	}

	private static boolean hasExceptionCause(Exception e) {
		return e.getCause() != null && e.getCause() instanceof Exception;
	}
}