/***
 * 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.interceptor;

import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;

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

import br.com.caelum.vraptor.HeaderParam;
import br.com.caelum.vraptor.InterceptionException;
import br.com.caelum.vraptor.Intercepts;
import br.com.caelum.vraptor.Lazy;
import br.com.caelum.vraptor.Validator;
import br.com.caelum.vraptor.core.InterceptorStack;
import br.com.caelum.vraptor.core.Localization;
import br.com.caelum.vraptor.core.MethodInfo;
import br.com.caelum.vraptor.http.MutableRequest;
import br.com.caelum.vraptor.http.ParameterNameProvider;
import br.com.caelum.vraptor.http.ParametersProvider;
import br.com.caelum.vraptor.resource.ResourceMethod;
import br.com.caelum.vraptor.validator.Message;
import br.com.caelum.vraptor.view.FlashScope;

/**
 * An interceptor which instantiates parameters and provide them to the stack.
 *
 * @author Guilherme Silveira
 */
@Intercepts(after=ResourceLookupInterceptor.class)
@Lazy
public class ParametersInstantiatorInterceptor implements Interceptor {
	private final ParametersProvider provider;
	private final ParameterNameProvider parameterNameProvider;
	private final MethodInfo parameters;

	private static final Logger logger = LoggerFactory.getLogger(ParametersInstantiatorInterceptor.class);
	private final Validator validator;
	private final Localization localization;
	private final List<Message> errors = new ArrayList<Message>();
	private final MutableRequest request;
	private final FlashScope flash;

	public ParametersInstantiatorInterceptor(ParametersProvider provider, ParameterNameProvider parameterNameProvider, MethodInfo parameters,
		Validator validator, Localization localization, MutableRequest request, FlashScope flash) {
		this.provider = provider;
		this.parameterNameProvider = parameterNameProvider;
		this.parameters = parameters;
		this.validator = validator;
		this.localization = localization;
		this.request = request;
		this.flash = flash;
	}

	public boolean accepts(ResourceMethod method) {
		return method.getMethod().getParameterTypes().length > 0;
	}

	public void intercept(InterceptorStack stack, ResourceMethod method, Object resourceInstance) throws InterceptionException {
		Enumeration<String> names = request.getParameterNames();
		while (names.hasMoreElements()) {
			fixParameter(names.nextElement());
		}
		
		addHeaderParametersToAttribute(method);
		
		Object[] values = getParametersFor(method);

		validator.addAll(errors);

		if (!errors.isEmpty()) {
			logger.debug("There are conversion errors: {}", errors);
		}
		logger.debug("Parameter values for {} are {}", method, values);

		parameters.setParameters(values);
		stack.next(method, resourceInstance);
	}
 
	private void addHeaderParametersToAttribute(ResourceMethod method) {
		Method trueMethod = method.getMethod();

		String[] parametersLocal = parameterNameProvider.parameterNamesFor(trueMethod);

		Annotation[][] annotations = trueMethod.getParameterAnnotations();
		for (int i = 0; i < annotations.length; i++) {
			for (Annotation annotation : annotations[i]) {
				if (annotation instanceof HeaderParam) {
					HeaderParam headerParam = (HeaderParam) annotation;
					String value = request.getHeader(headerParam.value());
					request.setAttribute(parametersLocal[i], value);
				}
			}
		}

	}

	private void fixParameter(String name) {
		if (name.contains(".class.")) {
			throw new IllegalArgumentException("Bug Exploit Attempt with parameter: " + name + "!!!");
		}
		if (name.contains("[]")) {
			String[] values = request.getParameterValues(name);
			for (int i = 0; i < values.length; i++) {
				request.setParameter(name.replace("[]", "[" + i + ']'), values[i]);
			}
		}
	}

	private Object[] getParametersFor(ResourceMethod method) {
		Object[] args = flash.consumeParameters(method);
		if (args == null) {
			return provider.getParametersFor(method, errors, localization.getBundle());
		}
		return args;
	}
}