/*
 * Licensed to DuraSpace under one or more contributor license agreements.
 * See the NOTICE file distributed with this work for additional information
 * regarding copyright ownership.
 *
 * DuraSpace licenses this file to you 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.fcrepo.http.commons.api;

import static org.slf4j.LoggerFactory.getLogger;

import java.util.Map;
import javax.servlet.http.HttpServletResponse;
import javax.ws.rs.core.UriInfo;

import org.fcrepo.kernel.api.models.FedoraResource;

import org.slf4j.Logger;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ApplicationObjectSupport;
import org.springframework.stereotype.Component;

import com.google.common.collect.Multimap;

/**
 * Inject optional headers from external processes
 *
 * @author whikloj
 * @since 2015-10-30
 */
@Component
public class HttpHeaderInjector extends ApplicationObjectSupport {

    private static final Logger LOGGER = getLogger(HttpHeaderInjector.class);

    private ApplicationContext applicationContext;

    @Override
    protected void initApplicationContext() throws BeansException {
        applicationContext = getApplicationContext();
    }

    @Override
    protected boolean isContextRequired() {
        return true;
    }

    /**
     * Add additional Http Headers
     *
     * @param servletResponse the response
     * @param uriInfo the URI context
     * @param resource the resource
     */
    public void addHttpHeaderToResponseStream(final HttpServletResponse servletResponse,
                                              final UriInfo uriInfo,
                                              final FedoraResource resource) {

        getUriAwareHttpHeaderFactories().forEach((bean, factory) -> {
            LOGGER.debug("Adding HTTP headers using: {}", bean);
            final Multimap<String, String> h = factory.createHttpHeadersForResource(uriInfo, resource);

            h.entries().forEach(entry -> {
                servletResponse.addHeader(entry.getKey(), entry.getValue());
            });
        });
    }

    private Map<String, UriAwareHttpHeaderFactory> getUriAwareHttpHeaderFactories() {
        return applicationContext.getBeansOfType(UriAwareHttpHeaderFactory.class);
    }

}