/**
 * Licensed to Apereo under one or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information regarding copyright ownership. Apereo
 * 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 the
 * following location:
 *
 * <p>http://www.apache.org/licenses/LICENSE-2.0
 *
 * <p>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.apereo.portal.rendering;

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.xml.transform.OutputKeys;
import org.apereo.portal.character.stream.CharacterEventReader;
import org.apereo.portal.character.stream.events.CharacterDataEvent;
import org.apereo.portal.character.stream.events.CharacterEvent;
import org.apereo.portal.character.stream.events.CharacterEventTypes;
import org.apereo.portal.events.IPortletExecutionEventFactory;
import org.apereo.portal.url.IPortalRequestInfo;
import org.apereo.portal.url.IUrlSyntaxProvider;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;

/**
 * Top level class that initiates rendering via a {@link CharacterPipelineComponent}
 *
 */
public class DynamicRenderingPipeline implements IPortalRenderingPipeline {
    public static final String CHARACTER_SET = "UTF-8";
    public static final String DEFAULT_MEDIA_TYPE = "text/html";

    protected final Logger logger = LoggerFactory.getLogger(getClass());

    private CharacterPipelineComponent pipeline;
    private IPortletExecutionEventFactory portalEventFactory;
    private IUrlSyntaxProvider urlSyntaxProvider;

    @Autowired
    public void setUrlSyntaxProvider(IUrlSyntaxProvider urlSyntaxProvider) {
        this.urlSyntaxProvider = urlSyntaxProvider;
    }

    @Autowired
    public void setPortalEventFactory(IPortletExecutionEventFactory portalEventFactory) {
        this.portalEventFactory = portalEventFactory;
    }

    /**
     * The root element in the rendering pipeline. This element MUST only return {@link
     * CharacterEventTypes#CHARACTER} type events.
     */
    public void setPipeline(CharacterPipelineComponent pipeline) {
        this.pipeline = pipeline;
    }

    @Override
    public void renderState(HttpServletRequest req, HttpServletResponse res)
            throws ServletException, IOException {
        //Disable page caching
        res.setHeader("pragma", "no-cache");
        res.setHeader("Cache-Control", "no-cache, max-age=0, must-revalidate");
        res.setDateHeader("Expires", 0);

        final long startTime = System.nanoTime();

        final PipelineEventReader<CharacterEventReader, CharacterEvent> pipelineEventReader =
                this.pipeline.getEventReader(req, res);
        final String mediaType = getMediaType(req, res, pipelineEventReader);

        // set the response mime type
        final String contentType = mediaType + "; charset=" + CHARACTER_SET;
        res.setContentType(contentType);

        final PrintWriter writer = res.getWriter();

        for (final CharacterEvent event : pipelineEventReader) {
            if (CharacterEventTypes.CHARACTER != event.getEventType()) {
                throw new RenderingPipelineConfigurationException(
                        "Only "
                                + CharacterEventTypes.CHARACTER
                                + " events are supported in the top level renderer. "
                                + event.getEventType()
                                + " is not supported.");
            }

            final String data = ((CharacterDataEvent) event).getData();
            writer.print(data);
            writer.flush();
            res.flushBuffer();
        }

        final long executionTime = System.nanoTime() - startTime;
        final IPortalRequestInfo portalRequestInfo =
                this.urlSyntaxProvider.getPortalRequestInfo(req);
        this.portalEventFactory.publishPortalRenderEvent(
                req, this, req.getPathInfo(), executionTime, portalRequestInfo);
    }

    /** Determine the media type to use for the response */
    protected String getMediaType(
            HttpServletRequest req,
            HttpServletResponse res,
            PipelineEventReader<CharacterEventReader, CharacterEvent> pipelineEventReader) {
        final String mediaType = pipelineEventReader.getOutputProperty(OutputKeys.MEDIA_TYPE);
        if (mediaType != null) {
            return mediaType;
        }

        this.logger.warn(
                "No mediaType was specified in the pipeline output properties, defaulting to "
                        + DEFAULT_MEDIA_TYPE);
        return DEFAULT_MEDIA_TYPE;
    }

    @Override
    public String toString() {
        return "DynamicRenderingPipeline using url syntax provider ["
                + this.urlSyntaxProvider
                + "] and wrapping pipeline component ["
                + this.pipeline
                + "].";
    }
}