/*
 * Solo - A small and beautiful blogging system written in Java.
 * Copyright (c) 2010-present, b3log.org
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
package org.b3log.solo.processor;

import org.apache.commons.lang.StringEscapeUtils;
import org.apache.commons.lang.time.DateFormatUtils;
import org.b3log.latke.Keys;
import org.b3log.latke.Latkes;
import org.b3log.latke.ioc.Inject;
import org.b3log.latke.logging.Level;
import org.b3log.latke.logging.Logger;
import org.b3log.latke.repository.FilterOperator;
import org.b3log.latke.repository.PropertyFilter;
import org.b3log.latke.repository.Query;
import org.b3log.latke.repository.SortDirection;
import org.b3log.latke.servlet.HttpMethod;
import org.b3log.latke.servlet.RequestContext;
import org.b3log.latke.servlet.annotation.RequestProcessing;
import org.b3log.latke.servlet.annotation.RequestProcessor;
import org.b3log.latke.servlet.renderer.TextXmlRenderer;
import org.b3log.latke.util.URLs;
import org.b3log.latke.util.XMLs;
import org.b3log.solo.model.ArchiveDate;
import org.b3log.solo.model.Article;
import org.b3log.solo.model.Page;
import org.b3log.solo.model.Tag;
import org.b3log.solo.model.sitemap.Sitemap;
import org.b3log.solo.model.sitemap.URL;
import org.b3log.solo.repository.ArchiveDateRepository;
import org.b3log.solo.repository.ArticleRepository;
import org.b3log.solo.repository.PageRepository;
import org.b3log.solo.repository.TagRepository;
import org.json.JSONArray;
import org.json.JSONObject;

import javax.servlet.http.HttpServletResponse;

/**
 * Sitemap processor.
 *
 * @author <a href="http://88250.b3log.org">Liang Ding</a>
 * @version 1.0.2.6, Jan 15, 2019
 * @since 0.3.1
 */
@RequestProcessor
public class SitemapProcessor {

    /**
     * Logger.
     */
    private static final Logger LOGGER = Logger.getLogger(SitemapProcessor.class);

    /**
     * Article repository.
     */
    @Inject
    private ArticleRepository articleRepository;

    /**
     * Page repository.
     */
    @Inject
    private PageRepository pageRepository;

    /**
     * Tag repository.
     */
    @Inject
    private TagRepository tagRepository;

    /**
     * Archive date repository.
     */
    @Inject
    private ArchiveDateRepository archiveDateRepository;

    /**
     * Returns the sitemap.
     *
     * @param context the specified context
     */
    @RequestProcessing(value = "/sitemap.xml", method = HttpMethod.GET)
    public void sitemap(final RequestContext context) {
        final TextXmlRenderer renderer = new TextXmlRenderer();
        context.setRenderer(renderer);

        try {
            final Sitemap sitemap = new Sitemap();
            addArticles(sitemap);
            addNavigations(sitemap);
            addTags(sitemap);
            addArchives(sitemap);

            String content = sitemap.toString();
            content = XMLs.format(content);
            LOGGER.log(Level.INFO, "Generated sitemap");
            renderer.setContent(content);
        } catch (final Exception e) {
            LOGGER.log(Level.ERROR, "Generates sitemap failed", e);

            context.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE);
        }
    }

    /**
     * Adds articles into the specified sitemap.
     *
     * @param sitemap the specified sitemap
     * @throws Exception exception
     */
    private void addArticles(final Sitemap sitemap) throws Exception {
        final Query query = new Query().setPage(1, Integer.MAX_VALUE).
                setFilter(new PropertyFilter(Article.ARTICLE_STATUS, FilterOperator.EQUAL, Article.ARTICLE_STATUS_C_PUBLISHED)).
                addSort(Article.ARTICLE_CREATED, SortDirection.DESCENDING).
                select(Article.ARTICLE_PERMALINK, Article.ARTICLE_UPDATED);
        final JSONObject articleResult = articleRepository.get(query);
        final JSONArray articles = articleResult.getJSONArray(Keys.RESULTS);

        for (int i = 0; i < articles.length(); i++) {
            final JSONObject article = articles.getJSONObject(i);
            final String permalink = article.getString(Article.ARTICLE_PERMALINK);

            final URL url = new URL();
            url.setLoc(StringEscapeUtils.escapeXml(Latkes.getServePath() + permalink));
            final long updated = article.getLong(Article.ARTICLE_UPDATED);
            final String lastMod = DateFormatUtils.ISO_DATETIME_TIME_ZONE_FORMAT.format(updated);
            url.setLastMod(lastMod);

            sitemap.addURL(url);
        }
    }

    /**
     * Adds navigations into the specified sitemap.
     *
     * @param sitemap the specified sitemap
     * @throws Exception exception
     */
    private void addNavigations(final Sitemap sitemap) throws Exception {
        final JSONObject result = pageRepository.get(new Query());
        final JSONArray pages = result.getJSONArray(Keys.RESULTS);

        for (int i = 0; i < pages.length(); i++) {
            final JSONObject page = pages.getJSONObject(i);
            final String permalink = page.getString(Page.PAGE_PERMALINK);

            final URL url = new URL();

            // The navigation maybe a page or a link
            // Just filters for user mistakes tolerance
            if (!permalink.contains("://")) {
                url.setLoc(Latkes.getServePath() + permalink);
            } else {
                url.setLoc(permalink);
            }

            sitemap.addURL(url);
        }
    }

    /**
     * Adds tags (tag-articles) and tags wall (/tags.html) into the specified sitemap.
     *
     * @param sitemap the specified sitemap
     * @throws Exception exception
     */
    private void addTags(final Sitemap sitemap) throws Exception {
        final JSONObject result = tagRepository.get(new Query());
        final JSONArray tags = result.getJSONArray(Keys.RESULTS);

        for (int i = 0; i < tags.length(); i++) {
            final JSONObject tag = tags.getJSONObject(i);
            final String link = URLs.encode(tag.getString(Tag.TAG_TITLE));

            final URL url = new URL();

            url.setLoc(Latkes.getServePath() + "/tags/" + link);

            sitemap.addURL(url);
        }

        // Tags wall
        final URL url = new URL();

        url.setLoc(Latkes.getServePath() + "/tags.html");
        sitemap.addURL(url);
    }

    /**
     * Adds archives (archive-articles) into the specified sitemap.
     *
     * @param sitemap the specified sitemap
     * @throws Exception exception
     */
    private void addArchives(final Sitemap sitemap) throws Exception {
        final JSONObject result = archiveDateRepository.get(new Query());
        final JSONArray archiveDates = result.getJSONArray(Keys.RESULTS);

        for (int i = 0; i < archiveDates.length(); i++) {
            final JSONObject archiveDate = archiveDates.getJSONObject(i);
            final long time = archiveDate.getLong(ArchiveDate.ARCHIVE_TIME);
            final String dateString = DateFormatUtils.format(time, "yyyy/MM");

            final URL url = new URL();

            url.setLoc(Latkes.getServePath() + "/archives/" + dateString);

            sitemap.addURL(url);
        }
    }
}
