/*
 * Solo - A small and beautiful blogging system written in Java.
 * Copyright (c) 2010-2019, b3log.org & hacpai.com
 *
 * 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.plugin.list;

import org.apache.commons.lang.StringUtils;
import org.b3log.latke.event.AbstractEventListener;
import org.b3log.latke.event.Event;
import org.b3log.solo.event.EventTypes;
import org.b3log.solo.model.Article;
import org.json.JSONObject;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.parser.Parser;
import org.jsoup.select.Elements;

import java.util.ArrayList;
import java.util.List;

/**
 * List (table of contents of an article) handler.
 *
 * @author <a href="http://88250.b3log.org">Liang Ding</a>
 * @author <a href="http://www.annpeter.cn">Ann Peter</a>
 * @author <a href="http://vanessa.b3log.org">Vanessa</a>
 * @version 1.0.2.2, Mar 19, 2019
 * @since 0.6.7
 */
public class ListHandler extends AbstractEventListener<JSONObject> {

    @Override
    public String getEventType() {
        return EventTypes.BEFORE_RENDER_ARTICLE;
    }

    @Override
    public void action(final Event<JSONObject> event) {
        final JSONObject data = event.getData();
        final JSONObject article = data.optJSONObject(Article.ARTICLE);
        final String content = article.optString(Article.ARTICLE_CONTENT);
        final Document doc = Jsoup.parse(content, StringUtils.EMPTY, Parser.htmlParser());
        doc.outputSettings().prettyPrint(false);

        final List<JSONObject> toc = new ArrayList<>();
        final Elements hs = doc.select("h1, h2, h3, h4, h5");
        for (int i = 0; i < hs.size(); i++) {
            final Element element = hs.get(i);
            final String tagName = element.tagName().toLowerCase();
            final String text = element.text();
            final String id = "b3_solo_" + tagName + "_" + i;
            element.attr("id", id);
            final JSONObject li = new JSONObject().
                    put("className", "toc__" + tagName).
                    put("id", id).
                    put("text", text);
            toc.add(li);
        }
        final Element body = doc.getElementsByTag("body").get(0);
        article.put(Article.ARTICLE_CONTENT, body.html());
        article.put(Article.ARTICLE_T_TOC, (Object) toc);
    }
}
