/*
 * 				Firetweet - Twitter client for Android
 * 
 *  Copyright (C) 2012-2014 Mariotaku Lee <mariotaku.lee@gmail.com>
 * 
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU 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 General Public License for more details.
 * 
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.getlantern.firetweet.util;

import java.util.Vector;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class HtmlLinkExtractor {

    private final Pattern patternTag, patternLink;

    private static final String HTML_A_TAG_PATTERN = "(?i)<a([^>]+)>(.+?)</a>";
    private static final String HTML_A_HREF_TAG_PATTERN = "\\s*(?i)href\\s*=\\s*(\"([^\"]*\")|'[^']*'|([^'\">\\s]+))";

    public HtmlLinkExtractor() {
        patternTag = Pattern.compile(HTML_A_TAG_PATTERN);
        patternLink = Pattern.compile(HTML_A_HREF_TAG_PATTERN);
    }

    /**
     * Validate html with regular expression
     *
     * @param html html content for validation
     * @return Vector links and link text
     */
    public Vector<HtmlLink> grabLinks(final String html) {
        final Vector<HtmlLink> result = new Vector<HtmlLink>();
        final Matcher matcherTag = patternTag.matcher(html);
        while (matcherTag.find()) {
            final String href = matcherTag.group(1); // href
            final String linkText = matcherTag.group(2); // link text
            final Matcher matcherLink = patternLink.matcher(href);
            while (matcherLink.find()) {
                final String link = matcherLink.group(1); // link
                final HtmlLink obj = new HtmlLink(link, linkText);
                result.add(obj);
            }
        }
        return result;
    }

    public static class HtmlLink {

        private final String link;
        private final String text;

        private HtmlLink(final String link, final String text) {
            this.link = replaceInvalidChar(link);
            this.text = text;
        }

        public String getLink() {
            return link;
        }

        public String getLinkText() {
            return text;
        }

        private static String replaceInvalidChar(String link) {
            link = link.replaceAll("'", "");
            link = link.replaceAll("\"", "");
            return link;
        }

    }
}