/*
 * Copyright (c) 2017, cxy7.com
 *
 * Licensed 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.b3log.solo.service;

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

import org.b3log.solo.Latkes;
import org.b3log.solo.dao.ArticleDao;
import org.b3log.solo.dao.PageDao;
import org.b3log.solo.dao.repository.RepositoryException;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.math.NumberUtils;
import org.apache.commons.validator.routines.UrlValidator;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

/**
 * Permalink query service.
 *
 * @author <a href="http://cxy7.com">XyCai</a>
 * @version 1.0.0.2, Mar 4, 2014
 * @since 0.6.1
 */
@Service
public class PermalinkQueryService {

	/**
	 * Logger.
	 */
	private static Logger logger = LoggerFactory.getLogger(PermalinkQueryService.class);

	/**
	 * Page repository.
	 */
	@Autowired
	private PageDao pageDao;

	/**
	 * Article repository.
	 */
	@Autowired
	private ArticleDao articleDao;

	/**
	 * Reserved permalinks.
	 */
	public static final String[] RESERVED_LINKS = new String[] { "/", "/article", "/tags.html", "/tags", "/page",
			"/blog-articles-feed.do", "/tag-articles-feed.do", "/blog-articles-rss.do", "/tag-articles-rss.do",
			"/get-random-articles.do", "/article-random-double-gen.do", "/captcha.do", "/kill-browser",
			"/add-article-comment.do", "/add-article-from-symphony-comment.do", "/add-page-comment.do",
			"/get-article-content", "/sitemap.xml", "/login", "/logout", "/forgot", "/get-article-content",
			"/admin-index.do", "/admin-article.do", "/admin-article-list.do", "/admin-link-list.do",
			"/admin-preference.do", "/admin-file-list.do", "/admin-page-list.do", "/admin-others.do",
			"/admin-draft-list.do", "/admin-user-list.do", "/admin-plugin-list.do", "/admin-main.do", "/admin-about.do",
			"/admin-label", "/admin-about.do", "/rm-all-data.do", "/init", "/register.html" };

	/**
	 * Checks whether the specified article permalink matches the system
	 * generated format pattern ("/articles/yyyy/MM/dd/${articleId}.html").
	 * 
	 * @param permalink
	 *            the specified permalink
	 * @return {@code true} if matches, returns {@code false} otherwise
	 */
	public static boolean matchDefaultArticlePermalinkFormat(final String permalink) {
		final Pattern pattern = Pattern.compile("/articles/\\d{4}/\\d{2}/\\d{2}/\\d+\\.html");
		final Matcher matcher = pattern.matcher(permalink);

		return matcher.matches();
	}

	/**
	 * Checks whether the specified page permalink matches the system generated
	 * format pattern ("/pages/${pageId}.html").
	 * 
	 * @param permalink
	 *            the specified permalink
	 * @return {@code true} if matches, returns {@code false} otherwise
	 */
	public static boolean matchDefaultPagePermalinkFormat(final String permalink) {
		final Pattern pattern = Pattern.compile("/pages/\\d+\\.html");
		final Matcher matcher = pattern.matcher(permalink);

		return matcher.matches();
	}

	/**
	 * Checks whether the specified permalink is a
	 * {@link #invalidArticlePermalinkFormat(java.lang.String) invalid article
	 * permalink format} and
	 * {@link #invalidPagePermalinkFormat(java.lang.String) invalid page
	 * permalink format}.
	 * 
	 * @param permalink
	 *            the specified permalink
	 * @return {@code true} if invalid, returns {@code false} otherwise
	 */
	public static boolean invalidPermalinkFormat(final String permalink) {
		return invalidArticlePermalinkFormat(permalink) && invalidPagePermalinkFormat(permalink);
	}

	/**
	 * Checks whether the specified article permalink is invalid on format.
	 * 
	 * @param permalink
	 *            the specified article permalink
	 * @return {@code true} if invalid, returns {@code false} otherwise
	 */
	public static boolean invalidArticlePermalinkFormat(final String permalink) {
		if (StringUtils.isBlank(permalink)) {
			return true;
		}

		if (matchDefaultArticlePermalinkFormat(permalink)) {
			return false;
		}

		return invalidUserDefinedPermalinkFormat(permalink);
	}

	/**
	 * Checks whether the specified page permalink is invalid on format.
	 * 
	 * @param permalink
	 *            the specified page permalink
	 * @return {@code true} if invalid, returns {@code false} otherwise
	 */
	public static boolean invalidPagePermalinkFormat(final String permalink) {
		if (StringUtils.isBlank(permalink)) {
			return true;
		}

		if (matchDefaultPagePermalinkFormat(permalink)) {
			return false;
		}

		return invalidUserDefinedPermalinkFormat(permalink);
	}

	/**
	 * Checks whether the specified user-defined permalink is invalid on format.
	 * 
	 * @param permalink
	 *            the specified user-defined permalink
	 * @return {@code true} if invalid, returns {@code false} otherwise
	 */
	private static boolean invalidUserDefinedPermalinkFormat(final String permalink) {
		if (StringUtils.isBlank(permalink)) {
			return true;
		}

		if (isReservedLink(permalink)) {
			return true;
		}
		if (NumberUtils.isDigits(permalink.substring(1))) {
			// See issue 120
			// (http://code.google.com/p/b3log-solo/issues/detail?id=120#c4) for
			// more details
			return true;
		}

		int slashCnt = 0;

		for (int i = 0; i < permalink.length(); i++) {
			if ('/' == permalink.charAt(i)) {
				slashCnt++;
			}

			if (slashCnt > 1) {
				return true;
			}
		}

		return !UrlValidator.getInstance().isValid(Latkes.getServer() + permalink);
	}

	/**
	 * Determines whether the specified request URI is a reserved link.
	 * 
	 * <p>
	 * A URI starts with one of {@link PermalinkQueryService#RESERVED_LINKS
	 * reserved links} will be treated as reserved link.
	 * </p>
	 * 
	 * @param requestURI
	 *            the specified request URI
	 * @return {@code true} if it is a reserved link, returns {@code false}
	 *         otherwise
	 */
	private static boolean isReservedLink(final String requestURI) {
		for (int i = 0; i < RESERVED_LINKS.length; i++) {
			final String reservedLink = RESERVED_LINKS[i];

			if (reservedLink.startsWith(requestURI)) {

				return true;
			}
		}

		return false;
	}

	/**
	 * Determines whether the specified permalink exists.
	 *
	 * @param permalink
	 *            the specified permalink
	 * @return {@code true} if exists, returns {@code false} otherwise
	 */
	public boolean exist(final String permalink) {
		try {
			return isReservedLink(permalink) || null != articleDao.getByPermalink(permalink)
					|| null != pageDao.getByPermalink(permalink) || permalink.endsWith(".ftl");
		} catch (final RepositoryException e) {
			logger.error("Determines whether the permalink[" + permalink + "] exists failed, returns true", e);

			return true;
		}
	}

	/**
	 * Sets the article repository with the specified article repository.
	 * 
	 * @param articleDao
	 *            the specified article repository
	 */
	public void setArticleRepository(final ArticleDao articleDao) {
		this.articleDao = articleDao;
	}

	/**
	 * Set the page repository with the specified page repository.
	 * 
	 * @param pageDao
	 *            the specified page repository
	 */
	public void setPageRepository(final PageDao pageDao) {
		this.pageDao = pageDao;
	}
}