/*
 * Copyright (c) 2010-2015, b3log.org
 *
 * 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.filter;


import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.lang.StringUtils;
import org.b3log.latke.Keys;
import org.b3log.latke.Latkes;
import org.b3log.latke.ioc.LatkeBeanManager;
import org.b3log.latke.ioc.Lifecycle;
import org.b3log.latke.logging.Level;
import org.b3log.latke.logging.Logger;
import org.b3log.latke.repository.RepositoryException;
import org.b3log.latke.servlet.DispatcherServlet;
import org.b3log.latke.servlet.HTTPRequestContext;
import org.b3log.latke.servlet.HTTPRequestMethod;
import org.b3log.latke.servlet.HttpControl;
import org.b3log.latke.servlet.renderer.HTTP500Renderer;
import org.b3log.solo.model.Article;
import org.b3log.solo.model.Page;
import org.b3log.solo.repository.ArticleRepository;
import org.b3log.solo.repository.PageRepository;
import org.b3log.solo.repository.impl.ArticleRepositoryImpl;
import org.b3log.solo.repository.impl.PageRepositoryImpl;
import org.b3log.solo.service.ArticleQueryService;
import org.b3log.solo.service.PermalinkQueryService;
import org.json.JSONObject;


/**
 * Article/Page permalink filter.
 *
 * @author <a href="http://88250.b3log.org">Liang Ding</a>
 * @version 1.0.1.7, Jan 8, 2013
 * @since 0.3.1
 * @see org.b3log.solo.processor.ArticleProcessor#showArticle(org.b3log.latke.servlet.HTTPRequestContext, 
 * javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse) 
 * @see org.b3log.solo.processor.PageProcessor#showPage(org.b3log.latke.servlet.HTTPRequestContext) 
 */
public final class PermalinkFilter implements Filter {

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

    @Override
    public void init(final FilterConfig filterConfig) throws ServletException {}

    /**
     * Tries to dispatch request to article processor.
     *
     * @param request the specified request
     * @param response the specified response
     * @param chain filter chain
     * @throws IOException io exception
     * @throws ServletException servlet exception
     */
    @Override
    public void doFilter(final ServletRequest request, final ServletResponse response, final FilterChain chain)
        throws IOException, ServletException {
        final HttpServletRequest httpServletRequest = (HttpServletRequest) request;
        final HttpServletResponse httpServletResponse = (HttpServletResponse) response;

        final String requestURI = httpServletRequest.getRequestURI();

        LOGGER.log(Level.DEBUG, "Request URI[{0}]", requestURI);

        final String contextPath = Latkes.getContextPath();
        final String permalink = StringUtils.substringAfter(requestURI, contextPath);

        if (PermalinkQueryService.invalidPermalinkFormat(permalink)) {
            LOGGER.log(Level.DEBUG, "Skip filter request[URI={0}]", permalink);
            chain.doFilter(request, response);

            return;
        }

        JSONObject article;
        JSONObject page = null;

        final LatkeBeanManager beanManager = Lifecycle.getBeanManager();

        try {
            final ArticleRepository articleRepository = beanManager.getReference(ArticleRepositoryImpl.class);

            article = articleRepository.getByPermalink(permalink);
            
            if (null == article) {
                final PageRepository pageRepository = beanManager.getReference(PageRepositoryImpl.class);
         
                page = pageRepository.getByPermalink(permalink);
            }

            if (null == page && null == article) {
                LOGGER.log(Level.DEBUG, "Not found article/page with permalink[{0}]", permalink);
                chain.doFilter(request, response);

                return;
            }
        } catch (final RepositoryException e) {
            LOGGER.log(Level.ERROR, "Processes article permalink filter failed", e);
            httpServletResponse.sendError(HttpServletResponse.SC_NOT_FOUND);

            return;
        }

        // If requests an article and the article need view passowrd, sends redirect to the password form
        final ArticleQueryService articleQueryService = beanManager.getReference(ArticleQueryService.class);

        if (null != article && articleQueryService.needViewPwd(httpServletRequest, article)) {
            try {
                httpServletResponse.sendRedirect(
                    Latkes.getServePath() + "/console/article-pwd?articleId=" + article.optString(Keys.OBJECT_ID));
                return;
            } catch (final Exception e) {
                httpServletResponse.sendError(HttpServletResponse.SC_NOT_FOUND);
                return;
            }
        }

        dispatchToArticleOrPageProcessor(request, response, article, page);
    }

    /**
     * Dispatches the specified request to the specified article or page 
     * processor with the specified response.
     * 
     * @param request the specified request
     * @param response the specified response
     * @param article the specified article
     * @param page the specified page
     * @throws ServletException servlet exception
     * @throws IOException io exception
     * @see HTTPRequestDispatcher#dispatch(org.b3log.latke.servlet.HTTPRequestContext) 
     */
    private void dispatchToArticleOrPageProcessor(final ServletRequest request, final ServletResponse response,
        final JSONObject article, final JSONObject page)
        throws ServletException, IOException {
        final HTTPRequestContext context = new HTTPRequestContext();

        context.setRequest((HttpServletRequest) request);
        context.setResponse((HttpServletResponse) response);

        if (null != article) {
            request.setAttribute(Article.ARTICLE, article);
            request.setAttribute(Keys.HttpRequest.REQUEST_URI, Latkes.getContextPath() + "/article");
        } else {
            request.setAttribute(Page.PAGE, page);
            request.setAttribute(Keys.HttpRequest.REQUEST_URI, Latkes.getContextPath() + "/page");
        }

        request.setAttribute(Keys.HttpRequest.REQUEST_METHOD, HTTPRequestMethod.GET.name());

        final HttpControl httpControl = new HttpControl(DispatcherServlet.SYS_HANDLER.iterator(), context);

        try {
            httpControl.nextHandler();
        } catch (final Exception e) {
            context.setRenderer(new HTTP500Renderer(e));
        }

        DispatcherServlet.result(context);
    }

    @Override
    public void destroy() {}
}
