content: /*
   * Solo - A small and beautiful blogging system written in Java.
   * Copyright (c) 2010-present, b3log.org
   *
   * Solo is licensed under Mulan PSL v2.
   * You can use this software according to the terms and conditions of the Mulan PSL v2.
   * You may obtain a copy of Mulan PSL v2 at:
   *         http://license.coscl.org.cn/MulanPSL2
   * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT, MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
   * See the Mulan PSL v2 for more details.
   */
  package org.b3log.solo.util;
  
  import org.apache.commons.codec.digest.DigestUtils;
  import org.apache.commons.io.FileUtils;
  import org.apache.commons.lang3.StringUtils;
  import org.apache.commons.lang3.time.DateFormatUtils;
  import org.apache.logging.log4j.Level;
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  import org.b3log.latke.Latkes;
  import org.b3log.latke.http.RequestContext;
  import org.b3log.latke.util.Requests;
  import org.b3log.latke.util.Strings;
  import org.b3log.solo.model.Article;
  import org.b3log.solo.processor.SkinRenderer;
  import org.json.JSONObject;
  
  import java.io.ByteArrayInputStream;
  import java.io.ByteArrayOutputStream;
  import java.io.File;
  import java.nio.charset.StandardCharsets;
  import java.nio.file.Path;
  import java.nio.file.Paths;
  import java.util.Arrays;
  import java.util.List;
  import java.util.concurrent.ThreadLocalRandom;
  import java.util.concurrent.TimeUnit;
  import java.util.zip.GZIPInputStream;
  import java.util.zip.GZIPOutputStream;
  
  /**
   * Static utilities. 页面静态化 https://github.com/88250/solo/issues/107
   *
   * @author <a href="http://88250.b3log.org">Liang Ding</a>
   * @version 1.0.1.2, Jul 4, 2020
   * @since 4.1.0
   */
  public final class Statics {
  
      /**
       * Logger.
       */
      private static final Logger LOGGER = LogManager.getLogger(Statics.class);
  
      /**
       * Generated page expire time.
       */
      private static final long EXPIRED = TimeUnit.HOURS.toMillis(6);
  
      private static File DIR;
  
      static {
          final String userHome = System.getProperty("user.home");
          final Path staticCache = Paths.get(userHome, ".solo", "static-cache");
          final String staticDir = staticCache.toString();
          if (StringUtils.isNotBlank(staticDir)) {
              try {
                  FileUtils.forceMkdir(new File(staticDir));
                  DIR = new File(staticDir);
              } catch (final Exception e) {
                  LOGGER.log(Level.ERROR, "Creates static cache dir failed", e);
              }
          }
      }
  
      /**
       * Gets static HTML.
       *
       * @param context the specified context
       * @return HTML, returns {@code null} if not found
       */
      public static String get(final RequestContext context) {
          if (Solos.GEN_STATIC_SITE || Latkes.RuntimeMode.DEVELOPMENT == Latkes.getRuntimeMode()) {
              // 生成静态站点时和开发环境时不走缓存
              return null;
          }
  
          if (Solos.isLoggedIn(context)) {
              // 登录用户不走缓存
              return null;
          }
  
          final String remoteAddr = Requests.getRemoteAddr(context.getRequest());
          if (Strings.isIPv4(remoteAddr)) {
              // 直接用 IP 访问不走缓存
              return null;
          }
  
          final String key = key(context);
          if (null == key) {
              return null;
          }
  
          final Path path = Paths.get(DIR.getAbsolutePath(), key);
          final File file = path.toFile();
          if (!file.exists()) {
              return null;
          }
  
          final long now = System.currentTimeMillis();
          final long lastModified = file.lastModified();
          if (EXPIRED <= now - lastModified) {
              return null;
          }
  
          return readFile(file);
      }
  
      /**
       * Puts static HTML.
       *
       * @param context the specified context
       */
      public static void put(final RequestContext context) {
          if (Solos.GEN_STATIC_SITE) {
              // 生成静态站点时不走缓存
              return;
          }
  
          if (Solos.isLoggedIn(context)) {
              // 登录用户生成的内容不写入缓存
              return;
          }
  
          final String key = key(context);
          if (null == key) {
              return;
          }
  
          final Path path = Paths.get(DIR.getAbsolutePath(), key);
          final File file = path.toFile();
          if (file.exists()) {
              final long now = System.currentTimeMillis();
              final long lastModified = file.lastModified();
              if (EXPIRED > now - lastModified) {
                  return;
              }
          }
  
          try {
              final byte[] html = context.getResponse().getBytes();
              byte[] commpressed = gzip(html);
              if (null == commpressed) {
                  commpressed = html;
              }
              FileUtils.writeByteArrayToFile(path.toFile(), commpressed);
          } catch (final Exception e) {
              LOGGER.log(Level.ERROR, "Writes static file failed", e);
          }
      }
  
      /**
       * Clears all files under ~/.solo/static-cache.
       */
      public static void clear() {
          try {
              FileUtils.cleanDirectory(DIR);
          } catch (final Exception e) {
              LOGGER.log(Level.ERROR, "Clears static cached files failed", e);
          }
      }
  
      private static String readFile(final File file) {
          try {
              final byte[] compressed = FileUtils.readFileToByteArray(file);
              byte[] html = unGzip(compressed);
              if (null == html) {
                  html = compressed;
              }
              final String content = new String(html, StandardCharsets.UTF_8);
              final List<String> lines = Arrays.asList(content.split("\n"));
              final long elapsed = ThreadLocalRandom.current().nextLong(64, 128);
              final String dateString = DateFormatUtils.format(System.currentTimeMillis(), "yyyy/MM/dd HH:mm:ss");
              final String lastLine = String.format(SkinRenderer.LATKE_INFO, elapsed, dateString);
              lines.set(lines.size() - 1, lastLine);
  
              return StringUtils.join(lines, "\n");
          } catch (final Exception e) {
              LOGGER.log(Level.ERROR, "Reads static file failed", e);
          }
  
          return null;
      }
  
      /**
       * Calculates key of the specified context.
       *
       * @param context the specified context
       * @return key, returns {@code null} if can not be static
       */
      private static String key(final RequestContext context) {
          if (null == DIR) {
              return null;
          }
  
          if (!StringUtils.equalsIgnoreCase("get", context.method())) {
              return null;
          }
  
          String ret, requestURL;
  
          // 判断文章自定义链接
          final JSONObject article = (JSONObject) context.attr(Article.ARTICLE);
          if (null != article) {
              requestURL = article.optString(Article.ARTICLE_PERMALINK);
          } else {
              requestURL = context.requestURI();
          }
          String requestQueryStr = context.requestQueryStr();
          if (StringUtils.isNotBlank(requestQueryStr)) {
              requestURL += "?" + requestQueryStr;
          }
  
          ret = StringUtils.replace(requestURL, "/", "_");
          ret = StringUtils.replace(ret, "?", "_");
          if (Solos.isMobile(context.getRequest())) {
              ret = "m" + ret;
          }
          if (SkinRenderer.isPJAX(context)) {
              ret += "pjax";
          }
          ret = DigestUtils.md5Hex(ret);
          return ret;
      }
  
      private static byte[] gzip(final byte[] data) {
          try (final ByteArrayOutputStream out = new ByteArrayOutputStream();
               final GZIPOutputStream zout = new GZIPOutputStream(out)) {
              zout.write(data);
              zout.close();
              return out.toByteArray();
          } catch (final Exception e) {
              LOGGER.log(Level.ERROR, "Gzip failed", e);
  
              return null;
          }
      }
  
      private static byte[] unGzip(final byte[] compressed) {
          try (final ByteArrayOutputStream out = new ByteArrayOutputStream();
               final ByteArrayInputStream in = new ByteArrayInputStream(compressed);
               final GZIPInputStream zin = new GZIPInputStream(in)) {
  
              final byte[] buffer = new byte[1024];
              int offset;
              while ((offset = zin.read(buffer)) != -1) {
                  out.write(buffer, 0, offset);
              }
  
              return out.toByteArray();
          } catch (final Exception e) {
              LOGGER.log(Level.ERROR, "UnGzip failed", e);
  
              return null;
          }
      }
  
      private Statics() {
      }
  }
  