// Copyright (C) 2014 The Android Open Source Project
//
// 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 com.google.gerrit.server.plugins;

import static com.google.gerrit.server.plugins.PluginLoader.asTemp;

import com.google.common.base.MoreObjects;
import com.google.gerrit.server.config.SitePaths;
import com.google.inject.Inject;

import org.eclipse.jgit.internal.storage.file.FileSnapshot;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.jar.JarFile;
import java.util.jar.Manifest;

public class JarPluginProvider implements ServerPluginProvider {
  static final String PLUGIN_TMP_PREFIX = "plugin_";
  static final String JAR_EXTENSION = ".jar";
  static final Logger log = LoggerFactory.getLogger(JarPluginProvider.class);

  private final Path tmpDir;

  @Inject
  JarPluginProvider(SitePaths sitePaths) {
    tmpDir = sitePaths.tmp_dir;
  }

  @Override
  public boolean handles(Path srcPath) {
    String fileName = srcPath.getFileName().toString();
    return fileName.endsWith(JAR_EXTENSION)
        || fileName.endsWith(JAR_EXTENSION + ".disabled");
  }

  @Override
  public String getPluginName(Path srcPath) {
    try {
      return MoreObjects.firstNonNull(getJarPluginName(srcPath),
          PluginLoader.nameOf(srcPath));
    } catch (IOException e) {
      throw new IllegalArgumentException("Invalid plugin file " + srcPath
          + ": cannot get plugin name", e);
    }
  }

  public static String getJarPluginName(Path srcPath) throws IOException {
    try (JarFile jarFile = new JarFile(srcPath.toFile())) {
      return jarFile.getManifest().getMainAttributes()
          .getValue("Gerrit-PluginName");
    }
  }

  @Override
  public ServerPlugin get(Path srcPath, FileSnapshot snapshot,
      PluginDescription description) throws InvalidPluginException {
    try {
      String name = getPluginName(srcPath);
      String extension = getExtension(srcPath);
      try (InputStream in = Files.newInputStream(srcPath)) {
        Path tmp = asTemp(in, tempNameFor(name), extension, tmpDir);
        return loadJarPlugin(name, srcPath, snapshot, tmp, description);
      }
    } catch (IOException e) {
      throw new InvalidPluginException("Cannot load Jar plugin " + srcPath, e);
    }
  }

  @Override
  public String getProviderPluginName() {
    return "gerrit";
  }

  private static String getExtension(Path path) {
    return getExtension(path.getFileName().toString());
  }

  private static String getExtension(String name) {
    int ext = name.lastIndexOf('.');
    return 0 < ext ? name.substring(ext) : "";
  }

  private static String tempNameFor(String name) {
    SimpleDateFormat fmt = new SimpleDateFormat("yyMMdd_HHmm");
    return PLUGIN_TMP_PREFIX + name + "_" + fmt.format(new Date()) + "_";
  }

  public static Path storeInTemp(String pluginName, InputStream in,
      SitePaths sitePaths) throws IOException {
    if (!Files.exists(sitePaths.tmp_dir)) {
      Files.createDirectories(sitePaths.tmp_dir);
    }
    return asTemp(in, tempNameFor(pluginName), ".jar", sitePaths.tmp_dir);
  }

  private ServerPlugin loadJarPlugin(String name, Path srcJar,
      FileSnapshot snapshot, Path tmp, PluginDescription description)
      throws IOException, InvalidPluginException, MalformedURLException {
    JarFile jarFile = new JarFile(tmp.toFile());
    boolean keep = false;
    try {
      Manifest manifest = jarFile.getManifest();
      Plugin.ApiType type = Plugin.getApiType(manifest);

      List<URL> urls = new ArrayList<>(2);
      String overlay = System.getProperty("gerrit.plugin-classes");
      if (overlay != null) {
        Path classes = Paths.get(overlay).resolve(name).resolve("main");
        if (Files.isDirectory(classes)) {
          log.info(String.format("plugin %s: including %s", name, classes));
          urls.add(classes.toUri().toURL());
        }
      }
      urls.add(tmp.toUri().toURL());

      ClassLoader pluginLoader =
          new URLClassLoader(urls.toArray(new URL[urls.size()]),
              PluginLoader.parentFor(type));

      JarScanner jarScanner = createJarScanner(tmp);
      ServerPlugin plugin = new ServerPlugin(name, description.canonicalUrl,
          description.user, srcJar, snapshot, jarScanner,
          description.dataDir, pluginLoader);
      plugin.setCleanupHandle(new CleanupHandle(tmp, jarFile));
      keep = true;
      return plugin;
    } finally {
      if (!keep) {
        jarFile.close();
      }
    }
  }

  private JarScanner createJarScanner(Path srcJar)
      throws InvalidPluginException {
    try {
      return new JarScanner(srcJar);
    } catch (IOException e) {
      throw new InvalidPluginException("Cannot scan plugin file " + srcJar, e);
    }
  }
}