/*
 * Sonar, open source software quality management tool.
 * Copyright (C) 2008-2012 SonarSource
 * mailto:contact AT sonarsource DOT com
 *
 * Sonar is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or (at your option) any later version.
 *
 * Sonar 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with Sonar; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02
 */
package org.sonar.plugins.findbugs;

import com.google.common.collect.Lists;
import edu.umd.cs.findbugs.DetectorFactoryCollection;
import edu.umd.cs.findbugs.FindBugs;
import edu.umd.cs.findbugs.FindBugs2;
import edu.umd.cs.findbugs.Plugin;
import edu.umd.cs.findbugs.PluginException;
import edu.umd.cs.findbugs.Priorities;
import edu.umd.cs.findbugs.Project;
import edu.umd.cs.findbugs.XMLBugReporter;
import edu.umd.cs.findbugs.config.UserPreferences;
import edu.umd.cs.findbugs.plugins.DuplicatePluginIdException;
import org.apache.commons.io.FileUtils;
import org.apache.commons.io.IOUtils;
import org.apache.commons.io.output.NullOutputStream;
import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.sonar.api.BatchExtension;
import org.sonar.api.utils.SonarException;
import org.sonar.api.utils.TimeProfiler;

import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintStream;
import java.net.URL;
import java.util.Collection;
import java.util.Enumeration;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

/**
 * @since 2.4
 */
public class FindbugsExecutor implements BatchExtension {

  private static final String FINDBUGS_CORE_PLUGIN_ID = "edu.umd.cs.findbugs.plugins.core";

  private static final Logger LOG = LoggerFactory.getLogger(FindbugsExecutor.class);

  private FindbugsConfiguration configuration;

  public FindbugsExecutor(FindbugsConfiguration configuration) {
    this.configuration = configuration;
  }

  public File execute() {
    TimeProfiler profiler = new TimeProfiler().start("Execute Findbugs " + FindbugsVersion.getVersion());
    // We keep a handle on the current security manager because FB plays with it and we need to restore it before shutting down the executor
    // service
    SecurityManager currentSecurityManager = System.getSecurityManager();
    ClassLoader initialClassLoader = Thread.currentThread().getContextClassLoader();
    Thread.currentThread().setContextClassLoader(FindBugs2.class.getClassLoader());

    OutputStream xmlOutput = null;
    Collection<Plugin> customPlugins = null;
    ExecutorService executorService = Executors.newSingleThreadExecutor();
    try {
      final FindBugs2 engine = new FindBugs2();

      customPlugins = loadFindbugsPlugins();

      disableUpdateChecksOnEveryPlugin();

      Project project = configuration.getFindbugsProject();
      engine.setProject(project);

      XMLBugReporter xmlBugReporter = new XMLBugReporter(project);
      xmlBugReporter.setPriorityThreshold(Priorities.LOW_PRIORITY);
      xmlBugReporter.setAddMessages(true);

      File xmlReport = configuration.getTargetXMLReport();
      if (xmlReport != null) {
        LOG.info("Findbugs output report: " + xmlReport.getAbsolutePath());
        xmlOutput = FileUtils.openOutputStream(xmlReport);
      } else {
        xmlOutput = new NullOutputStream();
      }
      xmlBugReporter.setOutputStream(new PrintStream(xmlOutput));

      engine.setBugReporter(xmlBugReporter);

      UserPreferences userPreferences = UserPreferences.createDefaultUserPreferences();
      userPreferences.setEffort(configuration.getEffort());
      engine.setUserPreferences(userPreferences);

      engine.addFilter(configuration.saveIncludeConfigXml().getAbsolutePath(), true);
      engine.addFilter(configuration.saveExcludeConfigXml().getAbsolutePath(), false);

      for (File filterFile : configuration.getExcludesFilters()) {
        if (filterFile.isFile()) {
          engine.addFilter(filterFile.getAbsolutePath(), false);
        } else {
          LOG.warn("FindBugs filter-file not found: {}", filterFile);
        }
      }

      engine.setDetectorFactoryCollection(DetectorFactoryCollection.instance());
      engine.setAnalysisFeatureSettings(FindBugs.DEFAULT_EFFORT);

      engine.finishSettings();

      executorService.submit(new FindbugsTask(engine)).get(configuration.getTimeout(), TimeUnit.MILLISECONDS);

      profiler.stop();

      return xmlReport;
    } catch (Exception e) {
      throw new SonarException("Can not execute Findbugs", e);
    } finally {
      // we set back the original security manager BEFORE shutting down the executor service, otherwise there's a problem with Java 5
      System.setSecurityManager(currentSecurityManager);
      resetCustomPluginList(customPlugins);
      executorService.shutdown();
      IOUtils.closeQuietly(xmlOutput);
      Thread.currentThread().setContextClassLoader(initialClassLoader);
    }
  }

  private static class FindbugsTask implements Callable<Object> {

    private FindBugs2 engine;

    public FindbugsTask(FindBugs2 engine) {
      this.engine = engine;
    }

    public Object call() throws Exception {
      try {
        engine.execute();
      } finally {
        engine.dispose();
      }
      return null;
    }
  }

  private Collection<Plugin> loadFindbugsPlugins() {
    ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();

    List<String> pluginJarPathList = Lists.newArrayList();
    try {
      Enumeration<URL> urls = contextClassLoader.getResources("findbugs.xml");
      while (urls.hasMoreElements()) {
        URL url = urls.nextElement();
        pluginJarPathList.add(StringUtils.removeStart(StringUtils.substringBefore(url.toString(), "!"), "jar:file:"));
      }
    } catch (IOException e) {
      throw new SonarException(e);
    }

    List<Plugin> customPluginList = Lists.newArrayList();
    for (String path : pluginJarPathList) {
      try {
        Plugin plugin = Plugin.addCustomPlugin(new File(path).toURI(), contextClassLoader);
        if (plugin != null) {
          customPluginList.add(plugin);
          LOG.info("Found findbugs plugin: " + path);
        }
      } catch (PluginException e) {
        LOG.warn("Failed to load plugin for custom detector: " + path);
      } catch (DuplicatePluginIdException e) {
        // FB Core plugin is always loaded, so we'll get an exception for it always
        if (!FINDBUGS_CORE_PLUGIN_ID.equals(e.getPluginId())) {
          // log only if it's not the FV Core plugin
          LOG.debug("Plugin already loaded: exception ignored: " + e.getMessage());
        }
      }
    }

    return customPluginList;
  }

  /**
   * Disable the update check for every plugin. See http://findbugs.sourceforge.net/updateChecking.html
   */
  private void disableUpdateChecksOnEveryPlugin() {
    for (Plugin plugin : Plugin.getAllPlugins()) {
      plugin.setMyGlobalOption("noUpdateChecks", "true");
    }
  }

  private static void resetCustomPluginList(Collection<Plugin> customPlugins) {
    if (customPlugins != null) {
      for (Plugin plugin : customPlugins) {
        Plugin.removeCustomPlugin(plugin);
      }
    }
  }

}