/*
    * This file is part of dependency-check-core.
    *
    * 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.
   *
   * Copyright (c) 2012 Jeremy Long. All Rights Reserved.
   */
  package org.owasp.dependencycheck.data.update;
  
  import java.net.MalformedURLException;
  import java.util.Calendar;
  import java.util.HashSet;
  import java.util.Set;
  import java.util.concurrent.ExecutionException;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Executors;
  import java.util.concurrent.Future;
  import org.owasp.dependencycheck.data.nvdcve.CveDB;
  import org.owasp.dependencycheck.data.nvdcve.DatabaseException;
  import org.owasp.dependencycheck.data.nvdcve.DatabaseProperties;
  import static org.owasp.dependencycheck.data.nvdcve.DatabaseProperties.MODIFIED;
  import org.owasp.dependencycheck.data.update.exception.InvalidDataException;
  import org.owasp.dependencycheck.data.update.exception.UpdateException;
  import org.owasp.dependencycheck.data.update.nvd.DownloadTask;
  import org.owasp.dependencycheck.data.update.nvd.NvdCveInfo;
  import org.owasp.dependencycheck.data.update.nvd.ProcessTask;
  import org.owasp.dependencycheck.data.update.nvd.UpdateableNvdCve;
  import org.owasp.dependencycheck.exception.NoDataException;
  import org.owasp.dependencycheck.utils.DateUtil;
  import org.owasp.dependencycheck.utils.DownloadFailedException;
  import org.owasp.dependencycheck.utils.InvalidSettingException;
  import org.owasp.dependencycheck.utils.Settings;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Class responsible for updating the NVD CVE data.
   *
   * @author Jeremy Long
   */
  public class NvdCveUpdater extends BaseUpdater implements CachedWebDataSource {
  
      /**
       * The logger
       */
      private static final Logger LOGGER = LoggerFactory.getLogger(NvdCveUpdater.class);
      /**
       * The max thread pool size to use when downloading files.
       */
      public static final int MAX_THREAD_POOL_SIZE = Settings.getInt(Settings.KEYS.MAX_DOWNLOAD_THREAD_POOL_SIZE, 3);
  
      /**
       * <p>
       * Downloads the latest NVD CVE XML file from the web and imports it into the current CVE Database.</p>
       *
       * @throws UpdateException is thrown if there is an error updating the database
       */
      @Override
      public void update() throws UpdateException {
          try {
              openDataStores();
              if (checkUpdate()) {
                  final UpdateableNvdCve updateable = getUpdatesNeeded();
                  if (updateable.isUpdateNeeded()) {
                      performUpdate(updateable);
                  }
              }
          } catch (MalformedURLException ex) {
              LOGGER.warn(
                      "NVD CVE properties files contain an invalid URL, unable to update the data to use the most current data.");
              LOGGER.debug("", ex);
          } catch (DownloadFailedException ex) {
              LOGGER.warn(
                      "Unable to download the NVD CVE data; the results may not include the most recent CPE/CVEs from the NVD.");
              if (Settings.getString(Settings.KEYS.PROXY_SERVER) == null) {
                  LOGGER.info(
                          "If you are behind a proxy you may need to configure dependency-check to use the proxy.");
              }
              LOGGER.debug("", ex);
          } finally {
              closeDataStores();
          }
      }
  
      /**
       * Checks if the NVD CVE XML files were last checked recently. As an optimization, we can avoid repetitive checks against the
       * NVD. Setting CVE_CHECK_VALID_FOR_HOURS determines the duration since last check before checking again. A database property
       * stores the timestamp of the last check.
       *
      * @return true to proceed with the check, or false to skip.
      * @throws UpdateException thrown when there is an issue checking for updates.
      */
     private boolean checkUpdate() throws UpdateException {
         boolean proceed = true;
         // If the valid setting has not been specified, then we proceed to check...
         final int validForHours = Settings.getInt(Settings.KEYS.CVE_CHECK_VALID_FOR_HOURS, 0);
         if (dataExists() && 0 < validForHours) {
             // ms Valid = valid (hours) x 60 min/hour x 60 sec/min x 1000 ms/sec
             final long msValid = validForHours * 60L * 60L * 1000L;
             final long lastChecked = Long.parseLong(getProperties().getProperty(DatabaseProperties.LAST_CHECKED, "0"));
             final long now = System.currentTimeMillis();
             proceed = (now - lastChecked) > msValid;
             if (proceed) {
                 getProperties().save(DatabaseProperties.LAST_CHECKED, Long.toString(now));
             } else {
                 LOGGER.info("Skipping NVD check since last check was within {} hours.", validForHours);
                 LOGGER.debug("Last NVD was at {}, and now {} is within {} ms.",
                         lastChecked, now, msValid);
             }
         }
         return proceed;
     }
 
     /**
      * Checks the CPE Index to ensure documents exists.
      */
     private boolean dataExists() {
         CveDB cve = null;
         try {
             cve = new CveDB();
             cve.open();
             return cve.dataExists();
         } catch (DatabaseException ex) {
             return false;
         } finally {
             if (cve != null) {
                 cve.close();
             }
         }
     }
 
     /**
      * Downloads the latest NVD CVE XML file from the web and imports it into the current CVE Database.
      *
      * @param updateable a collection of NVD CVE data file references that need to be downloaded and processed to update the
      * database
      * @throws UpdateException is thrown if there is an error updating the database
      */
     public void performUpdate(UpdateableNvdCve updateable) throws UpdateException {
         int maxUpdates = 0;
         try {
             for (NvdCveInfo cve : updateable) {
                 if (cve.getNeedsUpdate()) {
                     maxUpdates += 1;
                 }
             }
             if (maxUpdates <= 0) {
                 return;
             }
             if (maxUpdates > 3) {
                 LOGGER.info(
                         "NVD CVE requires several updates; this could take a couple of minutes.");
             }
             if (maxUpdates > 0) {
                 openDataStores();
             }
 
             final int poolSize = (MAX_THREAD_POOL_SIZE < maxUpdates) ? MAX_THREAD_POOL_SIZE : maxUpdates;
 
             final ExecutorService downloadExecutors = Executors.newFixedThreadPool(poolSize);
             final ExecutorService processExecutor = Executors.newSingleThreadExecutor();
             final Set<Future<Future<ProcessTask>>> downloadFutures = new HashSet<Future<Future<ProcessTask>>>(maxUpdates);
             for (NvdCveInfo cve : updateable) {
                 if (cve.getNeedsUpdate()) {
                     final DownloadTask call = new DownloadTask(cve, processExecutor, getCveDB(), Settings.getInstance());
                     downloadFutures.add(downloadExecutors.submit(call));
                 }
             }
             downloadExecutors.shutdown();
 
             //next, move the future future processTasks to just future processTasks
             final Set<Future<ProcessTask>> processFutures = new HashSet<Future<ProcessTask>>(maxUpdates);
             for (Future<Future<ProcessTask>> future : downloadFutures) {
                 Future<ProcessTask> task = null;
                 try {
                     task = future.get();
                 } catch (InterruptedException ex) {
                     downloadExecutors.shutdownNow();
                     processExecutor.shutdownNow();
 
                     LOGGER.debug("Thread was interrupted during download", ex);
                     throw new UpdateException("The download was interrupted", ex);
                 } catch (ExecutionException ex) {
                     downloadExecutors.shutdownNow();
                     processExecutor.shutdownNow();
 
                     LOGGER.debug("Thread was interrupted during download execution", ex);
                     throw new UpdateException("The execution of the download was interrupted", ex);
                 }
                 if (task == null) {
                     downloadExecutors.shutdownNow();
                     processExecutor.shutdownNow();
                     LOGGER.debug("Thread was interrupted during download");
                     throw new UpdateException("The download was interrupted; unable to complete the update");
                 } else {
                     processFutures.add(task);
                 }
             }
 
             for (Future<ProcessTask> future : processFutures) {
                 try {
                     final ProcessTask task = future.get();
                     if (task.getException() != null) {
                         throw task.getException();
                     }
                 } catch (InterruptedException ex) {
                     processExecutor.shutdownNow();
                     LOGGER.debug("Thread was interrupted during processing", ex);
                     throw new UpdateException(ex);
                 } catch (ExecutionException ex) {
                     processExecutor.shutdownNow();
                     LOGGER.debug("Execution Exception during process", ex);
                     throw new UpdateException(ex);
                 } finally {
                     processExecutor.shutdown();
                 }
             }
 
             if (maxUpdates >= 1) { //ensure the modified file date gets written (we may not have actually updated it)
                 getProperties().save(updateable.get(MODIFIED));
                 LOGGER.info("Begin database maintenance.");
                 getCveDB().cleanupDatabase();
                 LOGGER.info("End database maintenance.");
             }
         } finally {
             closeDataStores();
         }
     }
 
     /**
      * Determines if the index needs to be updated. This is done by fetching the NVD CVE meta data and checking the last update
      * date. If the data needs to be refreshed this method will return the NvdCveUrl for the files that need to be updated.
      *
      * @return the collection of files that need to be updated
      * @throws MalformedURLException is thrown if the URL for the NVD CVE Meta data is incorrect
      * @throws DownloadFailedException is thrown if there is an error. downloading the NVD CVE download data file
      * @throws UpdateException Is thrown if there is an issue with the last updated properties file
      */
     protected final UpdateableNvdCve getUpdatesNeeded() throws MalformedURLException, DownloadFailedException, UpdateException {
         UpdateableNvdCve updates = null;
         try {
             updates = retrieveCurrentTimestampsFromWeb();
         } catch (InvalidDataException ex) {
             final String msg = "Unable to retrieve valid timestamp from nvd cve downloads page";
             LOGGER.debug(msg, ex);
             throw new DownloadFailedException(msg, ex);
         } catch (InvalidSettingException ex) {
             LOGGER.debug("Invalid setting found when retrieving timestamps", ex);
             throw new DownloadFailedException("Invalid settings", ex);
         }
 
         if (updates == null) {
             throw new DownloadFailedException("Unable to retrieve the timestamps of the currently published NVD CVE data");
         }
         if (!getProperties().isEmpty()) {
             try {
                 final long lastUpdated = Long.parseLong(getProperties().getProperty(DatabaseProperties.LAST_UPDATED, "0"));
                 final long now = System.currentTimeMillis();
                 final int days = Settings.getInt(Settings.KEYS.CVE_MODIFIED_VALID_FOR_DAYS, 7);
                 if (lastUpdated == updates.getTimeStamp(MODIFIED)) {
                     updates.clear(); //we don't need to update anything.
                 } else if (DateUtil.withinDateRange(lastUpdated, now, days)) {
                     for (NvdCveInfo entry : updates) {
                         if (MODIFIED.equals(entry.getId())) {
                             entry.setNeedsUpdate(true);
                         } else {
                             entry.setNeedsUpdate(false);
                         }
                     }
                 } else { //we figure out which of the several XML files need to be downloaded.
                     for (NvdCveInfo entry : updates) {
                         if (MODIFIED.equals(entry.getId())) {
                             entry.setNeedsUpdate(true);
                         } else {
                             long currentTimestamp = 0;
                             try {
                                 currentTimestamp = Long.parseLong(getProperties().getProperty(DatabaseProperties.LAST_UPDATED_BASE
                                         + entry.getId(), "0"));
                             } catch (NumberFormatException ex) {
                                 LOGGER.debug("Error parsing '{}' '{}' from nvdcve.lastupdated",
                                         DatabaseProperties.LAST_UPDATED_BASE, entry.getId(), ex);
                             }
                             if (currentTimestamp == entry.getTimestamp()) {
                                 entry.setNeedsUpdate(false);
                             }
                         }
                     }
                 }
             } catch (NumberFormatException ex) {
                 LOGGER.warn("An invalid schema version or timestamp exists in the data.properties file.");
                 LOGGER.debug("", ex);
             }
         }
         return updates;
     }
 
     /**
      * Retrieves the timestamps from the NVD CVE meta data file.
      *
      * @return the timestamp from the currently published nvdcve downloads page
      * @throws MalformedURLException thrown if the URL for the NVD CCE Meta data is incorrect.
      * @throws DownloadFailedException thrown if there is an error downloading the nvd cve meta data file
      * @throws InvalidDataException thrown if there is an exception parsing the timestamps
      * @throws InvalidSettingException thrown if the settings are invalid
      */
     private UpdateableNvdCve retrieveCurrentTimestampsFromWeb()
             throws MalformedURLException, DownloadFailedException, InvalidDataException, InvalidSettingException {
 
         final UpdateableNvdCve updates = new UpdateableNvdCve();
         updates.add(MODIFIED, Settings.getString(Settings.KEYS.CVE_MODIFIED_20_URL),
                 Settings.getString(Settings.KEYS.CVE_MODIFIED_12_URL),
                 false);
 
         final int start = Settings.getInt(Settings.KEYS.CVE_START_YEAR);
         final int end = Calendar.getInstance().get(Calendar.YEAR);
         final String baseUrl20 = Settings.getString(Settings.KEYS.CVE_SCHEMA_2_0);
         final String baseUrl12 = Settings.getString(Settings.KEYS.CVE_SCHEMA_1_2);
         for (int i = start; i <= end; i++) {
             updates.add(Integer.toString(i), String.format(baseUrl20, i),
                     String.format(baseUrl12, i),
                     true);
         }
         return updates;
     }
 
 }