package com.atlassian.plugin.osgi.container.impl;
   
   import com.atlassian.plugin.osgi.container.OsgiContainerException;
   import com.atlassian.plugin.osgi.container.OsgiPersistentCache;
   import org.apache.commons.io.FileUtils;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import java.io.File;
  import java.io.IOException;
  
  import static com.google.common.base.Preconditions.checkNotNull;
  import static com.google.common.base.Preconditions.checkState;
  
  /**
   * Default implementation of persistent cache.  Handles clearing of directories if an upgrade has been detected.
   *
   * @since 2.2.0
   */
  public class DefaultOsgiPersistentCache implements OsgiPersistentCache
  {
      private final File osgiBundleCache;
      private final File frameworkBundleCache;
      private final File transformedPluginCache;
      private final Logger log = LoggerFactory.getLogger(DefaultOsgiPersistentCache.class);
  
      /**
       * Constructs a cache, using the passed file as the base directory for cache subdirectories
       * @param baseDir The base directory
       */
      public DefaultOsgiPersistentCache(final File baseDir)
      {
          checkState(checkNotNull(baseDir).exists(), "The base directory for OSGi persistent caches should exist, %s", baseDir);
          osgiBundleCache = new File(baseDir, "felix");
          frameworkBundleCache = new File(baseDir, "framework-bundles");
          transformedPluginCache = new File(baseDir, "transformed-plugins");
          validate(null);
      }
  
      /**
       * Constructor added in the 2.2.0 beta timeframe, but was made redundant later.  Application version is not used.
       * @deprecated
       */
      @Deprecated
      public DefaultOsgiPersistentCache(final File baseDir, final String applicationVersion)
      {
          this(baseDir);
      }
  
      public File getFrameworkBundleCache()
      {
          return frameworkBundleCache;
      }
  
      public File getOsgiBundleCache()
      {
          return osgiBundleCache;
      }
  
      public File getTransformedPluginCache()
      {
          return transformedPluginCache;
      }
  
      public void clear() throws OsgiContainerException
      {
          try
          {
              FileUtils.cleanDirectory(frameworkBundleCache);
              FileUtils.cleanDirectory(osgiBundleCache);
              FileUtils.cleanDirectory(transformedPluginCache);
          }
          catch (final IOException e)
          {
              throw new OsgiContainerException("Unable to clear OSGi caches", e);
          }
      }
  
      public void validate(final String cacheValidationKey)
      {
          ensureDirectoryExists(frameworkBundleCache);
          ensureDirectoryExists(osgiBundleCache);
          ensureDirectoryExists(transformedPluginCache);
  
          try
          {
              FileUtils.cleanDirectory(osgiBundleCache);
          }
          catch (final IOException e)
          {
              throw new OsgiContainerException("Unable to clean the cache directory: " + osgiBundleCache, e);
          }
  
          if (cacheValidationKey != null)
          {
              final String newHash = String.valueOf(cacheValidationKey.hashCode());
              final File versionFile = new File(transformedPluginCache, "cache.key");
              if (versionFile.exists())
              {
                 String oldVersion = null;
                 try
                 {
                     oldVersion = FileUtils.readFileToString(versionFile);
                 }
                 catch (final IOException e)
                 {
                     log.debug("Unable to read cache key file", e);
                 }
                 if (!newHash.equals(oldVersion))
                 {
                     log.info("Application upgrade detected, clearing OSGi cache directories");
                     clear();
                 }
                 else
                 {
                     return;
                 }
             }
 
             try
             {
                 FileUtils.writeStringToFile(versionFile, newHash);
             }
             catch (final IOException e)
             {
                 log.warn("Unable to write cache key file, so will be unable to detect upgrades", e);
             }
         }
     }
 
     private void ensureDirectoryExists(final File dir)
     {
         if (dir.exists() && !dir.isDirectory())
         {
             throw new IllegalArgumentException("'"+dir+"' is not a directory");
         }
 
         if (!dir.exists() && !dir.mkdir())
         {
             throw new IllegalArgumentException("Directory '"+dir+"' cannot be created");
         }
     }
 }