package com.atlassian.plugin.util.resource;
   
   import java.io.File;
   import java.io.IOException;
   import java.io.InputStream;
   import java.net.MalformedURLException;
   import java.net.URL;
   import java.util.ArrayList;
   import java.util.Collections;
  import java.util.List;
  
  import com.google.common.base.Splitter;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Loads resources from directories configured via the system property {@code plugin.resource.directories}, which should
   * be a comma-delimited list of file paths that contain resources to load.
   *
   * @since 2.2.0
   */
  public class AlternativeDirectoryResourceLoader implements AlternativeResourceLoader
  {
      private static final Logger log = LoggerFactory.getLogger(AlternativeDirectoryResourceLoader.class);
      private static final Splitter splitter = Splitter.on(',').trimResults().omitEmptyStrings();
  
      public static final String PLUGIN_RESOURCE_DIRECTORIES = "plugin.resource.directories";
  
      private final List<File> resourceDirectories;
  
      public AlternativeDirectoryResourceLoader()
      {
          String dirs = System.getProperty(PLUGIN_RESOURCE_DIRECTORIES);
          List<File> tmp = new ArrayList<File>();
          if (dirs != null)
          {
              for (String dir : splitter.split(dirs))
              {
                  File file = new File(dir);
                  if (file.exists())
                  {
                      log.debug("Found alternative resource directory "+dir);
                      tmp.add(file);
                  }
                  else
                  {
                      log.warn("Resource directory "+dir+", which resolves to "+file.getAbsolutePath()+" does not exist");
                  }
              }
          }
  
          resourceDirectories = Collections.unmodifiableList(tmp);
      }
      /**
       * Retrieve the URL of the resource from the directories.
       *
       * @param path the name of the resource to be loaded
       * @return The URL to the resource, or null if the resource is not found
       */
      public URL getResource(String path)
      {
          for (File dir : resourceDirectories)
          {
              File file = new File(dir, path);
              if (file.exists())
              {
                  try
                  {
                      return file.toURL();
                  }
                  catch (MalformedURLException e)
                  {
                      log.error("Malformed URL: "+file.toString(), e);
                  }
              }
              else
              {
                  log.debug("File "+file+" not found, ignoring");
              }
          }
          return null;
      }
  
      /**
       * Load a given resource from the directories.
       *
       * @param name The name of the resource to be loaded.
       * @return An InputStream for the resource, or null if the resource is not found.
       */
      public InputStream getResourceAsStream(String name)
      {
          URL url = getResource(name);
          if (url != null)
          {
              try
              {
                  return url.openStream();
              }
             catch (IOException e)
             {
                 log.error("Unable to open URL "+url, e);
             }
         }
         return null;
     }
 
     public List<File> getResourceDirectories()
     {
         return resourceDirectories;
     }
 
 
 }