package org.cyclopsgroup.kaufman.aws;
   
   import java.io.File;
   import java.io.IOException;
   
   import org.apache.commons.logging.Log;
   import org.apache.commons.logging.LogFactory;
   import org.springframework.beans.factory.DisposableBean;
   import org.springframework.beans.factory.FactoryBean;
  
  import com.amazonaws.auth.AWSCredentials;
  import com.amazonaws.auth.AWSCredentialsProvider;
  import com.amazonaws.auth.InstanceProfileCredentialsProvider;
  import com.amazonaws.internal.StaticCredentialsProvider;
  import com.amazonaws.services.s3.AmazonS3;
  import com.amazonaws.services.s3.AmazonS3Client;
  import com.amazonaws.services.s3.model.GetObjectRequest;
  import com.amazonaws.services.s3.model.ObjectMetadata;
  
  /**
   * A spring bean that downloads S3 object into a local file, return the file and
   * delete it when Spring context disposes.
   */
  public class S3FileFactoryBean
      implements FactoryBean<File>, DisposableBean
  {
      private static final Log LOG = LogFactory.getLog( S3FileFactoryBean.class );
  
      private final String bucketName, objectKey;
  
      private File localFile;
  
      private final AmazonS3 s3Client;
  
      public S3FileFactoryBean( AmazonS3 s3Client, String bucketName,
                                String objectKey )
      {
          this.s3Client = s3Client;
          this.bucketName = bucketName;
          this.objectKey = objectKey;
      }
  
      public S3FileFactoryBean( AWSCredentials creds, String bucketName,
                                String objectKey )
      {
          this( new StaticCredentialsProvider( creds ), bucketName, objectKey );
      }
  
      public S3FileFactoryBean( AWSCredentialsProvider creds, String bucketName,
                                String objectKey )
      {
          this( new AmazonS3Client( creds ), bucketName, objectKey );
      }
  
      public S3FileFactoryBean( String bucketName, String objectKey )
      {
          this( new InstanceProfileCredentialsProvider(), bucketName, objectKey );
      }
  
      @Override
      public void destroy()
      {
          if ( localFile.exists() )
          {
              localFile.delete();
              LOG.info( "Local file " + localFile + " is deleted" );
          }
      }
  
      @Override
      public File getObject()
          throws IOException
      {
          if ( localFile == null )
          {
              localFile =
                  File.createTempFile( S3FileFactoryBean.class.getSimpleName(),
                                       ".tmp" );
              LOG.info( "Using default local file " + localFile );
          }
          LOG.info( String.format( "Getting object %s:%s into local file %s",
                                   bucketName, objectKey,
                                   localFile.getAbsolutePath() ) );
          ObjectMetadata result =
              s3Client.getObject( new GetObjectRequest( bucketName, objectKey ),
                                  localFile );
          LOG.info( "Call to S3 succeeded and returned " + result );
          return localFile;
      }
  
      @Override
      public Class<File> getObjectType()
      {
          return File.class;
      }
  
      @Override
      public boolean isSingleton()
      {
         return true;
     }
 
     public void setLocalFile( File localFile )
     {
         this.localFile = localFile;
     }
 }