package com.meltmedia.jgroups.aws;
   
   import com.amazonaws.AmazonServiceException;
   import com.amazonaws.auth.AWSCredentialsProvider;
   import com.amazonaws.auth.BasicAWSCredentials;
   import com.amazonaws.handlers.RequestHandler;
   import com.amazonaws.internal.StaticCredentialsProvider;
   import com.amazonaws.services.ec2.AmazonEC2;
   import com.amazonaws.services.ec2.AmazonEC2Client;
  import com.amazonaws.transform.Unmarshaller;
  import org.w3c.dom.Node;
  
  import java.lang.reflect.Field;
  import java.util.List;
  
  
  /**
   * A factory for AmazonEC2 instances.
   */
  @SuppressWarnings("deprecation")
  public class EC2Factory {
    private static String EC2_ENDPOINT_TEMPLATE = "ec2.{REGION}.amazonaws.com";
  
    public static AmazonEC2 create(
        final InstanceIdentity instanceIdentity,
        final String accessKey,
        final String secretKey,
        final String credentialsProviderClass,
        final CredentialsProviderFactory credentialsProviderFactory,
        final Boolean logAwsErrorMessages) throws Exception {
  
      final AmazonEC2 ec2 = setupEC2Client(
          instanceIdentity.region,
          accessKey,
          secretKey,
          credentialsProviderClass,
          credentialsProviderFactory);
  
      //Lets do some good old reflection work to add a unmarshaller to the AmazonEC2Client just to log the exceptions from soap.
      if (logAwsErrorMessages) {
        setupAWSExceptionLogging(ec2);
      }
      return ec2;
    }
  
    private static AmazonEC2 setupEC2Client(
        final String region,
        final String accessKey,
        final String secretKey,
        final String credentialsProviderClass,
        final CredentialsProviderFactory credentialsProviderFactory) throws Exception {
  
      final String endpoint = EC2_ENDPOINT_TEMPLATE.replace("{REGION}", region);
      final AWSCredentialsProvider credentialsProvider = accessKey == null && secretKey == null ?
          credentialsProviderFactory.createCredentialsProvider(credentialsProviderClass) :
          new StaticCredentialsProvider(new BasicAWSCredentials(accessKey, secretKey));
  
      final AmazonEC2 ec2 = new AmazonEC2Client(credentialsProvider);
      ec2.setEndpoint(endpoint);
      return ec2;
    }
  
    /**
     * Sets up the AmazonEC2Client to log soap faults from the AWS EC2 api server.
     */
    private static void setupAWSExceptionLogging(AmazonEC2 ec2) {
      boolean accessible = false;
      Field exceptionUnmarshallersField = null;
      try {
        exceptionUnmarshallersField = AmazonEC2Client.class.getDeclaredField("exceptionUnmarshallers");
        accessible = exceptionUnmarshallersField.isAccessible();
        exceptionUnmarshallersField.setAccessible(true);
        @SuppressWarnings("unchecked") final List<Unmarshaller<AmazonServiceException, Node>> exceptionUnmarshallers = (List<Unmarshaller<AmazonServiceException, Node>>) exceptionUnmarshallersField.get(ec2);
        exceptionUnmarshallers.add(0, new AWSFaultLogger());
        ((AmazonEC2Client) ec2).addRequestHandler((RequestHandler) exceptionUnmarshallers.get(0));
      } catch (Throwable t) {
        //I don't care about this.
      } finally {
        if (exceptionUnmarshallersField != null) {
          try {
            exceptionUnmarshallersField.setAccessible(accessible);
          } catch (SecurityException se) {
            //I don't care about this.
          }
        }
      }
    }
  
  }