package at.gv.egovernment.moa.spss.server.invoke;

import java.lang.reflect.Constructor;
import java.util.HashMap;
import java.util.Map;

import iaik.IAIKException;
import iaik.IAIKRuntimeException;

import at.gv.egovernment.moa.spss.MOAApplicationException;
import at.gv.egovernment.moa.spss.MOAException;
import at.gv.egovernment.moa.spss.MOASystemException;


/**
 * Map an exception from the <code>iaik</code> namespace to a
 * <code>MOAException</code>.
 * 
 * @author Patrick Peck
 * @version $Id$
 */
public class IaikExceptionMapper {

  /** The argument classes for <code>MOAException</code>s. */
  private static final Class[] CONSTRUCTOR_ARGS =
    new Class[] { String.class, Object[].class, Throwable.class };
  /** The exception mapping, as an array. */
  private static final Object[][] MESSAGES =
    {
      { iaik.IAIKException.class, "9900", MOASystemException.class },
      { iaik.IAIKRuntimeException.class, "9901", MOASystemException.class },
      { iaik.server.modules.xmlsign.XMLSignatureCreationException.class, "2220", MOAApplicationException.class },
      { iaik.server.modules.xmlsign.XMLSignatureCreationRuntimeException.class, "2220", MOAApplicationException.class },
      { iaik.server.modules.xmlsign.InvalidKeyException.class, "2221", MOAApplicationException.class }, 
      { iaik.server.modules.xmlsign.ManifestException.class, "2222", MOAApplicationException.class },
      { iaik.server.modules.xmlsign.ReferenceException.class, "2223", MOAApplicationException.class },
      { iaik.server.modules.xmlsign.HashUnavailableException.class, "2224", MOAApplicationException.class },
      { iaik.server.modules.xmlsign.SignatureAlgorithmException.class, "2225", MOAApplicationException.class },
      { iaik.server.modules.xmlsign.SignatureEmbeddingException.class, "2226", MOAApplicationException.class },
      { iaik.server.modules.xmlsign.SignatureValueException.class, "2227", MOAApplicationException.class },
      { iaik.server.modules.xmlsign.SignedPropertyException.class, "2228", MOAApplicationException.class },
      { iaik.server.modules.xmlsign.SignerCertificateUnavailableException.class, "2229", MOAApplicationException.class },
      { iaik.server.modules.xmlsign.SupplementException.class, "2230", MOAApplicationException.class },
      { iaik.server.modules.xmlsign.TransformationException.class, "2233", MOAApplicationException.class },
      { iaik.server.modules.cmsverify.CMSSignatureVerificationException.class, "2240", MOAApplicationException.class },
      { iaik.server.modules.cmsverify.CMSSignatureVerificationRuntimeException.class, "2240", MOAApplicationException.class },
      { iaik.server.modules.cmsverify.AlgorithmNotSupportedException.class, "2241", MOAApplicationException.class },
      { iaik.server.modules.cmsverify.CMSSignatureParsingException.class, "2242", MOAApplicationException.class },
      { iaik.server.modules.cmsverify.SignerCertificateUnavailableException.class, "2243", MOAApplicationException.class },
      { iaik.server.modules.cmsverify.CMSSignatureVerificationRuntimeException.class, "2247", MOAApplicationException.class },
      { iaik.server.modules.cmsverify.InitException.class, "2248", MOAApplicationException.class }, 
      { iaik.server.modules.xmlverify.XMLSignatureVerificationException.class, "2240", MOAApplicationException.class },
      { iaik.server.modules.xmlverify.XMLSignatureVerificationRuntimeException.class, "2240", MOAApplicationException.class },
      { iaik.server.modules.xmlverify.AlgorithmNotSupportedException.class, "2241", MOAApplicationException.class },
      { iaik.server.modules.xmlverify.ManifestException.class, "2262", MOAApplicationException.class },
      { iaik.server.modules.xmlverify.PropertiesException.class, "2263", MOAApplicationException.class },
      { iaik.server.modules.xmlverify.ReferenceException.class, "2264", MOAApplicationException.class },
      { iaik.server.modules.xmlverify.HashUnavailableException.class, "2224", MOAApplicationException.class },
      { iaik.server.modules.xmlverify.SignerCertificateUnavailableException.class, "2243", MOAApplicationException.class },
      { iaik.server.modules.xmlverify.SupplementException.class, "2230", MOAApplicationException.class },
      { iaik.server.modules.xmlverify.TransformationException.class, "2265", MOAApplicationException.class },
      { iaik.server.modules.xmlverify.TransformationParsingException.class, "2269", MOAApplicationException.class }
  };
  
  /** The single instance of this class. */
  private static IaikExceptionMapper instance;
  /** The exception mapping, as a <code>Map</code> for fast lookup. */
  private Map messages = new HashMap();

  /**
   * Get the single instance of this class.
   * 
   * @return The single instance of this class.
   */
  public static synchronized IaikExceptionMapper getInstance() {
    if (instance == null) {
      instance = new IaikExceptionMapper();
    }
    return instance;
  }

  /**
   * Create a new <code>IaikExceptionMapper</code>.
   * 
   * Protected to disallow multple instances.
   */
  protected IaikExceptionMapper() {
    registerMessages();
  }

  /**
   * Build the complete <code>IAIKException</code> to message code mapping.
   */
  protected void registerMessages() {
    int i;

    for (i = 0; i < MESSAGES.length; i++) {
      registerMessage(
        (Class) MESSAGES[i][0],
        (String) MESSAGES[i][1],
        (Class) MESSAGES[i][2]);
    }
  }

  /**
   * Register a single <code>IAIKException</code> to message mapping.
   * 
   * @param iaikExceptionClass An exception from the <code>iaik</code> package. 
   * @param messageId The corresponding error message id.
   * @param moaExceptionClass The type of <code>MOAException</code> that the
   * <code>IAIKException</code> is mapped to (usually
   * <code>MOAApplicationException</code> or <code>MOASystemException</code>).
   */
  protected void registerMessage(
    Class iaikExceptionClass,
    String messageId,
    Class moaExceptionClass) {

    messages.put(
      iaikExceptionClass,
      new ExceptionMappingInfo(messageId, moaExceptionClass));
  }

  /**
   * Map an <code>IAIKException</code> to a <code>MOAException</code>.
   * 
   * @param iaikException The <code>IAIKException</code> to map. 
   * @return A <code>MOAException</code> containing the message for the
   * given <code>IAIKException</code>.
   */
  public MOAException map(IAIKException iaikException) {
    return mapImpl(iaikException);
  }

  /**
   * Map an <code>IAIKRuntimeException</code> to a <code>MOAException</code>.
   * 
   * @param iaikException The <code>IAIKException</code> to map. 
   * @return A <code>MOAException</code> containing the message for the
   * given <code>IAIKRuntimeException</code>.
   */
  public MOAException map(IAIKRuntimeException iaikException) {
    return mapImpl(iaikException);
  }

  /**
   * Map an <code>IAIKException</code> or <code>IAIKRuntimeException</code> to a
   * <code>MOAException</code>.
   * 
   * @param iaikException The <code>IAIKException</code> or
   * <code>IAIKRuntimeException</code> to map.
   * @return A <code>MOAException</code> containing the message for the
   * given <code>IAIKRuntimeException</code>.
   */
  private MOAException mapImpl(Exception iaikException) {
    MOAException moaException = createMoaException(iaikException);

    if (moaException == null) {
      return new MOASystemException("9999", null, iaikException);
    }
    return moaException;
  }

  /**
   * Create a <code>MOAException</code> from a given <code>IAIKException</code>
   * by looking it up in the mapping.
   * 
   * @param iaikException The <code>IAIKException</code> to map.
   * @return A <code>MOAException</code> with an error code corresponding to
   * the given <code>IAIKException</code>. Returns <code>null</code>, if no
   * mapping could be found.
   */
  protected MOAException createMoaException(Exception iaikException) {
    ExceptionMappingInfo info = lookupMessage(iaikException.getClass());
    Constructor constructor;

    if (info == null) {
      return null;
    }

    // instantiate the proper MOAException and return it
    try {
      constructor =
        info.getMoaExceptionClass().getConstructor(CONSTRUCTOR_ARGS);
      return (MOAException) constructor.newInstance(
        new Object[] {
          info.getMessageId(),
          new Object[] { iaikException.getMessage()},
          iaikException });
    } catch (Exception e) {
      return null;
    }
  }

  /**
   * Recursively look up the message associated with an
   * <code>IAIKException</code>.
   * 
   * This method walks up the exception inheritance hierarchy until it finds a
   * mapping.
   * 
   * @param iaikExceptionClass The <code>IAIKException</code> to look up.
   * @return Information about the message id and
   * <code>MOAException</code> class that the <code>iaikExceptionClass</code>
   * maps to. If no mapping could be found, <code>null</code> is returned.
   */
  protected ExceptionMappingInfo lookupMessage(Class iaikExceptionClass) {
    ExceptionMappingInfo info;

    // break if 
    if (iaikExceptionClass.equals(Exception.class)) {
      return null;
    }

    // look up the exception class
    info = (ExceptionMappingInfo) messages.get(iaikExceptionClass);
    if (info == null) {
      return lookupMessage(iaikExceptionClass.getSuperclass());
    }
    return info;
  }

}

/**
 * A class containing a mapping from an error message ID to a
 * <code>MOAException</code> class.
 * 
 * @author Patrick Peck
 * @version $Id$
 */
class ExceptionMappingInfo {
  /** The message ID. */
  private String messageId;
  /** The <code>MOAException</code> class. */
  private Class moaExceptionClass;

  /**
   * Create a new <code>ExceptionMappingInfo</code>.
   * 
   * @param messageId The message ID.
   * @param moaExceptionClass The <code>MOAException</code> class. 
   */
  public ExceptionMappingInfo(String messageId, Class moaExceptionClass) {
    this.messageId = messageId;
    this.moaExceptionClass = moaExceptionClass;
  }

  /**
   * Return the message ID.
   * 
   * @return The message ID.
   */
  public String getMessageId() {
    return messageId;
  }

  /**
   * Returns the <code>MOAException</code> class that the message ID maps to.
   * 
   * @return The <code>MOAException</code> class.
   */
  public Class getMoaExceptionClass() {
    return moaExceptionClass;
  }

}