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

import java.io.IOException;
import java.io.InputStream;
import java.util.Date;
import java.util.Iterator;
import java.util.List;

import iaik.IAIKException;
import iaik.IAIKRuntimeException;
import iaik.server.modules.cmsverify.CMSSignatureVerificationModule;
import iaik.server.modules.cmsverify.CMSSignatureVerificationModuleFactory;
import iaik.server.modules.cmsverify.CMSSignatureVerificationProfile;
import iaik.server.modules.cmsverify.CMSSignatureVerificationResult;

import at.gv.egovernment.moa.logging.LoggingContext;
import at.gv.egovernment.moa.logging.LoggingContextManager;

import at.gv.egovernment.moa.spss.MOAApplicationException;
import at.gv.egovernment.moa.spss.MOAException;
import at.gv.egovernment.moa.spss.api.cmsverify.CMSContent;
import at.gv.egovernment.moa.spss.api.cmsverify.CMSContentExcplicit;
import at.gv.egovernment.moa.spss.api.cmsverify.CMSContentReference;
import at.gv.egovernment.moa.spss.api.cmsverify.CMSDataObject;
import at.gv.egovernment.moa.spss.api.cmsverify.VerifyCMSSignatureRequest;
import at.gv.egovernment.moa.spss.api.cmsverify.VerifyCMSSignatureResponse;
import at.gv.egovernment.moa.spss.server.logging.IaikLog;
import at.gv.egovernment.moa.spss.server.logging.TransactionId;
import at.gv.egovernment.moa.spss.server.transaction.TransactionContext;
import at.gv.egovernment.moa.spss.server.transaction.TransactionContextManager;

/**
 * A class providing an interface to the
 * <code>CMSSignatureVerificationModule</code>.
 * 
 * This class performs the invocation of the 
 * <code>iaik.server.modules.cmsverify.CMSSignatureVerificationModule</code>
 * from a <code>VerifyCMSSignatureRequest</code>. The result of the invocation 
 * is integrated into a <code>VerifyCMSSignatureResponse</code> returned.
 * 
 * @author Patrick Peck
 * @version $Id$
 */
public class CMSSignatureVerificationInvoker {

  /** The single instance of this class. */
  private static CMSSignatureVerificationInvoker instance = null;

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

  /**
   * Create a new <code>CMSSignatureVerificationInvoker</code>.
   * 
   * Protected to disallow multiple instances.
   */
  protected CMSSignatureVerificationInvoker() {
  }

  /**
   * Verify a CMS signature.
   * 
   * @param request The <code>VerifyCMSSignatureRequest</code> containing the
   * CMS signature, as well as additional data needed for verification.
   * @return Element A <code>VerifyCMSSignatureResponse</code> containing the
   * answer to the <code>VerifyCMSSignatureRequest</code>.
   * @throws MOAException An error occurred while processing the request.
   */
  public VerifyCMSSignatureResponse verifyCMSSignature(VerifyCMSSignatureRequest request)
    throws MOAException {
    CMSSignatureVerificationProfileFactory profileFactory =
      new CMSSignatureVerificationProfileFactory(request);
    VerifyCMSSignatureResponseBuilder responseBuilder =
      new VerifyCMSSignatureResponseBuilder();
    TransactionContext context =
      TransactionContextManager.getInstance().getTransactionContext();
    LoggingContext loggingCtx =
      LoggingContextManager.getInstance().getLoggingContext();
    InputStream signature;
    InputStream signedContent;
    CMSSignatureVerificationProfile profile;
    Date signingTime;
    List results;
    CMSSignatureVerificationResult result;
    int[] signatories;
    InputStream input;
    byte[] buf = new byte[256];

    // get the signature
    signature = request.getCMSSignature();

    // get the signed content
    signedContent = getSignedContent(request);

    // build the profile
    profile = profileFactory.createProfile();

    // get the signing time
    signingTime = request.getDateTime();

    // verify the signature
    try {
      CMSSignatureVerificationModule module =
        CMSSignatureVerificationModuleFactory.getInstance();

      module.setLog(new IaikLog(loggingCtx.getNodeID()));

      module.init(
        signature,
        signedContent,
        profile,
        new TransactionId(context.getTransactionID()));
      input = module.getInputStream();

      while (input.read(buf) > 0);
      results = module.verifySignature(signingTime);
    } catch (IAIKException e) {
      MOAException moaException = IaikExceptionMapper.getInstance().map(e);
      throw moaException;
    } catch (IAIKRuntimeException e) {
      MOAException moaException = IaikExceptionMapper.getInstance().map(e);
      throw moaException;
    } catch (IOException e) {
      throw new MOAApplicationException("2244", null, e);
    }

    // build the response: for each signatory add the result to the response
    signatories = request.getSignatories();
    if (signatories == VerifyCMSSignatureRequest.ALL_SIGNATORIES) {
      Iterator resultIter;

      for (resultIter = results.iterator(); resultIter.hasNext();) {
        result = (CMSSignatureVerificationResult) resultIter.next();
        responseBuilder.addResult(result);
      }
    } else {
      int i;

      for (i = 0; i < signatories.length; i++) {
        int sigIndex = signatories[i] - 1;

        try {
          result =
            (CMSSignatureVerificationResult) results.get(signatories[i] - 1);
          responseBuilder.addResult(result);
        } catch (IndexOutOfBoundsException e) {
          throw new MOAApplicationException(
            "2249",
            new Object[] { new Integer(sigIndex)});
        }
      }
    }

    return responseBuilder.getResponse();
  }

  /**
   * Get the signed content contained either in the request itself or given as a
   * reference to external data.
   * 
   * @param request The <code>VerifyCMSSignatureRequest</code> containing the
   * signed content (or the reference to the signed content).
   * @return InputStream A stream providing the signed content data, or
   * <code>null</code> if no signed content was provided with the request.
   * @throws MOAApplicationException An error occurred building the stream.
   */
  private InputStream getSignedContent(VerifyCMSSignatureRequest request)
    throws MOAApplicationException {

    CMSDataObject dataObj;
    CMSContent content;

    // select the Content element
    dataObj = request.getDataObject();
    if (dataObj == null) {
      return null;
    }
    content = dataObj.getContent();

    // build the content data
    switch (content.getContentType()) {
      case CMSContent.EXPLICIT_CONTENT :
        return ((CMSContentExcplicit) content).getBinaryContent();
      case CMSContent.REFERENCE_CONTENT :
        String reference = ((CMSContentReference) content).getReference();
        if (!"".equals(reference)) {
          ExternalURIResolver resolver = new ExternalURIResolver();
          return resolver.resolve(reference);
        } else {
          return null;
        }
      default :
        return null;
    }

  }

}