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

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.cert.X509Certificate;

import javax.servlet.http.HttpServletRequest;

import org.w3c.dom.Document;
import org.w3c.dom.Element;

import org.apache.axis.AxisFault;
import org.apache.axis.MessageContext;
import org.apache.axis.handlers.BasicHandler;
import org.apache.axis.transport.http.HTTPConstants;
import org.apache.axis.utils.Messages;
import org.apache.axis.utils.XMLUtils;

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

import at.gv.egovernment.moa.spss.MOASystemException;
import at.gv.egovernment.moa.spss.server.config.ConfigurationProvider;
import at.gv.egovernment.moa.spss.server.transaction.TransactionContext;
import at.gv.egovernment.moa.spss.server.transaction.TransactionContextManager;
import at.gv.egovernment.moa.spss.server.transaction.TransactionIDGenerator;
import at.gv.egovernment.moa.spss.util.MessageProvider;

/**
 * An handler that is invoked on each web service request and performs some
 * central message handling.
 * 
 * Mainly sets up the <code>TransactionContext</code> for the current
 * transaction (i.e. web service request).
 * 
 * @author Patrick Peck
 * @author Stefan Knirsch
 * @version $Id$
 */
public class AxisHandler extends BasicHandler {

  /** The resource names of the messages to load. */  
  private static final String MOA_SPSS_WSDL_RESOURCE_ = "/resources/wsdl/MOA-SPSS-1.2.wsdl";

  /** The property name for accessing the HTTP request. */
  private static final String REQUEST_PROPERTY = HTTPConstants.MC_HTTP_SERVLETREQUEST;
  
  /** The property name for accessing the X509 client certificate chain. */
  private static final String X509_CERTIFICATE_PROPERTY = "javax.servlet.request.X509Certificate";
  
  /** The property name for accessing the SOAP action header. */
  private static final String SOAP_ACTION_HEADER = "soapaction";

  /**
   * Handle an invocation of this handler. 
   * 
   * @param msgContext Information about this request/response.
   * @throws AxisFault An error occurred during processing of the request.
   * @see org.apache.axis.Handler#invoke(MessageContext)
   */
  public void invoke(MessageContext msgContext) throws AxisFault {
    if (!msgContext.getPastPivot()) {
      handleRequest(msgContext);
    } else {
      handleResponse(msgContext);
    }
  }

  /**
   * This method is called by <code>invoke</code> to handle incoming requests.
   * 
   * @param msgContext The context as provided to <code>invoke</code>.
   * @throws AxisFault An error occurred during processing of the request.
   */
  private void handleRequest(MessageContext msgContext) throws AxisFault {
    try {
      // generate a unique transaction id and build the TransactionContext
      // for this request
      HttpServletRequest request =
        (HttpServletRequest) msgContext.getProperty(REQUEST_PROPERTY);

      X509Certificate[] clientCert =
        (X509Certificate[]) request.getAttribute(X509_CERTIFICATE_PROPERTY);

      ConfigurationProvider configuration =
        ConfigurationProvider.getInstance();

      TransactionContext context =
        new TransactionContext(
          TransactionIDGenerator.nextID(),
          clientCert,
          configuration);

      context.setRequestName((String) request.getHeader(SOAP_ACTION_HEADER));

      setUpContexts(context);
      
      // log some information about the request
      info(
        "handler.00",
        new Object[] {
          context.getTransactionID(),
          msgContext.getTargetService()});
      info("handler.01", new Object[] { request.getRemoteAddr()});
      if (clientCert != null) {
        info(
          "handler.02",
          new Object[] {
            clientCert[0].getSubjectDN(),
            clientCert[0].getSerialNumber(),
            clientCert[0].getIssuerDN()});

      } else {
        info("handler.03", null);
      }
      if (Logger.isDebugEnabled()) {
        String msg = msgContext.getCurrentMessage().getSOAPPartAsString();
        Logger.debug(new LogMsg(msg));
      }
    } catch (MOASystemException e) {
      MOASystemException se = new MOASystemException("2900", null, e);
      AxisFault fault = AxisFault.makeFault(se);
      fault.setFaultDetail(new Element[] { se.toErrorResponse()});
      throw fault;
    } catch (Throwable t) {
      MOASystemException e = new MOASystemException("2900", null, t);
      AxisFault fault = AxisFault.makeFault(e);
      fault.setFaultDetail(new Element[] { e.toErrorResponse()});
      throw fault;
    }
  }

  /**
   * This method is called by <code>invoke</code> to handle outgoing
   * responses.
   * 
   * @param msgContext The context as provided to <code>invoke</code>.
   * @throws AxisFault An error occurred during processing of the response.
   */
  private void handleResponse(MessageContext msgContext) throws AxisFault {
    info("handler.04", null);
    if (Logger.isDebugEnabled()) {
      String msg = msgContext.getCurrentMessage().getSOAPPartAsString();
      Logger.debug(new LogMsg(msg));
    }
    tearDownContexts();
  }

  /**
   * Called, when the processing of the web service fails.
   * 
   * @param msgContext Information about the current request.
   * @see org.apache.axis.Handler#onFault(org.apache.axis.MessageContext)
   */
  public void onFault(MessageContext msgContext) {
    info("handler.05", null);
    tearDownContexts();
  }

  /**
   * Set up the thread-local contexts (<code>TransactionContext</code> and
   * <code>LoggingContext</code>).
   * 
   * @param context The <code>TransactionContext</code> to set for the current
   * request.
   */
  private void setUpContexts(TransactionContext context) {
    // set the transaction context in the TransactionContextManager
    TransactionContextManager tcm = TransactionContextManager.getInstance();
    tcm.setTransactionContext(context);

    // set the logging context in the LoggingContextManager
    LoggingContextManager lcm = LoggingContextManager.getInstance();
    LoggingContext lc = new LoggingContext(context.getTransactionID());
    lcm.setLoggingContext(lc);
  }

  /**
   * Tear down the thread-local contexts.
   */
  private void tearDownContexts() {
    // unset the transaction context
    TransactionContextManager tcm = TransactionContextManager.getInstance();
    tcm.setTransactionContext(null);

    // unset the logging context
    LoggingContextManager lcm = LoggingContextManager.getInstance();
    lcm.setLoggingContext(null);
  }

  /**
   * Generate the WSDL into the <code>msgContext</code>.
   * 
   * The code of this method is more or less copied from the 
   * <code>org.apache.axis.handlers.soap.SOAPService</code> class contained in
   * the 1.1 release of Axis to allow for a missing <code>wsdlFile</code> (so
   * that a resource by the same name is searched for in the classpath). The
   * implementation of this method should be obsolete if Axis 1.1 or higher is
   * used.
   * 
   * @param msgContext The <code>MessageContext</code> that will contain the
   * WSDL description of the current web service.
   * @throws AxisFault An error occurred producing the WSDL.
   */
  public void generateWSDL(MessageContext msgContext) throws AxisFault {
    InputStream instream = null;

    try {
      String filename = MOA_SPSS_WSDL_RESOURCE_;
      File file = new File(filename);
      if (file.exists()) {
        //if this resolves to a file, load it
        instream = new FileInputStream(filename);
      } else {
        //else load a named resource in our classloader. 
        instream = this.getClass().getResourceAsStream(filename);
        if (instream == null) {
          String errorText = Messages.getMessage("wsdlFileMissing", filename);
          throw new AxisFault(errorText);
        }
      }
      Document doc = XMLUtils.newDocument(instream);
      msgContext.setProperty("WSDL", doc);
    } catch (Exception e) {
      throw AxisFault.makeFault(e);
    } finally {
      if (instream != null) {
        try {
          instream.close();
        } catch (IOException e) {
          // ok to do nothing here
        }
      }
    }
  }

  /**
   * Utility function to issue an info message to the log.
   * 
   * @param messageId The ID of the message to log.
   * @param parameters Additional message parameters.
   */
  private static void info(String messageId, Object[] parameters) {
    MessageProvider msg = MessageProvider.getInstance();

    Logger.info(new LogMsg(msg.getMessage(messageId, parameters)));
  }

}