package org.appfuse.webapp.action;

import java.io.PrintWriter;
import java.io.StringWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.struts.Globals;
import org.apache.struts.action.ActionError;
import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ExceptionHandler;
import org.apache.struts.config.ExceptionConfig;


/**
 * Implementation of <strong>ExceptionHandler</strong> that
 * handles any Exceptions that are bundles up to the Action
 * layer.  This allows us to remove generic try/catch statements
 * from our Action Classes.
 *
 * <p>
 * <a href="ActionExceptionHandler.java.html"><i>View Source</i></a>
 * </p>
 *
 * @author <a href="mailto:matt@raibledesigns.com">Matt Raible</a>
 * @version $Revision: 1.5 $ $Date: 2003/12/11 21:30:48 $
 */
public final class ActionExceptionHandler extends ExceptionHandler {
    private Log log = LogFactory.getLog(ActionExceptionHandler.class);

    /**
     * This method handles any java.lang.Exceptions that are not
     * caught in previous classes.  It will loop through and get
     * all the causes (exception chain), create ActionErrors,
     * add them to the request and then forward to the input.
     *
     * @see org.apache.struts.action.ExceptionHandler#execute
     *      (
     *          java.lang.Exception,
     *          org.apache.struts.config.ExceptionConfig,
     *          org.apache.struts.action.ActionMapping,
     *          org.apache.struts.action.ActionForm,
     *          javax.servlet.http.HttpServletRequest,
     *          javax.servlet.http.HttpServletResponse
     *      )
     */
    public ActionForward execute(Exception ex, ExceptionConfig ae,
                                 ActionMapping mapping,
                                 ActionForm formInstance,
                                 HttpServletRequest request,
                                 HttpServletResponse response)
      throws ServletException {
        // if there's already errors in the request, don't process
        ActionErrors errors =
            (ActionErrors) request.getAttribute(Globals.ERROR_KEY);

        if (errors != null) {
            return null;
        }

        ActionForward forward =
            super.execute(ex, ae, mapping, formInstance, request, response);

        ActionError error = null;
        String property = null;

        // log the exception to the default logger
        logException(ex);
        // Get the chained exceptions (causes) and add them to the
        // list of errors as well
        while (ex != null) {
            String msg = ex.getMessage();
            error = new ActionError("errors.detail", msg);
            property = error.getKey();
            ex = (Exception) ex.getCause();

            if ((ex != null) && (ex.getMessage() != null)) {
                // check to see if the child message is the same
                // if so, don't store it
                if (msg.indexOf(ex.getMessage()) == -1) {
                    storeException(request, property, error, forward);
                }
            } else {
                storeException(request, property, error, forward);
            }
        }

        return forward;
    }

    /**
     * This method overrides the the ExceptionHandler's storeException
     * method in order to create more than one error message.
     *
     * @param request - The request we are handling
     * @param property  - The property name to use for this error
     * @param error - The error generated from the exception mapping
     * @param forward - The forward generated from the input path (from the form or exception mapping)
     * @param scope - The scope of the exception mapping.
     */
    protected void storeException(HttpServletRequest request,
                                  String property, ActionError error,
                                  ActionForward forward) {
        ActionErrors errors =
            (ActionErrors) request.getAttribute(Globals.ERROR_KEY);

        if (errors == null) {
            errors = new ActionErrors();
        }

        errors.add(property, error);

        request.setAttribute(Globals.ERROR_KEY, errors);
    }
    protected void logException(Exception ex) {
        StringWriter sw = new StringWriter();
        ex.printStackTrace(new PrintWriter(sw));
        log.error(sw.toString());
    }
}