/*****************************************************************************
 * Copyright 2011 Zdenko Vrabel
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * 
 *****************************************************************************/
package org.zdevra.guice.mvc;

import org.zdevra.guice.mvc.exceptions.NoMethodInvoked;

import java.io.PrintWriter;
import java.util.logging.Level;
import java.util.logging.Logger;

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

/**
 * Implementation show the exception's details on web output. All unhandled  
 * exceptions are routed from {@link ExceptionResolver} to this handler.
 * 
 * @see ExceptionResolver
 * @see GuiceExceptionResolver 
 */
class DefaultExceptionHandler implements ExceptionHandler {

    private static final Logger logger = Logger.getLogger(DefaultExceptionHandler.class.getName());

    @Override
    public void handleException(Throwable t, HttpServlet servlet, HttpServletRequest req, HttpServletResponse resp) {
        resp.setStatus(t instanceof NoMethodInvoked ? HttpServletResponse.SC_NOT_FOUND : HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
        resp.setContentType("text/html");
        try {
            logger.log(Level.SEVERE, "Unhandled exception caught by Lime default handler (" + t.getClass().getName() + ")", t);

            String msg = t.getLocalizedMessage() == null ? "" : t.getLocalizedMessage();
            PrintWriter writer = resp.getWriter();
            writer.write(
                    "<HTML><STYLE>body {font-family: Arial,Helvetica,sans-serif;} .stacktrace "
                    + "{background: #EEE; padding-left: 10px; padding-top: 5px; padding-bottom: 5px;"
                    + "margin-top: 0px; margin-bottom: 10px; display: block; font-family: monospace; }"
                    + "</STYLE> <BODY> <H2>Unhandled exception caught (");

            writer.write(t.getClass().getName());
            writer.write(")</H2><B>Message:</B>");
            writer.write(msg);
            writer.write("<BR><BR><B>Stack trace:</B><pre class=\"stacktrace\">\n");
            t.printStackTrace(writer);
            writer.write("\n</pre>Lime MVC default exception handler</BODY></HTML>");
        } catch (Exception e) {
            logger.log(Level.SEVERE, "Error in default handler", e);
        }
    }
}