/*

 * Licensed to the Apache Software Foundation (ASF) under one or more

 * contributor license agreements.  See the NOTICE file distributed with

 * this work for additional information regarding copyright ownership.

 * The ASF licenses this file to You 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.apache.catalina.valves;

import java.io.IOException;

import java.io.Writer;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServletResponse;

import org.apache.catalina.Globals;

import org.apache.catalina.connector.Request;

import org.apache.catalina.connector.Response;

import org.apache.catalina.util.RequestUtil;

import org.apache.catalina.util.ServerInfo;

import org.apache.catalina.util.StringManager;

/**

 * <p>Implementation of a Valve that outputs HTML error pages.</p>

 *

 * <p>This Valve should be attached at the Host level, although it will work

 * if attached to a Context.</p>

 *

 * <p>HTML code from the Cocoon 2 project.</p>

 *

 * @author Remy Maucherat

 * @author Craig R. McClanahan

 * @author <a href="mailto:nicolaken@supereva.it">Nicola Ken Barozzi</a> Aisa

 * @author <a href="mailto:stefano@apache.org">Stefano Mazzocchi</a>

 * @author Yoav Shapira

 */

public class ErrorReportValve

    extends ValveBase {

    // ----------------------------------------------------- Instance Variables

    /**

     * The descriptive information related to this implementation.

     */

    private static final String info =

        "org.apache.catalina.valves.ErrorReportValve/1.0";

    /**

     * The StringManager for this package.

     */

    protected static StringManager sm =

        StringManager.getManager(Constants.Package);

    // ------------------------------------------------------------- Properties

    /**

     * Return descriptive information about this Valve implementation.

     */

    public String getInfo() {

        return (info);

    }

    // --------------------------------------------------------- Public Methods

    /**

     * Invoke the next Valve in the sequence. When the invoke returns, check

     * the response state, and output an error report is necessary.

     *

     * @param request The servlet request to be processed

     * @param response The servlet response to be created

     *

     * @exception IOException if an input/output error occurs

     * @exception ServletException if a servlet error occurs

     */

    public void invoke(Request request, Response response)

        throws IOException, ServletException {

        // Perform the request

        getNext().invoke(request, response);

        Throwable throwable =

            (Throwable) request.getAttribute(Globals.EXCEPTION_ATTR);

        if (response.isCommitted()) {

            return;

        }

        if (throwable != null) {

            // The response is an error

            response.setError();

            // Reset the response (if possible)

            try {

                response.reset();

            } catch (IllegalStateException e) {

                ;

            }

            response.sendError

                (HttpServletResponse.SC_INTERNAL_SERVER_ERROR);

        }

        response.setSuspended(false);

        try {

            report(request, response, throwable);

        } catch (Throwable tt) {

            ;

        }

    }

    // ------------------------------------------------------ Protected Methods

    /**

     * Prints out an error report.

     *

     * @param request The request being processed

     * @param response The response being generated

     * @param throwable The exception that occurred (which possibly wraps

     *  a root cause exception

     */

    protected void report(Request request, Response response,

                          Throwable throwable) {

        // Do nothing on non-HTTP responses

        int statusCode = response.getStatus();

        // Do nothing on a 1xx, 2xx and 3xx status

        // Do nothing if anything has been written already

        if ((statusCode < 400) || (response.getContentCount() > 0))

            return;

        String message = RequestUtil.filter(response.getMessage());

        if (message == null)

            message = "";

        // Do nothing if there is no report for the specified status code

        String report = null;

        try {

            report = sm.getString("http." + statusCode, message);

        } catch (Throwable t) {

            ;

        }

        if (report == null)

            return;

        StringBuffer sb = new StringBuffer();

        sb.append("<html><head><title>");

        sb.append(ServerInfo.getServerInfo()).append(" - ");

        sb.append(sm.getString("errorReportValve.errorReport"));

        sb.append("</title>");

        sb.append("<style><!--");

        sb.append(org.apache.catalina.util.TomcatCSS.TOMCAT_CSS);

        sb.append("--></style> ");

        sb.append("</head><body>");

        sb.append("<h1>");

        sb.append(sm.getString("errorReportValve.statusHeader",

                               "" + statusCode, message)).append("</h1>");

        sb.append("<HR size=\"1\" noshade=\"noshade\">");

        sb.append("<p><b>type</b> ");

        if (throwable != null) {

            sb.append(sm.getString("errorReportValve.exceptionReport"));

        } else {

            sb.append(sm.getString("errorReportValve.statusReport"));

        }

        sb.append("</p>");

        sb.append("<p><b>");

        sb.append(sm.getString("errorReportValve.message"));

        sb.append("</b> <u>");

        sb.append(message).append("</u></p>");

        sb.append("<p><b>");

        sb.append(sm.getString("errorReportValve.description"));

        sb.append("</b> <u>");

        sb.append(report);

        sb.append("</u></p>");

        if (throwable != null) {

            String stackTrace = getPartialServletStackTrace(throwable);

            sb.append("<p><b>");

            sb.append(sm.getString("errorReportValve.exception"));

            sb.append("</b> <pre>");

            sb.append(RequestUtil.filter(stackTrace));

            sb.append("</pre></p>");

            int loops = 0;

            Throwable rootCause = throwable.getCause();

            while (rootCause != null && (loops < 10)) {

                stackTrace = getPartialServletStackTrace(rootCause);

                sb.append("<p><b>");

                sb.append(sm.getString("errorReportValve.rootCause"));

                sb.append("</b> <pre>");

                sb.append(RequestUtil.filter(stackTrace));

                sb.append("</pre></p>");

                // In case root cause is somehow heavily nested

                rootCause = rootCause.getCause();

                loops++;

            }

            sb.append("<p><b>");

            sb.append(sm.getString("errorReportValve.note"));

            sb.append("</b> <u>");

            sb.append(sm.getString("errorReportValve.rootCauseInLogs",

                                   ServerInfo.getServerInfo()));

            sb.append("</u></p>");

        }

        sb.append("<HR size=\"1\" noshade=\"noshade\">");

        sb.append("<h3>").append(ServerInfo.getServerInfo()).append("</h3>");

        sb.append("</body></html>");

        try {

            try {

                response.setContentType("text/html");

                response.setCharacterEncoding("utf-8");

            } catch (Throwable t) {

                if (container.getLogger().isDebugEnabled())

                    container.getLogger().debug("status.setContentType", t);

            }

            Writer writer = response.getReporter();

            if (writer != null) {

                // If writer is null, it's an indication that the response has

                // been hard committed already, which should never happen

                writer.write(sb.toString());

            }

        } catch (IOException e) {

            ;

        } catch (IllegalStateException e) {

            ;

        }

    }

    /**

     * Print out a partial servlet stack trace (truncating at the last 

     * occurrence of javax.servlet.).

     */

    protected String getPartialServletStackTrace(Throwable t) {

        StringBuffer trace = new StringBuffer();

        trace.append(t.toString()).append('\n');

        StackTraceElement[] elements = t.getStackTrace();

        int pos = elements.length;

        for (int i = 0; i < elements.length; i++) {

            if ((elements[i].getClassName().startsWith

                 ("org.apache.catalina.core.ApplicationFilterChain"))

                && (elements[i].getMethodName().equals("internalDoFilter"))) {

                pos = i;

            }

        }

        for (int i = 0; i < pos; i++) {

            if (!(elements[i].getClassName().startsWith

                  ("org.apache.catalina.core."))) {

                trace.append('\t').append(elements[i].toString()).append('\n');

            }

        }

        return trace.toString();

    }

}