DefaultErrorHandler.java

/**
 * Copyright (c) Codice Foundation
 * <p>
 * This is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser
 * General Public License as published by the Free Software Foundation, either version 3 of the
 * License, or any later version.
 * <p>
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
 * even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details. A copy of the GNU Lesser General Public License
 * is distributed along with this program and can be found at
 * <http://www.gnu.org/licenses/lgpl.html>.
 */
package org.codice.ddf.platform.error.handler.impl;

import static org.boon.Boon.toJson;

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.Base64;
import java.util.HashMap;
import java.util.Map;

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

import org.apache.commons.io.IOUtils;
import org.apache.commons.lang.exception.ExceptionUtils;
import org.codice.ddf.platform.error.handler.ErrorHandler;
import org.eclipse.jetty.util.ByteArrayISO8859Writer;
import org.osgi.framework.Bundle;
import org.osgi.framework.FrameworkUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class DefaultErrorHandler implements ErrorHandler {

    public static final String SERVER_ERROR_PLEASE_SEE_LOGS = "Server Error, please see logs.";

    private static final Logger LOGGER = LoggerFactory.getLogger(DefaultErrorHandler.class);

    private static final int BUFFER_SIZE = 4096;

    private String indexHtml = SERVER_ERROR_PLEASE_SEE_LOGS;

    private void initIndexHtml() {
        if (SERVER_ERROR_PLEASE_SEE_LOGS.equals(indexHtml)) {
            Bundle bundle = FrameworkUtil.getBundle(DefaultErrorHandler.class);
            if (null != bundle) {
                try {
                    indexHtml = IOUtils.toString(bundle.getEntry("/index.html")
                            .openStream());
                } catch (Exception e) {
                    LOGGER.debug("Unable to read/parse index.html.", e);
                }
            } else {
                LOGGER.debug("Unable to retrieve Bundle");
            }
        }
    }

    @Override
    public void handleError(int code, String message, String type, Throwable throwable, String uri,
            HttpServletRequest request, HttpServletResponse response) {
        initIndexHtml();

        String stack = ExceptionUtils.getFullStackTrace(throwable);

        Map<String, String> jsonMap = new HashMap<>();
        jsonMap.put("code", String.valueOf(code));
        jsonMap.put("message", message);
        jsonMap.put("type", type);
        jsonMap.put("throwable", stack);
        jsonMap.put("uri", uri);
        String data = toJson(jsonMap);
        String encodedBytes = Base64.getEncoder()
                .encodeToString(data.getBytes(StandardCharsets.UTF_8));

        String localIndexHtml = indexHtml.replace("WINDOW_DATA", "\"" + encodedBytes + "\"");

        response.setStatus(code);
        response.setContentType("text/html");
        try (ByteArrayISO8859Writer writer = new ByteArrayISO8859Writer(BUFFER_SIZE)) {
            writer.write(localIndexHtml);
            writer.flush();
            writer.writeTo(response.getOutputStream());
        } catch (IOException e) {
            LOGGER.debug("Unable to write error html data to client.");
        }
    }

}