/*
 * 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.qpid.server.management.plugin.filter;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.qpid.server.util.ConnectionScopedRuntimeException;
import org.apache.qpid.server.util.ExternalServiceException;
import org.apache.qpid.server.util.ExternalServiceTimeoutException;
import org.apache.qpid.server.util.ServerScopedRuntimeException;

public class ExceptionHandlingFilter implements Filter
{
    private static final Logger LOGGER = LoggerFactory.getLogger(ExceptionHandlingFilter.class);

    private Thread.UncaughtExceptionHandler _uncaughtExceptionHandler;

    @Override
    public void init(FilterConfig filterConfig) throws ServletException
    {
        _uncaughtExceptionHandler = Thread.getDefaultUncaughtExceptionHandler();
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException
    {
        final String requestURI = ((HttpServletRequest) servletRequest).getRequestURI();
        try
        {
            filterChain.doFilter(servletRequest, servletResponse);
        }
        catch (ServerScopedRuntimeException | Error e)
        {
            try
            {
                if (e instanceof ServerScopedRuntimeException
                    && servletResponse instanceof HttpServletResponse
                    && !servletResponse.isCommitted())
                {
                    ((HttpServletResponse) servletResponse).sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
                }
            }
            finally
            {
                if (_uncaughtExceptionHandler == null)
                {
                    LOGGER.error("Fatal system error", e);
                }
                else
                {
                    _uncaughtExceptionHandler.uncaughtException(Thread.currentThread(), e);
                }
            }

            throw e;
        }
        catch (ExternalServiceTimeoutException e)
        {
            LOGGER.warn("External request timeout ", e);
            sendError(e, servletResponse, HttpServletResponse.SC_GATEWAY_TIMEOUT);
        }
        catch (ExternalServiceException e)
        {
            LOGGER.warn("External request failed ", e);
            sendError(e, servletResponse, HttpServletResponse.SC_BAD_GATEWAY);
        }
        catch (IOException | ServletException e)
        {
            LOGGER.debug("Exception in servlet '{}': ", requestURI, e);
            throw e;
        }
        catch (ConnectionScopedRuntimeException e)
        {
            if (LOGGER.isDebugEnabled())
            {
                LOGGER.debug("Exception in servlet '{}':", requestURI, e);
            }
            else
            {
                LOGGER.info("Exception in servlet '{}' : {}", requestURI, e.getMessage());
            }
            throw e;
        }
        catch (RuntimeException e)
        {
            LOGGER.error("Unexpected exception in servlet '{}': ", requestURI, e);
            throw e;
        }
    }

    @Override
    public void destroy()
    {
        // noop
    }

    private void sendError(final RuntimeException underlyingException,
                           final ServletResponse servletResponse,
                           final int responseCode) throws IOException
    {
        if (servletResponse instanceof HttpServletResponse && !servletResponse.isCommitted())
        {
            ((HttpServletResponse) servletResponse).sendError(responseCode);
        }
        else
        {
            throw underlyingException;
        }
    }
}