/**
 * 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.hadoop.fs.http.server;

import org.apache.hadoop.lib.service.FileSystemAccessException;
import org.apache.hadoop.lib.wsrs.ExceptionProvider;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.slf4j.MDC;

import javax.ws.rs.core.Response;
import javax.ws.rs.ext.Provider;
import java.io.FileNotFoundException;
import java.io.IOException;

/**
 * JAX-RS <code>ExceptionMapper</code> implementation that maps HttpFSServer's
 * exceptions to HTTP status codes.
 */
@Provider
public class HttpFSExceptionProvider extends ExceptionProvider {
  private static Logger AUDIT_LOG = LoggerFactory.getLogger("httpfsaudit");
  private static Logger LOG = LoggerFactory.getLogger(HttpFSExceptionProvider.class);

  /**
   * Maps different exceptions thrown by HttpFSServer to HTTP status codes.
   * <p/>
   * <ul>
   * <li>SecurityException : HTTP UNAUTHORIZED</li>
   * <li>FileNotFoundException : HTTP NOT_FOUND</li>
   * <li>IOException : INTERNAL_HTTP SERVER_ERROR</li>
   * <li>UnsupporteOperationException : HTTP BAD_REQUEST</li>
   * <li>all other exceptions : HTTP INTERNAL_SERVER_ERROR </li>
   * </ul>
   *
   * @param throwable exception thrown.
   *
   * @return mapped HTTP status code
   */
  @Override
  public Response toResponse(Throwable throwable) {
    Response.Status status;
    if (throwable instanceof FileSystemAccessException) {
      throwable = throwable.getCause();
    }
    if (throwable instanceof SecurityException) {
      status = Response.Status.UNAUTHORIZED;
    } else if (throwable instanceof FileNotFoundException) {
      status = Response.Status.NOT_FOUND;
    } else if (throwable instanceof IOException) {
      status = Response.Status.INTERNAL_SERVER_ERROR;
    } else if (throwable instanceof UnsupportedOperationException) {
      status = Response.Status.BAD_REQUEST;
    } else {
      status = Response.Status.INTERNAL_SERVER_ERROR;
    }
    return createResponse(status, throwable);
  }

  /**
   * Logs the HTTP status code and exception in HttpFSServer's log.
   *
   * @param status HTTP status code.
   * @param throwable exception thrown.
   */
  @Override
  protected void log(Response.Status status, Throwable throwable) {
    String method = MDC.get("method");
    String path = MDC.get("path");
    String message = getOneLineMessage(throwable);
    AUDIT_LOG.warn("FAILED [{}:{}] response [{}] {}", new Object[]{method, path, status, message});
    LOG.warn("[{}:{}] response [{}] {}", new Object[]{method, path, status, message, throwable});
  }

}