# See handled exceptions in the log file
log4j.logger.org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver=debug

/**
 * REST exception handlers defined at a global level for the application
 */
@ControllerAdvice
public class RestResponseEntityExceptionHandler extends ResponseEntityExceptionHandler {
    private static final Logger log = LoggerFactory.getLogger(RestResponseEntityExceptionHandler.class);

    /**
     * Catch all for any other exceptions...
     */
    @ExceptionHandler({ Exception.class })
    @ResponseBody
    public ResponseEntity<?> handleAnyException(Exception e) {
        return errorResponse(e, HttpStatus.INTERNAL_SERVER_ERROR);
    }

    /**
     * Handle failures commonly thrown from code
     */
    @ExceptionHandler({ InvocationTargetException.class, IllegalArgumentException.class, ClassCastException.class,
            ConversionFailedException.class })
    @ResponseBody
    public ResponseEntity handleMiscFailures(Throwable t) {
        return errorResponse(t, HttpStatus.BAD_REQUEST);
    }

    /**
     * Send a 409 Conflict in case of concurrent modification
     */
    @ExceptionHandler({ ObjectOptimisticLockingFailureException.class, OptimisticLockingFailureException.class,
            DataIntegrityViolationException.class })
    @ResponseBody
    public ResponseEntity handleConflict(Exception ex) {
        return errorResponse(ex, HttpStatus.CONFLICT);
    }

    protected ResponseEntity<ExceptionMessage> errorResponse(Throwable throwable,
                                                                                HttpStatus status) {
        if (null != throwable) {
            log.error("error caught: " + throwable.getMessage(), throwable);
            return response(new ExceptionMessage(throwable), status);
        } else {
            log.error("unknown error caught in RESTController, {}", status);
            return response(null, status);
        }
    }

    protected <T> ResponseEntity<T> response(T body, HttpStatus status) {
        log.debug("Responding with a status of {}", status);
        return new ResponseEntity<>(body, new HttpHeaders(), status);
    }
}