Add error pages for different errors

Closes #93 (closed)

src/main/java/nl/tudelft/submit/controller/ErrorController.java

@@ -17,13 +17,27 @@
  */
 package nl.tudelft.submit.controller;
 
+import javax.servlet.http.HttpServletResponse;
+
+import nl.tudelft.librador.exception.DTOValidationException;
+import nl.tudelft.submit.exception.DisallowedUploadException;
+import nl.tudelft.submit.exception.ScoreFormatException;
+
+import org.springframework.data.rest.webmvc.ResourceNotFoundException;
+import org.springframework.http.HttpStatus;
+import org.springframework.security.access.AccessDeniedException;
 import org.springframework.web.bind.annotation.ControllerAdvice;
 import org.springframework.web.bind.annotation.ExceptionHandler;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.ResponseStatus;
+import org.springframework.web.reactive.function.client.WebClientResponseException;
+import org.springframework.web.server.ResponseStatusException;
+import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler;
 
 import io.sentry.Sentry;
 
 @ControllerAdvice
-public class ErrorController {
+public class ErrorController extends ResponseEntityExceptionHandler {
 	/**
 	 * Prints the exception stack trace and returns the error page with the default error message.
 	 *
@@ -31,10 +45,88 @@ public class ErrorController {
 	 * @return   the link to the error page
 	 */
 	@ExceptionHandler(Exception.class)
-	public void exception(Exception e) throws Exception {
+	public String exception(Exception e) throws Exception {
 		e.printStackTrace();
 		Sentry.captureException(e);
 
-		throw (e);
+		return "error/error";
+	}
+
+	/**
+	 * Returns the error page when a request is forbidden.
+	 *
+	 * @return The page to load
+	 */
+	@ResponseStatus(HttpStatus.FORBIDDEN)
+	@ExceptionHandler(AccessDeniedException.class)
+	public String forbidden() {
+		return "error/forbidden";
+	}
+
+	/**
+	 * Returns the error page when a resource is not found.
+	 *
+	 * @return The page to load
+	 */
+	@ResponseStatus(HttpStatus.NOT_FOUND)
+	@ExceptionHandler(ResourceNotFoundException.class)
+	public String notFound() {
+		return "error/not_found";
+	}
+
+	/**
+	 * Returns the error page when a request is a bad request.
+	 *
+	 * @return The page to load
+	 */
+	@ResponseStatus(HttpStatus.BAD_REQUEST)
+	@ExceptionHandler({ WebClientResponseException.BadRequest.class, DisallowedUploadException.class,
+			ScoreFormatException.class })
+	public String badRequest() {
+		return "error/bad_request";
+	}
+
+	/**
+	 * Returns the error page when a request contains an invalid entity.
+	 *
+	 * @return The page to load
+	 */
+	@ResponseStatus(HttpStatus.UNPROCESSABLE_ENTITY)
+	@ExceptionHandler(DTOValidationException.class)
+	public String unprocessableEntity() {
+		return "error/unprocessable_entity";
 	}
+
+	/**
+	 * Handles a response status exception.
+	 *
+	 * @return The page to load
+	 */
+	@ExceptionHandler(ResponseStatusException.class)
+	public String responseStatusException(ResponseStatusException e, HttpServletResponse resp)
+			throws Exception {
+		resp.setStatus(e.getStatus().value());
+
+		switch (e.getStatus()) {
+			case FORBIDDEN:
+				return forbidden();
+			case NOT_FOUND:
+				return notFound();
+			case UNPROCESSABLE_ENTITY:
+				return unprocessableEntity();
+			default:
+				return exception(e);
+		}
+	}
+
+	/**
+	 * Handles any leftover exceptions.
+	 *
+	 * @return The page to load
+	 */
+	@GetMapping("/error")
+	public String defaultErrorMappingHandler(Exception e) throws Exception {
+		return exception(e);
+	}
+
 }