Redirect to enroll page when not enrolled

What does this mr do?

When a user tries to access a lab page when they are not enrolled to the edition of the course, they will be redirected to the enrol page.

Screenshots

before

after

Does this MR meet the acceptance criteria?

• I have added a changelog entry to reflect the significant changes I made.
• Tests were created to test the feature.
• I have updated the documentation accordingly.
• I adhere to the style guide. Closes #381 (closed)

src/main/java/nl/tudelft/queue/controller/LabController.java

@@ -20,8 +20,12 @@ package nl.tudelft.queue.controller;
 import java.time.LocalDateTime;
 import java.util.Comparator;
 import java.util.List;
+import java.util.Optional;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 
+import javax.servlet.http.HttpServletRequest;
 import javax.transaction.Transactional;
 
 import nl.tudelft.labracore.api.dto.AssignmentSummaryDTO;
@@ -47,6 +51,7 @@ import nl.tudelft.queue.model.enums.LabType;
 import nl.tudelft.queue.model.labs.ExamLab;
 import nl.tudelft.queue.model.labs.RegularLab;
 import nl.tudelft.queue.model.labs.SlottedLab;
+import nl.tudelft.queue.repository.LabRepository;
 import nl.tudelft.queue.service.LabService;
 import nl.tudelft.queue.service.PermissionService;
 import nl.tudelft.queue.service.RequestService;
@@ -54,16 +59,17 @@ import nl.tudelft.queue.service.RequestTableService;
 
 import org.modelmapper.ModelMapper;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.security.access.AccessDeniedException;
 import org.springframework.security.access.prepost.PreAuthorize;
 import org.springframework.stereotype.Controller;
 import org.springframework.ui.Model;
-import org.springframework.web.bind.annotation.GetMapping;
-import org.springframework.web.bind.annotation.PathVariable;
-import org.springframework.web.bind.annotation.PostMapping;
-import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.*;
 
 @Controller
 public class LabController {
+	@Autowired
+	private LabRepository labRepository;
+
 	@Autowired
 	private LabService ls;
 
@@ -499,4 +505,25 @@ public class LabController {
 				.map(EditionSummaryDTO::getId).collect(Collectors.toList()), model);
 	}
 
+	/**
+	 * Handles any {@link AccessDeniedException} thrown in this controller.
+	 *
+	 * @param  request The HTTP request associated with this exception.
+	 *
+	 * @return         The enrol page when the exception is thrown from a /lab/* page. Otherwise return the
+	 *                 403 error page.
+	 */
+	@ExceptionHandler(AccessDeniedException.class)
+	public String redirectToEnrolPage(HttpServletRequest request) {
+		Pattern testPattern = Pattern.compile("/lab/([0-9]+)/*");
+		Matcher matcher = testPattern.matcher(request.getRequestURI());
+		if (matcher.matches() && matcher.groupCount() == 1) {
+			Optional<Lab> lab = labRepository.findById(Long.parseLong(matcher.group(1)));
+			var session = sCache.getOrThrow(lab.orElseThrow().getSession());
+			var edition = session.getEdition().getId();
+			return "redirect:/edition/" + edition + "/enrol";
+		}
+		return "error/403";
+	}
+
 }