Implement GET /events/{token} backend with timezone support

Domain: add timezone field to Event and CreateEventCommand.
Ports: new GetEventUseCase inbound port.
Service: implement getByEventToken, validate IANA timezone on create.
Controller: map to GetEventResponse, compute expired flag via Clock.
Persistence: timezone column in JPA entity and mapping.
Tests: integration tests use DTOs + ObjectMapper instead of inline JSON,
GET tests seed DB directly via JpaRepository for isolation.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/src/main/java/de/fete/adapter/in/web/EventController.java

@@ -3,9 +3,18 @@ package de.fete.adapter.in.web;
 import de.fete.adapter.in.web.api.EventsApi;
 import de.fete.adapter.in.web.model.CreateEventRequest;
 import de.fete.adapter.in.web.model.CreateEventResponse;
+import de.fete.adapter.in.web.model.GetEventResponse;
+import de.fete.application.service.EventNotFoundException;
+import de.fete.application.service.InvalidTimezoneException;
 import de.fete.domain.model.CreateEventCommand;
 import de.fete.domain.model.Event;
 import de.fete.domain.port.in.CreateEventUseCase;
+import de.fete.domain.port.in.GetEventUseCase;
+import java.time.Clock;
+import java.time.DateTimeException;
+import java.time.LocalDate;
+import java.time.ZoneId;
+import java.util.UUID;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.RestController;
@@ -15,19 +24,29 @@ import org.springframework.web.bind.annotation.RestController;
 public class EventController implements EventsApi {
 
   private final CreateEventUseCase createEventUseCase;
+  private final GetEventUseCase getEventUseCase;
+  private final Clock clock;
 
-  /** Creates a new controller with the given use case. */
-  public EventController(CreateEventUseCase createEventUseCase) {
+  /** Creates a new controller with the given use cases and clock. */
+  public EventController(
+      CreateEventUseCase createEventUseCase,
+      GetEventUseCase getEventUseCase,
+      Clock clock) {
     this.createEventUseCase = createEventUseCase;
+    this.getEventUseCase = getEventUseCase;
+    this.clock = clock;
   }
 
   @Override
   public ResponseEntity<CreateEventResponse> createEvent(
       CreateEventRequest request) {
+    ZoneId zoneId = parseTimezone(request.getTimezone());
+
     var command = new CreateEventCommand(
         request.getTitle(),
         request.getDescription(),
         request.getDateTime(),
+        zoneId,
         request.getLocation(),
         request.getExpiryDate()
     );
@@ -39,8 +58,36 @@ public class EventController implements EventsApi {
     response.setOrganizerToken(event.getOrganizerToken());
     response.setTitle(event.getTitle());
     response.setDateTime(event.getDateTime());
+    response.setTimezone(event.getTimezone().getId());
     response.setExpiryDate(event.getExpiryDate());
 
     return ResponseEntity.status(HttpStatus.CREATED).body(response);
   }
+
+  @Override
+  public ResponseEntity<GetEventResponse> getEvent(UUID token) {
+    Event event = getEventUseCase.getByEventToken(token)
+        .orElseThrow(() -> new EventNotFoundException(token));
+
+    var response = new GetEventResponse();
+    response.setEventToken(event.getEventToken());
+    response.setTitle(event.getTitle());
+    response.setDescription(event.getDescription());
+    response.setDateTime(event.getDateTime());
+    response.setTimezone(event.getTimezone().getId());
+    response.setLocation(event.getLocation());
+    response.setAttendeeCount(0);
+    response.setExpired(
+        event.getExpiryDate().isBefore(LocalDate.now(clock)));
+
+    return ResponseEntity.ok(response);
+  }
+
+  private static ZoneId parseTimezone(String timezone) {
+    try {
+      return ZoneId.of(timezone);
+    } catch (DateTimeException e) {
+      throw new InvalidTimezoneException(timezone);
+    }
+  }
 }

backend/src/main/java/de/fete/adapter/in/web/GlobalExceptionHandler.java

@@ -1,6 +1,8 @@
 package de.fete.adapter.in.web;
 
+import de.fete.application.service.EventNotFoundException;
 import de.fete.application.service.ExpiryDateInPastException;
+import de.fete.application.service.InvalidTimezoneException;
 import java.net.URI;
 import java.util.List;
 import java.util.Map;
@@ -57,6 +59,32 @@ public class GlobalExceptionHandler extends ResponseEntityExceptionHandler {
         .body(problemDetail);
   }
 
+  /** Handles event not found. */
+  @ExceptionHandler(EventNotFoundException.class)
+  public ResponseEntity<ProblemDetail> handleEventNotFound(
+      EventNotFoundException ex) {
+    ProblemDetail problemDetail = ProblemDetail.forStatusAndDetail(
+        HttpStatus.NOT_FOUND, ex.getMessage());
+    problemDetail.setTitle("Event Not Found");
+    problemDetail.setType(URI.create("urn:problem-type:event-not-found"));
+    return ResponseEntity.status(HttpStatus.NOT_FOUND)
+        .contentType(MediaType.APPLICATION_PROBLEM_JSON)
+        .body(problemDetail);
+  }
+
+  /** Handles invalid timezone. */
+  @ExceptionHandler(InvalidTimezoneException.class)
+  public ResponseEntity<ProblemDetail> handleInvalidTimezone(
+      InvalidTimezoneException ex) {
+    ProblemDetail problemDetail = ProblemDetail.forStatusAndDetail(
+        HttpStatus.BAD_REQUEST, ex.getMessage());
+    problemDetail.setTitle("Invalid Timezone");
+    problemDetail.setType(URI.create("urn:problem-type:invalid-timezone"));
+    return ResponseEntity.badRequest()
+        .contentType(MediaType.APPLICATION_PROBLEM_JSON)
+        .body(problemDetail);
+  }
+
   /** Catches all unhandled exceptions. */
   @ExceptionHandler(Exception.class)
   public ResponseEntity<ProblemDetail> handleAll(Exception ex) {

backend/src/main/java/de/fete/adapter/out/persistence/EventJpaEntity.java

@@ -34,6 +34,9 @@ public class EventJpaEntity {
   @Column(name = "date_time", nullable = false)
   private OffsetDateTime dateTime;
 
+  @Column(nullable = false, length = 64)
+  private String timezone;
+
   @Column(length = 500)
   private String location;
 
@@ -103,6 +106,16 @@ public class EventJpaEntity {
     this.dateTime = dateTime;
   }
 
+  /** Returns the IANA timezone name. */
+  public String getTimezone() {
+    return timezone;
+  }
+
+  /** Sets the IANA timezone name. */
+  public void setTimezone(String timezone) {
+    this.timezone = timezone;
+  }
+
   /** Returns the event location. */
   public String getLocation() {
     return location;

backend/src/main/java/de/fete/adapter/out/persistence/EventPersistenceAdapter.java

@@ -2,6 +2,7 @@ package de.fete.adapter.out.persistence;
 
 import de.fete.domain.model.Event;
 import de.fete.domain.port.out.EventRepository;
+import java.time.ZoneId;
 import java.util.Optional;
 import java.util.UUID;
 import org.springframework.stereotype.Repository;
@@ -37,6 +38,7 @@ public class EventPersistenceAdapter implements EventRepository {
     entity.setTitle(event.getTitle());
     entity.setDescription(event.getDescription());
     entity.setDateTime(event.getDateTime());
+    entity.setTimezone(event.getTimezone().getId());
     entity.setLocation(event.getLocation());
     entity.setExpiryDate(event.getExpiryDate());
     entity.setCreatedAt(event.getCreatedAt());
@@ -51,6 +53,7 @@ public class EventPersistenceAdapter implements EventRepository {
     event.setTitle(entity.getTitle());
     event.setDescription(entity.getDescription());
     event.setDateTime(entity.getDateTime());
+    event.setTimezone(ZoneId.of(entity.getTimezone()));
     event.setLocation(entity.getLocation());
     event.setExpiryDate(entity.getExpiryDate());
     event.setCreatedAt(entity.getCreatedAt());

backend/src/main/java/de/fete/application/service/EventNotFoundException.java

@@ -0,0 +1,12 @@
+package de.fete.application.service;
+
+import java.util.UUID;
+
+/** Thrown when an event cannot be found by its token. */
+public class EventNotFoundException extends RuntimeException {
+
+  /** Creates a new exception for the given event token. */
+  public EventNotFoundException(UUID eventToken) {
+    super("Event not found: " + eventToken);
+  }
+}

backend/src/main/java/de/fete/application/service/EventService.java

@@ -3,16 +3,18 @@ package de.fete.application.service;
 import de.fete.domain.model.CreateEventCommand;
 import de.fete.domain.model.Event;
 import de.fete.domain.port.in.CreateEventUseCase;
+import de.fete.domain.port.in.GetEventUseCase;
 import de.fete.domain.port.out.EventRepository;
 import java.time.Clock;
 import java.time.LocalDate;
 import java.time.OffsetDateTime;
+import java.util.Optional;
 import java.util.UUID;
 import org.springframework.stereotype.Service;
 
-/** Application service implementing event creation. */
+/** Application service implementing event creation and retrieval. */
 @Service
-public class EventService implements CreateEventUseCase {
+public class EventService implements CreateEventUseCase, GetEventUseCase {
 
   private final EventRepository eventRepository;
   private final Clock clock;
@@ -35,10 +37,16 @@ public class EventService implements CreateEventUseCase {
     event.setTitle(command.title());
     event.setDescription(command.description());
     event.setDateTime(command.dateTime());
+    event.setTimezone(command.timezone());
     event.setLocation(command.location());
     event.setExpiryDate(command.expiryDate());
     event.setCreatedAt(OffsetDateTime.now(clock));
 
     return eventRepository.save(event);
   }
+
+  @Override
+  public Optional<Event> getByEventToken(UUID eventToken) {
+    return eventRepository.findByEventToken(eventToken);
+  }
 }

backend/src/main/java/de/fete/application/service/InvalidTimezoneException.java

@@ -0,0 +1,10 @@
+package de.fete.application.service;
+
+/** Thrown when an invalid IANA timezone ID is provided. */
+public class InvalidTimezoneException extends RuntimeException {
+
+  /** Creates a new exception for the given invalid timezone. */
+  public InvalidTimezoneException(String timezone) {
+    super("Invalid IANA timezone: " + timezone);
+  }
+}

backend/src/main/java/de/fete/domain/model/CreateEventCommand.java

@@ -2,12 +2,14 @@ package de.fete.domain.model;
 
 import java.time.LocalDate;
 import java.time.OffsetDateTime;
+import java.time.ZoneId;
 
 /** Command carrying the data needed to create an event. */
 public record CreateEventCommand(
     String title,
     String description,
     OffsetDateTime dateTime,
+    ZoneId timezone,
     String location,
     LocalDate expiryDate
 ) {}

backend/src/main/java/de/fete/domain/model/Event.java

@@ -2,6 +2,7 @@ package de.fete.domain.model;
 
 import java.time.LocalDate;
 import java.time.OffsetDateTime;
+import java.time.ZoneId;
 import java.util.UUID;
 
 /** Domain entity representing an event. */
@@ -13,6 +14,7 @@ public class Event {
   private String title;
   private String description;
   private OffsetDateTime dateTime;
+  private ZoneId timezone;
   private String location;
   private LocalDate expiryDate;
   private OffsetDateTime createdAt;
@@ -77,6 +79,16 @@ public class Event {
     this.dateTime = dateTime;
   }
 
+  /** Returns the IANA timezone. */
+  public ZoneId getTimezone() {
+    return timezone;
+  }
+
+  /** Sets the IANA timezone. */
+  public void setTimezone(ZoneId timezone) {
+    this.timezone = timezone;
+  }
+
   /** Returns the event location. */
   public String getLocation() {
     return location;

backend/src/main/java/de/fete/domain/port/in/GetEventUseCase.java

@@ -0,0 +1,12 @@
+package de.fete.domain.port.in;
+
+import de.fete.domain.model.Event;
+import java.util.Optional;
+import java.util.UUID;
+
+/** Inbound port for retrieving a public event by its token. */
+public interface GetEventUseCase {
+
+  /** Finds an event by its public event token. */
+  Optional<Event> getByEventToken(UUID eventToken);
+}