feat(TrainingCancellation): enhance cancellation functionality and localization support

- Updated the training cancellation controller to accept training group IDs, improving the cancellation process.
- Modified the database schema to include a JSON field for training group IDs in the training cancellations table.
- Enhanced the TrainingCancellation model to support the new training group IDs field.
- Updated the training cancellation service to normalize and handle training group IDs effectively.
- Added localization support for training cancellation features across multiple languages, improving user experience.

backend/services/trainingCancellationService.js

@@ -24,10 +24,11 @@ class TrainingCancellationService {
     });
   }
 
-  async upsertTrainingCancellation(userToken, clubId, date, reason, endDate = null) {
+  async upsertTrainingCancellation(userToken, clubId, date, reason, endDate = null, trainingGroupIds = []) {
     await checkAccess(userToken, clubId);
     const normalizedStartDate = this.normalizeDate(date);
     const normalizedEndDate = this.normalizeDate(endDate || date);
+    const normalizedTrainingGroupIds = this.normalizeTrainingGroupIds(trainingGroupIds);
     if (!normalizedStartDate || !normalizedEndDate) {
       throw new HttpError('Ungültiges Datum', 400);
     }
@@ -41,6 +42,7 @@ class TrainingCancellationService {
       endDate: normalizedEndDate,
       date: normalizedStartDate,
       reason: String(reason || '').trim() || null,
+      trainingGroupIds: normalizedTrainingGroupIds,
     });
     return cancellation || await TrainingCancellation.findOne({
       where: { clubId, startDate: normalizedStartDate, endDate: normalizedEndDate },
@@ -71,6 +73,30 @@ class TrainingCancellationService {
     const text = String(date || '').slice(0, 10);
     return /^\d{4}-\d{2}-\d{2}$/.test(text) ? text : null;
   }
+
+  normalizeTrainingGroupIds(trainingGroupIds) {
+    const values = this.parseTrainingGroupIdsValue(trainingGroupIds);
+    return [...new Set(
+      values
+        .map(id => Number.parseInt(id, 10))
+        .filter(id => Number.isInteger(id) && id > 0)
+    )];
+  }
+
+  parseTrainingGroupIdsValue(trainingGroupIds) {
+    if (Array.isArray(trainingGroupIds)) return trainingGroupIds;
+    if (trainingGroupIds === null || trainingGroupIds === undefined || trainingGroupIds === '') return [];
+    if (typeof trainingGroupIds === 'string') {
+      try {
+        const parsed = JSON.parse(trainingGroupIds);
+        if (Array.isArray(parsed)) return parsed;
+        if (parsed !== null && parsed !== undefined) return [parsed];
+      } catch (error) {
+        return trainingGroupIds.split(',');
+      }
+    }
+    return [];
+  }
 }
 
 export default new TrainingCancellationService();