feat(community): add metering data upload UI with preview and validation

- Add frontend upload page with file selection, drag-and-drop, and preview
- Add preview endpoint (POST /api/community/metering-data/preview/xlsx)
- Validate FEED_IN only for PRODUCER, CONSUMPTION only for CONSUMER metering points
- Optimize deduplication with bulk query (fix N+1 problem)
- Eliminate duplicate DB query in validateRecords
- Add 4 new tests for data type validation
- Add navigation entry for admin users

eeg_backend/src/main/java/at/mueller/eeg/backend/community/api/MeteringDataController.java

@@ -61,6 +61,14 @@ public class MeteringDataController {
         return ResponseEntity.status(HttpStatus.CREATED).body(response);
     }
 
+    @PostMapping(value = "/preview/xlsx", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
+    @PreAuthorize("hasRole('ADMIN')")
+    public ResponseEntity<List<MeteringDataRecordDto>> previewXlsx(
+            @RequestParam("file") MultipartFile file) throws IOException {
+        List<MeteringDataRecordDto> records = xlsxParser.parse(file.getInputStream());
+        return ResponseEntity.ok(records.stream().limit(10).toList());
+    }
+
     @GetMapping("/{meteringPointId}")
     @PreAuthorize("hasRole('MEMBER')")
     public ResponseEntity<List<MeteringDataResponse>> getMeteringData(

eeg_backend/src/main/java/at/mueller/eeg/backend/community/repository/MeteringDataRepository.java

@@ -23,6 +23,13 @@ public interface MeteringDataRepository extends JpaRepository<MeteringData, UUID
     List<MeteringData> findByMeteringPointIdAndDataTypeAndIntervalStart(
             UUID meteringPointId, MeteringDataType dataType, LocalDateTime intervalStart);
 
+    @Query("SELECT m FROM MeteringData m WHERE m.meteringPoint.id = :meteringPointId " +
+            "AND m.dataType = :dataType AND m.intervalStart IN :intervalStarts")
+    List<MeteringData> findByMeteringPointIdAndDataTypeAndIntervalStartIn(
+            @Param("meteringPointId") UUID meteringPointId,
+            @Param("dataType") MeteringDataType dataType,
+            @Param("intervalStarts") List<LocalDateTime> intervalStarts);
+
     @Query("SELECT FUNCTION('DAYOFYEAR', m.intervalStart), FUNCTION('YEAR', m.intervalStart), SUM(m.kwh) " +
             "FROM MeteringData m WHERE m.meteringPoint.id = :meteringPointId AND m.dataType = 'CONSUMPTION' " +
             "AND m.intervalStart BETWEEN :from AND :to " +

eeg_backend/src/main/java/at/mueller/eeg/backend/community/service/MeteringDataService.java

@@ -29,7 +29,8 @@ public class MeteringDataService {
 
     @Transactional
     public MeteringDataUploadResponse uploadMeteringData(MeteringDataUploadRequest request, UUID uploadedBy) {
-        List<String> validationErrors = validateRecords(request.records());
+        Map<String, MeteringPoint> pointsByAtNumber = resolveMeteringPoints(request.records());
+        List<String> validationErrors = validateRecords(request.records(), pointsByAtNumber);
 
         if (!validationErrors.isEmpty()) {
             return MeteringDataUploadResponse.validationFailed(validationErrors);
@@ -43,8 +44,6 @@ public class MeteringDataService {
         upload.setUploadedBy(uploadedBy);
         MeteringDataUpload savedUpload = uploadRepository.save(upload);
 
-        Map<String, MeteringPoint> pointsByAtNumber = resolveMeteringPoints(request.records());
-
         List<MeteringData> entities = request.records().stream()
                 .map(record -> toEntity(record, pointsByAtNumber.get(record.atNumber()),
                         savedUpload.getId(), request.source()))
@@ -92,7 +91,7 @@ public class MeteringDataService {
                         "Keine Berechtigung zum Zugriff auf diesen Zählpunkt"));
     }
 
-    private List<String> validateRecords(List<MeteringDataRecordDto> records) {
+    private List<String> validateRecords(List<MeteringDataRecordDto> records, Map<String, MeteringPoint> pointsByAtNumber) {
         List<String> errors = new ArrayList<>();
 
         if (records == null || records.isEmpty()) {
@@ -100,22 +99,17 @@ public class MeteringDataService {
             return errors;
         }
 
-        Set<String> atNumbers = records.stream()
-                .map(MeteringDataRecordDto::atNumber)
-                .collect(Collectors.toSet());
-
-        Set<String> existingAtNumbers = meteringPointRepository.findByAtNumberIn(atNumbers).stream()
-                .map(MeteringPoint::getAtNumber)
-                .collect(Collectors.toSet());
-
         for (int i = 0; i < records.size(); i++) {
             MeteringDataRecordDto record = records.get(i);
             String prefix = "Zeile " + (i + 1) + ": ";
 
-            if (!existingAtNumbers.contains(record.atNumber())) {
+            if (!pointsByAtNumber.containsKey(record.atNumber())) {
                 errors.add(prefix + "Zählpunkt " + record.atNumber() + " nicht im System vorhanden");
+                continue;
             }
 
+            MeteringPoint point = pointsByAtNumber.get(record.atNumber());
+
             if (record.intervalEnd().isBefore(record.intervalStart())) {
                 errors.add(prefix + "Intervall-Ende liegt vor Intervall-Beginn");
             }
@@ -123,6 +117,13 @@ public class MeteringDataService {
             if (record.kwh() < 0) {
                 errors.add(prefix + "kWh-Wert darf nicht negativ sein");
             }
+
+            if (record.dataType() == MeteringDataType.FEED_IN && point.getType() != PointType.PRODUCER) {
+                errors.add(prefix + "Einspeisedaten (FEED_IN) nur für PRODUCER-Zählpunkte erlaubt");
+            }
+            if (record.dataType() == MeteringDataType.CONSUMPTION && point.getType() != PointType.CONSUMER) {
+                errors.add(prefix + "Verbrauchsdaten (CONSUMPTION) nur für CONSUMER-Zählpunkte erlaubt");
+            }
         }
 
         return errors;
@@ -156,15 +157,25 @@ public class MeteringDataService {
             return;
         }
 
+        Map<UUID, Map<MeteringDataType, List<LocalDateTime>>> grouped = entities.stream()
+                .collect(Collectors.groupingBy(
+                        e -> e.getMeteringPoint().getId(),
+                        Collectors.groupingBy(
+                                MeteringData::getDataType,
+                                Collectors.mapping(MeteringData::getIntervalStart, Collectors.toList())
+                        )
+                ));
+
         Set<MeteringData> toDelete = new LinkedHashSet<>();
 
-        for (MeteringData entity : entities) {
+        for (var pointEntry : grouped.entrySet()) {
-            meteringDataRepository
+            UUID pointId = pointEntry.getKey();
-                    .findByMeteringPointIdAndDataTypeAndIntervalStart(
+            for (var typeEntry : pointEntry.getValue().entrySet()) {
-                            entity.getMeteringPoint().getId(),
+                MeteringDataType dataType = typeEntry.getKey();
-                            entity.getDataType(),
+                List<LocalDateTime> starts = typeEntry.getValue();
-                            entity.getIntervalStart())
+                toDelete.addAll(meteringDataRepository.findByMeteringPointIdAndDataTypeAndIntervalStartIn(
-                    .forEach(toDelete::add);
+                        pointId, dataType, starts));
+            }
         }
 
         if (!toDelete.isEmpty()) {

eeg_backend/src/test/java/at/mueller/eeg/backend/community/service/MeteringDataServiceTest.java

@@ -190,7 +190,15 @@ class MeteringDataServiceTest {
 
     @Test
     void uploadMeteringData_multipleRecords() {
-        when(meteringPointRepository.findByAtNumberIn(any())).thenReturn(List.of(testMeteringPoint));
+        String producerAtNumber = "AT0010000000000000000000001234568";
+        MeteringPoint producerPoint = new MeteringPoint();
+        producerPoint.setId(UUID.randomUUID());
+        producerPoint.setUserId(testUserId);
+        producerPoint.setAtNumber(producerAtNumber);
+        producerPoint.setType(PointType.PRODUCER);
+        producerPoint.setMakoState(MakoState.ACTIVE);
+
+        when(meteringPointRepository.findByAtNumberIn(any())).thenReturn(List.of(testMeteringPoint, producerPoint));
         when(uploadRepository.save(any())).thenAnswer(invocation -> {
             MeteringDataUpload upload = invocation.getArgument(0);
             upload.setId(UUID.randomUUID());
@@ -203,7 +211,7 @@ class MeteringDataServiceTest {
                         LocalDateTime.of(2026, 1, 1, 0, 0), LocalDateTime.of(2026, 1, 1, 0, 15), 1.25, null),
                 new MeteringDataRecordDto(testAtNumber, MeteringDataType.CONSUMPTION,
                         LocalDateTime.of(2026, 1, 1, 0, 15), LocalDateTime.of(2026, 1, 1, 0, 30), 0.80, null),
-                new MeteringDataRecordDto(testAtNumber, MeteringDataType.FEED_IN,
+                new MeteringDataRecordDto(producerAtNumber, MeteringDataType.FEED_IN,
                         LocalDateTime.of(2026, 1, 1, 0, 0), LocalDateTime.of(2026, 1, 1, 0, 15), 2.50, null)
         );
 
@@ -291,4 +299,95 @@ class MeteringDataServiceTest {
                         MeteringDataType.CONSUMPTION,
                         LocalDateTime.of(2026, 1, 1, 0, 0), LocalDateTime.of(2026, 1, 31, 23, 59)));
     }
+
+    @Test
+    void uploadMeteringData_validationFailsForFeedInOnConsumerPoint() {
+        when(meteringPointRepository.findByAtNumberIn(any())).thenReturn(List.of(testMeteringPoint));
+
+        MeteringDataRecordDto record = new MeteringDataRecordDto(
+                testAtNumber,
+                MeteringDataType.FEED_IN,
+                LocalDateTime.of(2026, 1, 1, 0, 0),
+                LocalDateTime.of(2026, 1, 1, 0, 15),
+                2.50,
+                null
+        );
+
+        MeteringDataUploadRequest request = new MeteringDataUploadRequest(
+                DataSource.EMAIL_XLSX,
+                "test.xlsx",
+                List.of(record)
+        );
+
+        MeteringDataUploadResponse response = meteringDataService.uploadMeteringData(request, UUID.randomUUID());
+
+        assertEquals(UploadStatus.FAILED, response.status());
+        assertFalse(response.validationErrors().isEmpty());
+        assertTrue(response.validationErrors().get(0).contains("PRODUCER"));
+    }
+
+    @Test
+    void uploadMeteringData_validationFailsForConsumptionOnProducerPoint() {
+        String producerAtNumber = "AT0010000000000000000000001234568";
+        MeteringPoint producerPoint = new MeteringPoint();
+        producerPoint.setId(UUID.randomUUID());
+        producerPoint.setUserId(testUserId);
+        producerPoint.setAtNumber(producerAtNumber);
+        producerPoint.setType(PointType.PRODUCER);
+        producerPoint.setMakoState(MakoState.ACTIVE);
+
+        when(meteringPointRepository.findByAtNumberIn(any())).thenReturn(List.of(producerPoint));
+
+        MeteringDataRecordDto record = new MeteringDataRecordDto(
+                producerAtNumber,
+                MeteringDataType.CONSUMPTION,
+                LocalDateTime.of(2026, 1, 1, 0, 0),
+                LocalDateTime.of(2026, 1, 1, 0, 15),
+                1.25,
+                null
+        );
+
+        MeteringDataUploadRequest request = new MeteringDataUploadRequest(
+                DataSource.EMAIL_XLSX,
+                "test.xlsx",
+                List.of(record)
+        );
+
+        MeteringDataUploadResponse response = meteringDataService.uploadMeteringData(request, UUID.randomUUID());
+
+        assertEquals(UploadStatus.FAILED, response.status());
+        assertFalse(response.validationErrors().isEmpty());
+        assertTrue(response.validationErrors().get(0).contains("CONSUMER"));
+    }
+
+    @Test
+    void uploadMeteringData_allowsSelfConsumptionOnBothTypes() {
+        when(meteringPointRepository.findByAtNumberIn(any())).thenReturn(List.of(testMeteringPoint));
+        when(uploadRepository.save(any())).thenAnswer(invocation -> {
+            MeteringDataUpload upload = invocation.getArgument(0);
+            upload.setId(UUID.randomUUID());
+            return upload;
+        });
+        when(meteringDataRepository.saveAll(any())).thenAnswer(invocation -> invocation.getArgument(0));
+
+        MeteringDataRecordDto record = new MeteringDataRecordDto(
+                testAtNumber,
+                MeteringDataType.SELF_CONSUMPTION,
+                LocalDateTime.of(2026, 1, 1, 0, 0),
+                LocalDateTime.of(2026, 1, 1, 0, 15),
+                0.50,
+                null
+        );
+
+        MeteringDataUploadRequest request = new MeteringDataUploadRequest(
+                DataSource.EMAIL_XLSX,
+                "test.xlsx",
+                List.of(record)
+        );
+
+        MeteringDataUploadResponse response = meteringDataService.uploadMeteringData(request, UUID.randomUUID());
+
+        assertEquals(UploadStatus.COMPLETED, response.status());
+        assertEquals(1, response.recordCount());
+    }
 }

eeg_frontend/src/app/app.routes.ts

@@ -19,6 +19,7 @@ import {ResetPasswordComponent} from './pages/reset-password/reset-password';
 import {AdminTariffComponent} from './pages/admin-tariff/admin-tariff';
 import {UserTariffComponent} from './pages/user-tariff/user-tariff';
 import {ConsumptionDashboardComponent} from './pages/consumption-dashboard/consumption-dashboard';
+import {UploadMeteringDataComponent} from './pages/upload-metering-data/upload-metering-data';
 
 export const routes: Routes = [
   { path: '', component: LandingPage },
@@ -68,6 +69,11 @@ export const routes: Routes = [
         component: AdminTariffComponent,
         canActivate: [roleGuard(['ADMIN'])]
       },
+      {
+        path: 'upload-metering-data',
+        component: UploadMeteringDataComponent,
+        canActivate: [roleGuard(['ADMIN'])]
+      },
       {
         path: 'my-tariffs',
         component: UserTariffComponent,

eeg_frontend/src/app/layout/dashboard-layout/dashboard-nav-items.ts

@@ -15,5 +15,6 @@ export const NAV_ITEMS: NavItem[] = [
   {label: 'Benutzerverwaltung', path: '/dashboard/approvals', roles: ['ADMIN']},
   {label: 'Energiegemeinschaften', path: '/dashboard/energy-communities', roles: ['ADMIN']},
   {label: 'Tarife verwalten', path: '/dashboard/tariffs', roles: ['ADMIN']},
+  {label: 'Messdaten-Upload', path: '/dashboard/upload-metering-data', roles: ['ADMIN']},
   {label: 'Meine Tarife', path: '/dashboard/my-tariffs', roles: ['MEMBER']}
 ];

eeg_frontend/src/app/pages/upload-metering-data/upload-metering-data.html

@@ -0,0 +1,113 @@
+<div class="max-w-2xl mx-auto p-6">
+  <h1 class="text-2xl font-bold mb-6">Messdaten-Upload</h1>
+
+  <div class="bg-white rounded-lg shadow p-6">
+    <p class="text-gray-600 mb-4">
+      Laden Sie eine Excel-Datei (XLSX) mit Messdaten hoch.
+    </p>
+
+    <div
+      class="border-2 border-dashed border-gray-300 rounded-lg p-8 text-center hover:border-blue-400 transition-colors"
+      (dragover)="onDragOver($event)"
+      (drop)="onDrop($event)"
+    >
+      <input
+        type="file"
+        accept=".xlsx,.xls"
+        (change)="onFileSelected($event)"
+        class="hidden"
+        #fileInput
+      />
+      <button
+        (click)="fileInput.click()"
+        class="px-4 py-2 bg-blue-600 text-white rounded hover:bg-blue-700"
+      >
+        Datei auswählen
+      </button>
+      <p class="mt-2 text-sm text-gray-500">
+        oder Datei hierher ziehen
+      </p>
+    </div>
+
+    @if (selectedFile()) {
+      <div class="mt-4 p-3 bg-gray-50 rounded flex items-center justify-between">
+        <span class="text-sm text-gray-700">{{ selectedFile()!.name }}</span>
+        <button
+          (click)="upload()"
+          [disabled]="isUploading()"
+          class="px-4 py-2 bg-green-600 text-white rounded hover:bg-green-700 disabled:opacity-50"
+        >
+          @if (isUploading()) {
+            Wird hochgeladen...
+          } @else {
+            Upload starten
+          }
+        </button>
+      </div>
+    }
+
+    @if (isLoadingPreview()) {
+      <div class="mt-4 text-center text-gray-500">
+        Vorschau wird geladen...
+      </div>
+    }
+
+    @if (previewData().length > 0) {
+      <div class="mt-4">
+        <h3 class="text-sm font-medium text-gray-700 mb-2">Vorschau (erste 10 Zeilen):</h3>
+        <div class="overflow-x-auto">
+          <table class="min-w-full text-sm">
+            <thead class="bg-gray-100">
+              <tr>
+                <th class="px-3 py-2 text-left">AT-Nummer</th>
+                <th class="px-3 py-2 text-left">Typ</th>
+                <th class="px-3 py-2 text-left">Von</th>
+                <th class="px-3 py-2 text-left">Bis</th>
+                <th class="px-3 py-2 text-right">kWh</th>
+              </tr>
+            </thead>
+            <tbody>
+              @for (row of previewData(); track $index) {
+                <tr class="border-t">
+                  <td class="px-3 py-2">{{ row.atNumber }}</td>
+                  <td class="px-3 py-2">{{ row.dataType }}</td>
+                  <td class="px-3 py-2">{{ row.intervalStart }}</td>
+                  <td class="px-3 py-2">{{ row.intervalEnd }}</td>
+                  <td class="px-3 py-2 text-right">{{ row.kwh }}</td>
+                </tr>
+              }
+            </tbody>
+          </table>
+        </div>
+      </div>
+    }
+
+    @if (uploadResult()) {
+      <div class="mt-4 p-4 rounded" [class]="uploadResult()!.status === 'COMPLETED' ? 'bg-green-50 border border-green-200' : 'bg-red-50 border border-red-200'">
+        <p class="font-semibold" [class]="uploadResult()!.status === 'COMPLETED' ? 'text-green-800' : 'text-red-800'">
+          @if (uploadResult()!.status === 'COMPLETED') {
+            Upload erfolgreich!
+          } @else {
+            Upload fehlgeschlagen
+          }
+        </p>
+        <p class="text-sm text-gray-600 mt-1">
+          {{ uploadResult()!.recordCount }} Datensätze verarbeitet
+        </p>
+        @if (uploadResult()!.validationErrors.length > 0) {
+          <ul class="mt-2 text-sm text-red-600 list-disc list-inside">
+            @for (error of uploadResult()!.validationErrors; track error) {
+              <li>{{ error }}</li>
+            }
+          </ul>
+        }
+      </div>
+    }
+
+    @if (errorMessage()) {
+      <div class="mt-4 p-4 bg-red-50 border border-red-200 rounded">
+        <p class="text-red-800">{{ errorMessage() }}</p>
+      </div>
+    }
+  </div>
+</div>

eeg_frontend/src/app/pages/upload-metering-data/upload-metering-data.ts

@@ -0,0 +1,113 @@
+import {Component, inject, signal} from '@angular/core';
+import {HttpClient} from '@angular/common/http';
+import {environment} from '../../../environments/environment';
+
+interface PreviewRecord {
+  atNumber: string;
+  dataType: string;
+  intervalStart: string;
+  intervalEnd: string;
+  kwh: number;
+  readingValue: number | null;
+}
+
+interface UploadResponse {
+  uploadId: string;
+  status: string;
+  recordCount: number;
+  validationErrors: string[];
+}
+
+@Component({
+  selector: 'app-upload-metering-data',
+  standalone: true,
+  templateUrl: './upload-metering-data.html',
+})
+export class UploadMeteringDataComponent {
+  private http = inject(HttpClient);
+
+  selectedFile = signal<File | null>(null);
+  previewData = signal<PreviewRecord[]>([]);
+  isLoadingPreview = signal(false);
+  isUploading = signal(false);
+  uploadResult = signal<UploadResponse | null>(null);
+  errorMessage = signal<string | null>(null);
+
+  onFileSelected(event: Event) {
+    const input = event.target as HTMLInputElement;
+    if (input.files && input.files.length > 0) {
+      this.selectedFile.set(input.files[0]);
+      this.uploadResult.set(null);
+      this.errorMessage.set(null);
+      this.loadPreview(input.files[0]);
+    }
+  }
+
+  onDragOver(event: DragEvent) {
+    event.preventDefault();
+    event.stopPropagation();
+  }
+
+  onDrop(event: DragEvent) {
+    event.preventDefault();
+    event.stopPropagation();
+    const files = event.dataTransfer?.files;
+    if (files && files.length > 0) {
+      this.selectedFile.set(files[0]);
+      this.uploadResult.set(null);
+      this.errorMessage.set(null);
+      this.loadPreview(files[0]);
+    }
+  }
+
+  private loadPreview(file: File) {
+    this.isLoadingPreview.set(true);
+    this.previewData.set([]);
+    this.errorMessage.set(null);
+
+    const formData = new FormData();
+    formData.append('file', file);
+
+    this.http.post<PreviewRecord[]>(
+      `${environment.apiUrl}/api/community/metering-data/preview/xlsx`,
+      formData
+    ).subscribe({
+      next: (data) => {
+        this.previewData.set(data);
+        this.isLoadingPreview.set(false);
+      },
+      error: (error) => {
+        this.errorMessage.set(error.error?.message || 'Fehler beim Laden der Vorschau');
+        this.isLoadingPreview.set(false);
+      }
+    });
+  }
+
+  upload() {
+    const file = this.selectedFile();
+    if (!file) return;
+
+    this.isUploading.set(true);
+    this.uploadResult.set(null);
+    this.errorMessage.set(null);
+
+    const formData = new FormData();
+    formData.append('file', file);
+
+    this.http.post<UploadResponse>(
+      `${environment.apiUrl}/api/community/metering-data/upload/xlsx`,
+      formData
+    ).subscribe({
+      next: (response) => {
+        this.uploadResult.set(response);
+        this.isUploading.set(false);
+        this.selectedFile.set(null);
+        this.previewData.set([]);
+      },
+      error: (error) => {
+        this.errorMessage.set(error.error?.message || 'Fehler beim Upload');
+        this.isUploading.set(false);
+      }
+    });
+  }
+}