wrote service method to update location data

lib/services/files_service.dart

@@ -1,4 +1,5 @@
 import 'package:dio/dio.dart';
+import "package:latlong2/latlong.dart";
 import 'package:logging/logging.dart';
 import 'package:path/path.dart';
 import 'package:photos/core/configuration.dart';
@@ -85,6 +86,38 @@ class FilesService {
     }
   }
 
+  Future<void> bulkEditLocationData(
+    List<EnteFile> files,
+    LatLng location,
+  ) async {
+    final List<EnteFile> uploadedFiles =
+        files.where((element) => element.uploadedFileID != null).toList();
+
+    final List<EnteFile> remoteFilesToUpdate = [];
+    final Map<int, Map<String, dynamic>> fileIDToUpdateMetadata = {};
+    for (EnteFile remoteFile in uploadedFiles) {
+      // discard files not owned by user and also dedupe already processed
+      // files
+      if (remoteFile.ownerID != _config.getUserID()! ||
+          fileIDToUpdateMetadata.containsKey(remoteFile.uploadedFileID!)) {
+        continue;
+      }
+
+      remoteFilesToUpdate.add(remoteFile);
+      fileIDToUpdateMetadata[remoteFile.uploadedFileID!] = {
+        latKey: location.latitude,
+        longKey: location.longitude,
+      };
+    }
+    if (remoteFilesToUpdate.isNotEmpty) {
+      await FileMagicService.instance.updatePublicMagicMetadata(
+        remoteFilesToUpdate,
+        null,
+        metadataUpdateMap: fileIDToUpdateMetadata,
+      );
+    }
+  }
+
   // Note: this method is not used anywhere, but it is kept for future
   // reference when we add bulk EditTime feature
   Future<void> bulkEditTime(

lib/ui/viewer/location/update_location_data_widget.dart

@@ -2,6 +2,7 @@ import "package:flutter/material.dart";
 import "package:flutter_map/flutter_map.dart";
 import "package:latlong2/latlong.dart";
 import "package:photos/models/file/file.dart";
+import "package:photos/services/files_service.dart";
 import "package:photos/ui/map/map_button.dart";
 import "package:photos/ui/map/tile/layers.dart";
 
@@ -71,7 +72,10 @@ class _UpdateLocationDataWidgetState extends State<UpdateLocationDataWidget> {
                 // icon: Icons.add_location_alt_outlined,
                 icon: Icons.check,
 
-                onPressed: () {},
+                onPressed: () async {
+                  await FilesService.instance
+                      .bulkEditLocationData(widget.files, selectedLocation!);
+                },
                 heroTag: 'add-location',
               ),
               const SizedBox(height: 16),