[mob][photos] In-app public link fixes (#4495)

## Description

Fixed these issues:
- Unrelated files coming up (these are local device files) in public
link when opened in-app.
- Max number of files in link capped to 2000.
- Sort order not working.

mobile/lib/services/collections_service.dart

@@ -1067,6 +1067,24 @@ class CollectionsService {
       _cachedPublicAlbumToken[collection.id] = authToken!;
       _cachedPublicCollectionID.add(collection.id);
       _cachedPublicAlbumKey[collection.id] = albumKey;
+
+      if (collectionData['pubMagicMetadata'] != null) {
+        final utfEncodedMmd = await CryptoUtil.decryptChaCha(
+          CryptoUtil.base642bin(collectionData['pubMagicMetadata']['data']),
+          collectionKey,
+          CryptoUtil.base642bin(
+            collectionData['pubMagicMetadata']['header'],
+          ),
+        );
+        collection.mMdPubEncodedJson = utf8.decode(utfEncodedMmd);
+        collection.mMbPubVersion =
+            collectionData['pubMagicMetadata']['version'];
+        collection.pubMagicMetadata =
+            CollectionPubMagicMetadata.fromEncodedJson(
+          collection.mMdPubEncodedJson ?? '{}',
+        );
+      }
+
       collection.setName(_getDecryptedCollectionName(collection));
       return collection;
     } catch (e, s) {

mobile/lib/ui/tabs/home_widget.dart

@@ -306,8 +306,12 @@ class _HomeWidgetState extends State<HomeWidget> {
                   if (result) {
                     await dialog.show();
 
-                    final List<EnteFile> sharedFiles = await _diffFetcher
-                        .getPublicFiles(context, collection.id);
+                    final List<EnteFile> sharedFiles =
+                        await _diffFetcher.getPublicFiles(
+                      context,
+                      collection.id,
+                      collection.pubMagicMetadata.asc ?? false,
+                    );
                     await dialog.hide();
                     Navigator.of(context).pop();
 
@@ -334,8 +338,11 @@ class _HomeWidgetState extends State<HomeWidget> {
       } else {
         await dialog.show();
 
-        final List<EnteFile> sharedFiles =
-            await _diffFetcher.getPublicFiles(context, collection.id);
+        final List<EnteFile> sharedFiles = await _diffFetcher.getPublicFiles(
+          context,
+          collection.id,
+          collection.pubMagicMetadata.asc ?? false,
+        );
         await dialog.hide();
 
         await routeToPage(

mobile/lib/ui/viewer/file/file_widget.dart

@@ -27,7 +27,9 @@ class FileWidget extends StatelessWidget {
   Widget build(BuildContext context) {
     // Specify key to ensure that the widget is rebuilt when the file changes
     // Before changing this, ensure that file deletes are handled properly
-    final String fileKey = "file_${file.generatedID}";
+
+    final String fileKey =
+        "file_genID_${file.generatedID}___file_id_${file.uploadedFileID}";
     if (file.fileType == FileType.livePhoto ||
         file.fileType == FileType.image) {
       return ZoomableLiveImageNew(

mobile/lib/ui/viewer/file/zoomable_live_image_new.dart

@@ -51,6 +51,8 @@ class _ZoomableLiveImageNewState extends State<ZoomableLiveImageNew>
 
   @override
   void initState() {
+    super.initState();
+
     _enteFile = widget.enteFile;
     _logger.info(
       'initState for ${_enteFile.generatedID} with tag ${_enteFile.tag} and name ${_enteFile.displayName}',
@@ -64,7 +66,6 @@ class _ZoomableLiveImageNewState extends State<ZoomableLiveImageNew>
         isGuestView = event.isGuestView;
       });
     });
-    super.initState();
   }
 
   void _onLongPressEvent(bool isPressed) {

mobile/lib/utils/diff_fetcher.dart

@@ -21,69 +21,84 @@ class DiffFetcher {
   Future<List<EnteFile>> getPublicFiles(
     BuildContext context,
     int collectionID,
+    bool sortAsc,
   ) async {
     try {
       final authToken = await CollectionsService.instance
           .getSharedPublicAlbumToken(collectionID);
       final authJWTToken = await CollectionsService.instance
           .getSharedPublicAlbumTokenJWT(collectionID);
+      bool hasMore = false;
+      final sharedFiles = <EnteFile>[];
 
       final headers = {
         "X-Auth-Access-Token": authToken,
         if (authJWTToken != null) "X-Auth-Access-Token-JWT": authJWTToken,
       };
 
-      final response = await _enteDio.get(
-        "/public-collection/diff",
-        options: Options(headers: headers),
-        queryParameters: {"sinceTime": 0},
-      );
+      int sinceTime = 0;
 
-      final diff = response.data["diff"] as List;
-      final startTime = DateTime.now();
-      final sharedFiles = <EnteFile>[];
-
-      for (final item in diff) {
-        final file = EnteFile();
-        if (item["isDeleted"]) {
-          continue;
-        }
-        file.uploadedFileID = item["id"];
-        file.collectionID = item["collectionID"];
-        file.ownerID = item["ownerID"];
-        file.encryptedKey = item["encryptedKey"];
-        file.keyDecryptionNonce = item["keyDecryptionNonce"];
-        file.fileDecryptionHeader = item["file"]["decryptionHeader"];
-        file.thumbnailDecryptionHeader = item["thumbnail"]["decryptionHeader"];
-        file.metadataDecryptionHeader = item["metadata"]["decryptionHeader"];
-        if (item["info"] != null) {
-          file.fileSize = item["info"]["fileSize"];
-        }
-        final fileKey = getFileKey(file);
-        final encodedMetadata = await CryptoUtil.decryptChaCha(
-          CryptoUtil.base642bin(item["metadata"]["encryptedData"]),
-          fileKey,
-          CryptoUtil.base642bin(file.metadataDecryptionHeader!),
+      do {
+        final response = await _enteDio.get(
+          "/public-collection/diff",
+          options: Options(headers: headers),
+          queryParameters: {"sinceTime": sinceTime},
         );
-        final Map<String, dynamic> metadata =
-            jsonDecode(utf8.decode(encodedMetadata));
-        file.applyMetadata(metadata);
-        if (item['pubMagicMetadata'] != null) {
-          final utfEncodedMmd = await CryptoUtil.decryptChaCha(
-            CryptoUtil.base642bin(item['pubMagicMetadata']['data']),
-            fileKey,
-            CryptoUtil.base642bin(item['pubMagicMetadata']['header']),
-          );
-          file.pubMmdEncodedJson = utf8.decode(utfEncodedMmd);
-          file.pubMmdVersion = item['pubMagicMetadata']['version'];
-          file.pubMagicMetadata =
-              PubMagicMetadata.fromEncodedJson(file.pubMmdEncodedJson!);
-        }
-        sharedFiles.add(file);
-      }
 
-      _logger.info('[Collection-$collectionID] parsed ${diff.length} '
-          'diff items ( ${sharedFiles.length} updated) in ${DateTime.now().difference(startTime).inMilliseconds}ms');
+        final diff = response.data["diff"] as List;
+        hasMore = response.data["hasMore"] as bool;
+
+        for (final item in diff) {
+          final file = EnteFile();
+          if (item["isDeleted"]) {
+            continue;
+          }
+          file.uploadedFileID = item["id"];
+          file.collectionID = item["collectionID"];
+          file.ownerID = item["ownerID"];
+          file.encryptedKey = item["encryptedKey"];
+          file.keyDecryptionNonce = item["keyDecryptionNonce"];
+          file.fileDecryptionHeader = item["file"]["decryptionHeader"];
+          file.thumbnailDecryptionHeader =
+              item["thumbnail"]["decryptionHeader"];
+          file.metadataDecryptionHeader = item["metadata"]["decryptionHeader"];
+          if (item["info"] != null) {
+            file.fileSize = item["info"]["fileSize"];
+          }
+          final fileKey = getFileKey(file);
+          final encodedMetadata = await CryptoUtil.decryptChaCha(
+            CryptoUtil.base642bin(item["metadata"]["encryptedData"]),
+            fileKey,
+            CryptoUtil.base642bin(file.metadataDecryptionHeader!),
+          );
+          final Map<String, dynamic> metadata =
+              jsonDecode(utf8.decode(encodedMetadata));
+          file.applyMetadata(metadata);
+          if (item['pubMagicMetadata'] != null) {
+            final utfEncodedMmd = await CryptoUtil.decryptChaCha(
+              CryptoUtil.base642bin(item['pubMagicMetadata']['data']),
+              fileKey,
+              CryptoUtil.base642bin(item['pubMagicMetadata']['header']),
+            );
+            file.pubMmdEncodedJson = utf8.decode(utfEncodedMmd);
+            file.pubMmdVersion = item['pubMagicMetadata']['version'];
+            file.pubMagicMetadata =
+                PubMagicMetadata.fromEncodedJson(file.pubMmdEncodedJson!);
+          }
+
+          // To avoid local file to be used as thumbnail or full file.
+          file.localID = null;
+
+          sharedFiles.add(file);
+        }
+
+        if (diff.isNotEmpty) {
+          sinceTime = diff.last["updationTime"];
+        }
+      } while (hasMore);
+      if (sortAsc) {
+        sharedFiles.sort((a, b) => a.creationTime!.compareTo(b.creationTime!));
+      }
       return sharedFiles;
     } catch (e, s) {
       _logger.severe("Failed to decrypt collection ", e, s);