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SyncService keeps local decks.json and quiz_sessions.json files in sync with Google Drive AppData using a timestamp-based smart merge. It requires a valid GoogleAuthService instance with active credentials.

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Constructor

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SyncService(auth_service)

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auth_service
GoogleAuthService
required
An authenticated GoogleAuthService instance. The service uses it to obtain OAuth credentials and build the Drive API client on first use.
from services.auth_service import GoogleAuthService
from services.sync_service import SyncService

auth = GoogleAuthService()
sync = SyncService(auth)

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Public methods

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sync_decks() → Tuple[bool, str]

Synchronize the local decks.json with the copy stored in Google Drive AppData.
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(bool, str)
Tuple[bool, str]
(True, "Đồng bộ Decks thành công") on success, or (False, error_message) on failure.
Smart merge algorithm:
1

Download remote file

Looks up decks.json in the Drive AppData folder. Downloads and parses it if found.
2

Load local file

Reads the local decks.json via load_decks() and builds a lookup by deck_id.
3

Merge by timestamp

For each deck that exists in both local and remote, compares the updated_at field. The newer version wins. If timestamps are equal, the local copy is kept.
4

Handle remote-only and local-only decks

Decks that exist only on Drive are pulled down locally. Decks that exist only locally are retained as-is.
5

Preserve local image paths

When a remote deck wins the merge, local image_path values are re-injected into the remote deck’s cards by card_id. Drive does not store image files, only metadata.
6

Save and upload

Writes the merged list to local decks.json without bumping updated_at timestamps, then uploads the merged file back to Drive.

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sync_quiz_sessions() → Tuple[bool, str]

Synchronize quiz_sessions.json with Google Drive AppData using the same timestamp-based merge strategy.
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(bool, str)
Tuple[bool, str]
(True, "Đồng bộ Sessions thành công") on success, or (False, error_message) on failure.
Unlike deck sync, quiz session merge does not need to preserve image paths. The newer updated_at value for each deck_id key wins outright.

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perform_full_sync() → Tuple[bool, str]

Run sync_decks followed by sync_quiz_sessions in sequence. Returns immediately on the first failure.
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(bool, str)
Tuple[bool, str]
(True, "Đồng bộ thành công") if both steps succeed. Returns the failure tuple from whichever step failed first.
Returns (False, "Chưa đăng nhập Google Drive") if auth_service.is_logged_in() is False before attempting either sync step.

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Error codes

ConditionReturned message
No internet connection"Không có kết nối mạng"
Drive API HTTP error"Lỗi Google Drive: <status_code>"
Not authenticated"Chưa đăng nhập Google Drive"
Other exception"Lỗi: <exception_message>"
Internet connectivity is checked by attempting a TCP connection to Google DNS (8.8.8.8:53) with a 3-second timeout before any Drive API call is made.

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Usage example

from services.auth_service import GoogleAuthService
from services.sync_service import SyncService

auth = GoogleAuthService()
sync = SyncService(auth)

success, message = sync.perform_full_sync()
if success:
    print("Sync complete")
else:
    print(f"Sync failed: {message}")
To sync only decks (for example, after saving a new deck but before closing the app): 
success, message = sync.sync_decks()

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ExportService

Export decks to Quizlet-compatible text files.

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