Notifications api.

Stores the notifications to database, and they can be retrieved.

src/tjts5901/app.py

@@ -76,6 +76,9 @@ def create_app(config: Optional[Dict] = None) -> Flask:
     from .auth import init_auth
     init_auth(flask_app)
 
+    from .notification import init_notification
+    init_notification(flask_app)
+
     from .currency import init_currency
     init_currency(flask_app)
 

src/tjts5901/models.py

@@ -145,3 +145,29 @@ class AccessToken(db.Document):
 
     expires = DateTimeField(required=False)
     "Date and time that the token expires."
+
+
+class Notification(db.Document):
+    """
+    Represents a message between two users, or a message to a user from
+    the system.
+    """
+
+    meta = {"indexes": [
+        {"fields": [
+            "user",
+            "read_at",
+            "created_at",
+        ]}
+    ]}
+
+    id: ObjectId
+
+    user = ReferenceField(User, required=True)
+
+    category = StringField(max_length=100, default="message")
+    message = StringField(required=True)
+    title = StringField(max_length=120)
+
+    created_at = DateTimeField(required=True, default=datetime.utcnow)
+    read_at = DateTimeField(required=False)

src/tjts5901/notification.py

+"""
+This module provides a way to send notifications to users.
+"""
+
+import dataclasses
+from datetime import datetime
+import logging
+
+from flask import get_flashed_messages, Blueprint
+from flask_login import current_user
+from flask_babel import force_locale, lazy_gettext
+
+from .models import Notification, User
+
+bp = Blueprint('notification', __name__, url_prefix='/')
+
+logger = logging.getLogger(__name__)
+
+@dataclasses.dataclass
+class Message:
+    """
+    Represents a message to be displayed to the user.
+    """
+    message: str
+    category: str
+
+    # Additional field for the template
+    title: str = lazy_gettext("Message")
+
+    created_at: datetime = dataclasses.field(default_factory=datetime.utcnow)
+
+
+def init_notification(app):
+    """
+    Initialize the notifications module.
+    """
+    app.register_blueprint(bp)
+    app.jinja_env.globals.update(get_notifications=get_notifications)
+
+
+def send_notification(user, message, category="message", title=None):
+    """
+    Send a notification to the given user.
+
+    :param user: The user to send the message to.
+    :param subject: The subject of the message.
+    :param message: The message to send.
+    """
+
+    # Change the locale to the message recipient locale.
+    with force_locale(user.locale):
+        notification = Notification(
+            user=user,
+            message=str(message),
+            category=category,
+            title=str(title),
+        )
+        notification.save()
+
+
+def get_notifications(user: User = current_user) -> list[Message]:
+    """
+    Get the messages for the given user.
+
+    Flash messages are returned first, followed by database messages.
+    Messages are marked as read when they are retrieved.
+
+    Notice: the listing query might not return recently added messages.
+
+    :param user: The user to get the messages for.
+    :return: A list of messages.
+    """
+
+    messages = []
+
+    # Get the flash messages first
+    for category, message in get_flashed_messages(with_categories=True):
+        messages.append(Message(message, category))
+
+    if user is None or not user.is_authenticated:
+        logger.debug("User is not authenticated, returning flash messages.")
+        return messages
+
+    # Get the database messages
+    notifications = Notification.objects(user=user, read_at=None).order_by('-created_at').all()
+
+    for notification in notifications:
+        messages.append(Message(notification.message, notification.category, notification.title))
+
+    # Mark the messages as read
+    notifications.update(read_at=datetime.utcnow())
+
+    return messages