Feature: Admin Notification API for Camp Volunteers

Description

Implement a backend endpoint that allows administrators to broadcast updates to volunteers signed up for the upcoming medical camp via email and/or push notifications.

Technical Requirements

• Endpoint: POST /api/v1/admin/notifications/broadcast (Admin role guarded).
• Request Payload:

  {
    "title": "string",
    "message": "string",
    "send_email": boolean,
    "send_push": boolean
  }
  
  

Logic

1. Filter users where role == 'volunteer' and they are actively signed up for the current camp.
2. Use FastAPI BackgroundTasks to handle bulk execution asynchronously to avoid API timeouts.
3. Integrate with the existing mailing system for email delivery.
4. Integrate a push notification service (e.g., Firebase Admin SDK) using stored device tokens (e.g., fcm_token on the user model).

Test Cases (Backend Validation)

• TC-BE-01 (Unauthorized Access): Verify that requests from non-admin roles (e.g., regular volunteers or unauthenticated requests) return a 403 Forbidden or 401 Unauthorized status code.
• TC-BE-02 (Payload Validation): Verify that submitting an empty title or message returns a 422 Unprocessable Entity error.
• TC-BE-03 (Target Filtering): Mock a database setup with 3 users: (A) Signed-up volunteer, (B) Non-signed-up volunteer, and (C) Doctor. Verify that only user (A) is fetched in the broadcast query loop.
• TC-BE-04 (Async Execution): Verify that the endpoint returns a 202 Accepted response instantly, before the simulated bulk email/push functions finish running in the background.
• TC-BE-05 (Channel Toggles): Verify that if send_email is false and send_push is true, the mailing service task is completely skipped and only the push gateway is invoked.

Acceptance Criteria

• Endpoint securely validates admin credentials.
• API successfully filters only camp-enrolled volunteers.
• API processes sending in the background and returns a quick response.