Sync coursework with the Google Classroom API

Steps

1. Enable the Google Classroom API in the Google Cloud Console, configure an OAuth 2.0 credential with the appropriate scopes (e.g., https://www.googleapis.com/auth/classroom.courses.readonly, classroom.coursework.students), and obtain user or service account tokens via the OAuth 2.0 authorization flow.
2. List courses using GET https://classroom.googleapis.com/v1/courses with query parameters teacherId or studentId to scope results; use pageToken from the nextPageToken field to paginate through all courses.
3. Retrieve coursework for a course via GET /v1/courses/:courseId/courseWork; each CourseWork object includes id, title, dueDate, maxPoints, and workType (ASSIGNMENT, SHORT_ANSWER_QUESTION, MULTIPLE_CHOICE_QUESTION).
4. Fetch student submissions via GET /v1/courses/:courseId/courseWork/:courseWorkId/studentSubmissions?userId=me (or a specific userId for domain-wide delegation); the response includes state, assignedGrade, and submissionHistory.
5. To receive real-time roster or coursework changes without polling, use the Classroom Push Notifications API: register a Pub/Sub topic at GET /v1/registrations and subscribe your service to receive change events.
6. When writing grades back, PATCH to /v1/courses/:courseId/courseWork/:courseWorkId/studentSubmissions/:id with updateMask=assignedGrade and call the :return action to finalize the submission.