| """How long pictures are kept (PRD ANS-3): answer pictures until the end of the school year (31 August), unreferenced pictures for a day, | |
| assignment pages until their assignment is removed. Grades and teachers' notes are never touched: only the pictures go.""" | |
| from __future__ import annotations | |
| from datetime import date, timedelta | |
| ORPHAN_AGE = timedelta(hours=24) | |
| def expires_on(day: date) -> date: | |
| """The last day an answer picture made on `day` is kept: 31 August of its school year (1 September to 31 August).""" | |
| return date(day.year + 1 if day.month >= 9 else day.year, 8, 31) | |
| def is_expired(created_day: date, today: date) -> bool: | |
| """An answer picture is removed from 1 September on.""" | |
| return today > expires_on(created_day) | |