Move a Lesson’s Time

There are two different moves, done on two different screens:

Moving the standing slot (the reservation)

On /admin/schedule.php, press Edit and drag the reservation’s cell onto an empty slot — a different time, a different teacher’s column, even a different location’s column. When the cell holds a single booking, anywhere on the cell starts the drag. The drop can’t land on an occupied cell, and a client-side check refuses drops that would run past the end of the day or into the next booking. Standing hold blocks drag the same way (they post to their own endpoint but follow the same conflict rules); one-off hold blocks on the weekly calendar do not.

⌘Z (Ctrl+Z) undoes the last move — up to 20 per editing session. The undo re-posts the item to where it came from and is validated like any other move, so a since-occupied origin refuses the undo with the reason.

The server (ReservationManagement::updateReservation) then:

1. Validates the destination — the teacher must actually be assigned to that location this semester, and the slot is swept for conflicts before anything is written: against other reservations and hold blocks (teacher-wide, across all locations — a teacher can’t be in two places), and against every future occurrence date, including one-off lessons and hold blocks. The first conflict aborts the whole move with a specific message (“This teacher already has Ana’s weekly slot at 3:00–3:30 pm…”).
2. Updates the reservation row (teacher, location, day, time).
3. Moves the future lessons, if the reservation is confirmed:
   • Same day of week — each future lesson still sitting at the old standing time is updated in place to the new time, so its notes, resources, attendance marks, substitute, and location override all survive.
   • Different day of week — the future lessons are regenerated on the new weekday’s active dates. Per-occurrence data on the dropped dates is lost (notes, attendance, substitutes), so prefer same-day moves when a week has history on it.

Two things are always left alone: past lessons stay exactly where they were taught, and weeks that were individually hand-moved (their time no longer matches the standing time) keep their custom time — the move only carries the weeks still following the schedule.

Pending reservations move the same way but have no lessons yet, so only the reservation row changes.

Rescheduling a single week

On /admin/calendar_week.php, press Edit and drag the lesson to an empty cell. One drag can change the time, the date (within the displayed week), the teacher, and the location at once:

• Dropped on a different teacher’s column — that teacher becomes the substitute for that week only; the reservation is untouched. Dropping it back on its own teacher’s column clears the substitute.
• Dropped on a different location’s column — recorded as a one-week location override.
• The destination is conflict-checked against whoever ends up teaching; cancelled lessons don’t block a drop (a cancelled slot is free).

A cancelled lesson itself cannot be moved. After a hand-move, the lesson shows a “Time moved from 3:00 pm” note in the calendar — and, as above, it is thereafter excluded from standing-slot moves.

The lesson modal deliberately has no time field: moving is always done by dragging, so there is exactly one way to do it and it is always conflict-checked.