package services

import "errors"

// Where a staff assignment request is actually asking to put somebody.
//
// Its own function because the dangerous case is a quiet one. Unassigning is a
// real instruction — people leave a shop before the next one opens, and the
// alternative to holding them unassigned is deleting the account and losing who
// did what — but it looks exactly like a `locationid` that failed to arrive.
// A JSON body missing the field, a form that posted a blank, a client that
// dropped it: all of them present as 0.
//
// So 0 alone never unassigns. `unassign` has to be sent, deliberately, and a
// request that names no branch and does not ask to unassign is refused rather
// than guessed at.
func ResolveAssignment(locationID int, unassign bool) (int, error) {
	if unassign {
		// An explicit request wins even if a branch was also sent — the caller
		// said what they wanted, and honouring the leftover id instead would be
		// the same silent guess in reverse.
		return 0, nil
	}
	if locationID <= 0 {
		return 0, errors.New(
			"give a locationid, or send unassign:true to take them off a branch")
	}
	return locationID, nil
}