Function 4
Get Next Order to Ship
FIFO Queue · Canceled orders di-skip (lazy deletion) · Loop sampai active order ditemukan
Sequence Flow — loop [queue not empty and front is canceled]
getNextOrderToShip() → peek()
Lihat elemen terdepan queue
front() → get(order_id) → isActive?
Cek apakah order masih aktif
pop() — skip canceled order
Loop: cek order berikutnya
isActive? true → pop()
Order aktif ditemukan!
11. return active order
Return order siap kirim