def __init__(self, sku, on_hand_buffer=None):
self.sku = sku
# Minimum on hand quantity before we need to physically verify stock levels, off by default
self.on_hand_buffer = on_hand_buffer if on_hand_buffer else 0
self.tracker = TrackingStateMachine()
self.tracker.add_state(OnHandState("OnHand"))
self.tracker.add_state(CommittedState("Committed"))
self.tracker.add_state(BackorderState("Backorder"))
self.tracker.add_state(FulfilledState("Fulfilled"))
self.tracker.add_state(PurchaseOrderState("PurchaseOrder"))
self.tracker.add_state(LostAndFoundState("Lost"))
self.tracker.add_state(LostAndFoundState("Found"))
self.tracker.add_transition("commit", "OnHand", "Committed")
self.tracker.add_transition("allocate", "OnHand", "Backorder")
self.tracker.add_transition("fulfill_backorder", "Backorder",
"Committed")
self.tracker.add_transition("cancel_backorder", "Backorder", "OnHand")
self.tracker.add_action("verify", "Committed")
self.tracker.add_transition("verify_out_of_stock", "Committed",
"Backorder")
self.tracker.add_transition("backorder_commitment", "Committed",
"Backorder")
self.tracker.add_transition("revert", "Committed", "OnHand")
self.tracker.add_transition("fulfill", "Committed", "Fulfilled")
self.tracker.add_transition("delivery", "PurchaseOrder", "OnHand")
self.tracker.add_action("cancel_purchase_order", "PurchaseOrder")
self.tracker.add_transition("lost", "OnHand", "Lost")
self.tracker.add_transition("found", "Found", "OnHand")
# Some shortcut attributes
self.on_hand = self.tracker.state("OnHand")
self.committed = self.tracker.state("Committed")
self.verification = self.tracker.state("Verify")
self.backorders = self.tracker.state("Backorder")
self.fulfilled = self.tracker.state("Fulfilled")
self.purchase_orders = self.tracker.state("PurchaseOrder")
self.lost = self.tracker.state("Lost")
self.found = self.tracker.state("Found")
