flowchart Order Processing Pipeline

(Receive Order) -> [Validate Input] -> <Valid?>
  -yes-> [Check Inventory] -> <In Stock?>
    -yes-> [[Process Payment]] -> <Payment OK?>
      -yes-> [Ship Order] -> /Send Confirmation/ -> (Complete)
      -no-> [Retry Payment] -> <Retries Left?>
        -yes-> [[Process Payment]]
        -no-> [Cancel Order] -> /Notify Customer/ -> (Failed)
    -no-> /Notify Backorder/ -> <Accept Wait?>
      -yes-> [Queue Order] -> [Check Inventory]
      -no-> [Refund] -> (Cancelled)
  -no-> [Log Validation Error~] -> /Show Error/ -> (Rejected)