multi: move DBMPPayment to paymentsdb package

payments/db/interface.go

@@ -89,3 +89,35 @@ type PaymentControl interface {
 	// completed, and the payment has reached a final terminal state.
 	DeleteFailedAttempts(lntypes.Hash) error
 }
+
+// DBMPPayment is an interface that represents the payment state during a
+// payment lifecycle.
+type DBMPPayment interface {
+	// GetState returns the current state of the payment.
+	GetState() *MPPaymentState
+
+	// Terminated returns true if the payment is in a final state.
+	Terminated() bool
+
+	// GetStatus returns the current status of the payment.
+	GetStatus() PaymentStatus
+
+	// NeedWaitAttempts specifies whether the payment needs to wait for the
+	// outcome of an attempt.
+	NeedWaitAttempts() (bool, error)
+
+	// GetHTLCs returns all HTLCs of this payment.
+	GetHTLCs() []HTLCAttempt
+
+	// InFlightHTLCs returns all HTLCs that are in flight.
+	InFlightHTLCs() []HTLCAttempt
+
+	// AllowMoreAttempts is used to decide whether we can safely attempt
+	// more HTLCs for a given payment state. Return an error if the payment
+	// is in an unexpected state.
+	AllowMoreAttempts() (bool, error)
+
+	// TerminalInfo returns the settled HTLC attempt or the payment's
+	// failure reason.
+	TerminalInfo() (*HTLCAttempt, *FailureReason)
+}