fix: settle excess token usage with negative balance (#304)

backend/internal/repository/finance_token_test.go

@@ -99,3 +99,144 @@ func TestSettleArkVideoTokenOrderFromPollUsage(t *testing.T) {
 		t.Fatalf("settled account = %#v", account)
 	}
 }
+
+func TestSettleArkVideoTokenOrderSupplementsUnderreservation(t *testing.T) {
+	db, err := gorm.Open(sqlite.Open("file:finance-token-supplement?mode=memory&cache=shared"), &gorm.Config{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := db.AutoMigrate(&model.CreditAccount{}, &model.BillingOrder{}, &model.ApiCallLog{}, &model.CreditLedgerEntry{}); err != nil {
+		t.Fatal(err)
+	}
+	const (
+		reserved   = int64(3_049_738)
+		actual     = int64(3_115_222)
+		supplement = actual - reserved
+	)
+	if err := db.Create(&model.CreditAccount{UserID: "user-1", AvailableMicrocredits: 1_000_000, ReservedMicrocredits: reserved}).Error; err != nil {
+		t.Fatal(err)
+	}
+	if err := db.Create(&model.BillingOrder{
+		ID: "order-1", UserID: "user-1", IdempotencyKey: "task:task-1", Capability: "video", BillingMode: "token",
+		AmountMicrocredits: reserved, ReservedAmountMicrocredits: reserved, OutputTokenPriceMicrocredits: 18_200_000,
+		MultiplierBasisPoints: 10_000, Status: model.BillingStatusRunning,
+	}).Error; err != nil {
+		t.Fatal(err)
+	}
+	if err := db.Create(&model.ApiCallLog{
+		ID: "poll-log-1", BillingOrderID: "order-1", RequestKind: "poll", Billable: false,
+		Status: model.ApiCallStatusSucceeded, UsageAvailable: true, OutputTokens: 171_166,
+	}).Error; err != nil {
+		t.Fatal(err)
+	}
+
+	repo := &Repository{db: db}
+	if err := repo.SettleBillingOrder("order-1", "ark-task-1"); err != nil {
+		t.Fatalf("SettleBillingOrder() error = %v", err)
+	}
+	var order model.BillingOrder
+	if err := db.First(&order, "id = ?", "order-1").Error; err != nil {
+		t.Fatal(err)
+	}
+	if order.Status != model.BillingStatusSettled || order.ActualAmountMicrocredits != actual || order.OutputTokens != 171_166 || !order.UsageAvailable {
+		t.Fatalf("settled order = %#v", order)
+	}
+	var account model.CreditAccount
+	if err := db.First(&account, "user_id = ?", "user-1").Error; err != nil {
+		t.Fatal(err)
+	}
+	if account.AvailableMicrocredits != 1_000_000-supplement || account.ReservedMicrocredits != 0 {
+		t.Fatalf("settled account = %#v", account)
+	}
+	var entry model.CreditLedgerEntry
+	if err := db.First(&entry, "billing_order_id = ? AND type = ?", "order-1", model.CreditLedgerConsume).Error; err != nil {
+		t.Fatal(err)
+	}
+	if entry.AmountMicrocredits != -actual || entry.AvailableDeltaMicrocredits != -supplement || entry.ReservedDeltaMicrocredits != -reserved {
+		t.Fatalf("consume entry = %#v", entry)
+	}
+}
+
+func TestSettleArkVideoTokenOrderAllowsNegativeBalance(t *testing.T) {
+	db, err := gorm.Open(sqlite.Open("file:finance-token-negative-balance?mode=memory&cache=shared"), &gorm.Config{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := db.AutoMigrate(&model.CreditAccount{}, &model.BillingOrder{}, &model.ApiCallLog{}, &model.CreditLedgerEntry{}); err != nil {
+		t.Fatal(err)
+	}
+	const reserved = int64(3_049_738)
+	if err := db.Create(&model.CreditAccount{UserID: "user-1", AvailableMicrocredits: 10_000, ReservedMicrocredits: reserved}).Error; err != nil {
+		t.Fatal(err)
+	}
+	if err := db.Create(&model.BillingOrder{
+		ID: "order-1", UserID: "user-1", IdempotencyKey: "task:task-1", Capability: "video", BillingMode: "token",
+		AmountMicrocredits: reserved, ReservedAmountMicrocredits: reserved, OutputTokenPriceMicrocredits: 18_200_000,
+		MultiplierBasisPoints: 10_000, Status: model.BillingStatusRunning,
+	}).Error; err != nil {
+		t.Fatal(err)
+	}
+	if err := db.Create(&model.ApiCallLog{
+		ID: "poll-log-1", BillingOrderID: "order-1", RequestKind: "poll", Billable: false,
+		Status: model.ApiCallStatusSucceeded, UsageAvailable: true, OutputTokens: 171_166,
+	}).Error; err != nil {
+		t.Fatal(err)
+	}
+
+	repo := &Repository{db: db}
+	err = repo.SettleBillingOrder("order-1", "ark-task-1")
+	if err != nil {
+		t.Fatalf("SettleBillingOrder() error = %v", err)
+	}
+	var order model.BillingOrder
+	if err := db.First(&order, "id = ?", "order-1").Error; err != nil {
+		t.Fatal(err)
+	}
+	if order.Status != model.BillingStatusSettled || order.ActualAmountMicrocredits != 3_115_222 || order.OutputTokens != 171_166 || !order.UsageAvailable {
+		t.Fatalf("settled order = %#v", order)
+	}
+	var account model.CreditAccount
+	if err := db.First(&account, "user_id = ?", "user-1").Error; err != nil {
+		t.Fatal(err)
+	}
+	if account.AvailableMicrocredits != -55_484 || account.ReservedMicrocredits != 0 {
+		t.Fatalf("settled account = %#v", account)
+	}
+	var entry model.CreditLedgerEntry
+	if err := db.First(&entry, "billing_order_id = ? AND type = ?", "order-1", model.CreditLedgerConsume).Error; err != nil {
+		t.Fatal(err)
+	}
+	if entry.AvailableAfterMicrocredits != -55_484 || entry.AvailableDeltaMicrocredits != -65_484 {
+		t.Fatalf("consume entry = %#v", entry)
+	}
+}
+
+func TestNegativeBalanceBlocksNewReservationsAndAcceptsRepayment(t *testing.T) {
+	db, err := gorm.Open(sqlite.Open("file:finance-negative-balance-repayment?mode=memory&cache=shared"), &gorm.Config{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := db.AutoMigrate(&model.CreditAccount{}, &model.BillingOrder{}, &model.CreditLedgerEntry{}); err != nil {
+		t.Fatal(err)
+	}
+	if err := db.Create(&model.CreditAccount{UserID: "user-1", AvailableMicrocredits: -1_000_000}).Error; err != nil {
+		t.Fatal(err)
+	}
+
+	repo := &Repository{db: db}
+	order := model.BillingOrder{
+		ID: "order-1", UserID: "user-1", IdempotencyKey: "task:task-1",
+		AmountMicrocredits: 1, ReservedAmountMicrocredits: 1, Status: model.BillingStatusReserved,
+	}
+	if err := repo.ReserveBillingOrder(&order); !errors.Is(err, ErrInsufficientCredits) {
+		t.Fatalf("ReserveBillingOrder() error = %v", err)
+	}
+
+	account, err := repo.AdjustCredits("user-1", "admin-1", 100_000_000, "充值入账")
+	if err != nil {
+		t.Fatalf("AdjustCredits() error = %v", err)
+	}
+	if account.AvailableMicrocredits != 99_000_000 {
+		t.Fatalf("available balance = %d", account.AvailableMicrocredits)
+	}
+}