feat(*): 模型计费与渠道目录 - 支持视频 Token 报价结算和稳定模型展示

backend/internal/kernel/token_billing.go

@@ -0,0 +1,41 @@
+package kernel
+
+import (
+	"errors"
+	"math/big"
+)
+
+var (
+	ErrInvalidTokenBilling  = errors.New("invalid token billing parameters")
+	ErrTokenBillingOverflow = errors.New("token billing amount overflows int64")
+)
+
+type TokenBillingTerm struct {
+	Tokens            int64
+	PriceMicrocredits int64
+}
+
+// TokenBillingAmount 按每百万 Token 单价及万分比倍率汇总费用，只对最终微积分金额上取整。
+func TokenBillingAmount(multiplierBPS int64, terms ...TokenBillingTerm) (int64, error) {
+	if multiplierBPS <= 0 {
+		return 0, ErrInvalidTokenBilling
+	}
+	var total, product big.Int
+	for _, term := range terms {
+		if term.Tokens < 0 || term.PriceMicrocredits < 0 {
+			return 0, ErrInvalidTokenBilling
+		}
+		product.Mul(big.NewInt(term.Tokens), big.NewInt(term.PriceMicrocredits))
+		total.Add(&total, &product)
+	}
+	total.Mul(&total, big.NewInt(multiplierBPS))
+	var remainder big.Int
+	total.QuoRem(&total, big.NewInt(10_000_000_000), &remainder)
+	if remainder.Sign() != 0 {
+		total.Add(&total, big.NewInt(1))
+	}
+	if !total.IsInt64() {
+		return 0, ErrTokenBillingOverflow
+	}
+	return total.Int64(), nil
+}

backend/internal/kernel/token_billing_test.go

@@ -0,0 +1,90 @@
+package kernel
+
+import (
+	"errors"
+	"math"
+	"testing"
+)
+
+func TestTokenBillingAmount(t *testing.T) {
+	for _, test := range []struct {
+		name       string
+		multiplier int64
+		terms      []TokenBillingTerm
+		want       int64
+	}{
+		{
+			name: "maximum configured price", multiplier: 10_000,
+			terms: []TokenBillingTerm{{Tokens: 10_000_000, PriceMicrocredits: 1_000_000_000_000}},
+			want:  10_000_000_000_000,
+		},
+		{
+			name: "maximum configured price with multiplier", multiplier: 12_500,
+			terms: []TokenBillingTerm{{Tokens: 10_000_000, PriceMicrocredits: 1_000_000_000_000}},
+			want:  12_500_000_000_000,
+		},
+		{
+			name: "round once after combining terms", multiplier: 10_000,
+			terms: []TokenBillingTerm{{Tokens: 1, PriceMicrocredits: 400_000}, {Tokens: 1, PriceMicrocredits: 400_000}, {Tokens: 1, PriceMicrocredits: 100_000}},
+			want:  1,
+		},
+		{
+			name: "apply multiplier before rounding", multiplier: 12_500,
+			terms: []TokenBillingTerm{{Tokens: 1, PriceMicrocredits: 400_000}, {Tokens: 1, PriceMicrocredits: 400_000}},
+			want:  1,
+		},
+		{
+			name: "fractional microcredit rounds up", multiplier: 1,
+			terms: []TokenBillingTerm{{Tokens: 1, PriceMicrocredits: 1}},
+			want:  1,
+		},
+		{
+			name: "maximum int64 result after overflowing intermediate sum", multiplier: 10_000,
+			terms: []TokenBillingTerm{{Tokens: math.MaxInt64, PriceMicrocredits: 500_000}, {Tokens: math.MaxInt64, PriceMicrocredits: 500_000}},
+			want:  math.MaxInt64,
+		},
+		{
+			name: "free usage", multiplier: math.MaxInt64,
+			terms: []TokenBillingTerm{{Tokens: math.MaxInt64, PriceMicrocredits: 0}},
+			want:  0,
+		},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			amount, err := TokenBillingAmount(test.multiplier, test.terms...)
+			if err != nil || amount != test.want {
+				t.Fatalf("TokenBillingAmount() = %d, %v; want %d", amount, err, test.want)
+			}
+		})
+	}
+}
+
+func TestTokenBillingAmountRejectsInvalidParametersAndFinalOverflow(t *testing.T) {
+	for _, test := range []struct {
+		name       string
+		multiplier int64
+		terms      []TokenBillingTerm
+		wantErr    error
+	}{
+		{name: "zero multiplier", terms: []TokenBillingTerm{{Tokens: 1, PriceMicrocredits: 1}}, wantErr: ErrInvalidTokenBilling},
+		{name: "negative multiplier", multiplier: -1, wantErr: ErrInvalidTokenBilling},
+		{name: "negative tokens", multiplier: 10_000, terms: []TokenBillingTerm{{Tokens: -1}}, wantErr: ErrInvalidTokenBilling},
+		{name: "negative price even with zero tokens", multiplier: 10_000, terms: []TokenBillingTerm{{PriceMicrocredits: -1}}, wantErr: ErrInvalidTokenBilling},
+		{
+			name: "final amount overflow", multiplier: 10_001,
+			terms:   []TokenBillingTerm{{Tokens: math.MaxInt64, PriceMicrocredits: 1_000_000}},
+			wantErr: ErrTokenBillingOverflow,
+		},
+		{
+			name: "rounding causes final overflow", multiplier: 10_000,
+			terms:   []TokenBillingTerm{{Tokens: math.MaxInt64, PriceMicrocredits: 1_000_000}, {Tokens: 1, PriceMicrocredits: 1}},
+			wantErr: ErrTokenBillingOverflow,
+		},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			amount, err := TokenBillingAmount(test.multiplier, test.terms...)
+			if amount != 0 || !errors.Is(err, test.wantErr) {
+				t.Fatalf("TokenBillingAmount() = %d, %v; want 0, %v", amount, err, test.wantErr)
+			}
+		})
+	}
+}