42 lines
1.1 KiB
Go
42 lines
1.1 KiB
Go
package kernel
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import (
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"errors"
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"math/big"
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)
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var (
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ErrInvalidTokenBilling = errors.New("invalid token billing parameters")
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ErrTokenBillingOverflow = errors.New("token billing amount overflows int64")
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)
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type TokenBillingTerm struct {
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Tokens int64
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PriceMicrocredits int64
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}
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// 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。
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func TokenBillingAmount(multiplierBPS int64, terms ...TokenBillingTerm) (int64, error) {
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if multiplierBPS <= 0 {
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return 0, ErrInvalidTokenBilling
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}
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var total, product big.Int
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for _, term := range terms {
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if term.Tokens < 0 || term.PriceMicrocredits < 0 {
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return 0, ErrInvalidTokenBilling
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}
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product.Mul(big.NewInt(term.Tokens), big.NewInt(term.PriceMicrocredits))
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total.Add(&total, &product)
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}
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total.Mul(&total, big.NewInt(multiplierBPS))
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var remainder big.Int
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total.QuoRem(&total, big.NewInt(10_000_000_000), &remainder)
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if remainder.Sign() != 0 {
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total.Add(&total, big.NewInt(1))
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}
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if !total.IsInt64() {
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return 0, ErrTokenBillingOverflow
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}
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return total.Int64(), nil
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}
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