split.gno

 1package memba_market_core_v2
 2
 3// SplitProceedsBPS computes the three-way split of a sale price into platform fee,
 4// creator royalty, and seller proceeds, with the platform fee in basis points
 5// supplied by the caller (read per-lane from memba_market_config) instead of the
 6// frozen FeeBPS constant. This is the spine that lets every engine charge a
 7// DAO-tunable, per-lane fee while sharing one audited money-math implementation.
 8//
 9// `feeBPS` is validated to [0, MaxFeeBPS] — the 5% ceiling the DAO can never exceed
10// — so a misconfigured or compromised config realm cannot make an engine overcharge.
11// `royaltyAmount` is the actual amount from RoyaltyInfo (NOT bps); floored at 0 and
12// clamped to MaxRoyaltyBPS of price. A zero fee is permitted (feeBPS may legitimately
13// be 0, or round to 0 on a small price); engines that must guarantee non-zero protocol
14// revenue (e.g. fungible OTC partial fills) enforce a per-fill minimum notional at
15// their call site — that is an engine concern, not pure money-math.
16func SplitProceedsBPS(price, feeBPS, royaltyAmount int64) (fee, royalty, seller int64) {
17	if price < MinPrice {
18		panic("price below minimum")
19	}
20	if price > MaxPrice {
21		panic("price above maximum")
22	}
23	if feeBPS < 0 {
24		panic("feeBPS negative")
25	}
26	if feeBPS > MaxFeeBPS {
27		panic("feeBPS above maximum")
28	}
29	fee = price * feeBPS / 10000
30	royalty = royaltyAmount
31	if royalty < 0 {
32		royalty = 0
33	}
34	maxRoy := price * MaxRoyaltyBPS / 10000
35	if royalty > maxRoy {
36		royalty = maxRoy
37	}
38	if fee+royalty >= price {
39		panic("fee plus royalty exceeds price")
40	}
41	seller = price - fee - royalty
42	if seller <= 0 {
43		panic("seller amount not positive")
44	}
45	return
46}
47
48// SplitProceeds is the frozen FeeBPS (2.0%) conformance path, kept behaviorally
49// identical to memba_nft_market_v3's splitProceeds. It delegates to SplitProceedsBPS
50// with the default FeeBPS so existing engines are unchanged.
51func SplitProceeds(price, royaltyAmount int64) (fee, royalty, seller int64) {
52	return SplitProceedsBPS(price, FeeBPS, royaltyAmount)
53}