sendfun_sdk/math/
fees.rs

1pub struct FeeSplitArgs {
2	pub fee_amount: u64,
3	pub protocol_bps: u64,
4	pub lp_bps: u64,
5	pub base_total_bps: u64,
6	pub decay_premium_bps: u64,
7}
8
9/// `(protocol, lp, creator, sniper)`: LP/creator round down; protocol gets
10/// the premium and the remainder, so `sniper` is a subset of `protocol`.
11#[must_use]
12pub fn split_fee_amount(args: FeeSplitArgs) -> Option<(u64, u64, u64, u64)> {
13	let fee_amount = args.fee_amount;
14	// Zero fees split successfully even when total BPS is zero.
15	if fee_amount == 0 {
16		return Some((0, 0, 0, 0));
17	}
18	let effective_total_bps =
19		args.base_total_bps.checked_add(args.decay_premium_bps)?;
20	if effective_total_bps == 0 {
21		return None;
22	}
23
24	if args.base_total_bps == 0 {
25		return Some((fee_amount, 0, 0, fee_amount));
26	}
27
28	let lp_fee = u128::from(fee_amount)
29		.checked_mul(u128::from(args.lp_bps))?
30		.checked_div(u128::from(effective_total_bps))?;
31	let lp_fee = u64::try_from(lp_fee).ok()?;
32
33	let creator_bps = args
34		.base_total_bps
35		.checked_sub(args.protocol_bps)?
36		.checked_sub(args.lp_bps)?;
37	let creator_fee = u128::from(fee_amount)
38		.checked_mul(u128::from(creator_bps))?
39		.checked_div(u128::from(effective_total_bps))?;
40	let creator_fee = u64::try_from(creator_fee).ok()?;
41
42	let sniper_fee = u128::from(fee_amount)
43		.checked_mul(u128::from(args.decay_premium_bps))?
44		.checked_div(u128::from(effective_total_bps))?;
45	let sniper_fee = u64::try_from(sniper_fee).ok()?;
46
47	let protocol_fee =
48		fee_amount.checked_sub(lp_fee)?.checked_sub(creator_fee)?;
49
50	Some((protocol_fee, lp_fee, creator_fee, sniper_fee))
51}
52
53#[cfg(test)]
54mod tests {
55	use super::*;
56
57	const STANDARD: FeeSplitArgs = FeeSplitArgs {
58		fee_amount: 1000,
59		protocol_bps: 200,
60		lp_bps: 200,
61		base_total_bps: 1000,
62		decay_premium_bps: 0,
63	};
64
65	#[test]
66	fn test_split_fee_amount_no_dust_lost() {
67		let (protocol_fee, lp_fee, creator_fee, sniper_fee) =
68			split_fee_amount(STANDARD).unwrap();
69
70		assert_eq!(protocol_fee, 200);
71		assert_eq!(lp_fee, 200);
72		assert_eq!(creator_fee, 600);
73		assert_eq!(sniper_fee, 0);
74		assert_eq!(protocol_fee + lp_fee + creator_fee, 1000);
75	}
76
77	#[test]
78	fn test_split_fee_amount_protocol_wins_rounding() {
79		let (protocol_fee, lp_fee, creator_fee, sniper_fee) =
80			split_fee_amount(FeeSplitArgs {
81				fee_amount: 1001,
82				..STANDARD
83			})
84			.unwrap();
85
86		assert_eq!(lp_fee, 200);
87		assert_eq!(creator_fee, 600);
88		assert_eq!(protocol_fee, 201);
89		assert_eq!(sniper_fee, 0);
90		assert_eq!(protocol_fee + lp_fee + creator_fee, 1001);
91	}
92
93	#[test]
94	fn test_split_fee_with_decay_protocol_wins_rounding() {
95		let (protocol_fee, lp_fee, creator_fee, sniper_fee) =
96			split_fee_amount(FeeSplitArgs {
97				fee_amount: 1001,
98				decay_premium_bps: 500,
99				..STANDARD
100			})
101			.unwrap();
102
103		assert_eq!(lp_fee, 133);
104		assert_eq!(creator_fee, 400);
105		assert_eq!(protocol_fee, 468);
106		assert_eq!(sniper_fee, 333);
107		assert_eq!(protocol_fee + lp_fee + creator_fee, 1001);
108	}
109
110	#[test]
111	fn test_split_fee_max_amount() {
112		let fee_amount = 1_000_000_000_000_000u64;
113		let result = split_fee_amount(FeeSplitArgs {
114			fee_amount,
115			protocol_bps: 100,
116			lp_bps: 100,
117			base_total_bps: 300,
118			decay_premium_bps: 0,
119		});
120		assert!(result.is_some());
121		let (protocol, lp, creator, _decay) = result.unwrap();
122		assert_eq!(protocol + lp + creator, fee_amount);
123	}
124
125	#[test]
126	fn test_split_fee_zero_amount() {
127		assert_eq!(
128			split_fee_amount(FeeSplitArgs {
129				fee_amount: 0,
130				protocol_bps: 100,
131				lp_bps: 100,
132				base_total_bps: 300,
133				decay_premium_bps: 0,
134			}),
135			Some((0, 0, 0, 0)),
136		);
137	}
138
139	#[test]
140	fn test_split_fee_invalid_bps_underflows() {
141		assert_eq!(
142			split_fee_amount(FeeSplitArgs {
143				protocol_bps: 600,
144				lp_bps: 500,
145				..STANDARD
146			}),
147			None,
148		);
149	}
150
151	#[test]
152	fn test_split_fee_zero_total_bps() {
153		assert_eq!(
154			split_fee_amount(FeeSplitArgs {
155				fee_amount: 1000,
156				protocol_bps: 0,
157				lp_bps: 0,
158				base_total_bps: 0,
159				decay_premium_bps: 0,
160			}),
161			None,
162		);
163	}
164
165	#[test]
166	fn test_split_fee_zero_amount_and_zero_total_bps() {
167		assert_eq!(
168			split_fee_amount(FeeSplitArgs {
169				fee_amount: 0,
170				protocol_bps: 0,
171				lp_bps: 0,
172				base_total_bps: 0,
173				decay_premium_bps: 0,
174			}),
175			Some((0, 0, 0, 0)),
176		);
177	}
178}
sendfun_sdk/math/fees.rs

sendfun_sdk/math/
fees.rs
