simulator-api 0.22.1

//! Pricing a reroute stream in dollars using nothing but the stream.
//!
//! No oracle and no external feed. SOL/USD comes from the range's own SOL<->USDC reroutes, the
//! other majors from their pairings against SOL, USDC and USDT, and everything else from its
//! major<->exotic legs. A derived price needs [`MIN_SAMPLES`] observations before it is trusted;
//! the SOL anchor is exempt, since every other price hangs from it.

use std::collections::HashMap;

use solana_address::Address;

use super::record::{LegRecord, SwapMode};
use crate::mints;

const LAMPORTS_PER_SOL: f64 = 1e9;
/// Sub-SOL probe swaps realize off-market and drag the median, so the anchor ignores them.
const ONE_SOL_LAMPORTS: u128 = 1_000_000_000;
const USDC_UNITS_PER_USD: f64 = 1e6;
/// A derived price needs at least this many samples to be trusted.
const MIN_SAMPLES: usize = 3;

/// One ExactIn reroute. ExactOut is excluded: its `amount` is in the output token and would
/// poison every ratio it entered.
struct Sample {
    input_mint: Address,
    output_mint: Address,
    amount: u128,
    original_output: u128,
}

/// Retained until the range ends, because a median cannot be folded. Two mints and two amounts
/// against a notification's multi-KB route plans, which is what lets a report skip the stream.
#[derive(Default)]
pub struct Samples(Vec<Sample>);

impl Samples {
    /// Keeps the leg as a pricing sample only if it can price something: ExactIn, a realized and
    /// nonzero original output, a nonzero input amount, the original didn't fail, and at least
    /// one side is a major to anchor on. Anything else is silently dropped.
    pub fn push(&mut self, record: &LegRecord) {
        let Some(original_output) = record.original_realized_output_amount else {
            return;
        };
        if record.swap_mode != SwapMode::ExactIn
            || record.amount == 0
            || original_output == 0
            || record.original_failed
        {
            return;
        }
        // Every derivation anchors on a major, so a leg between two exotics is unreadable.
        if !mints::is_major(&record.input_mint) && !mints::is_major(&record.output_mint) {
            return;
        }
        self.0.push(Sample {
            input_mint: record.input_mint,
            output_mint: record.output_mint,
            amount: u128::from(record.amount),
            original_output: u128::from(original_output),
        });
    }

    /// `None` when the range carries no SOL<->USDC ExactIn reroutes to anchor on.
    pub fn prices(&self) -> Option<Prices> {
        let sol_usd = sol_price(&self.0)?;
        let mut prices = Prices {
            sol_usd,
            priced: priced_major_prices(&self.0, sol_usd),
            exotic: HashMap::new(),
        };
        prices.exotic = exotic_unit_prices(&self.0, &prices);
        Some(prices)
    }
}

/// Per-range prices, derived from the range's own reroutes.
pub struct Prices {
    sol_usd: f64,
    /// USD per whole unit for the priced majors.
    priced: HashMap<Address, f64>,
    /// USD per *raw* unit for exotics, inferred from their major<->exotic legs.
    exotic: HashMap<Address, f64>,
}

impl Prices {
    pub const fn sol_usd(&self) -> f64 {
        self.sol_usd
    }

    /// `None` when the range could not price the mint, which the report counts rather than
    /// folding in as zero.
    ///
    /// Linear in `raw` on every path, so a caller may sum one mint's raw amounts and convert the
    /// total once, or pass an amount a weight has already scaled out of whole units.
    pub fn usd(&self, mint: &Address, raw: f64) -> Option<f64> {
        self.scaled_major(mint, raw)
            .or_else(|| self.exotic.get(mint).map(|unit| raw * unit))
    }

    /// [`Self::usd`] for a mint still in its wire form. Unparseable is unpriceable.
    pub fn usd_str(&self, mint: &str, raw: f64) -> Option<f64> {
        self.usd(&mint.parse().ok()?, raw)
    }

    /// The majors alone, which is what [`exotic_unit_prices`] reads while building the exotics.
    fn scaled_major(&self, mint: &Address, raw: f64) -> Option<f64> {
        if *mint == mints::SOL {
            return Some(raw / LAMPORTS_PER_SOL * self.sol_usd);
        }
        if let Some(decimals) = mints::stable_decimals(mint) {
            return Some(raw / 10f64.powi(decimals as i32));
        }
        let decimals = mints::priced_decimals(mint)?;
        let unit = self.priced.get(mint)?;
        Some(raw / 10f64.powi(decimals as i32) * unit)
    }
}

fn median(values: &mut [f64]) -> f64 {
    values.sort_by(|a, b| a.total_cmp(b));
    let n = values.len();
    match n % 2 {
        1 => values[n / 2],
        _ => (values[n / 2 - 1] + values[n / 2]) / 2.0,
    }
}

fn median_of(mut values: Vec<f64>) -> Option<f64> {
    (values.len() >= MIN_SAMPLES).then(|| median(&mut values))
}

fn sol_price(samples: &[Sample]) -> Option<f64> {
    let mut ratios: Vec<f64> = samples
        .iter()
        .filter_map(|sample| {
            let (input, output) = (sample.input_mint, sample.output_mint);
            if input == mints::SOL && output == mints::USDC && sample.amount >= ONE_SOL_LAMPORTS {
                Some(
                    (sample.original_output as f64 / USDC_UNITS_PER_USD)
                        / (sample.amount as f64 / LAMPORTS_PER_SOL),
                )
            } else if input == mints::USDC
                && output == mints::SOL
                && sample.original_output >= ONE_SOL_LAMPORTS
            {
                Some(
                    (sample.amount as f64 / USDC_UNITS_PER_USD)
                        / (sample.original_output as f64 / LAMPORTS_PER_SOL),
                )
            } else {
                None
            }
        })
        .collect();
    (!ratios.is_empty()).then(|| median(&mut ratios))
}

/// Median USD per priced major, from its pairings with USDC/USDT ($1) and SOL, both directions.
fn priced_major_prices(samples: &[Sample], sol_usd: f64) -> HashMap<Address, f64> {
    let mut per_mint: HashMap<Address, Vec<f64>> = HashMap::new();
    for sample in samples {
        let oriented = [
            (
                sample.input_mint,
                sample.output_mint,
                sample.amount,
                sample.original_output,
            ),
            (
                sample.output_mint,
                sample.input_mint,
                sample.original_output,
                sample.amount,
            ),
        ];
        for (mint, other, mint_raw, other_raw) in oriented {
            let Some(decimals) = mints::priced_decimals(&mint) else {
                continue;
            };
            let other_usd = if other == mints::USDC || other == mints::USDT {
                other_raw as f64 / USDC_UNITS_PER_USD
            } else if other == mints::SOL {
                other_raw as f64 / LAMPORTS_PER_SOL * sol_usd
            } else {
                continue;
            };
            per_mint
                .entry(mint)
                .or_default()
                .push(other_usd / (mint_raw as f64 / 10f64.powi(decimals as i32)));
        }
    }
    per_mint
        .into_iter()
        .filter_map(|(mint, ratios)| Some((mint, median_of(ratios)?)))
        .collect()
}

/// Median USD per raw unit for each exotic, from its major<->exotic legs.
fn exotic_unit_prices(samples: &[Sample], prices: &Prices) -> HashMap<Address, f64> {
    let mut per_mint: HashMap<Address, Vec<f64>> = HashMap::new();
    for sample in samples {
        let (input, output) = (sample.input_mint, sample.output_mint);
        match (mints::is_major(&input), mints::is_major(&output)) {
            (true, false) => {
                if let Some(usd) = prices.scaled_major(&input, sample.amount as f64) {
                    per_mint
                        .entry(output)
                        .or_default()
                        .push(usd / sample.original_output as f64);
                }
            }
            (false, true) => {
                if let Some(usd) = prices.scaled_major(&output, sample.original_output as f64) {
                    per_mint
                        .entry(input)
                        .or_default()
                        .push(usd / sample.amount as f64);
                }
            }
            _ => {}
        }
    }
    per_mint
        .into_iter()
        .filter_map(|(mint, ratios)| Some((mint, median_of(ratios)?)))
        .collect()
}

#[cfg(test)]
mod tests {
    use solana_address::address;

    use super::*;

    /// A longtail mint no table names, so it can only be priced through a major leg.
    const BONK: Address = address!("DezXAZ8z7PnrnRJjz3wXBoRgixCa6xjnB7YaB1pPB263");
    /// A governance blue-chip: parseable, deliberately not a major, and quoted by nobody below.
    const RAY: Address = address!("4k3Dyjzvzp8eMZWUXbBCjEvwSkkk59S5iCNLY3QrkX6R");
    /// What [`anchored`] derives, and what every price hanging off it is stated in.
    const SOL_USD: f64 = 100.0;

    fn sample_record(
        input: Address,
        output: Address,
        amount: u64,
        original_output: u64,
    ) -> LegRecord {
        LegRecord {
            original_signature: "sig".to_string(),
            input_mint: input,
            output_mint: output,
            amount,
            swap_mode: SwapMode::ExactIn,
            failed: false,
            original_failed: false,
            realized_output_amount: None,
            original_realized_output_amount: Some(original_output),
            route_plan: None,
            original_route_plan: None,
            realized_route_plan: None,
        }
    }

    /// Three SOL->USDC reroutes at [`SOL_USD`], which is the only thing a range needs before any
    /// other price can be derived.
    fn anchored() -> Samples {
        let mut samples = Samples::default();
        for (amount, output) in [
            (1_000_000_000, 100_000_000),
            (2_000_000_000, 200_000_000),
            (3_000_000_000, 300_000_000),
        ] {
            samples.push(&sample_record(mints::SOL, mints::USDC, amount, output));
        }
        samples
    }

    /// Sub-SOL swaps realize off-market and would drag the anchor. Two of each, so dropping the
    /// gate moves the median off `SOL_USD` instead of leaving the real legs a majority.
    #[test]
    fn the_sol_anchor_ignores_swaps_under_one_sol() {
        let mut samples = Samples::default();
        // Two dust swaps priced at $1000/SOL and two real ones at $100: ungated the median would
        // be 550.0.
        for (amount, output) in [
            (1_000, 1_000),
            (2_000, 2_000),
            (1_000_000_000, 100_000_000),
            (2_000_000_000, 200_000_000),
        ] {
            samples.push(&sample_record(mints::SOL, mints::USDC, amount, output));
        }
        let prices = samples.prices().expect("anchored");
        assert_eq!(prices.sol_usd(), SOL_USD);
    }

    /// The oriented-pair loop reads a priced major from either side of a leg, and the ratio has
    /// to invert with it — transposed, one cbBTC would be worth 1/60,000th of a dollar.
    #[test]
    fn a_priced_major_medians_both_orientations_of_its_legs() {
        let cbbtc = mints::PRICED_MAJORS[1].address;
        assert_eq!(mints::priced_decimals(&cbbtc), Some(8));
        let one_cbbtc: u64 = 1_00000000;

        let mut samples = anchored();
        // $59,000, $60,000 and — quoted the other way round — $61,000 per cbBTC.
        for (input, output, amount, original_output) in [
            (cbbtc, mints::USDC, one_cbbtc, 59_000_000_000),
            (cbbtc, mints::USDC, 2 * one_cbbtc, 120_000_000_000),
            (mints::USDC, cbbtc, 61_000_000_000, one_cbbtc),
        ] {
            samples.push(&sample_record(input, output, amount, original_output));
        }

        let prices = samples.prices().expect("anchored");
        assert_eq!(prices.usd(&cbbtc, one_cbbtc as f64), Some(60_000.0));
        // Linear in the raw amount, and read at cbBTC's eight decimals rather than USDC's six.
        assert_eq!(prices.usd(&cbbtc, one_cbbtc as f64 / 2.0), Some(30_000.0));
    }

    /// USD per raw exotic unit, folded exactly as the derivation folds it: the major side's
    /// dollars over the raw units they bought.
    fn unit_price(lamports: f64, exotic_raw: f64) -> f64 {
        lamports / LAMPORTS_PER_SOL * SOL_USD / exotic_raw
    }

    /// An exotic has no decimals to read, so it is priced per *raw* unit off its major leg.
    /// Transposing that division would price the whole longtail at ~1e10 dollars a unit.
    #[test]
    fn an_exotic_is_priced_per_raw_unit_off_its_major_leg() {
        let mut samples = anchored();
        // 1e12 BONK per SOL, then 2e12 (half the price per unit), then 1e12 again — so the
        // median unit is the one the first leg quotes, not the cheap outlier in the middle.
        for (lamports, bonk) in [
            (1_000_000_000, 1_000_000_000_000),
            (2_000_000_000, 4_000_000_000_000),
            (3_000_000_000, 3_000_000_000_000),
        ] {
            samples.push(&sample_record(mints::SOL, BONK, lamports, bonk));
        }

        let prices = samples.prices().expect("anchored");
        let unit = unit_price(1_000_000_000.0, 1_000_000_000_000.0);
        assert_eq!(prices.usd(&BONK, 1e12), Some(1e12 * unit));
        assert_eq!(prices.usd(&BONK, 5e11), Some(5e11 * unit));
    }

    /// USDe is 9 decimals; treating every stable as 1e6 values its legs 1000x over. Stable
    /// pricing reads decimals alone, so the USDe<->USDC legs below anchor nothing — the range
    /// still needs its own SOL<->USDC reroutes to produce a `Prices` at all.
    #[test]
    fn a_stable_is_valued_at_its_own_decimals() {
        let usde_mint = mints::STABLES[4].address;
        let mut samples = anchored();
        for _ in 0..3 {
            samples.push(&sample_record(
                usde_mint,
                mints::USDC,
                1_000_000_000,
                1_000_000,
            ));
        }
        let prices = samples.prices().expect("anchored");
        assert_eq!(prices.usd(&usde_mint, 1e6), Some(1e6 / 1e9));
        assert_eq!(prices.usd(&mints::USDC, 1e6), Some(1.0));
        // Linear in the raw amount on every path, which is what lets a caller sum first.
        assert_eq!(prices.usd(&usde_mint, 1e9), Some(1.0));
        assert_eq!(prices.usd(&mints::SOL, 1e9), Some(SOL_USD));
    }

    #[test]
    fn a_price_needs_enough_samples() {
        assert_eq!(median_of(vec![1.0, 2.0]), None);
        assert_eq!(median_of(vec![1.0, 2.0, 3.0]), Some(2.0));
        assert_eq!(median_of(vec![4.0, 1.0, 2.0, 3.0]), Some(2.5));
    }

    #[test]
    fn an_unpriceable_mint_is_none_rather_than_zero() {
        let prices = anchored().prices().expect("anchored");
        assert_eq!(prices.usd_str("SomeLongtailMintNobodyQuoted", 1e6), None);
        // A mint the range simply never traded is as unpriceable as an unparseable one.
        assert_eq!(prices.usd(&RAY, 1e6), None);
    }
}