spl_token_2022_interface/extension/scaled_ui_amount/

mod.rs

#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};
use {
    crate::{
        extension::{Extension, ExtensionType},
        trim_ui_amount_string,
    },
    bytemuck::{Pod, Zeroable},
    solana_program_error::ProgramError,
    spl_pod::{optional_keys::OptionalNonZeroPubkey, primitives::PodI64},
};

/// Scaled UI amount extension instructions
pub mod instruction;

/// `UnixTimestamp` expressed with an alignment-independent type
pub type UnixTimestamp = PodI64;

/// `f64` type that can be used in `Pod`s
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "serde", serde(from = "f64", into = "f64"))]
#[derive(Clone, Copy, Debug, Default, PartialEq, Pod, Zeroable)]
#[repr(transparent)]
pub struct PodF64(pub [u8; 8]);
impl PodF64 {
    fn from_primitive(n: f64) -> Self {
        Self(n.to_le_bytes())
    }
}
impl From<f64> for PodF64 {
    fn from(n: f64) -> Self {
        Self::from_primitive(n)
    }
}
impl From<PodF64> for f64 {
    fn from(pod: PodF64) -> Self {
        Self::from_le_bytes(pod.0)
    }
}

/// Scaled UI amount extension data for mints
#[repr(C)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "serde", serde(rename_all = "camelCase"))]
#[derive(Clone, Copy, Debug, Default, PartialEq, Pod, Zeroable)]
pub struct ScaledUiAmountConfig {
    /// Authority that can set the scaling amount and authority
    pub authority: OptionalNonZeroPubkey,
    /// Amount to multiply raw amounts by, outside of the decimal
    pub multiplier: PodF64,
    /// Unix timestamp at which `new_multiplier` comes into effective
    pub new_multiplier_effective_timestamp: UnixTimestamp,
    /// Next multiplier, once `new_multiplier_effective_timestamp` is reached
    pub new_multiplier: PodF64,
}
impl ScaledUiAmountConfig {
    fn current_multiplier(&self, unix_timestamp: i64) -> f64 {
        if unix_timestamp >= self.new_multiplier_effective_timestamp.into() {
            self.new_multiplier.into()
        } else {
            self.multiplier.into()
        }
    }

    fn total_multiplier(&self, decimals: u8, unix_timestamp: i64) -> f64 {
        self.current_multiplier(unix_timestamp) / 10_f64.powi(decimals as i32)
    }

    /// Convert a raw amount to its UI representation using the given decimals
    /// field.
    ///
    /// The value is converted to a float and then truncated towards 0. Excess
    /// zeroes or unneeded decimal point are trimmed.
    pub fn amount_to_ui_amount(
        &self,
        amount: u64,
        decimals: u8,
        unix_timestamp: i64,
    ) -> Option<String> {
        let scaled_amount = (amount as f64) * self.current_multiplier(unix_timestamp);
        let truncated_amount = scaled_amount.trunc() / 10_f64.powi(decimals as i32);
        let ui_amount = format!("{truncated_amount:.*}", decimals as usize);
        Some(trim_ui_amount_string(ui_amount, decimals))
    }

    /// Try to convert a UI representation of a token amount to its raw amount
    /// using the given decimals field.
    ///
    /// The string is parsed to a float, scaled, and then truncated towards 0
    /// before being converted to a fixed-point number.
    pub fn try_ui_amount_into_amount(
        &self,
        ui_amount: &str,
        decimals: u8,
        unix_timestamp: i64,
    ) -> Result<u64, ProgramError> {
        let scaled_amount = ui_amount
            .parse::<f64>()
            .map_err(|_| ProgramError::InvalidArgument)?;
        let amount = scaled_amount / self.total_multiplier(decimals, unix_timestamp);
        if amount > (u64::MAX as f64) || amount < (u64::MIN as f64) || amount.is_nan() {
            Err(ProgramError::InvalidArgument)
        } else {
            // this is important, if you truncate earlier, you'll get wrong "inf"
            // answers
            Ok(amount.trunc() as u64)
        }
    }
}
impl Extension for ScaledUiAmountConfig {
    const TYPE: ExtensionType = ExtensionType::ScaledUiAmount;
}

#[cfg(test)]
mod tests {
    use {super::*, proptest::prelude::*};

    const TEST_DECIMALS: u8 = 2;

    #[test]
    fn multiplier_choice() {
        let multiplier = 5.0;
        let new_multiplier = 10.0;
        let new_multiplier_effective_timestamp = 1;
        let config = ScaledUiAmountConfig {
            multiplier: PodF64::from(multiplier),
            new_multiplier: PodF64::from(new_multiplier),
            new_multiplier_effective_timestamp: UnixTimestamp::from(
                new_multiplier_effective_timestamp,
            ),
            ..Default::default()
        };
        assert_eq!(
            config.total_multiplier(0, new_multiplier_effective_timestamp),
            new_multiplier
        );
        assert_eq!(
            config.total_multiplier(0, new_multiplier_effective_timestamp - 1),
            multiplier
        );
        assert_eq!(config.total_multiplier(0, 0), multiplier);
        assert_eq!(config.total_multiplier(0, i64::MIN), multiplier);
        assert_eq!(config.total_multiplier(0, i64::MAX), new_multiplier);
    }

    #[test]
    fn specific_amount_to_ui_amount() {
        // 5x
        let config = ScaledUiAmountConfig {
            multiplier: PodF64::from(5.0),
            new_multiplier_effective_timestamp: UnixTimestamp::from(1),
            ..Default::default()
        };
        let ui_amount = config.amount_to_ui_amount(1, 0, 0).unwrap();
        assert_eq!(ui_amount, "5");
        // with 1 decimal place
        let ui_amount = config.amount_to_ui_amount(1, 1, 0).unwrap();
        assert_eq!(ui_amount, "0.5");
        // with 10 decimal places
        let ui_amount = config.amount_to_ui_amount(1, 10, 0).unwrap();
        assert_eq!(ui_amount, "0.0000000005");

        // huge amount with 10 decimal places
        let ui_amount = config.amount_to_ui_amount(10_000_000_000, 10, 0).unwrap();
        assert_eq!(ui_amount, "5");

        // huge values
        let config = ScaledUiAmountConfig {
            multiplier: PodF64::from(f64::MAX),
            new_multiplier_effective_timestamp: UnixTimestamp::from(1),
            ..Default::default()
        };
        let ui_amount = config.amount_to_ui_amount(u64::MAX, 0, 0).unwrap();
        assert_eq!(ui_amount, "inf");

        // truncation
        let config = ScaledUiAmountConfig {
            multiplier: PodF64::from(0.99),
            new_multiplier_effective_timestamp: UnixTimestamp::from(1),
            ..Default::default()
        };
        // This is really 0.99999... but it gets truncated
        let ui_amount = config.amount_to_ui_amount(101, 2, 0).unwrap();
        assert_eq!(ui_amount, "0.99");
    }

    #[test]
    fn specific_ui_amount_to_amount() {
        // constant 5x
        let config = ScaledUiAmountConfig {
            multiplier: 5.0.into(),
            new_multiplier_effective_timestamp: UnixTimestamp::from(1),
            ..Default::default()
        };
        let amount = config.try_ui_amount_into_amount("5.0", 0, 0).unwrap();
        assert_eq!(1, amount);
        // with 1 decimal place
        let amount = config
            .try_ui_amount_into_amount("0.500000000", 1, 0)
            .unwrap();
        assert_eq!(amount, 1);
        // with 10 decimal places
        let amount = config
            .try_ui_amount_into_amount("0.00000000050000000000000000", 10, 0)
            .unwrap();
        assert_eq!(amount, 1);

        // huge amount with 10 decimal places
        let amount = config
            .try_ui_amount_into_amount("5.0000000000000000", 10, 0)
            .unwrap();
        assert_eq!(amount, 10_000_000_000);

        // huge values
        let config = ScaledUiAmountConfig {
            multiplier: 5.0.into(),
            new_multiplier_effective_timestamp: UnixTimestamp::from(1),
            ..Default::default()
        };
        let amount = config
            .try_ui_amount_into_amount("92233720368547758075", 0, 0)
            .unwrap();
        assert_eq!(amount, u64::MAX);
        let config = ScaledUiAmountConfig {
            multiplier: f64::MAX.into(),
            new_multiplier_effective_timestamp: UnixTimestamp::from(1),
            ..Default::default()
        };
        // scientific notation "e"
        let amount = config
            .try_ui_amount_into_amount("1.7976931348623157e308", 0, 0)
            .unwrap();
        assert_eq!(amount, 1);
        let config = ScaledUiAmountConfig {
            multiplier: 9.745314011399998e288.into(),
            new_multiplier_effective_timestamp: UnixTimestamp::from(1),
            ..Default::default()
        };
        let amount = config
            .try_ui_amount_into_amount("1.7976931348623157e308", 0, 0)
            .unwrap();
        assert_eq!(amount, u64::MAX);
        // scientific notation "E"
        let amount = config
            .try_ui_amount_into_amount("1.7976931348623157E308", 0, 0)
            .unwrap();
        assert_eq!(amount, u64::MAX);

        // this is unfortunate, but underflows can happen due to floats
        let config = ScaledUiAmountConfig {
            multiplier: 1.0.into(),
            new_multiplier_effective_timestamp: UnixTimestamp::from(1),
            ..Default::default()
        };
        assert_eq!(
            u64::MAX,
            config
                .try_ui_amount_into_amount("18446744073709551616", 0, 0)
                .unwrap() // u64::MAX + 1
        );

        // overflow u64 fail
        let config = ScaledUiAmountConfig {
            multiplier: 0.1.into(),
            new_multiplier_effective_timestamp: UnixTimestamp::from(1),
            ..Default::default()
        };
        assert_eq!(
            Err(ProgramError::InvalidArgument),
            config.try_ui_amount_into_amount("18446744073709551615", 0, 0) // u64::MAX + 1
        );

        for fail_ui_amount in ["-0.0000000000000000000001", "inf", "-inf", "NaN"] {
            assert_eq!(
                Err(ProgramError::InvalidArgument),
                config.try_ui_amount_into_amount(fail_ui_amount, 0, 0)
            );
        }

        // truncation
        let config = ScaledUiAmountConfig {
            multiplier: PodF64::from(0.99),
            new_multiplier_effective_timestamp: UnixTimestamp::from(1),
            ..Default::default()
        };
        // There are a few possibilities for what "0.99" means, it could be 101
        // or 100 underlying tokens, but the result gives the fewest possible
        // tokens that give that UI amount.
        let amount = config.try_ui_amount_into_amount("0.99", 2, 0).unwrap();
        assert_eq!(amount, 100);
    }

    #[test]
    fn specific_amount_to_ui_amount_no_scale() {
        let config = ScaledUiAmountConfig {
            multiplier: 1.0.into(),
            new_multiplier_effective_timestamp: UnixTimestamp::from(1),
            ..Default::default()
        };
        for (amount, expected) in [(23, "0.23"), (110, "1.1"), (4200, "42"), (0, "0")] {
            let ui_amount = config
                .amount_to_ui_amount(amount, TEST_DECIMALS, 0)
                .unwrap();
            assert_eq!(ui_amount, expected);
        }
    }

    #[test]
    fn specific_ui_amount_to_amount_no_scale() {
        let config = ScaledUiAmountConfig {
            multiplier: 1.0.into(),
            new_multiplier_effective_timestamp: UnixTimestamp::from(1),
            ..Default::default()
        };
        for (ui_amount, expected) in [
            ("0.23", 23),
            ("0.20", 20),
            ("0.2000", 20),
            (".2", 20),
            ("1.1", 110),
            ("1.10", 110),
            ("42", 4200),
            ("42.", 4200),
            ("0", 0),
        ] {
            let amount = config
                .try_ui_amount_into_amount(ui_amount, TEST_DECIMALS, 0)
                .unwrap();
            assert_eq!(expected, amount);
        }

        // this is invalid with normal mints, but rounding for this mint makes it ok
        let amount = config
            .try_ui_amount_into_amount("0.111", TEST_DECIMALS, 0)
            .unwrap();
        assert_eq!(11, amount);

        // fail if invalid ui_amount passed in
        for ui_amount in ["", ".", "0.t"] {
            assert_eq!(
                Err(ProgramError::InvalidArgument),
                config.try_ui_amount_into_amount(ui_amount, TEST_DECIMALS, 0),
            );
        }
    }

    proptest! {
        #[test]
        fn amount_to_ui_amount(
            scale in 0f64..=f64::MAX,
            amount in 0..=u64::MAX,
            decimals in 0u8..20u8,
        ) {
            let config = ScaledUiAmountConfig {
                multiplier: scale.into(),
                new_multiplier_effective_timestamp: UnixTimestamp::from(1),
                ..Default::default()
            };
            let ui_amount = config.amount_to_ui_amount(amount, decimals, 0);
            assert!(ui_amount.is_some());
        }
    }
}