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use crate::{
ensure, round_up, to_balance, to_u256, MathError,
MathError::{InsufficientOutReserve, Overflow, ZeroReserve},
};
use core::convert::TryFrom;
use primitive_types::U256;
type Balance = u128;
const FIXED_ROUND_UP: Balance = 1;
pub fn calculate_spot_price(in_reserve: Balance, out_reserve: Balance, amount: Balance) -> Result<Balance, MathError> {
ensure!(in_reserve != 0, ZeroReserve);
if amount == 0 || out_reserve == 0 {
return to_balance!(0);
}
let (amount_hp, out_reserve_hp, in_reserve_hp) = to_u256!(amount, out_reserve, in_reserve);
let spot_price_hp = out_reserve_hp
.checked_mul(amount_hp)
.ok_or(Overflow)?
.checked_div(in_reserve_hp)
.ok_or(Overflow)?;
to_balance!(spot_price_hp)
}
pub fn calculate_out_given_in(
in_reserve: Balance,
out_reserve: Balance,
amount_in: Balance,
) -> Result<Balance, MathError> {
if amount_in == 0 {
return Ok(0);
};
let (in_reserve_hp, out_reserve_hp, amount_in_hp) = to_u256!(in_reserve, out_reserve, amount_in);
let denominator = in_reserve_hp.checked_add(amount_in_hp).ok_or(Overflow)?;
ensure!(!denominator.is_zero(), ZeroReserve);
let numerator = out_reserve_hp.checked_mul(amount_in_hp).ok_or(Overflow)?;
let sale_price_hp = numerator.checked_div(denominator).ok_or(Overflow)?;
to_balance!(sale_price_hp)
}
pub fn calculate_in_given_out(
out_reserve: Balance,
in_reserve: Balance,
amount_out: Balance,
) -> Result<Balance, MathError> {
if amount_out == 0 {
return Ok(0);
};
ensure!(amount_out <= out_reserve, InsufficientOutReserve);
let (out_reserve_hp, in_reserve_hp, amount_out_hp) = to_u256!(out_reserve, in_reserve, amount_out);
let numerator = in_reserve_hp.checked_mul(amount_out_hp).ok_or(Overflow)?;
let denominator = out_reserve_hp.checked_sub(amount_out_hp).ok_or(Overflow)?;
ensure!(!denominator.is_zero(), ZeroReserve);
let buy_price_hp = numerator.checked_div(denominator).ok_or(Overflow)?;
let result = to_balance!(buy_price_hp).ok();
round_up!(result.ok_or(Overflow)?)
}
pub fn calculate_liquidity_in(
asset_a_reserve: Balance,
asset_b_reserve: Balance,
amount: Balance,
) -> Result<Balance, MathError> {
ensure!(asset_a_reserve != 0, ZeroReserve);
let (a_reserve_hp, b_reserve_hp, amount_hp) = to_u256!(asset_a_reserve, asset_b_reserve, amount);
let b_required_hp = amount_hp
.checked_mul(b_reserve_hp)
.ok_or(Overflow)?
.checked_div(a_reserve_hp)
.ok_or(Overflow)?;
to_balance!(b_required_hp)
}
pub fn calculate_liquidity_out(
asset_a_reserve: Balance,
asset_b_reserve: Balance,
amount: Balance,
total_liquidity: Balance,
) -> Result<(Balance, Balance), MathError> {
ensure!(total_liquidity != 0, ZeroReserve);
let (a_reserve_hp, b_reserve_hp, amount_hp, liquidity_hp) =
to_u256!(asset_a_reserve, asset_b_reserve, amount, total_liquidity);
let remove_amount_a_hp = amount_hp
.checked_mul(a_reserve_hp)
.ok_or(Overflow)?
.checked_div(liquidity_hp)
.ok_or(Overflow)?;
let remove_amount_a = to_balance!(remove_amount_a_hp)?;
let remove_amount_b_hp = b_reserve_hp
.checked_mul(amount_hp)
.ok_or(Overflow)?
.checked_div(liquidity_hp)
.ok_or(Overflow)?;
let remove_amount_b = to_balance!(remove_amount_b_hp)?;
Ok((remove_amount_a, remove_amount_b))
}