pylon-utils 0.2.0

Common helpers for pylon contracts
Documentation 
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use cosmwasm_bignumber::{Decimal256, Uint256};
use cosmwasm_std::*;
use terra_cosmwasm::TerraQuerier;

pub fn compute_tax(deps: Deps, coin: &Coin) -> StdResult<Uint256> {
    let terra_querier = TerraQuerier::new(&deps.querier);
    let tax_rate = Decimal256::from((terra_querier.query_tax_rate()?).rate);
    let tax_cap = Uint256::from((terra_querier.query_tax_cap(coin.denom.to_string())?).cap);
    let amount = Uint256::from(coin.amount);
    Ok(std::cmp::min(
        amount * Decimal256::one() - amount / (Decimal256::one() + tax_rate),
        tax_cap,
    ))
}

pub fn deduct_tax(deps: Deps, coin: Coin) -> StdResult<Coin> {
    let tax_amount = compute_tax(deps, &coin)?;
    Ok(Coin {
        denom: coin.denom,
        amount: (Uint256::from(coin.amount) - tax_amount).into(),
    })
}