all files / plugins/assets/frax-eth/ SFraxEthCollateral.sol

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// SPDX-License-Identifier: BlueOak-1.0.0
pragma solidity 0.8.17;
 
import "@openzeppelin/contracts/utils/math/Math.sol";
import "../../../libraries/Fixed.sol";
import "../AppreciatingFiatCollateral.sol";
import "../OracleLib.sol";
import "./IsfrxEth.sol";
 
/**
 * @title SFraxEthCollateral
 * @notice Collateral plugin for Frax-ETH,
 * tok = sfrxETH
 * ref = frxETH
 * tar = ETH
 * UoA = USD
 */
contract SFraxEthCollateral is AppreciatingFiatCollateral {
    using OracleLib for AggregatorV3Interface;
    using FixLib for uint192;
 
    // solhint-disable no-empty-blocks
    /// @param config.chainlinkFeed Feed units: {UoA/target}
    constructor(CollateralConfig memory config, uint192 revenueHiding)
        AppreciatingFiatCollateral(config, revenueHiding)
    {}
 
    // solhint-enable no-empty-blocks
 
    /// Can revert, used by other contract functions in order to catch errors
    /// @return low {UoA/tok} The low price estimate
    /// @return high {UoA/tok} The high price estimate
    /// @return pegPrice {target/ref} The actual price observed in the peg
    function tryPrice()
        external
        view
        override
        returns (
            uint192 low,
            uint192 high,
            uint192 pegPrice
        )
    {
        // {UoA/tok} = {UoA/target} * {ref/tok} * {target/ref} (1)
        uint192 p = chainlinkFeed.price(oracleTimeout).mul(_underlyingRefPerTok());
        uint192 err = p.mul(oracleError, CEIL);
 
        low = p - err;
        high = p + err;
        // assert(low <= high); obviously true just by inspection
 
        pegPrice = targetPerRef();
    }
 
    /// @return {ref/tok} Quantity of whole reference units per whole collateral tokens
    function _underlyingRefPerTok() internal view override returns (uint192) {
        uint256 rate = IsfrxEth(address(erc20)).pricePerShare();
        return _safeWrap(rate);
    }
}