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feat: use Chainlink lib in Elastic Chainlink Proposal
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@ashhanai
ashhanai committed Oct 28, 2024
1 parent 3140f6d commit 7ea4de4
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259 changes: 19 additions & 240 deletions src/loan/terms/simple/proposal/PWNSimpleLoanElasticChainlinkProposal.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -3,15 +3,17 @@ pragma solidity 0.8.16;

import { MultiToken } from "MultiToken/MultiToken.sol";

import { IERC20Metadata } from "openzeppelin/interfaces/IERC20Metadata.sol";
import { Math } from "openzeppelin/utils/math/Math.sol";
import { Address } from "openzeppelin/utils/Address.sol";

import { IChainlinkAggregatorLike } from "pwn/interfaces/IChainlinkAggregatorLike.sol";
import { IChainlinkFeedRegistryLike } from "pwn/interfaces/IChainlinkFeedRegistryLike.sol";
import { ChainlinkDenominations } from "pwn/loan/lib/ChainlinkDenominations.sol";
import {
Chainlink,
ChainlinkDenominations,
IChainlinkFeedRegistryLike,
IChainlinkAggregatorLike
} from "pwn/loan/lib/Chainlink.sol";
import { PWNSimpleLoan } from "pwn/loan/terms/simple/loan/PWNSimpleLoan.sol";
import { PWNSimpleLoanProposal } from "pwn/loan/terms/simple/proposal/PWNSimpleLoanProposal.sol";
import { safeFetchDecimals } from "pwn/loan/utils/safeFetchDecimals.sol";


/**
Expand All @@ -21,6 +23,8 @@ import { PWNSimpleLoanProposal } from "pwn/loan/terms/simple/proposal/PWNSimpleL
* The amount of collateral and credit is specified during the proposal acceptance.
*/
contract PWNSimpleLoanElasticChainlinkProposal is PWNSimpleLoanProposal {
using Chainlink for IChainlinkFeedRegistryLike;
using Chainlink for IChainlinkAggregatorLike;

string public constant VERSION = "1.0";

Expand All @@ -29,16 +33,6 @@ contract PWNSimpleLoanElasticChainlinkProposal is PWNSimpleLoanProposal {
*/
uint256 public constant LOAN_TO_VALUE_DENOMINATOR = 1e4;

/**
* @notice Maximum Chainlink feed price age.
*/
uint256 public constant MAX_CHAINLINK_FEED_PRICE_AGE = 1 days;

/**
* @notice Grace period time for L2 Sequencer uptime feed.
*/
uint256 public constant L2_GRACE_PERIOD = 10 minutes;

/**
* @dev EIP-712 simple proposal struct type hash.
*/
Expand Down Expand Up @@ -136,35 +130,6 @@ contract PWNSimpleLoanElasticChainlinkProposal is PWNSimpleLoanProposal {
*/
error InsufficientCreditAmount(uint256 current, uint256 limit);

/**
* @notice Throw when Chainlink feed returns negative price.
*/
error ChainlinkFeedReturnedNegativePrice(address asset, address denominator, int256 price);

/**
* @notice Throw when Chainlink feed for asset is not found.
*/
error ChainlinkFeedNotFound(address asset);

/**
* @notice Throw when common denominator for credit and collateral assets is not found.
*/
error ChainlinkFeedCommonDenominatorNotFound(address creditAsset, address collateralAsset);

/**
* @notice Throw when Chainlink feed price is too old.
*/
error ChainlinkFeedPriceTooOld(address asset, uint256 updatedAt);

/**
* @notice Throw when L2 Sequencer uptime feed returns that the sequencer is down.
*/
error L2SequencerDown();

/**
* @notice Throw when L2 Sequencer uptime feed grace period is not over.
*/
error GracePeriodNotOver(uint256 timeSinceUp, uint256 gracePeriod);

constructor(
address _hub,
Expand Down Expand Up @@ -237,79 +202,18 @@ contract PWNSimpleLoanElasticChainlinkProposal is PWNSimpleLoanProposal {
address creditAddress, uint256 creditAmount, address collateralAddress, uint256 loanToValue
) public view returns (uint256) {
// check L2 sequencer uptime if necessary
if (address(l2SequencerUptimeFeed) != address(0)) {
(, int256 answer, uint256 startedAt,,) = l2SequencerUptimeFeed.latestRoundData();
if (answer == 1) {
// sequencer is down
revert L2SequencerDown();
}

uint256 timeSinceUp = block.timestamp - startedAt;
if (timeSinceUp <= L2_GRACE_PERIOD) {
// grace period is not over
revert GracePeriodNotOver({ timeSinceUp: timeSinceUp, gracePeriod: L2_GRACE_PERIOD });
}
}

// fetch data from price feeds
(uint256 creditPrice, uint8 creditPriceDecimals, address creditDenominator) = _findPrice(creditAddress);
(uint256 collateralPrice, uint8 collateralPriceDecimals, address collateralDenominator) = _findPrice(collateralAddress);

// convert prices to the same denominator
// Note: assume only USD, ETH, or BTC can be denominator
if (creditDenominator != collateralDenominator) {

// We can assume that most assets have price feed in USD. If not, we need to find common denominator.
// Table below shows conversions between assets.
// -------------------------
// | | USD | ETH | BTC | <-- credit
// | USD | X | ETH | BTC |
// | ETH | ETH | X | ETH |
// | BTC | BTC | ETH | X |
// -------------------------
// ^ collateral
//
// For this to work, we need to have this price feeds: ETH/USD, ETH/BTC, BTC/USD.
// This will cover most of the cases, where assets don't have price feed in USD.

bool success = true;
if (creditDenominator == ChainlinkDenominations.USD) {
(success, creditPrice, creditPriceDecimals) = _convertPriceDenominator({
nominatorPrice: creditPrice,
nominatorDecimals: creditPriceDecimals,
originalDenominator: creditDenominator,
newDenominator: collateralDenominator
});
} else {
(success, collateralPrice, collateralPriceDecimals) = _convertPriceDenominator({
nominatorPrice: collateralPrice,
nominatorDecimals: collateralPriceDecimals,
originalDenominator: collateralDenominator,
newDenominator: collateralDenominator == ChainlinkDenominations.USD
? creditDenominator
: ChainlinkDenominations.ETH
});
}

if (!success) {
revert ChainlinkFeedCommonDenominatorNotFound({
creditAsset: creditAddress,
collateralAsset: collateralAddress
});
}
}
l2SequencerUptimeFeed.checkSequencerUptime();

// scale prices to the same decimals
if (creditPriceDecimals > collateralPriceDecimals) {
collateralPrice = _scalePrice(collateralPrice, collateralPriceDecimals, creditPriceDecimals);
} else if (creditPriceDecimals < collateralPriceDecimals) {
creditPrice = _scalePrice(creditPrice, creditPriceDecimals, collateralPriceDecimals);
}

// Note: assume that if credit or collateral is not ERC20, function would fail before this point
// fetch asset prices
// Note: use ETH price feed for WETH asset due to absence of WETH price feed
(uint256 creditPrice, uint256 collateralPrice) = chainlinkFeedRegistry.fetchPricesWithCommonDenominator({
creditAsset: creditAddress == WETH ? ChainlinkDenominations.ETH : creditAddress,
collateralAsset: collateralAddress == WETH ? ChainlinkDenominations.ETH : collateralAddress
});

uint256 collateralDecimals = _safeFetchDecimals(collateralAddress);
uint256 creditDecimals = _safeFetchDecimals(creditAddress);
// fetch asset decimals
uint256 creditDecimals = safeFetchDecimals(creditAddress);
uint256 collateralDecimals = safeFetchDecimals(collateralAddress);

// calculate collateral amount
return Math.mulDiv(
Expand Down Expand Up @@ -401,129 +305,4 @@ contract PWNSimpleLoanElasticChainlinkProposal is PWNSimpleLoanProposal {
});
}


/*----------------------------------------------------------*|
|* # INTERNALS *|
|*----------------------------------------------------------*/

/**
* @notice Find price for an asset in USD, ETH, or BTC denominator.
* @param asset Address of an asset.
* @return price Price of an asset.
* @return priceDecimals Decimals of the price.
* @return denominator Address of a denominator asset.
*/
function _findPrice(address asset) internal view returns (uint256, uint8, address) {
(bool success, uint256 price, uint8 priceDecimals) = _fetchPrice(asset, ChainlinkDenominations.USD);
if (success) {
return (price, priceDecimals, ChainlinkDenominations.USD);
}

(success, price, priceDecimals) = _fetchPrice(asset, ChainlinkDenominations.ETH);
if (success) {
return (price, priceDecimals, ChainlinkDenominations.ETH);
}

(success, price, priceDecimals) = _fetchPrice(asset, ChainlinkDenominations.BTC);
if (success) {
return (price, priceDecimals, ChainlinkDenominations.BTC);
}

revert ChainlinkFeedNotFound({ asset: asset });
}

/**
* @notice Fetch price from Chainlink feed.
* @dev WETH price is fetched from the ETH price feed.
* @param asset Address of an asset.
* @param denominator Address of a denominator asset.
* @return success True if price was fetched successfully.
* @return price Price of an asset.
* @return decimals Decimals of a price.
*/
function _fetchPrice(address asset, address denominator) internal view returns (bool, uint256, uint8) {
if (asset == WETH) {
asset = ChainlinkDenominations.ETH;
}

try chainlinkFeedRegistry.getFeed(asset, denominator) returns (IChainlinkAggregatorLike aggregator) {
(, int256 price,, uint256 updatedAt,) = aggregator.latestRoundData();
if (price < 0) {
revert ChainlinkFeedReturnedNegativePrice({ asset: asset, denominator: denominator, price: price });
}
if (block.timestamp - updatedAt > MAX_CHAINLINK_FEED_PRICE_AGE) {
revert ChainlinkFeedPriceTooOld({ asset: asset, updatedAt: updatedAt });
}

uint8 decimals = aggregator.decimals();
return (true, uint256(price), decimals);
} catch {
return (false, 0, 0);
}
}

/**
* @notice Convert price denominator.
* @param nominatorPrice Price of an asset denomination in `originalDenominator`.
* @param nominatorDecimals Decimals of a price in `originalDenominator`.
* @param originalDenominator Address of an original denominator asset.
* @param newDenominator Address of a new denominator asset.
* @return success True if conversion was successful.
* @return nominatorPrice Price of an asset denomination in `newDenominator`.
* @return nominatorDecimals Decimals of a price in `newDenominator`.
*/
function _convertPriceDenominator(
uint256 nominatorPrice, uint8 nominatorDecimals, address originalDenominator, address newDenominator
) internal view returns (bool, uint256, uint8) {
(bool success, uint256 price, uint8 priceDecimals) = _fetchPrice({
asset: newDenominator, denominator: originalDenominator
});

if (!success) {
return (false, nominatorPrice, nominatorDecimals);
}

if (priceDecimals < nominatorDecimals) {
price = _scalePrice(price, priceDecimals, nominatorDecimals);
} else if (priceDecimals > nominatorDecimals) {
nominatorPrice = _scalePrice(nominatorPrice, nominatorDecimals, priceDecimals);
nominatorDecimals = priceDecimals;
}
nominatorPrice = Math.mulDiv(nominatorPrice, 10 ** nominatorDecimals, price);

return (true, nominatorPrice, nominatorDecimals);
}

/**
* @notice Scale price to new decimals.
* @param price Price to be scaled.
* @param priceDecimals Decimals of a price.
* @param newDecimals New decimals.
* @return Scaled price.
*/
function _scalePrice(
uint256 price, uint8 priceDecimals, uint8 newDecimals
) internal pure returns (uint256) {
if (priceDecimals < newDecimals) {
return price * 10 ** (newDecimals - priceDecimals);
} else if (priceDecimals > newDecimals) {
return price / 10 ** (priceDecimals - newDecimals);
}
return price;
}

/**
* @notice Fetch asset decimals.
* @dev If asset does not implement `decimals()`, function will return 0.
* @param asset Address of an asset.
* @return Decimals of an asset or 0 if asset does not implement `decimals()`.
*/
function _safeFetchDecimals(address asset) internal view returns (uint256) {
bytes memory rawDecimals = Address.functionStaticCall(asset, abi.encodeWithSignature("decimals()"));
if (rawDecimals.length == 0) {
return 0;
}
return abi.decode(rawDecimals, (uint256));
}

}
13 changes: 13 additions & 0 deletions src/loan/utils/safeFetchDecimals.sol
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Original file line number Diff line number Diff line change
@@ -0,0 +1,13 @@
// SPDX-License-Identifier: GPL-3.0-only
pragma solidity 0.8.16;

import { Address } from "openzeppelin/utils/Address.sol";


function safeFetchDecimals(address asset) view returns (uint256) {
bytes memory rawDecimals = Address.functionStaticCall(asset, abi.encodeWithSignature("decimals()"));
if (rawDecimals.length == 0) {
return 0;
}
return abi.decode(rawDecimals, (uint256));
}
38 changes: 0 additions & 38 deletions test/harness/PWNSimpleLoanElasticChainlinkProposalHarness.sol
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