96 lines
3.2 KiB
Solidity
96 lines
3.2 KiB
Solidity
pragma solidity 0.5.12;
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import "../interfaces/IUniswapV2.sol";
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import "../libraries/Math.sol";
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contract Oracle {
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using Math for uint256;
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struct TokenData {
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uint128 token0;
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uint128 token1;
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}
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struct TimeData {
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uint64 blockNumber;
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uint64 blockTimestamp;
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}
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address public exchange;
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bool public initialized;
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uint64 constant period = 1 days;
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TokenData private reservesCumulative;
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TimeData private lastUpdate;
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TokenData private currentPrice;
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constructor(address _exchange) public {
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exchange = _exchange;
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}
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function _updateCurrentPrice(TokenData memory averages, uint64 timeElapsed) private {
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TokenData memory nextPrice;
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if (timeElapsed >= period || (currentPrice.token0 == 0 && currentPrice.token1 == 0)) {
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nextPrice = averages;
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} else {
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nextPrice = TokenData({
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token0: (currentPrice.token0 * (period - timeElapsed) + averages.token0 * timeElapsed) / period,
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token1: (currentPrice.token1 * (period - timeElapsed) + averages.token1 * timeElapsed) / period
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});
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}
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currentPrice = nextPrice;
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}
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function initialize() external {
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require(!initialized, "Oracle: ALREADY_INITIALIZED");
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IUniswapV2 uniswapV2 = IUniswapV2(exchange);
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(uint128 reserveCumulativeToken0, uint128 reserveCumulativeToken1) = uniswapV2.getReservesCumulative();
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reservesCumulative.token0 = reserveCumulativeToken0;
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reservesCumulative.token1 = reserveCumulativeToken1;
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lastUpdate.blockNumber = block.number.downcastTo64();
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lastUpdate.blockTimestamp = block.timestamp.downcastTo64();
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initialized = true;
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}
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function updateCurrentPrice() external {
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require(initialized, "Oracle: UNINITIALIZED");
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uint64 blockNumber = block.number.downcastTo64();
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// if we haven't updated this block yet...
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if (blockNumber > lastUpdate.blockNumber) {
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IUniswapV2 uniswapV2 = IUniswapV2(exchange);
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(uint128 reserveCumulativeToken0, uint128 reserveCumulativeToken1) = uniswapV2.getReservesCumulative();
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uint128 blocksElapsed = blockNumber - lastUpdate.blockNumber;
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TokenData memory deltas = TokenData({
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token0: reserveCumulativeToken0 - reservesCumulative.token0,
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token1: reserveCumulativeToken1 - reservesCumulative.token1
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});
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TokenData memory averages = TokenData({
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token0: deltas.token0 / blocksElapsed,
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token1: deltas.token1 / blocksElapsed
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});
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uint64 blockTimestamp = block.timestamp.downcastTo64();
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uint64 timeElapsed = blockTimestamp - lastUpdate.blockTimestamp;
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_updateCurrentPrice(averages, timeElapsed);
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reservesCumulative.token0 = reserveCumulativeToken0;
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reservesCumulative.token1 = reserveCumulativeToken1;
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lastUpdate.blockNumber = blockNumber;
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lastUpdate.blockTimestamp = blockTimestamp;
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}
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}
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function getCurrentPrice() external view returns (uint128, uint128) {
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return (currentPrice.token0, currentPrice.token1);
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}
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}
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