MOST

// File: contracts/interfaces/IMostERC20.sol

pragma solidity >=0.6.2;

interface IMostERC20 {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);
    event LogRebase(uint indexed epoch, uint totalSupply);

    function name() external pure returns (string memory);
    function symbol() external pure returns (string memory);
    function decimals() external pure returns (uint8);
    function totalSupply() external view returns (uint);
    function epoch() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);

    function PERIOD() external pure returns (uint);

    function pair() external view returns (address);
    function rebaseSetter() external view returns (address);
    function creator() external view returns (address);
    function token0() external view returns (address);
    function token1() external view returns (address);
    function price0CumulativeLast() external view returns (uint);
    function price1CumulativeLast() external view returns (uint);
    function blockTimestampLast() external view returns (uint32);
    function initialize(address, address) external;
    function rebase() external returns (uint);
    function setRebaseSetter(address) external;
    function setCreator(address) external;
    function consult(address token, uint amountIn) external view returns (uint amountOut);
}

// File: contracts/interfaces/IERC20.sol

pragma solidity >=0.5.0;

interface IERC20 {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external view returns (string memory);
    function symbol() external view returns (string memory);
    function decimals() external view returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);
}

// File: @uniswap/v2-core/contracts/interfaces/IUniswapV2Pair.sol

pragma solidity >=0.5.0;

interface IUniswapV2Pair {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external pure returns (string memory);
    function symbol() external pure returns (string memory);
    function decimals() external pure returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);
    function PERMIT_TYPEHASH() external pure returns (bytes32);
    function nonces(address owner) external view returns (uint);

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;

    event Mint(address indexed sender, uint amount0, uint amount1);
    event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
    event Swap(
        address indexed sender,
        uint amount0In,
        uint amount1In,
        uint amount0Out,
        uint amount1Out,
        address indexed to
    );
    event Sync(uint112 reserve0, uint112 reserve1);

    function MINIMUM_LIQUIDITY() external pure returns (uint);
    function factory() external view returns (address);
    function token0() external view returns (address);
    function token1() external view returns (address);
    function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
    function price0CumulativeLast() external view returns (uint);
    function price1CumulativeLast() external view returns (uint);
    function kLast() external view returns (uint);

    function mint(address to) external returns (uint liquidity);
    function burn(address to) external returns (uint amount0, uint amount1);
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
    function skim(address to) external;
    function sync() external;

    function initialize(address, address) external;
}

// File: @uniswap/lib/contracts/libraries/FixedPoint.sol

pragma solidity >=0.4.0;

// a library for handling binary fixed point numbers (https://en.wikipedia.org/wiki/Q_(number_format))
library FixedPoint {
    // range: [0, 2**112 - 1]
    // resolution: 1 / 2**112
    struct uq112x112 {
        uint224 _x;
    }

    // range: [0, 2**144 - 1]
    // resolution: 1 / 2**112
    struct uq144x112 {
        uint _x;
    }

    uint8 private constant RESOLUTION = 112;

    // encode a uint112 as a UQ112x112
    function encode(uint112 x) internal pure returns (uq112x112 memory) {
        return uq112x112(uint224(x) << RESOLUTION);
    }

    // encodes a uint144 as a UQ144x112
    function encode144(uint144 x) internal pure returns (uq144x112 memory) {
        return uq144x112(uint256(x) << RESOLUTION);
    }

    // divide a UQ112x112 by a uint112, returning a UQ112x112
    function div(uq112x112 memory self, uint112 x) internal pure returns (uq112x112 memory) {
        require(x != 0, 'FixedPoint: DIV_BY_ZERO');
        return uq112x112(self._x / uint224(x));
    }

    // multiply a UQ112x112 by a uint, returning a UQ144x112
    // reverts on overflow
    function mul(uq112x112 memory self, uint y) internal pure returns (uq144x112 memory) {
        uint z;
        require(y == 0 || (z = uint(self._x) * y) / y == uint(self._x), "FixedPoint: MULTIPLICATION_OVERFLOW");
        return uq144x112(z);
    }

    // returns a UQ112x112 which represents the ratio of the numerator to the denominator
    // equivalent to encode(numerator).div(denominator)
    function fraction(uint112 numerator, uint112 denominator) internal pure returns (uq112x112 memory) {
        require(denominator > 0, "FixedPoint: DIV_BY_ZERO");
        return uq112x112((uint224(numerator) << RESOLUTION) / denominator);
    }

    // decode a UQ112x112 into a uint112 by truncating after the radix point
    function decode(uq112x112 memory self) internal pure returns (uint112) {
        return uint112(self._x >> RESOLUTION);
    }

    // decode a UQ144x112 into a uint144 by truncating after the radix point
    function decode144(uq144x112 memory self) internal pure returns (uint144) {
        return uint144(self._x >> RESOLUTION);
    }
}

// File: contracts/libraries/UniswapV2OracleLibrary.sol

pragma solidity >=0.5.0;



// library with helper methods for oracles that are concerned with computing average prices
library UniswapV2OracleLibrary {
    using FixedPoint for *;

    // helper function that returns the current block timestamp within the range of uint32, i.e. [0, 2**32 - 1]
    function currentBlockTimestamp() internal view returns (uint32) {
        return uint32(block.timestamp % 2 ** 32);
    }

    // produces the cumulative price using counterfactuals to save gas and avoid a call to sync.
    function currentCumulativePrices(
        address pair
    ) internal view returns (uint price0Cumulative, uint price1Cumulative, uint32 blockTimestamp) {
        blockTimestamp = currentBlockTimestamp();
        price0Cumulative = IUniswapV2Pair(pair).price0CumulativeLast();
        price1Cumulative = IUniswapV2Pair(pair).price1CumulativeLast();

        // if time has elapsed since the last update on the pair, mock the accumulated price values
        (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast) = IUniswapV2Pair(pair).getReserves();
        if (blockTimestampLast != blockTimestamp) {
            // subtraction overflow is desired
            uint32 timeElapsed = blockTimestamp - blockTimestampLast;
            // addition overflow is desired
            // counterfactual
            price0Cumulative += uint(FixedPoint.fraction(reserve1, reserve0)._x) * timeElapsed;
            // counterfactual
            price1Cumulative += uint(FixedPoint.fraction(reserve0, reserve1)._x) * timeElapsed;
        }
    }
}

// File: contracts/libraries/SafeMath.sol

pragma solidity =0.6.6;

// a library for performing overflow-safe math, courtesy of DappHub (https://github.com/dapphub/ds-math)

library SafeMath {
    function add(uint x, uint y) internal pure returns (uint z) {
        require((z = x + y) >= x, 'ds-math-add-overflow');
    }

    function sub(uint x, uint y) internal pure returns (uint z) {
        require((z = x - y) <= x, 'ds-math-sub-underflow');
    }

    function mul(uint x, uint y) internal pure returns (uint z) {
        require(y == 0 || (z = x * y) / y == x, 'ds-math-mul-overflow');
    }

    function abs(int a) internal pure returns (int) {
        require(a != int256(1) << 255, 'ds-math-mul-overflow');
        return a < 0 ? -a : a;
    }
}

// File: contracts/libraries/UniswapV2Library.sol

pragma solidity >=0.5.0;



library UniswapV2Library {
    using SafeMath for uint;

    // returns sorted token addresses, used to handle return values from pairs sorted in this order
    function sortTokens(address tokenA, address tokenB) internal pure returns (address token0, address token1) {
        require(tokenA != tokenB, 'UniswapV2Library: IDENTICAL_ADDRESSES');
        (token0, token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
        require(token0 != address(0), 'UniswapV2Library: ZERO_ADDRESS');
    }

    // calculates the CREATE2 address for a pair without making any external calls
    function pairFor(address factory, address tokenA, address tokenB) internal pure returns (address pair) {
        (address token0, address token1) = sortTokens(tokenA, tokenB);
        pair = address(uint(keccak256(abi.encodePacked(
                hex'ff',
                factory,
                keccak256(abi.encodePacked(token0, token1)),
                hex'96e8ac4277198ff8b6f785478aa9a39f403cb768dd02cbee326c3e7da348845f' // init code hash
            ))));
    }

    // fetches and sorts the reserves for a pair
    function getReserves(address factory, address tokenA, address tokenB) internal view returns (uint reserveA, uint reserveB) {
        (address token0,) = sortTokens(tokenA, tokenB);
        (uint reserve0, uint reserve1,) = IUniswapV2Pair(pairFor(factory, tokenA, tokenB)).getReserves();
        (reserveA, reserveB) = tokenA == token0 ? (reserve0, reserve1) : (reserve1, reserve0);
    }

    // given some amount of an asset and pair reserves, returns an equivalent amount of the other asset
    function quote(uint amountA, uint reserveA, uint reserveB) internal pure returns (uint amountB) {
        require(amountA > 0, 'UniswapV2Library: INSUFFICIENT_AMOUNT');
        require(reserveA > 0 && reserveB > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
        amountB = amountA.mul(reserveB) / reserveA;
    }

    // given an input amount of an asset and pair reserves, returns the maximum output amount of the other asset
    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) internal pure returns (uint amountOut) {
        require(amountIn > 0, 'UniswapV2Library: INSUFFICIENT_INPUT_AMOUNT');
        require(reserveIn > 0 && reserveOut > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
        uint amountInWithFee = amountIn.mul(997);
        uint numerator = amountInWithFee.mul(reserveOut);
        uint denominator = reserveIn.mul(1000).add(amountInWithFee);
        amountOut = numerator / denominator;
    }

    // given an output amount of an asset and pair reserves, returns a required input amount of the other asset
    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) internal pure returns (uint amountIn) {
        require(amountOut > 0, 'UniswapV2Library: INSUFFICIENT_OUTPUT_AMOUNT');
        require(reserveIn > 0 && reserveOut > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
        uint numerator = reserveIn.mul(amountOut).mul(1000);
        uint denominator = reserveOut.sub(amountOut).mul(997);
        amountIn = (numerator / denominator).add(1);
    }

    // performs chained getAmountOut calculations on any number of pairs
    function getAmountsOut(address factory, uint amountIn, address[] memory path) internal view returns (uint[] memory amounts) {
        require(path.length >= 2, 'UniswapV2Library: INVALID_PATH');
        amounts = new uint[](path.length);
        amounts[0] = amountIn;
        for (uint i; i < path.length - 1; i++) {
            (uint reserveIn, uint reserveOut) = getReserves(factory, path[i], path[i + 1]);
            amounts[i + 1] = getAmountOut(amounts[i], reserveIn, reserveOut);
        }
    }

    // performs chained getAmountIn calculations on any number of pairs
    function getAmountsIn(address factory, uint amountOut, address[] memory path) internal view returns (uint[] memory amounts) {
        require(path.length >= 2, 'UniswapV2Library: INVALID_PATH');
        amounts = new uint[](path.length);
        amounts[amounts.length - 1] = amountOut;
        for (uint i = path.length - 1; i > 0; i--) {
            (uint reserveIn, uint reserveOut) = getReserves(factory, path[i - 1], path[i]);
            amounts[i - 1] = getAmountIn(amounts[i], reserveIn, reserveOut);
        }
    }
}

// File: contracts/MostERC20.sol

pragma solidity =0.6.6;







contract MostERC20 is IMostERC20 {
    using FixedPoint for *;
    using SafeMath for uint;
    using SafeMath for int;

    string public constant override name = 'MOST';
    string public constant override symbol = 'MOST';
    uint8 public constant override decimals = 9;
    uint public override totalSupply;
    uint public override epoch;
    mapping(address => uint) private gonBalanceOf;
    mapping(address => mapping(address => uint)) public override allowance;

    uint public constant override PERIOD = 24 hours;

    uint private constant MAX_UINT256 = ~uint256(0);
    uint private constant INITIAL_FRAGMENTS_SUPPLY = 1 * 10**6 * 10**uint(decimals);
    uint8 private constant RATE_BASE = 100;
    uint8 private constant UPPER_BOUND = 106;
    uint8 private constant LOWER_BOUND = 96;

    // TOTAL_GONS is a multiple of INITIAL_FRAGMENTS_SUPPLY so that gonsPerFragment is an integer.
    // Use the highest value that fits in a uint256 for max granularity.
    uint private constant TOTAL_GONS = MAX_UINT256 - (MAX_UINT256 % INITIAL_FRAGMENTS_SUPPLY);

    // MAX_SUPPLY = maximum integer < (sqrt(4*TOTAL_GONS + 1) - 1) / 2
    uint private constant MAX_SUPPLY = ~uint128(0);  // (2^128) - 1

    uint private gonsPerFragment;

    address public override pair;
    address public override rebaseSetter;
    address public override creator;
    address public override token0;
    address public override token1;

    uint public override price0CumulativeLast;
    uint public override price1CumulativeLast;
    uint32 public override blockTimestampLast;
    FixedPoint.uq112x112 private price0Average;
    FixedPoint.uq112x112 private price1Average;

    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);
    event LogRebase(uint indexed epoch, uint totalSupply);

    constructor() public {
        creator = msg.sender;

        totalSupply = INITIAL_FRAGMENTS_SUPPLY;
        gonBalanceOf[msg.sender] = TOTAL_GONS;
        gonsPerFragment = TOTAL_GONS / totalSupply;

        emit Transfer(address(0), msg.sender, totalSupply);
    }

    function initialize(address factory, address tokenB) external override {
        require(msg.sender == creator, 'MOST: FORBIDDEN'); // sufficient check

        IUniswapV2Pair _pair = IUniswapV2Pair(UniswapV2Library.pairFor(factory, address(this), tokenB));
        pair = address(_pair);
        token0 = _pair.token0();
        token1 = _pair.token1();
        price0CumulativeLast = _pair.price0CumulativeLast(); // fetch the current accumulated price value (1 / 0)
        price1CumulativeLast = _pair.price1CumulativeLast(); // fetch the current accumulated price value (0 / 1)
        uint112 reserve0;
        uint112 reserve1;
        (reserve0, reserve1, blockTimestampLast) = _pair.getReserves();
        require(reserve0 != 0 && reserve1 != 0, 'MOST: NO_RESERVES'); // ensure that there's liquidity in the pair
    }

    function _approve(address owner, address spender, uint value) private {
        allowance[owner][spender] = value;
        emit Approval(owner, spender, value);
    }

    function _transfer(address from, address to, uint value) private {
        uint gonValue = value.mul(gonsPerFragment);
        gonBalanceOf[from] = gonBalanceOf[from].sub(gonValue);
        gonBalanceOf[to] = gonBalanceOf[to].add(gonValue);
        emit Transfer(from, to, value);
    }

    function balanceOf(address owner) external view override returns (uint) {
        return gonBalanceOf[owner] / gonsPerFragment;
    }

    function approve(address spender, uint value) external override returns (bool) {
        _approve(msg.sender, spender, value);
        return true;
    }

    function transfer(address to, uint value) external override returns (bool) {
        _transfer(msg.sender, to, value);
        return true;
    }

    function transferFrom(address from, address to, uint value) external override returns (bool) {
        if (allowance[from][msg.sender] != uint(-1)) {
            allowance[from][msg.sender] = allowance[from][msg.sender].sub(value);
        }
        _transfer(from, to, value);
        return true;
    }

    function rebase() external override returns (uint) {
        require(msg.sender == rebaseSetter, 'MOST: FORBIDDEN'); // sufficient check

        (uint price0Cumulative, uint price1Cumulative, uint32 blockTimestamp) =
            UniswapV2OracleLibrary.currentCumulativePrices(pair);
        uint32 timeElapsed = blockTimestamp - blockTimestampLast; // overflow is desired

        // ensure that at least one full period has passed since the last update
        require(timeElapsed >= PERIOD, 'MOST: PERIOD_NOT_ELAPSED');

        epoch = epoch.add(1);

        // overflow is desired, casting never truncates
        // cumulative price is in (uq112x112 price * seconds) units so we simply wrap it after division by time elapsed
        price0Average = FixedPoint.uq112x112(uint224((price0Cumulative - price0CumulativeLast) / timeElapsed));
        price1Average = FixedPoint.uq112x112(uint224((price1Cumulative - price1CumulativeLast) / timeElapsed));

        price0CumulativeLast = price0Cumulative;
        price1CumulativeLast = price1Cumulative;
        blockTimestampLast = blockTimestamp;

        uint priceAverage = consult(address(this), 10**uint(decimals));

        uint tokenBRemaining;
        if (address(this) == token0) {
            tokenBRemaining = 10 ** uint(IERC20(token1).decimals() - 2);
        } else {
            tokenBRemaining = 10 ** uint(IERC20(token0).decimals() - 2);
        }
        uint unitBase = RATE_BASE * tokenBRemaining;
        int256 supplyDelta;
        if (priceAverage > UPPER_BOUND * tokenBRemaining) {
            supplyDelta = 0 - int(totalSupply.mul(priceAverage.sub(unitBase)) / priceAverage);
        } else if (priceAverage < LOWER_BOUND * tokenBRemaining) {
            supplyDelta = int(totalSupply.mul(unitBase.sub(priceAverage)) / unitBase);
        } else {
            supplyDelta = 0;
        }

        supplyDelta = supplyDelta / 10;

        if (supplyDelta == 0) {
            emit LogRebase(epoch, totalSupply);
            return totalSupply;
        }

        if (supplyDelta < 0) {
            totalSupply = totalSupply.sub(uint256(supplyDelta.abs()));
        } else {
            totalSupply = totalSupply.add(uint256(supplyDelta));
        }

        if (totalSupply > MAX_SUPPLY) {
            totalSupply = MAX_SUPPLY;
        }

        gonsPerFragment = TOTAL_GONS / totalSupply;

        // From this point forward, gonsPerFragment is taken as the source of truth.
        // We recalculate a new totalSupply to be in agreement with the gonsPerFragment
        // conversion rate.
        // This means our applied supplyDelta can deviate from the requested supplyDelta,
        // but this deviation is guaranteed to be < (totalSupply^2)/(TOTAL_GONS - totalSupply).
        //
        // In the case of totalSupply <= MAX_UINT128 (our current supply cap), this
        // deviation is guaranteed to be < 1, so we can omit this step. If the supply cap is
        // ever increased, it must be re-included.
        // totalSupply = TOTAL_GONS / gonsPerFragment

        emit LogRebase(epoch, totalSupply);
        return totalSupply;
    }

    function setRebaseSetter(address _rebaseSetter) external override {
        require(msg.sender == creator, 'MOST: FORBIDDEN');
        rebaseSetter = _rebaseSetter;
    }

    function setCreator(address _creator) external override {
        require(msg.sender == creator, 'MOST: FORBIDDEN');
        creator = _creator;
    }

    // note this will always return 0 before update has been called successfully for the first time.
    function consult(address token, uint amountIn) public view override returns (uint amountOut) {
        if (token == token0) {
            amountOut = price0Average.mul(amountIn).decode144();
        } else {
            require(token == token1, 'MOST: INVALID_TOKEN');
            amountOut = price1Average.mul(amountIn).decode144();
        }
    }
}

{
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    "MostERC20.sol": "MostERC20"
  },
  "evmVersion": "istanbul",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": true,
    "runs": 999999
  },
  "remappings": []
}