harb/onchain/src/LiquidityManager.sol

// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.19;

import "@uniswap-v3-periphery/libraries/PositionKey.sol";
import "@uniswap-v3-core/libraries/FixedPoint128.sol";
import "@uniswap-v3-core/interfaces/IUniswapV3Pool.sol";
import "@aperture/uni-v3-lib/TickMath.sol";
import {LiquidityAmounts} from "@aperture/uni-v3-lib/LiquidityAmounts.sol";
import "@aperture/uni-v3-lib/PoolAddress.sol";
import "@aperture/uni-v3-lib/CallbackValidation.sol";
import "@openzeppelin/token/ERC20/IERC20.sol";
import "@openzeppelin/utils/math/SignedMath.sol";
import {Math} from "@openzeppelin/utils/math/Math.sol";
import {ABDKMath64x64} from "@abdk/ABDKMath64x64.sol";
import "./interfaces/IWETH9.sol";
import {Harberg} from "./Harberg.sol";


/**
 * @title LiquidityManager for Harberg Token on Uniswap V3
 * @notice Manages liquidity provisioning on Uniswap V3 for the Harberg token by maintaining three distinct positions:
 *         - Floor Position: Ensures a minimum price support by having enough reserve assets to potentially buy back the circulating supply of Harberg.
 *         - Anchor Position: Provides liquidity around the current market price to facilitate trading and maintain market stability.
 *         - Discovery Position: Expands liquidity by minting new Harberg tokens as the price rises, capturing potential growth in the ecosystem.
 *         The contract dynamically adjusts these positions in response to market movements to maintain strategic liquidity levels and support the Harberg token's price.
 *         It also collects and transfers fees generated from trading activities to a designated fee destination.
 * @dev Utilizes Uniswap V3's concentrated liquidity feature, enabling highly efficient use of capital. 
 */
contract LiquidityManager {
    using Math for uint256;
    // State variables to track total ETH spent
    uint256 public cumulativeVolumeWeightedPriceX96;
    uint256 public cumulativeVolume;
    // the minimum granularity of liquidity positions in the Uniswap V3 pool. this is a 1% pool.
    int24 internal constant TICK_SPACING = 200;
    // defines the width of the anchor position from the current price to discovery position.
    int24 internal constant ANCHOR_SPACING = 5 * TICK_SPACING;
    // DISCOVERY_SPACING determines the range above the current price where new tokens are minted and sold.
    // This spacing is much wider, allowing the contract to place liquidity far from the current market price,
    // aiming to capture potential price increases and support token issuance within strategic market bounds.
    int24 internal constant DISCOVERY_SPACING = 11000;
    // how much more liquidity per tick discovery is holding over anchor
    uint128 internal constant DISCOVERY_DEPTH = 450; // 500 // 500%
    int24 internal constant MAX_TICK_DEVIATION = 50; // how much is that?
    // only working with UNI V3 1% fee tier pools
    uint24 internal constant FEE = uint24(10_000);
    uint160 internal constant MIN_SQRT_RATIO = 4295128739;
    // ANCHOR_LIQ_SHARE is the mininum share of total ETH in control 
    // that will be left to put into anchor positon.
    uint256 internal constant MIN_ANCHOR_LIQ_SHARE = 5; // 5 = 5%
    uint256 internal constant MAX_ANCHOR_LIQ_SHARE = 25;
    // virtual liabilities that are added to push the calculated floor price down artificially,
    // creating a security margin for attacks on liquidity
    uint256 internal constant MIN_CAPITAL_INEFFICIENCY = 70;
    uint256 internal constant MAX_CAPITAL_INEFFICIENCY = 200;
    // used to double-check price with uni oracle
    uint32 internal constant PRICE_STABILITY_INTERVAL = 300; // 5 minutes in seconds

    // the address of the Uniswap V3 factory
    address private immutable factory;
    IWETH9 private immutable weth;
    Harberg private immutable harb;
    IUniswapV3Pool private immutable pool;
    bool private immutable token0isWeth;
    PoolKey private poolKey;

    // the 3 positions this contract is managing
    enum Stage { FLOOR, ANCHOR, DISCOVERY }

    struct TokenPosition {
        // the liquidity of the position
        uint128 liquidity;
        int24 tickLower;
        int24 tickUpper;
    }

    mapping(Stage => TokenPosition) public positions;
    // the address where liquidity fees will be sent
    address public feeDestination;
    // the minimum share of ETH that will be put into the anchor
    uint256 public anchorLiquidityShare;
    // the higher the inefficiency, the more conservative the positioning of floor
    uint256 public capitalInfefficiency;

    error ZeroAddressInSetter();
    error AddressAlreadySet();

    event EthScarcity(int24 currentTick, uint256 ethBalance, uint256 outstandingSupply, uint256 vwap, uint256 capitalInfefficiency, uint256 anchorLiquidityShare, int24 vwapTick);
    event EthAbundance(int24 currentTick, uint256 ethBalance, uint256 outstandingSupply, uint256 vwap, uint256 capitalInfefficiency, uint256 anchorLiquidityShare, int24 vwapTick);

    /// @dev Function modifier to ensure that the caller is the feeDestination
    modifier onlyFeeDestination() {
        require(msg.sender == address(feeDestination), "only callable by feeDestination");
        _;
    }

    /// @notice Creates a liquidity manager for managing Harberg token liquidity on Uniswap V3.
    /// @param _factory The address of the Uniswap V3 factory.
    /// @param _WETH9 The address of the WETH contract for handling ETH in trades.
    /// @param _harb The address of the Harberg token contract.
    /// @dev Computes the Uniswap pool address for the Harberg-WETH pair and sets up the initial configuration for the liquidity manager.
    constructor(address _factory, address _WETH9, address _harb) {
        factory = _factory;
        weth = IWETH9(_WETH9);
        poolKey = PoolAddress.getPoolKey(_WETH9, _harb, FEE);
        pool = IUniswapV3Pool(PoolAddress.computeAddress(factory, poolKey));
        harb = Harberg(_harb);
        token0isWeth = _WETH9 < _harb;
        anchorLiquidityShare = MAX_ANCHOR_LIQ_SHARE;
        capitalInfefficiency = MIN_CAPITAL_INEFFICIENCY; // starting at 95% fuzzer passes tests
    }

    /// @notice Callback function that Uniswap V3 calls for liquidity actions requiring minting or burning of tokens.
    /// @param amount0Owed The amount of token0 owed for the liquidity provision.
    /// @param amount1Owed The amount of token1 owed for the liquidity provision.
    /// @dev This function mints Harberg tokens as needed and handles WETH deposits for ETH conversions during liquidity interactions.
    function uniswapV3MintCallback(uint256 amount0Owed, uint256 amount1Owed, bytes calldata) external {
        CallbackValidation.verifyCallback(factory, poolKey);
        // take care of harb
        harb.mint(token0isWeth ? amount1Owed : amount0Owed);
        // pack ETH
        uint256 ethOwed = token0isWeth ? amount0Owed : amount1Owed;
        if (weth.balanceOf(address(this)) < ethOwed) {
            weth.deposit{value: address(this).balance}();
        }
        // do transfers
        if (amount0Owed > 0) IERC20(poolKey.token0).transfer(msg.sender, amount0Owed);
        if (amount1Owed > 0) IERC20(poolKey.token1).transfer(msg.sender, amount1Owed);
    }

    /// @notice Sets the address to which trading fees are transferred.
    /// @param feeDestination_ The address that will receive the collected trading fees.
    /// @dev Can only be called once to set the fee destination, further attempts will revert.
    function setFeeDestination(address feeDestination_) external {
        if (address(0) == feeDestination_) revert ZeroAddressInSetter();
        if (feeDestination != address(0)) revert AddressAlreadySet();
        feeDestination = feeDestination_;
    }

    function setAnchorLiquidityShare(uint256 anchorLiquidityShare_) external onlyFeeDestination {
        require(anchorLiquidityShare_ >= MIN_ANCHOR_LIQ_SHARE, "");
        require(anchorLiquidityShare_ <= MAX_ANCHOR_LIQ_SHARE, "");
        anchorLiquidityShare = anchorLiquidityShare_;
    }

    function setCapitalInfefficiency(uint256 capitalInfefficiency_) external onlyFeeDestination {
        require(capitalInfefficiency_ >= MIN_CAPITAL_INEFFICIENCY, "");
        require(capitalInfefficiency_ <= MAX_CAPITAL_INEFFICIENCY, "");
        capitalInfefficiency = capitalInfefficiency_;
    }

    function setMinStakeSupplyFraction(uint256 mssf_) external onlyFeeDestination {
        harb.setMinStakeSupplyFraction(mssf_);
    }

    receive() external payable {
    }



    /// @notice Calculates the Uniswap V3 tick corresponding to a given price ratio between Harberg and ETH.
    /// @param t0isWeth Boolean flag indicating if token0 is WETH.
    /// @param tokenAmount Amount of the Harberg token.
    /// @param ethAmount Amount of Ethereum.
    /// @return tick_ The calculated tick for the given price ratio.
    function tickAtPrice(bool t0isWeth, uint256 tokenAmount, uint256 ethAmount) internal pure returns (int24 tick_) {
        require(ethAmount > 0, "ETH amount cannot be zero");
        if (tokenAmount == 0) {
            tick_ = t0isWeth ? TickMath.MIN_TICK : TickMath.MAX_TICK;
        } else {
            // Use a fixed-point library or more precise arithmetic for the division here.
            // For example, using ABDKMath64x64 for a more precise division and square root calculation.
            int128 priceRatioX64 = ABDKMath64x64.div(
                int128(int256(tokenAmount)),
                int128(int256(ethAmount))
            );
            tick_ = tickAtPriceRatio(t0isWeth, priceRatioX64);
        }
    }

    function tickAtPriceRatio(bool t0isWeth, int128 priceRatioX64) internal pure returns (int24 tick_) {
        // Convert the price ratio into a sqrt price in the format expected by Uniswap's TickMath.
        uint160 sqrtPriceX96 = uint160(
            int160(ABDKMath64x64.sqrt(priceRatioX64) << 32)
        );
        tick_ = TickMath.getTickAtSqrtRatio(sqrtPriceX96);
        tick_ = t0isWeth ? tick_ : -tick_;
    }

    /// @notice Calculates the price ratio from a given Uniswap V3 tick as HARB/ETH.
    /// @param tick The tick for which to calculate the price ratio.
    /// @return priceRatioX96 The price ratio corresponding to the given tick.
    function priceAtTick(int24 tick) private pure returns (uint256 priceRatioX96) {
        //tick = (tick < 0) ? -tick : tick;
        uint256 sqrtRatioX96 = TickMath.getSqrtRatioAtTick(tick);
        priceRatioX96 = sqrtRatioX96.mulDiv(sqrtRatioX96, (1 << 96));
    }

    /// @notice Internal function to mint liquidity positions in the Uniswap V3 pool.
    /// @param stage The liquidity stage (floor, anchor, discovery) being adjusted.
    /// @param tickLower The lower bound of the tick range for the position.
    /// @param tickUpper The upper bound of the tick range for the position.
    /// @param liquidity The amount of liquidity to mint at the specified range.
    function _mint(Stage stage, int24 tickLower, int24 tickUpper, uint128 liquidity) internal {
        // create position
        pool.mint(
            address(this),
            tickLower,
            tickUpper,
            liquidity,
            abi.encode(poolKey)
        );

        // put into storage
        positions[stage] = TokenPosition({
            liquidity: liquidity,
            tickLower: tickLower,
            tickUpper: tickUpper
        });
    }

    /// @notice Internal function to set or adjust the floor, anchor, and discovery positions based on current market conditions and the manager's strategy.
    /// @param currentTick The current market tick.
    /// @dev Recalculates and realigns all liquidity positions according to the latest market data and strategic requirements.
    function _set(int24 currentTick) internal {

        // set Floor position
        int24 vwapTick;
        {
            uint256 outstandingSupply = harb.outstandingSupply();
            uint256 vwapX96 = 0;
            uint256 requiredEthForBuyback = 0;
            if (cumulativeVolume > 0) {
                vwapX96 = cumulativeVolumeWeightedPriceX96 / cumulativeVolume;
                requiredEthForBuyback = outstandingSupply.mulDiv(vwapX96, (1 << 96));
            }
            uint256 ethBalance = (address(this).balance + weth.balanceOf(address(this)));
            // leave at least ANCHOR_LIQ_SHARE% of supply for anchor
            uint256 floorEthBalance = ethBalance * (100 - anchorLiquidityShare) / 100;
            if (floorEthBalance < requiredEthForBuyback) {
                // not enough ETH, find a lower price
                requiredEthForBuyback = floorEthBalance;
                vwapTick = tickAtPrice(token0isWeth, outstandingSupply * capitalInfefficiency / 100 , requiredEthForBuyback);
                emit EthScarcity(currentTick, ethBalance, outstandingSupply, vwapX96, capitalInfefficiency, anchorLiquidityShare, vwapTick);                
            } else if (vwapX96 == 0) {
                requiredEthForBuyback = floorEthBalance;
                vwapTick = currentTick;
            } else {
                // recalculate vwap with capital inefficiency
                vwapX96 = cumulativeVolumeWeightedPriceX96 * capitalInfefficiency / 100 / cumulativeVolume; // in harb/eth
                vwapTick = tickAtPriceRatio(token0isWeth, int128(int256 (vwapX96 >> 32)));

                vwapTick = token0isWeth ? vwapTick : -vwapTick;
                emit EthAbundance(currentTick, ethBalance, outstandingSupply, vwapX96, capitalInfefficiency, anchorLiquidityShare, vwapTick);
            }
            // never make floor smaller than anchor
            if (requiredEthForBuyback < ethBalance * 3 / 4) {
                // use 3/4 instead of 1/2 to also account for liquidity of harb in anchor
                requiredEthForBuyback = ethBalance * 3 / 4;
            }
            // move floor below anchor, if needed
            if (token0isWeth) {
                vwapTick =  (vwapTick < currentTick + ANCHOR_SPACING) ? currentTick + ANCHOR_SPACING : vwapTick;
            } else {
                vwapTick =  (vwapTick > currentTick - ANCHOR_SPACING) ? currentTick - ANCHOR_SPACING : vwapTick;
            }

            // normalize tick position for pool          
            vwapTick = vwapTick / TICK_SPACING * TICK_SPACING;
            // calculate liquidity
            uint160 sqrtRatioAX96 = TickMath.getSqrtRatioAtTick(vwapTick);
            int24 floorTick = token0isWeth ? vwapTick + TICK_SPACING: vwapTick - TICK_SPACING;
            uint160 sqrtRatioBX96 = TickMath.getSqrtRatioAtTick(floorTick);
            uint128 liquidity;
            if (token0isWeth) {
                liquidity = LiquidityAmounts.getLiquidityForAmount0(
                    sqrtRatioAX96, sqrtRatioBX96, requiredEthForBuyback
                );
            } else {
                liquidity = LiquidityAmounts.getLiquidityForAmount1(
                    sqrtRatioAX96, sqrtRatioBX96, requiredEthForBuyback
                );
            }
            _mint(Stage.FLOOR, token0isWeth ? vwapTick : floorTick, token0isWeth ? floorTick : vwapTick, liquidity);
        }

        // set Anchor position
        uint128 anchorLiquidity;
        uint24 anchorWidth;
        {
            int24 tickLower = token0isWeth ? currentTick - ANCHOR_SPACING : vwapTick;
            int24 tickUpper = token0isWeth ? vwapTick : currentTick + ANCHOR_SPACING;
            tickLower = tickLower / TICK_SPACING * TICK_SPACING;
            tickUpper = tickUpper / TICK_SPACING * TICK_SPACING;
            uint160 sqrtRatioX96 = TickMath.getSqrtRatioAtTick(currentTick);
            uint160 sqrtRatioAX96 = TickMath.getSqrtRatioAtTick(tickLower);
            uint160 sqrtRatioBX96 = TickMath.getSqrtRatioAtTick(tickUpper);

            // adding a 2% balance margin, because liquidity calculations are inherently unprecise
            uint256 ethBalance = (address(this).balance + weth.balanceOf(address(this))) * 98 / 100;
            if (token0isWeth) {
                anchorLiquidity = LiquidityAmounts.getLiquidityForAmount0(
                    sqrtRatioX96, sqrtRatioBX96, ethBalance
                );
            } else {
                anchorLiquidity = LiquidityAmounts.getLiquidityForAmount1(
                    sqrtRatioAX96, sqrtRatioX96, ethBalance
                );
            }

            anchorWidth = uint24(tickUpper - tickLower);
            _mint(Stage.ANCHOR, tickLower, tickUpper, anchorLiquidity);
        }
        currentTick = currentTick / TICK_SPACING * TICK_SPACING;

        // set Discovery position
        {
            int24 tickLower = token0isWeth ? currentTick - DISCOVERY_SPACING - ANCHOR_SPACING : currentTick + ANCHOR_SPACING;
            int24 tickUpper = token0isWeth ? currentTick - ANCHOR_SPACING : currentTick + DISCOVERY_SPACING + ANCHOR_SPACING;
            uint160 sqrtRatioAX96 = TickMath.getSqrtRatioAtTick(tickLower);
            uint160 sqrtRatioBX96 = TickMath.getSqrtRatioAtTick(tickUpper);
            // discovery with x times as much liquidity per tick as anchor
            uint128 liquidity = anchorLiquidity * uint128(uint24(DISCOVERY_SPACING)) * DISCOVERY_DEPTH / 100 / anchorWidth;
            uint256 harbInDiscovery;
            if (token0isWeth) {
                harbInDiscovery = LiquidityAmounts.getAmount0ForLiquidity(
                    sqrtRatioAX96,
                    sqrtRatioBX96,
                    liquidity
                );
            } else {
                harbInDiscovery = LiquidityAmounts.getAmount1ForLiquidity(
                    sqrtRatioAX96,
                    sqrtRatioBX96,
                    liquidity
                );
            }
            _mint(Stage.DISCOVERY, tickLower, tickUpper, liquidity);
            harb.burn(harb.balanceOf(address(this)));            
        }
    }

    function _recordVolumeAndPrice(uint256 currentPriceX96, uint256 fee) internal {
        // assuming FEE is 1%
        uint256 volume = fee * 100;
        uint256 volumeWeightedPriceX96 = currentPriceX96 * volume;
        // Check for potential overflow. 10**70 is close to 2^256
        if (cumulativeVolumeWeightedPriceX96 > 10**70) {
            uint256 zipFactor = 10**35;
            uint256 desiredPrecision = 10**5;
            while (zipFactor * desiredPrecision > cumulativeVolume) {
                zipFactor /= desiredPrecision;
            }
            // Handle overflow: zip historic trade data
            cumulativeVolumeWeightedPriceX96 = cumulativeVolumeWeightedPriceX96 / zipFactor;
            // cumulativeVolume should be well higer than zipFactor
            cumulativeVolume = cumulativeVolume / zipFactor;
        }
        cumulativeVolumeWeightedPriceX96 += volumeWeightedPriceX96;
        cumulativeVolume += volume;
    }

    function _scrape() internal {
        uint256 fee0 = 0;
        uint256 fee1 = 0;
        uint256 currentPrice;
        for (uint256 i=uint256(Stage.FLOOR); i <= uint256(Stage.DISCOVERY); i++) {
            TokenPosition storage position = positions[Stage(i)];
            if (position.liquidity > 0) {
                (uint256 amount0, uint256 amount1) = pool.burn(position.tickLower, position.tickUpper, position.liquidity);
                // Collect the maximum possible amounts which include fees
                (uint256 collected0, uint256 collected1) = pool.collect(
                    address(this),
                    position.tickLower,
                    position.tickUpper,
                    type(uint128).max,  // Collect the max uint128 value, effectively trying to collect all
                    type(uint128).max
                );
                // Calculate the fees
                fee0 += collected0 - amount0;
                fee1 += collected1 - amount1;
                if (i == uint256(Stage.ANCHOR)) {
                    // the historic archor position is only an approximation for the price
                    int24 tick = token0isWeth ? -1 * (position.tickLower + ANCHOR_SPACING): position.tickUpper - ANCHOR_SPACING;
                    currentPrice = priceAtTick(tick);
                }
            }
        }

        // Transfer fees to the fee destination
        // and record transaction totals
        if (fee0 > 0) {
            if (token0isWeth) {
                IERC20(address(weth)).transfer(feeDestination, fee0);
                _recordVolumeAndPrice(currentPrice, fee0);
            } else {
                IERC20(address(harb)).transfer(feeDestination, fee0);
            }
        }
        if (fee1 > 0) {
            if (token0isWeth) {
                IERC20(address(harb)).transfer(feeDestination, fee1);
            } else {
                IERC20(address(weth)).transfer(feeDestination, fee1);
                _recordVolumeAndPrice(currentPrice, fee1);
            }
        }
    }

    function _isPriceStable(int24 currentTick) internal view returns (bool) {
        uint32[] memory secondsAgo = new uint32[](2);
        secondsAgo[0] = PRICE_STABILITY_INTERVAL; // 5 minutes ago
        secondsAgo[1] = 0;           // current block timestamp

        int56 tickCumulativeDiff;
        int24 averageTick;
        try pool.observe(secondsAgo) returns (int56[] memory tickCumulatives, uint160[] memory) {
            tickCumulativeDiff = tickCumulatives[1] - tickCumulatives[0];
            averageTick = int24(tickCumulativeDiff / int56(int32(PRICE_STABILITY_INTERVAL)));
        } catch {
            // try with a higher timeframe
            secondsAgo[0] = PRICE_STABILITY_INTERVAL * 200;
            (int56[] memory tickCumulatives, ) = pool.observe(secondsAgo);
            tickCumulativeDiff = tickCumulatives[1] - tickCumulatives[0];
            averageTick = int24(tickCumulativeDiff / int56(int32(PRICE_STABILITY_INTERVAL)));
        }

        return (currentTick >= averageTick - MAX_TICK_DEVIATION && currentTick <= averageTick + MAX_TICK_DEVIATION);
    }

    /// @notice Adjusts liquidity positions in response to an increase or decrease in the Harberg token's price.
    /// @dev This function should be called when significant price movement is detected. It recalibrates the liquidity ranges to align with the new market conditions.
    function recenter() external {
        // Fetch the current tick from the Uniswap V3 pool
        (, int24 currentTick, , , , , ) = pool.slot0();
        // check slippage with oracle
        require(_isPriceStable(currentTick), "price deviated from oracle");

        bool isUp = false;
        // check how price moved
        if (positions[Stage.ANCHOR].liquidity > 0) {
            // get the anchor position
            int24 anchorTickLower = positions[Stage.ANCHOR].tickLower;
            int24 anchorTickUpper = positions[Stage.ANCHOR].tickUpper;

            // center tick can be calculated positive and negative numbers the same
            int24 centerTick = token0isWeth ? anchorTickLower + ANCHOR_SPACING : anchorTickUpper - ANCHOR_SPACING;
            uint256 minAmplitude = uint256(uint24((anchorTickUpper - anchorTickLower) * 3 / 20));

            // Determine the correct comparison direction based on token0isWeth
            isUp = token0isWeth ? currentTick < centerTick : currentTick > centerTick;
            bool isEnough = SignedMath.abs(currentTick - centerTick) > minAmplitude;

            // Check Conditions
            require(isEnough, "amplitude not reached.");
        }

        // take out all old positions
        _scrape();
        if (isUp) {
            harb.setPreviousTotalSupply(harb.totalSupply());
        }
        // set new positions
        _set(currentTick);
    }

}