harb/onchain/src/BaseLineLP.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 {ABDKMath64x64} from "@abdk/ABDKMath64x64.sol";
import "./interfaces/IWETH9.sol";
import {Harb} from "./Harb.sol";


/**
 * @title LiquidityManager - A contract that implements an automated market making strategy.
 *  It maintains 3 positions:
 *  - The floor position guarantees the capacity needed to maintain a minimum price of the HARB token It is a very tight liquidity range with enough reserve assets to buy back the circulating supply.
 *  - The anchor range provides liquidity around the current market price, ensuring liquid trading conditions for the token, regardless of the market environment.
 *  - The discovery range starts 1000 ticks above the current market price and increases from there. It consists solely of unissued tokens, which are sold as the market price increases. 
 *    The liquidity surplus obtained from selling tokens in the discovery range is directed back into the floor and anchor positions.
 */  
contract BaseLineLP {
    int24 internal constant TICK_SPACING = 200;
    int24 internal constant ANCHOR_SPACING = 5 * TICK_SPACING;
    int24 internal constant DISCOVERY_SPACING = 11000;
    int24 internal constant MAX_TICK_DEVIATION = 50; // how much is that?
    // default fee of 1%
    uint24 internal constant FEE = uint24(10_000);
    uint160 internal constant MIN_SQRT_RATIO = 4295128739;
    uint256 internal constant ANCHOR_LIQ_SHARE = 5; // 5%
    uint256 internal constant CAPITAL_INEFFICIENCY = 120; // 20%

    enum Stage { FLOOR, ANCHOR, DISCOVERY }

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

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

    // State variables to track total ETH spent
    uint256 public cumulativeVolumeWeightedPrice;
    uint256 public cumulativeVolume;
    mapping(Stage => TokenPosition) public positions;
    address public feeDestination;

    error ZeroAddressInSetter();
    error AddressAlreadySet();

    // TODO: add events

    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 = Harb(_harb);
        token0isWeth = _WETH9 < _harb;
    }

    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);
    }

    function setFeeDestination(address feeDestination_) external {
        if (address(0) == feeDestination_) revert ZeroAddressInSetter();
        if (feeDestination != address(0)) revert AddressAlreadySet();
        feeDestination = feeDestination_;
    }

    //TODO: what to do with stuck funds if slide/shift become inoperable?
    receive() external payable {

    }

    function tickAtPrice(bool t0isWeth, uint256 tokenAmount, uint256 ethAmount) internal pure returns (int24 tick_) {
        require(ethAmount > 0, "ETH amount cannot be zero");
        uint160 sqrtPriceX96;
        if (tokenAmount == 0) {
            sqrtPriceX96 = MIN_SQRT_RATIO;
        } 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 priceRatio = ABDKMath64x64.div(
                int128(int256(tokenAmount)),
                int128(int256(ethAmount))
            );
            // Convert the price ratio into a sqrt price in the format expected by Uniswap's TickMath.
            sqrtPriceX96 = uint160(
                int160(ABDKMath64x64.sqrt(priceRatio) << 32)
            );
        }
        tick_ = TickMath.getTickAtSqrtRatio(sqrtPriceX96);
        tick_ = t0isWeth ? tick_ : -tick_;
    }

    function tickToPrice(int24 tick) public pure returns (uint256 priceRatio) {
        uint160 sqrtRatio = TickMath.getSqrtRatioAtTick(tick);
        uint256 adjustedSqrtRatio = uint256(sqrtRatio) / (1 << 48);
        priceRatio = adjustedSqrtRatio * adjustedSqrtRatio;
    }

    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
        });
    }

    function _set(uint160 sqrtPriceX96, int24 currentTick) internal {

        // ### set Floor position
        int24 vwapTick;
        {
            uint256 outstandingSupply = harb.outstandingSupply();
            uint256 vwap = 0;
            uint256 requiredEthForBuyback = 0;
            if (cumulativeVolume > 0) {
                vwap = cumulativeVolumeWeightedPrice / cumulativeVolume;
                requiredEthForBuyback = outstandingSupply * 10**18 / vwap;
            }
            uint256 ethBalance = (address(this).balance + weth.balanceOf(address(this)));
            // leave at least ANCHOR_LIQ_SHARE% of supply for anchor
            ethBalance = ethBalance * (100 - ANCHOR_LIQ_SHARE) / 100;
            if (ethBalance < requiredEthForBuyback) {
                // not enough ETH, find a lower price
                requiredEthForBuyback = ethBalance;
                outstandingSupply = outstandingSupply * CAPITAL_INEFFICIENCY / 100;
                vwapTick = tickAtPrice(token0isWeth, outstandingSupply , requiredEthForBuyback);
            } else if (vwap == 0) {
                requiredEthForBuyback = ethBalance;
                vwapTick = currentTick;
            } else {
                vwap = cumulativeVolumeWeightedPrice * CAPITAL_INEFFICIENCY / 100 / cumulativeVolume; // in harb/eth
                vwapTick = tickAtPrice(token0isWeth, token0isWeth ? vwap : 10**18, token0isWeth ? 10**18 : vwap);
                vwapTick = token0isWeth ? vwapTick : -vwapTick;
                if (requiredEthForBuyback < ethBalance) {
                    // invest a majority of the ETH still in floor, even though not needed
                    requiredEthForBuyback = (requiredEthForBuyback + (5 * ethBalance)) / 6; 
                }
            }  
            // 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 = LiquidityAmounts.getLiquidityForAmounts(
                sqrtPriceX96,
                sqrtRatioAX96,
                sqrtRatioBX96,
                token0isWeth ? requiredEthForBuyback : 0,
                token0isWeth ? 0 : requiredEthForBuyback
            );

            // mint
            _mint(Stage.FLOOR, token0isWeth ? vwapTick : floorTick, token0isWeth ? floorTick : vwapTick, liquidity);
        }

        // ### set Anchor position
        uint128 anchorLiquidity;
        {
            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);
            uint256 ethBalance = (address(this).balance + weth.balanceOf(address(this))) * 98 / 100;
            anchorLiquidity = LiquidityAmounts.getLiquidityForAmounts(
                sqrtRatioX96,
                sqrtRatioAX96,
                sqrtRatioBX96,
                token0isWeth ? ethBalance : 10**30,
                token0isWeth ? 10**30: ethBalance
            );
            _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 1.5 times as much liquidity per tick as anchor
            //       A * 3   11000    A * 55
            //   D = ----- * ----- =  ------
            //         2      600       2
            uint128 liquidity = anchorLiquidity * 55 / 2;
            uint256 harbInDiscovery;
            if (token0isWeth) {
                harbInDiscovery = LiquidityAmounts.getAmount0ForLiquidity(
                    sqrtRatioAX96,
                    sqrtRatioBX96,
                    liquidity
                );
            } else {
                harbInDiscovery = LiquidityAmounts.getAmount1ForLiquidity(
                    sqrtRatioAX96,
                    sqrtRatioBX96,
                    liquidity
                );
            }
            harb.mint(harbInDiscovery);
            _mint(Stage.DISCOVERY, tickLower, tickUpper, liquidity);
            harb.burn(harb.balanceOf(address(this)));            
        }
    }

    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)) {
                    int24 tick = token0isWeth ? -1 * (position.tickLower + ANCHOR_SPACING): position.tickUpper - ANCHOR_SPACING;
                    currentPrice = tickToPrice(tick);
                }
            }
        }

        // Transfer fees to the fee destination
        // and record transaction totals
        if (fee0 > 0) {
            if (token0isWeth) {
                IERC20(address(weth)).transfer(feeDestination, fee0);
                uint256 volume = fee0 * 100;
                uint256 volumeWeightedPrice = currentPrice * volume;
                cumulativeVolumeWeightedPrice += volumeWeightedPrice;
                cumulativeVolume += volume;
            } 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);
                uint256 volume = fee1 * 100;
                uint256 volumeWeightedPrice = currentPrice * volume;
                cumulativeVolumeWeightedPrice += volumeWeightedPrice;
                cumulativeVolume += volume;
            }
        }
    }

    function _isPriceStable(int24 currentTick) internal view returns (bool) {
        uint32 timeInterval = 300; // 5 minutes in seconds
        uint32[] memory secondsAgo = new uint32[](2);
        secondsAgo[0] = timeInterval; // 5 minutes ago
        secondsAgo[1] = 0;           // current block timestamp

        //(int56[] memory tickCumulatives,) = pool.observe(secondsAgo);
        int56 tickCumulativeDiff;
        int24 averageTick;
        try pool.observe(secondsAgo) returns (int56[] memory tickCumulatives, uint160[] memory) {
            tickCumulativeDiff = tickCumulatives[1] - tickCumulatives[0];
            averageTick = int24(tickCumulativeDiff / int56(int32(timeInterval)));
            // Process the data
        } catch {
            // TODO: Handle the error, possibly by trying with a different time interval or providing a default response
            return true;
        }

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

    // call this function when price has moved up x%
    // TODO: write a bot that calls this function regularly
    function shift() external {
        require(positions[Stage.ANCHOR].liquidity > 0, "Not initialized");
        // Fetch the current tick from the Uniswap V3 pool
        (uint160 sqrtPriceX96, int24 currentTick, , , , , ) = pool.slot0();
        // check slippage with oracle
        require(_isPriceStable(currentTick), "price deviated from oracle");

        // ## check price moved up
        {
            // Check if current tick is within the specified range
            int24 anchorTickLower = positions[Stage.ANCHOR].tickLower;
            int24 anchorTickUpper = positions[Stage.ANCHOR].tickUpper;

            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
            bool isUp = token0isWeth ? currentTick < centerTick : currentTick > centerTick;
            bool isEnough = SignedMath.abs(currentTick - centerTick) > minAmplitude;

            // Check Conditions
            require(isEnough, "amplitude not reached, come back later!");
            require(isUp, "call slide(), not shift()");
        }

        // ## scrape positions
        _scrape();
        harb.setPreviousTotalSupply(harb.totalSupply());
        _set(sqrtPriceX96, currentTick);
    }


    function slide() external {
        // Fetch the current tick from the Uniswap V3 pool
        (uint160 sqrtPriceX96, int24 currentTick, , , , , ) = pool.slot0();
        // check slippage with oracle
        require(_isPriceStable(currentTick), "price deviated from oracle");

        // ## check price moved down
        if (positions[Stage.ANCHOR].liquidity > 0) {
            // Check if current tick is within the specified range
            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
            bool isDown = token0isWeth ? currentTick > centerTick : currentTick < centerTick;
            bool isEnough = SignedMath.abs(currentTick - centerTick) > minAmplitude;

            // Check Conditions
            require(isEnough, "amplitude not reached, diamond hands!");
            require(isDown, "call shift(), not slide()");
        }

        _scrape();
        _set(sqrtPriceX96, currentTick);
    }

}