feat(4626 wrapper): implements a 4626 wrapping of debt tokens

src/vault/Wildcat4626Wrapper.sol

@@ -0,0 +1,297 @@
+// SPDX-License-Identifier: TODO
+pragma solidity >=0.8.20;
+
+import {IERC20Metadata} from "openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol";
+import {IERC4626} from "openzeppelin/contracts/interfaces/IERC4626.sol";
+import {ERC20} from "openzeppelin/contracts/token/ERC20/ERC20.sol";
+
+import {ReentrancyGuard} from "../ReentrancyGuard.sol";
+import {MathUtils, RAY} from "../libraries/MathUtils.sol";
+import {LibERC20} from "../libraries/LibERC20.sol";
+
+interface IWildcatMarketToken is IERC20Metadata {
+    function scaleFactor() external view returns (uint256);
+
+    function scaledBalanceOf(address account) external view returns (uint256);
+}
+
+/**
+ * @title Wildcat4626Wrapper
+ * @notice Wraps a debt token with an erc-4626 non-rebasing share token.
+ *  Shares mirror the market's scaled balance. 
+ */
+contract Wildcat4626Wrapper is ERC20, ReentrancyGuard, IERC4626 {
+    using MathUtils for uint256;
+    using LibERC20 for address;
+
+    error ZeroAddress();
+    error ZeroAssets();
+    error ZeroShares();
+    error CapExceeded();
+    error SharesMismatch(uint256 expected, uint256 actual);
+
+    IWildcatMarketToken public immutable wrappedMarket;
+    uint256 public immutable wrapperCap;
+
+    uint8 private immutable _decimals;
+
+    /**
+     * @param marketAddress the wildcat market (debt token) address to wrap
+     */
+    constructor(address marketAddress)
+        ERC20(_vaultName(marketAddress), _vaultSymbol(marketAddress))
+    {
+        if (marketAddress == address(0)) revert ZeroAddress();
+
+        wrappedMarket = IWildcatMarketToken(marketAddress);
+        wrapperCap = type(uint256).max;
+        _decimals = wrappedMarket.decimals();
+    }
+
+    function decimals() public view override(ERC20, IERC20Metadata) returns (uint8) {
+        return _decimals;
+    }
+
+    function _vaultName(address marketAddress) private view returns (string memory) {
+        if (marketAddress == address(0)) revert ZeroAddress();
+        string memory marketSymbol = IERC20Metadata(marketAddress).symbol();
+        return string.concat(marketSymbol, "X [4626 Vault Shares]");
+    }
+
+    function _vaultSymbol(address marketAddress) private view returns (string memory) {
+        if (marketAddress == address(0)) revert ZeroAddress();
+        string memory marketSymbol = IERC20Metadata(marketAddress).symbol();
+        return string.concat("v-", marketSymbol);
+    }
+
+    // -------------------------------------------------------------------------
+    // erc4626 view interface
+    // -------------------------------------------------------------------------
+
+    /// @notice Address of the wrapped Wildcat market token.
+    function market() public view returns (address) {
+        return address(wrappedMarket);
+    }
+
+    /// @notice Alias for the wrapped market so integrators can treat it as the ERC-4626 asset.
+    function asset() public view override(IERC4626) returns (address) {
+        return address(wrappedMarket);
+    }
+
+    /// @notice Total normalized market tokens the wrapper currently custodies.
+    function totalAssets() public view override returns (uint256) {
+        return wrappedMarket.balanceOf(address(this));
+    }
+
+    /// @notice Preview how many shares a deposit of `assets` would mint, rounded down.
+    function convertToShares(uint256 assets) public view override returns (uint256) {
+        if (assets == 0) return 0;
+        uint256 scaleFactor = wrappedMarket.scaleFactor();
+        return _convertToSharesDown(assets, scaleFactor);
+    }
+
+    /// @notice Preview how many assets burning `shares` yields, rounded down.
+    function convertToAssets(uint256 shares) public view override returns (uint256) {
+        if (shares == 0) return 0;
+        uint256 scaleFactor = wrappedMarket.scaleFactor();
+        return _convertToAssetsDown(shares, scaleFactor);
+    }
+
+    /// @notice Remaining normalized assets the wrapper can accept before hitting `wrapperCap`.
+    function maxDeposit(address) public view override returns (uint256) {
+        uint256 cap = wrapperCap;
+        if (cap == type(uint256).max) return cap;
+        uint256 held = totalAssets();
+        if (held >= cap) return 0;
+        return cap - held;
+    }
+
+    /// @notice Shares minted for depositing `assets`, rounded down.
+    function previewDeposit(uint256 assets) public view override returns (uint256) {
+        return convertToShares(assets);
+    }
+
+    /// @notice Remaining shares that could be minted without violating `wrapperCap`.
+    function maxMint(address) public view override returns (uint256) {
+        uint256 capAssets = maxDeposit(address(0));
+        if (capAssets == type(uint256).max) return capAssets;
+        uint256 scaleFactor = wrappedMarket.scaleFactor();
+        return _convertToSharesDown(capAssets, scaleFactor);
+    }
+
+    /// @notice Assets required to mint `shares`, rounded up so callers see worst-case cost.
+    function previewMint(uint256 shares) public view override returns (uint256) {
+        if (shares == 0) return 0;
+        uint256 scaleFactor = wrappedMarket.scaleFactor();
+        return _convertToAssetsUp(shares, scaleFactor);
+    }
+
+    /// @notice Maximum assets `owner_` can pull via `withdraw`, rounded down.
+    function maxWithdraw(address owner_) public view override returns (uint256) {
+        uint256 shares = balanceOf(owner_);
+        if (shares == 0) return 0;
+        uint256 scaleFactor = wrappedMarket.scaleFactor();
+        return _convertToAssetsDown(shares, scaleFactor);
+    }
+
+    /// @notice Shares that would be burned to withdraw `assets`, rounded up.
+    function previewWithdraw(uint256 assets) public view override returns (uint256) {
+        if (assets == 0) return 0;
+        uint256 scaleFactor = wrappedMarket.scaleFactor();
+        return _convertToSharesUp(assets, scaleFactor);
+    }
+
+    /// @notice All shares `owner_` currently holds.
+    function maxRedeem(address owner_) public view override returns (uint256) {
+        return balanceOf(owner_);
+    }
+
+    /// @notice Assets returned when redeeming `shares`, rounded down.
+    function previewRedeem(uint256 shares) public view override returns (uint256) {
+        return convertToAssets(shares);
+    }
+
+    // -------------------------------------------------------------------------
+    // Mutating interface
+    // -------------------------------------------------------------------------
+
+    /// @notice Pull `assets` from the caller and mint the resulting shares to `receiver`.
+    function deposit(uint256 assets, address receiver) external nonReentrant override returns (uint256 shares) {
+        if (assets == 0) revert ZeroAssets();
+
+        uint256 limit = maxDeposit(receiver);
+        if (assets > limit) revert CapExceeded();
+
+        uint256 scaleFactor = wrappedMarket.scaleFactor();
+        uint256 expectedShares = _scaledSharesForAssets(assets, scaleFactor);
+        if (expectedShares == 0) revert ZeroShares();
+
+        address assetAddress = address(wrappedMarket);
+        uint256 scaledBefore = wrappedMarket.scaledBalanceOf(address(this));
+        assetAddress.safeTransferFrom(msg.sender, address(this), assets);
+        uint256 scaledAfter = wrappedMarket.scaledBalanceOf(address(this));
+
+        shares = scaledAfter - scaledBefore;
+        if (shares != expectedShares) revert SharesMismatch(expectedShares, shares);
+
+        _mint(receiver, shares);
+        emit Deposit(msg.sender, receiver, assets, shares);
+    }
+
+    /// @notice Mint exactly `shares` to `receiver`, charging the caller the required assets (rounded up).
+    function mint(uint256 shares, address receiver) external nonReentrant override returns (uint256 assets) {
+        if (shares == 0) revert ZeroShares();
+
+        uint256 limit = maxMint(receiver);
+        if (shares > limit) revert CapExceeded();
+
+        uint256 scaleFactor = wrappedMarket.scaleFactor();
+        assets = _convertToAssetsUp(shares, scaleFactor);
+        if (assets == 0) revert ZeroAssets();
+
+        address assetAddress = address(wrappedMarket);
+        uint256 scaledBefore = wrappedMarket.scaledBalanceOf(address(this));
+        assetAddress.safeTransferFrom(msg.sender, address(this), assets);
+        uint256 scaledAfter = wrappedMarket.scaledBalanceOf(address(this));
+
+        uint256 mintedShares = scaledAfter - scaledBefore;
+        if (mintedShares != shares) revert SharesMismatch(shares, mintedShares);
+
+        _mint(receiver, shares);
+        emit Deposit(msg.sender, receiver, assets, shares);
+    }
+
+    /// @notice Withdraw `assets` to `receiver`, burning shares from `owner_` (shares rounded up).
+    function withdraw(uint256 assets, address receiver, address owner_)
+        external
+        nonReentrant
+        override
+        returns (uint256 shares)
+    {
+        if (assets == 0) revert ZeroAssets();
+
+        uint256 scaleFactor = wrappedMarket.scaleFactor();
+        shares = _scaledSharesForAssets(assets, scaleFactor);
+        if (shares == 0) revert ZeroShares();
+
+        if (msg.sender != owner_) {
+            _spendAllowance(owner_, msg.sender, shares);
+        }
+
+        uint256 scaledBefore = wrappedMarket.scaledBalanceOf(address(this));
+
+        _burn(owner_, shares);
+        address assetAddress = address(wrappedMarket);
+        assetAddress.safeTransfer(receiver, assets);
+        uint256 scaledAfter = wrappedMarket.scaledBalanceOf(address(this));
+
+        uint256 burnedShares = scaledBefore - scaledAfter;
+        if (burnedShares != shares) revert SharesMismatch(shares, burnedShares);
+        emit Withdraw(msg.sender, receiver, owner_, assets, shares);
+    }
+
+    /// @notice Redeem `shares` from `owner_` and send the corresponding assets to `receiver` (assets rounded down).
+    function redeem(uint256 shares, address receiver, address owner_)
+        external
+        nonReentrant
+        override
+        returns (uint256 assets)
+    {
+        if (shares == 0) revert ZeroShares();
+
+        if (msg.sender != owner_) {
+            _spendAllowance(owner_, msg.sender, shares);
+        }
+
+        uint256 scaleFactor = wrappedMarket.scaleFactor();
+        assets = _scaledAssetsForShares(shares, scaleFactor);
+        if (assets == 0) revert ZeroAssets();
+
+        uint256 scaledBefore = wrappedMarket.scaledBalanceOf(address(this));
+
+        _burn(owner_, shares);
+        address assetAddress = address(wrappedMarket);
+        assetAddress.safeTransfer(receiver, assets);
+        uint256 scaledAfter = wrappedMarket.scaledBalanceOf(address(this));
+
+        uint256 burnedShares = scaledBefore - scaledAfter;
+        if (burnedShares != shares) revert SharesMismatch(shares, burnedShares);
+
+        emit Withdraw(msg.sender, receiver, owner_, assets, shares);
+    }
+
+    // -------------------------------------------------------------------------
+    // Internal helpers
+    // -------------------------------------------------------------------------
+
+    function _convertToSharesDown(uint256 assets, uint256 scaleFactor) internal pure returns (uint256) {
+        return MathUtils.mulDiv(assets, RAY, scaleFactor);
+    }
+
+    function _convertToSharesUp(uint256 assets, uint256 scaleFactor) internal pure returns (uint256) {
+        return MathUtils.mulDivUp(assets, RAY, scaleFactor);
+    }
+
+    function _convertToAssetsDown(uint256 shares, uint256 scaleFactor) internal pure returns (uint256) {
+        return MathUtils.mulDiv(shares, scaleFactor, RAY);
+    }
+
+    function _convertToAssetsUp(uint256 shares, uint256 scaleFactor) internal pure returns (uint256) {
+        if (shares == 0) return 0;
+
+        uint256 assets = MathUtils.mulDiv(shares, scaleFactor, RAY);
+        if (assets.rayDiv(scaleFactor) < shares) {
+            assets += 1;
+        }
+
+        return assets;
+    }
+
+    function _scaledSharesForAssets(uint256 assets, uint256 scaleFactor) internal pure returns (uint256) {
+        return assets.rayDiv(scaleFactor);
+    }
+
+    function _scaledAssetsForShares(uint256 shares, uint256 scaleFactor) internal pure returns (uint256) {
+        return shares.rayMul(scaleFactor);
+    }
+}