chore: restore original directory structure (project under code-review-graph-main/)

code-review-graph-main/tests/fixtures/sample.sol

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+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.20;
+
+import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
+import "@openzeppelin/contracts/access/Ownable.sol";
+import {IERC20, IERC20Metadata} from "@openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol";
+
+// ─── Protocol constants ─────────────────────────────────────────────────────
+
+uint256 constant MAX_SUPPLY = 1_000_000_000 ether;
+address constant ZERO_ADDRESS = address(0);
+
+// ─── Types ──────────────────────────────────────────────────────────────────
+
+/// @notice Staker position tracked per epoch.
+struct StakerPosition {
+    address wallet;
+    uint256 stakedAmount;
+    uint256 rewardDebt;
+    uint64  epochJoined;
+    bool    isActive;
+}
+
+/// @notice Pool lifecycle.
+enum PoolStatus {
+    Active,
+    Paused,
+    Deprecated,
+    EmergencyShutdown
+}
+
+/// @notice 18-decimal fixed-point price.
+type Price is uint256;
+
+/// @notice Position receipt NFT identifier.
+type PositionId is uint128;
+
+// ─── Errors ─────────────────────────────────────────────────────────────────
+
+error InsufficientStake(uint256 requested, uint256 available);
+error PoolNotActive();
+
+// ─── Events ─────────────────────────────────────────────────────────────────
+
+event Staked(address indexed user, uint256 amount);
+event Unstaked(address indexed user, uint256 amount);
+
+// ─── Helpers ────────────────────────────────────────────────────────────────
+
+/// @notice 30 bp protocol fee.
+function protocolFee(uint256 amount) pure returns (uint256) {
+    return (amount * 30) / 10_000;
+}
+
+// ─── Interface ──────────────────────────────────────────────────────────────
+
+interface IStakingPool {
+    function stake(uint256 amount) external;
+    function unstake(uint256 amount) external returns (uint256);
+    function stakedBalance(address user) external view returns (uint256);
+}
+
+// ─── Library ────────────────────────────────────────────────────────────────
+
+/// @notice Fixed-point math for reward accumulator precision.
+library RewardMath {
+    uint256 internal constant PRECISION = 1e18;
+
+    function mulPrecise(uint256 a, uint256 b) internal pure returns (uint256) {
+        return (a * b) / PRECISION;
+    }
+
+    function divPrecise(uint256 a, uint256 b) internal pure returns (uint256) {
+        require(b > 0, "RewardMath: division by zero");
+        return (a * PRECISION) / b;
+    }
+}
+
+// ─── Core pool ──────────────────────────────────────────────────────────────
+
+/// @title StakingVault
+/// @notice Liquid staking pool. Deposit the underlying ERC-20, receive
+///         share tokens 1 : 1, accrue rewards over time.
+contract StakingVault is ERC20, Ownable, IStakingPool {
+    using RewardMath for uint256;
+
+    // ── Storage ────────────────────────────────────────────────────────
+
+    mapping(address => uint256) public stakes;
+    uint256 public totalStaked;
+    address public guardian;
+    PoolStatus public status;
+    uint256 constant MIN_STAKE = 0.01 ether;
+    uint256 immutable launchTime;
+    Price public assetPrice;
+    uint256 public accRewardPerShare;
+
+    // ── Events ─────────────────────────────────────────────────────────
+
+    event RewardAccrued(uint256 indexed epoch, uint256 amount);
+    event EmergencyExit(address indexed user, uint256 amount);
+
+    // ── Modifiers ──────────────────────────────────────────────────────
+
+    modifier nonZero(uint256 amount) {
+        require(amount > 0, "StakingVault: zero amount");
+        _;
+    }
+
+    modifier whenPoolActive() {
+        require(status == PoolStatus.Active, "StakingVault: pool not active");
+        _;
+    }
+
+    // ── Constructor ────────────────────────────────────────────────────
+
+    constructor(
+        string memory name,
+        string memory symbol
+    ) ERC20(name, symbol) Ownable(msg.sender) {
+        guardian    = msg.sender;
+        launchTime = block.timestamp;
+        status     = PoolStatus.Active;
+    }
+
+    // ── Core operations ────────────────────────────────────────────────
+
+    /// @inheritdoc IStakingPool
+    function stake(uint256 amount)
+        external
+        override
+        nonZero(amount)
+        whenPoolActive
+    {
+        uint256 fee = protocolFee(amount);
+        uint256 net = amount - fee;
+
+        stakes[msg.sender] += net;
+        totalStaked        += net;
+
+        _mint(msg.sender, net);
+        emit Staked(msg.sender, net);
+    }
+
+    /// @inheritdoc IStakingPool
+    function unstake(uint256 amount)
+        external
+        override
+        nonZero(amount)
+        returns (uint256)
+    {
+        uint256 staked = stakes[msg.sender];
+        if (staked < amount) {
+            revert InsufficientStake(amount, staked);
+        }
+
+        stakes[msg.sender] = staked - amount;
+        totalStaked        -= amount;
+
+        _burn(msg.sender, amount);
+        emit Unstaked(msg.sender, amount);
+        return amount;
+    }
+
+    /// @inheritdoc IStakingPool
+    function stakedBalance(address user) external view returns (uint256) {
+        return stakes[user];
+    }
+
+    // ── Emergency ──────────────────────────────────────────────────────
+
+    function emergencyWithdraw() external nonZero(stakes[msg.sender]) {
+        uint256 amount = stakes[msg.sender];
+        stakes[msg.sender] = 0;
+        totalStaked        -= amount;
+
+        _burn(msg.sender, amount);
+        emit EmergencyExit(msg.sender, amount);
+    }
+
+    // ── ETH handling (native staking variant) ──────────────────────────
+
+    receive() external payable {}
+    fallback() external payable {}
+}
+
+// ─── Boosted pool ───────────────────────────────────────────────────────────
+
+/// @title BoostedPool
+/// @notice Wraps StakingVault with an additional reward layer.
+///         Depositors earn base yield from the vault plus bonus
+///         rewards funded by governance.
+contract BoostedPool is StakingVault {
+    uint256 public bonusRate;
+
+    event BonusClaimed(address indexed user, uint256 reward);
+
+    constructor(
+        string memory name,
+        string memory symbol,
+        uint256 _bonusRate
+    ) StakingVault(name, symbol) {
+        bonusRate = _bonusRate;
+    }
+
+    function pendingBonus(address user) public view returns (uint256) {
+        if (totalStaked == 0) return 0;
+        return stakes[user].mulPrecise(bonusRate);
+    }
+
+    function claimBonus() external {
+        uint256 reward = pendingBonus(msg.sender);
+        require(reward > 0, "BoostedPool: nothing to claim");
+
+        _mint(msg.sender, reward);
+        emit BonusClaimed(msg.sender, reward);
+    }
+}