// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

/**
 * @title ReentrancyVault
 * @notice A vault with a classic reentrancy vulnerability in the withdraw function.
 *         DO NOT use in production. For research only.
 *
 * Attack vector: External call tomsg.sender before updating internal state.
 * The victim calls withdraw() and the attacker recursively drains the vault.
 */
contract ReentrancyVault {
    mapping(address => uint256) public balances;

    event Deposit(address indexed user, uint256 amount);
    event Withdraw(address indexed user, uint256 amount);

    function deposit() external payable {
        balances[msg.sender] += msg.value;
        emit Deposit(msg.sender, msg.value);
    }

    // Vulnerability: external call before state update
    function withdraw(uint256 amount) external {
        require(balances[msg.sender] >= amount, "Insufficient balance");

        // @audit-info - sends ETH before updating state (reentrancy vector)
        (bool success, ) = msg.sender.call{value: amount}("");
        require(success, "Transfer failed");

        balances[msg.sender] -= amount;
        emit Withdraw(msg.sender, amount);
    }

    function getBalance() external view returns (uint256) {
        return address(this).balance;
    }
}