// SPDX-License-Identifier: MIT
pragma solidity 0.8.38;

/// @notice BSC testnet only. No owner, game settlement or third-party withdrawal.
contract FlapAceTestVault {
    mapping(address => uint256) public balances;
    uint256 public totalLiability;
    bool private entered;
    event Deposited(address indexed account, uint256 amount);
    event Withdrawn(address indexed account, uint256 amount);
    error TestnetOnly();
    error InvalidAmount();
    error InsufficientBalance();
    error Reentrancy();
    error TransferFailed();

    constructor() { if (block.chainid != 97) revert TestnetOnly(); }
    modifier nonReentrant() {
        if (entered) revert Reentrancy();
        entered = true;
        _;
        entered = false;
    }
    function deposit() external payable nonReentrant { _deposit(); }
    receive() external payable nonReentrant { _deposit(); }
    function _deposit() private {
        if (msg.value == 0) revert InvalidAmount();
        balances[msg.sender] += msg.value;
        totalLiability += msg.value;
        emit Deposited(msg.sender, msg.value);
    }
    function withdraw(uint256 amount) external nonReentrant {
        if (amount == 0) revert InvalidAmount();
        if (amount > balances[msg.sender]) revert InsufficientBalance();
        balances[msg.sender] -= amount;
        totalLiability -= amount;
        (bool ok,) = payable(msg.sender).call{value: amount}("");
        if (!ok) revert TransferFailed();
        emit Withdrawn(msg.sender, amount);
    }
}