// SPDX-License-Identifier: MIT
pragma solidity ^0.8.19;

interface IOracle {
    function latestAnswer() external view returns (int256);
    function latestTimestamp() external view returns (uint256);
}

contract StaleOracleLending {
    IOracle public oracle;
    mapping(address => uint256) public collateral;

    constructor(address _oracle) {
        oracle = IOracle(_oracle);
    }

    function depositCollateral() external payable {
        collateral[msg.sender] += msg.value;
    }

    function borrow(uint256 amount) external {
        int256 price = oracle.latestAnswer();
        require(price > 0, "bad price");

        // no staleness check on latestTimestamp
        uint256 value = collateral[msg.sender] * uint256(price);
        require(value >= amount * 1e18, "insufficient collateral");
        payable(msg.sender).transfer(amount);
    }

    receive() external payable {}
}