contract NFTStakingLoan {
    // 抵押信息结构
    struct StakeInfo {
        address owner;        // 抵押人地址
        address nftAddress;   // NFT合约地址
        uint256 tokenId;      // NFT Token ID
        uint256 value;        // NFT估值
        uint256 borrowedAmount; // 借贷金额
        uint256 dueTime;      // 到期时间
        bool repaid;          // 是否已还款
        bool liquidated;      // 是否已清算
    }
}

function stakeNFT(address nftAddress, uint256 tokenId) external {
    // 验证NFT价值
    uint256 value = nftPriceOracle[nftAddress][tokenId];
    require(value > 0, "NFT has no valuation");
    
    // 转移NFT到合约
    IERC721(nftAddress).transferFrom(msg.sender, address(this), tokenId);
    
    // 记录抵押信息
    stakes[stakeCounter] = StakeInfo({...});
    stakeCounter++;
}

function borrow(uint256 stakeId) external {
    StakeInfo storage stake = stakes[stakeId];
    require(msg.sender == stake.owner, "Not your stake");
    
    // 计算借贷金额（50%抵押率）
    uint256 loanAmount = stake.value / 2;
    stake.borrowedAmount = loanAmount;
    stake.dueTime = block.timestamp + 1 days;
    
    // 转账给借款人
    payable(stake.owner).transfer(loanAmount);
}

function repay(uint256 stakeId) external payable {
    StakeInfo storage stake = stakes[stakeId];
    require(msg.value >= stake.borrowedAmount, "Insufficient repay");
    
    stake.repaid = true;
    // 归还NFT
    IERC721(stake.nftAddress).transferFrom(
        address(this), stake.owner, stake.tokenId
    );
}

function checkUpkeep(bytes calldata) 
    external view override 
    returns (bool upkeepNeeded, bytes memory performData) {
    
    for (uint256 i = 0; i < stakeCounter; i++) {
        StakeInfo storage s = stakes[i];
        if (!s.repaid && !s.liquidated && 
            s.dueTime > 0 && block.timestamp > s.dueTime) {
            return (true, abi.encode(i));
        }
    }
    return (false, bytes(""));
}
 
function performUpkeep(bytes calldata performData) external override {
    uint256 stakeId = abi.decode(performData, (uint256));
    liquidate(stakeId);
}

// 继承Chainlink Automation接口
contract NFTStakingLoan is AutomationCompatibleInterface {
    // 实现自动化检查逻辑
    function checkUpkeep(...) external view override;
    
    // 实现自动化执行逻辑
    function performUpkeep(...) external override;
}