X7 Lending Pool

The X7 Lending Pool contract includes functions for liquidating loans, buying out loans, depositing and returning ETH, calculating loan quotes and discounted quotes, splitting origination and premium fees, paying liquidation fees, and adding liquidity to an exchange pair. The contract ensures safe interactions with ERC20 tokens through the TransferHelper library, which includes functions for safe token approval and transfer. These functionalities collectively enable the contract to facilitate loan management, fee distribution, and liquidity provision in the lending platform.

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interface IWETH {
    function deposit() external payable;
    function transfer(address to, uint value) external returns (bool);
    function withdraw(uint) external;
}

interface IX7D {
    function mint(address to, uint256 amount) external;
    function burn(address from, uint256 amount) external;
}

interface IX7LendingTerm {
    function createLoan() external returns (uint256);
    function fundLoan(uint256 loanID) external;


}

// 1. Loan origination fee
// 2. Loan retention premium fee schedule
// 3. Principal repayment condition/maximum loan duration
// 4. Liquidation conditions and Reward
// 5. Loan duration

interface IX7LendingDiscountAuthority {
    function getFeeModifiers(
        address borrower,
        uint256[3] memory loanAmountDetails,
        uint256[3] memory loanDurationDetails
    ) external view returns (uint256, uint256);

    function useFeeModifiers(
        address borrower,
        uint256[3] memory loanAmountDetails,
        uint256[3] memory loanDurationDetails
    ) external returns (uint256, uint256);
}

interface IX7InitialLiquidityLoanTerm {

    function ownerOf(uint256 tokenId) external view returns (address owner);
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    function originateLoan(
        uint256 loanAmount,
        uint256 originationFee,
        uint256 loanLengthSeconds_,

        uint256 premiumFeeModifierNumerator_,
        uint256 originationFeeModifierNumerator_,

        address receiver,
        uint256 tokenId
    ) external payable;

    function minimumLoanAmount() external view returns (uint256);
    function maximumLoanAmount() external view returns (uint256);
    function minimumLoanLengthSeconds() external view returns (uint256);
    function maximumLoanLengthSeconds() external view returns (uint256);

    function getPrincipalDue(uint256 loanID, uint256 asOf) external view returns (uint256);
    function getPremiumsDue(uint256 loanID, uint256 asOf) external view returns (uint256);
    function getTotalDue(uint256 loanID, uint256 asOf) external view returns (uint256);
    function getRemainingLiability(uint256 loanID) external view returns (uint256);
    function getPremiumPaymentSchedule(uint256 loanID) external view returns (uint256[] memory, uint256[] memory);
    function getPrincipalPaymentSchedule(uint256 loanID) external view returns (uint256[] memory, uint256[] memory);

    function isComplete(uint256 loanID) external view returns (bool);
    function getOriginationAmounts(uint256 loanAmount) external view returns (uint256 loanAmountRounded, uint256 originationFee);
    function getQuote(uint256 loanAmount) external view returns (uint256 loanAmountRounded, uint256 originationFee, uint256 totalPremium);
    function getDiscountedQuote(uint256 loanAmount_, uint256 premiumFeeModifier, uint256 originationFeeModifier) external view returns (uint256 loanAmountRounded, uint256 originationFee, uint256 totalPremium);
    function recordPrincipalRepayment(uint256 loanID, uint256 amount) external returns (uint256 premiumPaid, uint256 principalPaid, uint256 refundAmount, uint256 remainingLiability);
    function recordPayment(uint256 loanID, uint256 amount) external returns (uint256 premiumPaid, uint256 principalPaid, uint256 refundAmount, uint256 remainingLiability);
    function liquidationAmount(uint256 loanID) external view returns (uint256);

    function loanAmount(uint256 loanID) external view returns (uint256);
    function principalAmountPaid(uint256 loanID) external view returns (uint256);

}


interface IXchangeFactory {
    function getPair(address tokenA, address tokenB) external view returns (address pair);
    function createPair(address tokenA, address tokenB) external returns (address pair);
}

interface IXchangeRouter {
    function factory() external pure returns (address);
    function WETH() external pure returns (address);
    function addLiquidityETH(
        address token,
        uint amountTokenDesired,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external payable returns (uint amountToken, uint amountETH, uint liquidity);
}

interface IXchangePair {
    function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
    function syncSafe(uint256, uint256) external;
    function withdrawTokensAgainstMinimumBalance(address tokenAddress, address to, uint112 amount) external returns (uint256);
    function setMinimumBalance(address tokenAddress, uint112 minimumAmount) external;
    function tokenMinimumBalance(address) external view returns (uint256);
}

interface X7DMinter {
    event FundsReturned(address indexed sender, uint256 amount);

    // Call this function to explicitly mint X7D
    function depositETH() external payable;

    // Call this function to return ETH to this contract without minting X7D
    function returnETH() external payable;

    // Call this function to mint X7D to a recipient of your choosing
    function depositETHForRecipient(address recipient) external payable;
}