LoanUtils.sol (Library for utilities and data structures)

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

library LendingLibrary {
    // Constants
    uint256 constant BASE_PERCENTAGE = 100;

    // Functions

    /**
     * @dev Calculates the origination fee.
     * @param loanAmount The principal loan amount.
     * @param feeRate The origination fee rate (percentage).
     * @return The calculated origination fee.
     */
    function calculateOriginationFee(uint256 loanAmount, uint256 feeRate) external pure returns (uint256) {
        return (loanAmount * feeRate) / BASE_PERCENTAGE;
    }

    /**
     * @dev Calculates the total repayment amount for a loan.
     * @param loanAmount The principal loan amount.
     * @param interestRate The annual interest rate (percentage).
     * @param term The loan term in seconds.
     * @return The total repayment amount.
     */
    function calculateTotalRepaymentAmount(
        uint256 loanAmount,
        uint256 interestRate,
        uint256 term
    ) external pure returns (uint256) {
        return loanAmount + ((loanAmount * interestRate * term) / (BASE_PERCENTAGE * 365 * 86400));
    }

    /**
     * @dev Calculates the utilization rate of a liquidity pool.
     * @param borrowedFunds The amount of borrowed funds.
     * @param availableLiquidity The available liquidity in the pool.
     * @return The utilization rate as a percentage (scaled by 1e18).
     */
    function calculateUtilizationRate(uint256 borrowedFunds, uint256 availableLiquidity) external pure returns (uint256) {
        require(borrowedFunds + availableLiquidity > 0, "No liquidity in pool");
        return (borrowedFunds * 1e18) / (borrowedFunds + availableLiquidity);
    }

    /**
     * @dev Calculates the CLR (collateral-to-loan ratio).
     * @param collateralAmount The collateral amount.
     * @param collateralRateUSD The collateral value in USD.
     * @param loanAmount The loan amount.
     * @param loanRateUSD The loan value in USD.
     * @return The CLR as a percentage (scaled by 1e18).
     */
    function calculateCLR(
        uint256 collateralAmount,
        uint256 collateralRateUSD,
        uint256 loanAmount,
        uint256 loanRateUSD
    ) external pure returns (uint256) {
        require(loanAmount > 0 && loanRateUSD > 0, "Invalid loan amount or rate");
        return (collateralAmount * collateralRateUSD * BASE_PERCENTAGE) / (loanAmount * loanRateUSD);
    }
}

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