protocol/src/abstract/ContinuousIndexing.sol at 2ea2235d67ca5a6feeb596c0fa4e8f99de050b94 · m0-foundation/protocol · GitHub

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// SPDX-License-Identifier: GPL-3.0

pragma solidity 0.8.26;

import { Initializable } from "../../lib/openzeppelin-contracts/contracts/proxy/utils/Initializable.sol";

import { IContinuousIndexing } from "../interfaces/IContinuousIndexing.sol";

import { ContinuousIndexingMath } from "../libs/ContinuousIndexingMath.sol";

/**
 * @title Abstract Continuous Indexing Contract to handle index updates in inheriting contracts.
 * @author M^0 Labs
 */
abstract contract ContinuousIndexing is IContinuousIndexing, Initializable {
    /* ============ Variables ============ */

    /// @inheritdoc IContinuousIndexing
    uint128 public latestIndex;

    /// @inheritdoc IContinuousIndexing
    uint40 public latestUpdateTimestamp;

    /* ============ Initializer ============ */

    /// @notice Initializes Proxy's storage.
    function _initialize() internal onlyInitializing {
        latestIndex = ContinuousIndexingMath.EXP_SCALED_ONE;
        latestUpdateTimestamp = uint40(block.timestamp);
    }

    /* ============ View/Pure Functions ============ */

    /// @inheritdoc IContinuousIndexing
    function currentIndex() public view virtual returns (uint128);

    /* ============ Internal Interactive Functions ============ */

    /**
     * @notice Updates the latest index and latest accrual time.
     * @param  index_ The new index to compute present amounts from principal amounts.
     */
    function _updateIndex(uint128 index_) internal virtual {
        if (index_ < latestIndex) revert DecreasingIndex(index_, latestIndex);
        latestIndex = index_;
        latestUpdateTimestamp = uint40(block.timestamp);

        emit IndexUpdated(index_);
    }

    /* ============ Internal View/Pure Functions ============ */

    /**
     * @dev    Returns the principal amount (rounded down) given the present amount, using the current index.
     * @param  presentAmount_ The present amount.
     * @return The principal amount rounded down.
     */
    function _getPrincipalAmountRoundedDown(uint240 presentAmount_) internal view returns (uint112) {
        return _getPrincipalAmountRoundedDown(presentAmount_, currentIndex());
    }

    /**
     * @dev    Returns the principal amount (rounded up) given the present amount and an index.
     * @param  presentAmount_ The present amount.
     * @return The principal amount rounded up.
     */
    function _getPrincipalAmountRoundedUp(uint240 presentAmount_) internal view returns (uint112) {
        return _getPrincipalAmountRoundedUp(presentAmount_, currentIndex());
    }

    /**
     * @dev    Returns the present amount (rounded down) given the principal amount and an index.
     * @param  principalAmount_ The principal amount.
     * @param  index_           An index.
     * @return The present amount rounded down.
     */
    function _getPresentAmountRoundedDown(uint112 principalAmount_, uint128 index_) internal pure returns (uint240) {
        return ContinuousIndexingMath.multiplyDown(principalAmount_, index_);
    }

    /**
     * @dev    Returns the present amount (rounded up) given the principal amount and an index.
     * @param  principalAmount_ The principal amount.
     * @param  index_           An index.
     * @return The present amount rounded up.
     */
    function _getPresentAmountRoundedUp(uint112 principalAmount_, uint128 index_) internal pure returns (uint240) {
        return ContinuousIndexingMath.multiplyUp(principalAmount_, index_);
    }

    /**
     * @dev    Returns the principal amount given the present amount, using the current index.
     * @param  presentAmount_ The present amount.
     * @param  index_         An index.
     * @return The principal amount rounded down.
     */
    function _getPrincipalAmountRoundedDown(uint240 presentAmount_, uint128 index_) internal pure returns (uint112) {
        return ContinuousIndexingMath.divideDown(presentAmount_, index_);
    }

    /**
     * @dev    Returns the principal amount given the present amount, using the current index.
     * @param  presentAmount_ The present amount.
     * @param  index_         An index.
     * @return The principal amount rounded up.
     */
    function _getPrincipalAmountRoundedUp(uint240 presentAmount_, uint128 index_) internal pure returns (uint112) {
        return ContinuousIndexingMath.divideUp(presentAmount_, index_);
    }
}