// SPDX-License-Identifier: MIT
pragma solidity ^0.8.23;

// interfaces
import {ITownsBase} from "src/tokens/towns/mainnet/ITowns.sol";

// libraries

// contracts

library TokenInflationLib {
    struct Layout {
        uint256 lastMintTime;
        address inflationReceiver;
        uint256 initialInflationRate;
        uint256 finalInflationRate;
        uint256 inflationDecayRate;
        uint256 finalInflationYears;
        bool overrideInflation;
        uint256 overrideInflationRate;
    }

    // keccak256(abi.encode(uint256(keccak256("tokens.towns.mainnet.lib.storage")) - 1)) &
    // ~bytes32(uint256(0xff))
    function layout() internal pure returns (Layout storage l) {
        bytes32 slot = 0x366bbacac8c1291905a47c4b12670e7c8ce975e09c84414dddf77ba98c85af00;
        assembly {
            l.slot := slot
        }
    }

    function initialize(ITownsBase.InflationConfig memory config) internal {
        Layout storage ds = layout();
        ds.lastMintTime = config.initialMintTime;
        ds.inflationReceiver = config.inflationReceiver;
        ds.initialInflationRate = config.initialInflationRate;
        ds.finalInflationRate = config.finalInflationRate;
        ds.inflationDecayRate = config.inflationDecayRate;
        ds.finalInflationYears = config.finalInflationYears;
    }

    function finalInflationRate() internal view returns (uint256) {
        return layout().finalInflationRate;
    }

    function inflationReceiver() internal view returns (address) {
        return layout().inflationReceiver;
    }

    function lastMintTime() internal view returns (uint256) {
        return layout().lastMintTime;
    }

    function setInflationReceiver(address receiver) internal {
        layout().inflationReceiver = receiver;
    }

    function updateLastMintTime() internal {
        layout().lastMintTime = block.timestamp;
    }

    function setOverrideInflation(
        bool overrideInflation,
        uint256 overrideInflationRateBps
    ) internal {
        layout().overrideInflation = overrideInflation;
        layout().overrideInflationRate = overrideInflationRateBps;
    }

    /**
     * @dev Returns the current inflation rate.
     * @return inflation rate in basis points (0-10_000)
     */
    function getCurrentInflationRateBPS(uint256 initialMintTime) internal view returns (uint256) {
        Layout storage ds = layout();

        if (ds.overrideInflation) return ds.overrideInflationRate; // override inflation rate

        uint256 yearsSinceInitialMint = (block.timestamp - initialMintTime) / 365 days;

        if (yearsSinceInitialMint >= ds.finalInflationYears) {
            return ds.finalInflationRate;
        }

        uint256 inflationRateDecrease = (yearsSinceInitialMint * ds.inflationDecayRate) /
            ds.finalInflationYears;
        return ds.initialInflationRate - inflationRateDecrease;
    }
}