// SPDX-License-Identifier: MIT
pragma solidity ^0.8.30;

import {Initializable} from "@openzeppelin-contracts-upgradeable-5.6.1/proxy/utils/Initializable.sol";
import {AccessControlUpgradeable} from "@openzeppelin-contracts-upgradeable-5.6.1/access/AccessControlUpgradeable.sol";
import {UUPSUpgradeable} from "@openzeppelin-contracts-upgradeable-5.6.1/proxy/utils/UUPSUpgradeable.sol";

import {IFeeRegistry} from "./interfaces/IFeeRegistry.sol";
import {Roles} from "./libraries/Roles.sol";

/// @title FeeRegistry
/// @notice Per-token protocol fee parameters and the treasury address.
///         Tokens without an explicit configuration fall back to protocol-wide default fees, so a
///         loan on an unlisted token is never silently zero-fee. Read at execution:
///         `originationFeeBps` funds the one-time borrower fee, `interestTakeRateBps` is snapshotted
///         immutably into each loan so later fee changes never affect live loans.
/// @dev UUPS-upgradeable singleton. Fees are bounded below 100% by hard caps so the admin cannot
///      brick or over-tax loans. Storage uses ERC-7201 namespacing; upgrades are gated by
///      `UPGRADER_ROLE` (a Timelock in production, distinct from the DEFAULT_ADMIN/FEE_MANAGER).
contract FeeRegistry is IFeeRegistry, Initializable, AccessControlUpgradeable, UUPSUpgradeable {
    struct FeeParams {
        uint16 originationFeeBps;
        uint16 interestTakeRateBps;
        bool isSet; // distinguishes an explicit (possibly zero) config from "use defaults"
    }

    /// @custom:storage-location erc7201:amish.storage.FeeRegistry
    struct FeeRegistryStorage {
        address treasury;
        FeeParams defaultFees;
        mapping(address token => FeeParams) tokenFees;
    }

    // keccak256(abi.encode(uint256(keccak256("amish.storage.FeeRegistry")) - 1)) & ~bytes32(uint256(0xff))
    bytes32 private constant STORAGE_LOCATION = 0xe835dd83c0c4483e40df3e0c501de3df67296b68fba8b61750e37b4b86025000;

    /// @notice Upper bound on the origination fee (10%). Defensive cap on admin power.
    uint16 public constant MAX_ORIGINATION_FEE_BPS = 1_000;

    /// @notice Upper bound on the interest take rate (50%). Defensive cap on admin power.
    uint16 public constant MAX_INTEREST_TAKE_BPS = 5_000;

    event TokenFeesUpdated(address indexed token, uint16 originationFeeBps, uint16 interestTakeRateBps);
    event DefaultFeesUpdated(uint16 originationFeeBps, uint16 interestTakeRateBps);
    event TreasuryUpdated(address indexed treasury);

    error FeeRegistry_OriginationFeeTooHigh(uint16 bps);
    error FeeRegistry_InterestTakeTooHigh(uint16 bps);
    error FeeRegistry_ZeroAddress();

    constructor() {
        _disableInitializers();
    }

    /// @param admin Holds DEFAULT_ADMIN_ROLE and FEE_MANAGER_ROLE.
    /// @param upgrader Holds UPGRADER_ROLE (a Timelock in production).
    /// @param initialTreasury Recipient of protocol fees.
    /// @param defaultOriginationFeeBps Fallback origination fee for unconfigured tokens.
    /// @param defaultInterestTakeRateBps Fallback interest take for unconfigured tokens.
    function initialize(
        address admin,
        address upgrader,
        address initialTreasury,
        uint16 defaultOriginationFeeBps,
        uint16 defaultInterestTakeRateBps
    ) external initializer {
        if (admin == address(0) || upgrader == address(0)) {
            revert FeeRegistry_ZeroAddress();
        }
        __AccessControl_init();
        _grantRole(DEFAULT_ADMIN_ROLE, admin);
        _grantRole(Roles.FEE_MANAGER_ROLE, admin);
        _grantRole(Roles.UPGRADER_ROLE, upgrader);
        _setTreasury(initialTreasury);
        _setDefaultFees(defaultOriginationFeeBps, defaultInterestTakeRateBps);
    }

    /// @notice Set the fee parameters for a specific token (overrides the defaults for it).
    function setTokenFees(address token, uint16 originationFeeBps, uint16 interestTakeRateBps)
        external
        onlyRole(Roles.FEE_MANAGER_ROLE)
    {
        _validateFees(originationFeeBps, interestTakeRateBps);
        _getStorage().tokenFees[token] = FeeParams(originationFeeBps, interestTakeRateBps, true);
        emit TokenFeesUpdated(token, originationFeeBps, interestTakeRateBps);
    }

    /// @notice Set the protocol-wide default fees applied to tokens with no explicit config.
    function setDefaultFees(uint16 originationFeeBps, uint16 interestTakeRateBps)
        external
        onlyRole(Roles.FEE_MANAGER_ROLE)
    {
        _setDefaultFees(originationFeeBps, interestTakeRateBps);
    }

    /// @notice Update the protocol treasury address.
    function setTreasury(address newTreasury) external onlyRole(Roles.FEE_MANAGER_ROLE) {
        _setTreasury(newTreasury);
    }

    /// @inheritdoc IFeeRegistry
    function feesFor(address token)
        external
        view
        override
        returns (uint16 originationFeeBps, uint16 interestTakeRateBps)
    {
        FeeRegistryStorage storage $ = _getStorage();
        FeeParams memory p = $.tokenFees[token];
        if (!p.isSet) p = $.defaultFees;
        return (p.originationFeeBps, p.interestTakeRateBps);
    }

    /// @notice The current default (fallback) fees.
    function defaultFees() external view returns (uint16 originationFeeBps, uint16 interestTakeRateBps) {
        FeeParams memory p = _getStorage().defaultFees;
        return (p.originationFeeBps, p.interestTakeRateBps);
    }

    /// @inheritdoc IFeeRegistry
    function treasury() external view override returns (address) {
        return _getStorage().treasury;
    }

    function _setDefaultFees(uint16 originationFeeBps, uint16 interestTakeRateBps) private {
        _validateFees(originationFeeBps, interestTakeRateBps);
        _getStorage().defaultFees = FeeParams(originationFeeBps, interestTakeRateBps, true);
        emit DefaultFeesUpdated(originationFeeBps, interestTakeRateBps);
    }

    function _setTreasury(address newTreasury) private {
        if (newTreasury == address(0)) revert FeeRegistry_ZeroAddress();
        _getStorage().treasury = newTreasury;
        emit TreasuryUpdated(newTreasury);
    }

    function _validateFees(uint16 originationFeeBps, uint16 interestTakeRateBps) private pure {
        if (originationFeeBps > MAX_ORIGINATION_FEE_BPS) revert FeeRegistry_OriginationFeeTooHigh(originationFeeBps);
        if (interestTakeRateBps > MAX_INTEREST_TAKE_BPS) revert FeeRegistry_InterestTakeTooHigh(interestTakeRateBps);
    }

    function _authorizeUpgrade(address) internal override onlyRole(Roles.UPGRADER_ROLE) {}

    function _getStorage() private pure returns (FeeRegistryStorage storage $) {
        assembly {
            $.slot := STORAGE_LOCATION
        }
    }
}