// SPDX-License-Identifier: BUSL-1.1
pragma solidity >=0.8.13;

import "../../interfaces/IJoin.sol";
import "@yield-protocol/utils-v2/src/token/IERC20.sol";
import "@yield-protocol/utils-v2/src/interfaces/IWETH9.sol";
import "@yield-protocol/utils-v2/src/token/MinimalTransferHelper.sol";
import "@yield-protocol/utils-v2/src/access/AccessControl.sol";
import "@yield-protocol/utils-v2/src/utils/Math.sol";
import "@yield-protocol/utils-v2/src/utils/Cast.sol";
import "./interfaces/IBatchAction.sol";
import "./ERC1155.sol";

contract NotionalJoin is IJoin, ERC1155TokenReceiver, AccessControl {
    using Math for *;
    using Cast for *;

    event FlashFeeFactorSet(uint256 indexed fee);
    event Redeemed(uint256 fCash, uint256 underlying, uint256 accrual);

    bytes32 internal constant FLASH_LOAN_RETURN =
        keccak256("ERC3156FlashBorrower.onFlashLoan");
    uint256 public constant FLASH_LOANS_DISABLED = type(uint256).max;

    address public immutable override asset;
    address public immutable underlying;
    address public immutable underlyingJoin;
    uint40 public immutable maturity; // Maturity date for fCash
    uint16 public immutable currencyId; // Notional currency id for the underlying
    uint256 public immutable fCashId; // This ERC1155 Join only accepts one fCashId from the ERC1155 token
    uint256 public storedBalance; // After maturity, this is reused as the balance for underlying
    uint256 public accrual; // fCash to underlying factor, with 18 decimals
    uint256 public flashFeeFactor = FLASH_LOANS_DISABLED; // Fee on flash loans, as a percentage in fixed point with 18 decimals. Flash loans disabled by default.

    constructor(
        address asset_,
        address underlying_,
        address underlyingJoin_,
        uint40 maturity_,
        uint16 currencyId_
    ) {
        asset = asset_;
        underlying = underlying_;
        maturity = maturity_;
        currencyId = currencyId_;
        underlyingJoin = underlyingJoin_;

        // TransferAssets.encodeAssetId
        fCashId = uint256(
            (bytes32(uint256(currencyId_)) << 48) |
                (bytes32(uint256(maturity_)) << 8) |
                bytes32(uint256(1))
        );
    }

    modifier afterMaturity() {
        require(block.timestamp >= maturity, "Only after maturity");
        _;
    }

    modifier beforeMaturity() {
        require(block.timestamp < maturity, "Only before maturity");
        _;
    }

    /// @dev Advertising through ERC165 the available functions
    function supportsInterface(bytes4 interfaceID)
        external
        pure
        returns (bool)
    {
        // ERC-165 support = `bytes4(keccak256('supportsInterface(bytes4)'))`.
        // ERC-1155 `ERC1155TokenReceiver` support = `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)")) ^ bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))`.
        return
            interfaceID == NotionalJoin.supportsInterface.selector ||
            interfaceID ==
            ERC1155TokenReceiver.onERC1155Received.selector ^
                ERC1155TokenReceiver.onERC1155BatchReceived.selector;
    }

    /// @dev Called by the sender after a transfer to verify it was received. Ensures only `fCashId` tokens are received.
    function onERC1155Received(
        address,
        address,
        uint256 id,
        uint256,
        bytes calldata
    ) external view override returns (bytes4) {
        require(id == fCashId, "Token fCashId not accepted");
        return ERC1155TokenReceiver.onERC1155Received.selector;
    }

    /// @dev Called by the sender after a batch transfer to verify it was received. Ensures only `fCashId` tokens are received.
    function onERC1155BatchReceived(
        address,
        address,
        uint256[] calldata ids,
        uint256[] calldata,
        bytes calldata
    ) external view override returns (bytes4) {
        uint256 length = ids.length;
        for (uint256 i; i < length; ++i)
            require(ids[i] == fCashId, "Token fCashId not accepted");
        return ERC1155TokenReceiver.onERC1155BatchReceived.selector;
    }

    /// @dev Take `amount` `asset` from `user` using `transferFrom`, minus any unaccounted `asset` in this contract.
    /// @param user Address of receiver of tokens
    /// @param amount Amount of tokens, always as an fCash amount.
    function join(address user, uint128 amount)
        external
        override
        auth
        returns (uint128)
    {
        return _join(user, amount);
    }

    /// @dev Take `amount` `asset` from `user` using `transferFrom`, minus any unaccounted `asset` in this contract.
    /// @param user Address of receiver of tokens
    /// @param amount Amount of tokens
    function _join(address user, uint128 amount)
        internal
        beforeMaturity
        returns (uint128)
    {
        ERC1155 token = ERC1155(asset);
        uint256 _storedBalance = storedBalance;
        uint256 available = token.balanceOf(address(this), fCashId) - _storedBalance; // Fine to panic if this underflows

        unchecked {
            storedBalance = _storedBalance + amount; // Unlikely that a uint128 added to the stored balance will make it overflow
            if (available < amount)
                token.safeTransferFrom(
                    user,
                    address(this),
                    fCashId,
                    amount - available,
                    ""
                );
        }
        return amount;
    }

    /// @dev Before maturity, transfer `amount` `asset` to `user`.
    /// @param user Address of receiver of tokens
    /// @param amount Amount of tokens, always as an fCash amount.
    /// After maturity, withdraw if necessary, then transfer `amount.wmul(accrual)` `underlying` to `user`.
    function exit(address user, uint128 amount)
        external
        override
        auth
        returns (uint128)
    {
        if (block.timestamp < maturity) {
            return _exit(user, amount);
        } else {
            if (accrual == 0) redeem(); // Redeem all fCash, switch to underlying join, set accrual.
            return _exitUnderlying(user, uint256(amount).wmul(accrual).u128()); // This converts from fCash units to underlying units
        }
    }

    /// @dev Transfer `amount` `asset` to `user`
    /// @param user Address of receiver of fCash tokens
    /// @param amount Amount of ERC1155 tokens
    function _exit(address user, uint128 amount) internal returns (uint128) {
        storedBalance -= amount;
        ERC1155(asset).safeTransferFrom(address(this), user, fCashId, amount, "");
        return amount;
    }

    /// @dev Transfer `amount` `underlying` to `user`
    /// @param user Recipient of token transfer
    /// @param amount Amount of underlying tokens to transfer
    function _exitUnderlying(address user, uint128 amount)
        internal
        returns (uint128)
    {
        IJoin(underlyingJoin).exit(user, amount);
        return amount;
    }

    /// @dev Converts all fCash holdings to underlying and send it to the main underlying join
    function redeem() public afterMaturity {
        require(accrual == 0, "Already redeemed");

        // Build an action to withdraw all mature fCash into underlying, then withdraw.
        IBatchAction.BalanceAction[]
            memory withdrawActions = new IBatchAction.BalanceAction[](1);
        withdrawActions[0] = IBatchAction.BalanceAction({
            actionType: IBatchAction.DepositActionType.None,
            currencyId: currencyId,
            depositActionAmount: 0,
            withdrawAmountInternalPrecision: 0,
            withdrawEntireCashBalance: true,
            redeemToUnderlying: true
        });

        IBatchAction(asset).batchBalanceAction(address(this), withdrawActions);

        // If this is an ETH Notional Join, we wrap all Ether we own on redemption. It should
        // only have arrived from Notional. Donations accepted :)
        if (fCashId >> 48 == 1) IWETH9(underlying).deposit{ value: address(this).balance }();

        uint256 underlyingBalance = IERC20(underlying).balanceOf(address(this));
        uint256 storedBalance_ = storedBalance;
        // The accrual covers the possible return from holding fCash after maturity, and also the change in decimals
        // from fCash to underlying. FCash always has 8 decimals. If the underlying is DAI multiplying fCash amounts
        // by the accrual will be add 10 decimals, and if the underlying is USDC the same will subtract 2 decimals.
        // There is a rounding loss when calculating the accrual and some wei will be forever locked in the join.
        accrual = underlyingBalance.wdiv(storedBalance_);

        // transfer underlying to main join
        MinimalTransferHelper.safeTransfer(
            IERC20(underlying),
            address(underlyingJoin),
            underlyingBalance
        );
        IJoin(underlyingJoin).join(address(this), underlyingBalance.u128());

        // no more fCash left in holding
        storedBalance = 0;

        emit Redeemed(storedBalance_, underlyingBalance, accrual);
    }

    /// @dev Retrieve any ERC20 tokens. Useful for airdropped tokens.
    /// @param token ERC20 contract object
    /// @param to Address of receiver
    function retrieve(IERC20 token, address to) external auth {
        require(
            address(token) != address(underlying),
            "Use exit for underlying"
        );
        MinimalTransferHelper.safeTransfer(
            token,
            to,
            token.balanceOf(address(this))
        );
    }

    /// @dev Retrieve any ERC1155 tokens other than the `asset`. Useful for airdropped tokens.
    /// @param token ERC1155 token passed as contract object
    /// @param id ID of ERC1155 token
    /// @param to Address of receiver
    function retrieveERC1155(
        ERC1155 token,
        uint256 id,
        address to
    ) external auth {
        require(
            address(token) != address(asset) || id != fCashId,
            "Use exit for asset"
        );
        token.safeTransferFrom(
            address(this),
            to,
            id,
            token.balanceOf(address(this), id),
            ""
        );
    }

    /// @dev Notional will send unwrapped ETH on redemption, which we have to wrap into WETH.
    receive() external payable {
        require(fCashId >> 48 == 1 && msg.sender == asset, "Only ETH NotionalJoins");
    }
}