// SPDX-License-Identifier: MIT
// Gearbox Protocol. Generalized leverage for DeFi protocols
// (c) Gearbox Holdings, 2022
pragma solidity ^0.8.10;

import { Balance } from "../libraries/Balances.sol";
import { MultiCall } from "../libraries/MultiCall.sol";
import { ICreditManagerV2, ICreditManagerV2Exceptions } from "./ICreditManagerV2.sol";
import { IVersion } from "./IVersion.sol";

interface ICreditFacadeExtended {
    /// @dev Stores expected balances (computed as current balance + passed delta)
    ///      and compare with actual balances at the end of a multicall, reverts
    ///      if at least one is less than expected
    /// @param expected Array of expected balance changes
    /// @notice This is an extenstion function that does not exist in the Credit Facade
    ///         itself and can only be used within a multicall
    function revertIfReceivedLessThan(Balance[] memory expected) external;

    /// @dev Enables token in enabledTokenMask for the Credit Account of msg.sender
    /// @param token Address of token to enable
    function enableToken(address token) external;

    /// @dev Disables a token on the caller's Credit Account
    /// @param token Token to disable
    /// @notice This is an extenstion function that does not exist in the Credit Facade
    ///         itself and can only be used within a multicall
    function disableToken(address token) external;

    /// @dev Adds collateral to borrower's credit account
    /// @param token Address of a collateral token
    /// @param amount Amount to add
    function addCollateral(address token, uint256 amount) external payable;

    /// @dev Increases debt for msg.sender's Credit Account
    /// - Borrows the requested amount from the pool
    /// - Updates the CA's borrowAmount / cumulativeIndexOpen
    ///   to correctly compute interest going forward
    /// - Performs a full collateral check
    ///
    /// @param amount Amount to borrow
    function increaseDebt(uint256 amount) external;

    /// @dev Decrease debt
    /// - Decreases the debt by paying the requested amount + accrued interest + fees back to the pool
    /// - It's also include to this payment interest accrued at the moment and fees
    /// - Updates cunulativeIndex to cumulativeIndex now
    ///
    /// @param amount Amount to increase borrowed amount
    function decreaseDebt(uint256 amount) external;
}

interface ICreditFacadeEvents {
    /// @dev Emits when Blacklist Helper is set for the Credit Facade upon creation
    event BlacklistHelperSet(address indexed blacklistHelper);

    /// @dev Emits when a new Credit Account is opened through the
    ///      Credit Facade
    event OpenCreditAccount(
        address indexed onBehalfOf,
        address indexed creditAccount,
        uint256 borrowAmount,
        uint16 referralCode
    );

    /// @dev Emits when the account owner closes their CA normally
    event CloseCreditAccount(address indexed borrower, address indexed to);

    /// @dev Emits when a Credit Account is liquidated due to low health factor
    event LiquidateCreditAccount(
        address indexed borrower,
        address indexed liquidator,
        address indexed to,
        uint256 remainingFunds
    );

    /// @dev Emits when a Credit Account is liquidated due to expiry
    event LiquidateExpiredCreditAccount(
        address indexed borrower,
        address indexed liquidator,
        address indexed to,
        uint256 remainingFunds
    );

    /// @dev Emits when remaining funds in underlying currency are sent to
    ///      the blacklist helper upon blacklisted borrower liquidation
    event UnderlyingSentToBlacklistHelper(
        address indexed borrower,
        uint256 amount
    );

    /// @dev Emits when the account owner increases CA's debt
    event IncreaseBorrowedAmount(address indexed borrower, uint256 amount);

    /// @dev Emits when the account owner reduces CA's debt
    event DecreaseBorrowedAmount(address indexed borrower, uint256 amount);

    /// @dev Emits when the account owner add new collateral to a CA
    event AddCollateral(
        address indexed onBehalfOf,
        address indexed token,
        uint256 value
    );

    /// @dev Emits when a multicall is started
    event MultiCallStarted(address indexed borrower);

    /// @dev Emits when a multicall is finished
    event MultiCallFinished();

    /// @dev Emits when Credit Account ownership is transferred
    event TransferAccount(address indexed oldOwner, address indexed newOwner);

    /// @dev Emits when the user changes approval for account transfers to itself from another address
    event TransferAccountAllowed(
        address indexed from,
        address indexed to,
        bool state
    );

    /// @dev Emits when the account owner enables a token on their CA
    event TokenEnabled(address indexed borrower, address indexed token);

    /// @dev Emits when the account owner disables a token on their CA
    event TokenDisabled(address indexed borrower, address indexed token);

    /// @dev Emits when pool incurs loss on account liquidation and facade forbids borrowing
    event IncurLossOnLiquidation(uint256 loss);
}

interface ICreditFacadeExceptions is ICreditManagerV2Exceptions {
    /// @dev Thrown if the CreditFacade is not expirable, and an aciton is attempted that
    ///      requires expirability
    error NotAllowedWhenNotExpirableException();

    /// @dev Thrown if whitelisted mode is enabled, and an action is attempted that is
    ///      not allowed in whitelisted mode
    error NotAllowedInWhitelistedMode();

    /// @dev Thrown if a user attempts to transfer a CA to an address that didn't allow it
    error AccountTransferNotAllowedException();

    /// @dev Thrown if a liquidator tries to liquidate an account with a health factor above 1
    error CantLiquidateWithSuchHealthFactorException();

    /// @dev Thrown if a liquidator tries to liquidate an account by expiry while a Credit Facade is not expired
    error CantLiquidateNonExpiredException();

    /// @dev Thrown if call data passed to a multicall is too short
    error IncorrectCallDataException();

    /// @dev Thrown inside account closure multicall if the borrower attempts an action that is forbidden on closing
    ///      an account
    error ForbiddenDuringClosureException();

    /// @dev Thrown if debt increase and decrease are subsequently attempted in one multicall
    error IncreaseAndDecreaseForbiddenInOneCallException();

    /// @dev Thrown if a selector that doesn't match any allowed function is passed to the Credit Facade
    ///      during a multicall
    error UnknownMethodException();

    /// @dev Thrown if a user tries to open an account or increase debt with increaseDebtForbidden mode on
    error IncreaseDebtForbiddenException();

    /// @dev Thrown if the account owner tries to transfer an unhealthy account
    error CantTransferLiquidatableAccountException();

    /// @dev Thrown if too much new debt was taken within a single block
    error BorrowedBlockLimitException();

    /// @dev Thrown if the new debt principal for a CA falls outside of borrowing limits
    error BorrowAmountOutOfLimitsException();

    /// @dev Thrown if one of the balances on a Credit Account is less than expected
    ///      at the end of a multicall, if revertIfReceivedLessThan was called
    error BalanceLessThanMinimumDesiredException(address);

    /// @dev Thrown if a user attempts to open an account on a Credit Facade that has expired
    error OpenAccountNotAllowedAfterExpirationException();

    /// @dev Thrown if expected balances are attempted to be set through revertIfReceivedLessThan twice
    error ExpectedBalancesAlreadySetException();

    /// @dev Thrown if a Credit Account has enabled forbidden tokens and the owner attempts to perform an action
    ///      that is not allowed with any forbidden tokens enabled
    error ActionProhibitedWithForbiddenTokensException();

    /// @dev Thrown when attempting to perform an action on behalf of a borrower
    ///      that is blacklisted in the underlying token
    error NotAllowedForBlacklistedAddressException();

    /// @dev Thrown when the pool receives less funds than borrowAmountWithInterest on account closure
    error LiquiditySanityCheckException();
}

interface ICreditFacade is
    ICreditFacadeEvents,
    ICreditFacadeExceptions,
    IVersion
{
    //
    // CREDIT ACCOUNT MANAGEMENT
    //

    /// @dev Opens credit account, borrows funds from the pool and pulls collateral
    /// without any additional action.
    /// @param amount The amount of collateral provided by the borrower
    /// @param onBehalfOf The address to open an account for. Transfers to it have to be allowed if
    /// msg.sender != obBehalfOf
    /// @param leverageFactor Percentage of the user's own funds to borrow. 100 is equal to 100% - borrows the same amount
    /// as the user's own collateral, equivalent to 2x leverage.
    /// @param referralCode Referral code that is used for potential rewards. 0 if no referral code provided.
    function openCreditAccount(
        uint256 amount,
        address onBehalfOf,
        uint16 leverageFactor,
        uint16 referralCode
    ) external payable;

    /// @dev Opens a Credit Account and runs a batch of operations in a multicall
    /// @param borrowedAmount Debt size
    /// @param onBehalfOf The address to open an account for. Transfers to it have to be allowed if
    /// msg.sender != obBehalfOf
    /// @param calls The array of MultiCall structs encoding the required operations. Generally must have
    /// at least a call to addCollateral, as otherwise the health check at the end will fail.
    /// @param referralCode Referral code which is used for potential rewards. 0 if no referral code provided
    function openCreditAccountMulticall(
        uint256 borrowedAmount,
        address onBehalfOf,
        MultiCall[] calldata calls,
        uint16 referralCode
    ) external payable;

    /// @dev Runs a batch of transactions within a multicall and closes the account
    /// - Wraps ETH to WETH and sends it msg.sender if value > 0
    /// - Executes the multicall - the main purpose of a multicall when closing is to convert all assets to underlying
    /// in order to pay the debt.
    /// - Closes credit account:
    ///    + Checks the underlying balance: if it is greater than the amount paid to the pool, transfers the underlying
    ///      from the Credit Account and proceeds. If not, tries to transfer the shortfall from msg.sender.
    ///    + Transfers all enabled assets with non-zero balances to the "to" address, unless they are marked
    ///      to be skipped in skipTokenMask
    /// - Emits a CloseCreditAccount event
    ///
    /// @param to Address to send funds to during account closing
    /// @param skipTokenMask Uint-encoded bit mask where 1's mark tokens that shouldn't be transferred
    /// @param calls The array of MultiCall structs encoding the operations to execute before closing the account.
    function closeCreditAccount(
        address to,
        uint256 skipTokenMask,
        MultiCall[] calldata calls
    ) external payable;

    /// @dev A version of `closeCreditAccount` with `convertWETH` parameter that is ignored.
    ///      Used for backward compatibility.
    function closeCreditAccount(
        address to,
        uint256 skipTokenMask,
        bool convertWETH,
        MultiCall[] calldata calls
    ) external payable;

    /// @dev Runs a batch of transactions within a multicall and liquidates the account
    /// - Computes the total value and checks that hf < 1. An account can't be liquidated when hf >= 1.
    ///   Total value has to be computed before the multicall, otherwise the liquidator would be able
    ///   to manipulate it.
    /// - Wraps ETH to WETH and sends it to msg.sender (liquidator) if value > 0
    /// - Executes the multicall - the main purpose of a multicall when liquidating is to convert all assets to underlying
    ///   in order to pay the debt.
    /// - Liquidate credit account:
    ///    + Computes the amount that needs to be paid to the pool. If totalValue * liquidationDiscount < borrow + interest + fees,
    ///      only totalValue * liquidationDiscount has to be paid. Since liquidationDiscount < 1, the liquidator can take
    ///      totalValue * (1 - liquidationDiscount) as premium. Also computes the remaining funds to be sent to borrower
    ///      as totalValue * liquidationDiscount - amountToPool.
    ///    + Checks the underlying balance: if it is greater than amountToPool + remainingFunds, transfers the underlying
    ///      from the Credit Account and proceeds. If not, tries to transfer the shortfall from the liquidator.
    ///    + Transfers all enabled assets with non-zero balances to the "to" address, unless they are marked
    ///      to be skipped in skipTokenMask. If the liquidator is confident that all assets were converted
    ///      during the multicall, they can set the mask to uint256.max - 1, to only transfer the underlying
    /// - Emits LiquidateCreditAccount event
    ///
    /// @param to Address to send funds to after liquidation
    /// @param skipTokenMask Uint-encoded bit mask where 1's mark tokens that shouldn't be transferred
    /// @param calls The array of MultiCall structs encoding the operations to execute before liquidating the account.
    function liquidateCreditAccount(
        address borrower,
        address to,
        uint256 skipTokenMask,
        MultiCall[] calldata calls
    ) external payable;

    /// @dev A version of `liquidateCreditAccount` with `convertWETH` parameter that is ignored.
    ///      Used for backward compatibility.
    function liquidateCreditAccount(
        address borrower,
        address to,
        uint256 skipTokenMask,
        bool convertWETH,
        MultiCall[] calldata calls
    ) external payable;

    /// @dev Runs a batch of transactions within a multicall and liquidates the account when
    /// this Credit Facade is expired
    /// The general flow of liquidation is nearly the same as normal liquidations, with two main differences:
    ///     - An account can be liquidated on an expired Credit Facade even with hf > 1. However,
    ///       no accounts can be liquidated through this function if the Credit Facade is not expired.
    ///     - Liquidation premiums and fees for liquidating expired accounts are reduced.
    /// It is still possible to normally liquidate an underwater Credit Account, even when the Credit Facade
    /// is expired.
    /// @param to Address to send funds to after liquidation
    /// @param skipTokenMask Uint-encoded bit mask where 1's mark tokens that shouldn't be transferred
    /// @param calls The array of MultiCall structs encoding the operations to execute before liquidating the account.
    /// @notice See more at https://dev.gearbox.fi/docs/documentation/credit/liquidation#liquidating-accounts-by-expiration
    function liquidateExpiredCreditAccount(
        address borrower,
        address to,
        uint256 skipTokenMask,
        MultiCall[] calldata calls
    ) external payable;

    /// @dev A version of `liquidateExpiredCreditAccount` with `convertWETH` parameter that is ignored.
    ///      Used for backward compatibility.
    function liquidateExpiredCreditAccount(
        address borrower,
        address to,
        uint256 skipTokenMask,
        bool convertWETH,
        MultiCall[] calldata calls
    ) external payable;

    /// @dev Adds collateral to borrower's credit account
    /// @param onBehalfOf Address of the borrower whose account is funded
    /// @param token Address of a collateral token
    /// @param amount Amount to add
    function addCollateral(
        address onBehalfOf,
        address token,
        uint256 amount
    ) external payable;

    /// @dev Executes a batch of transactions within a Multicall, to manage an existing account
    ///  - Wraps ETH and sends it back to msg.sender, if value > 0
    ///  - Executes the Multicall
    ///  - Performs a fullCollateralCheck to verify that hf > 1 after all actions
    /// @param calls The array of MultiCall structs encoding the operations to execute.
    function multicall(MultiCall[] calldata calls) external payable;

    /// @dev Returns true if the borrower has an open Credit Account
    /// @param borrower Borrower address
    function hasOpenedCreditAccount(address borrower)
        external
        view
        returns (bool);

    /// @dev Approves account transfer from another user to msg.sender
    /// @param from Address for which account transfers are allowed/forbidden
    /// @param state True is transfer is allowed, false if forbidden
    function approveAccountTransfer(address from, bool state) external;

    /// @dev Transfers credit account to another user
    /// By default, this action is forbidden, and the user has to approve transfers from sender to itself
    /// by calling approveAccountTransfer.
    /// This is done to prevent malicious actors from transferring compromised accounts to other users.
    /// @param to Address to transfer the account to
    function transferAccountOwnership(address to) external;

    //
    // GETTERS
    //

    /// @dev Calculates total value for provided Credit Account in underlying
    ///
    /// @param creditAccount Credit Account address
    /// @return total Total value in underlying
    /// @return twv Total weighted (discounted by liquidation thresholds) value in underlying
    function calcTotalValue(address creditAccount)
        external
        view
        returns (uint256 total, uint256 twv);

    /**
     * @dev Calculates health factor for the credit account
     *
     *          sum(asset[i] * liquidation threshold[i])
     *   Hf = --------------------------------------------
     *         borrowed amount + interest accrued + fees
     *
     *
     * More info: https://dev.gearbox.fi/developers/credit/economy#health-factor
     *
     * @param creditAccount Credit account address
     * @return hf = Health factor in bp (see PERCENTAGE FACTOR in PercentageMath.sol)
     */
    function calcCreditAccountHealthFactor(address creditAccount)
        external
        view
        returns (uint256 hf);

    /// @dev Returns true if token is a collateral token and is not forbidden,
    /// otherwise returns false
    /// @param token Token to check
    function isTokenAllowed(address token) external view returns (bool);

    /// @dev Returns the CreditManager connected to this Credit Facade
    function creditManager() external view returns (ICreditManagerV2);

    /// @dev Returns true if 'from' is allowed to transfer Credit Accounts to 'to'
    /// @param from Sender address to check allowance for
    /// @param to Receiver address to check allowance for
    function transfersAllowed(address from, address to)
        external
        view
        returns (bool);

    /// @return maxBorrowedAmountPerBlock Maximal amount of new debt that can be taken per block
    /// @return isIncreaseDebtForbidden True if increasing debt is forbidden
    /// @return expirationDate Timestamp of the next expiration (for expirable Credit Facades only)
    /// @return emergencyLiquidationDiscount Premium for liquidations when the system is paused
    function params()
        external
        view
        returns (
            uint128 maxBorrowedAmountPerBlock,
            bool isIncreaseDebtForbidden,
            uint40 expirationDate,
            uint16 emergencyLiquidationDiscount
        );

    /// @return minBorrowedAmount Minimal borrowed amount per credit account
    /// @return maxBorrowedAmount Maximal borrowed amount per credit account
    function limits()
        external
        view
        returns (uint128 minBorrowedAmount, uint128 maxBorrowedAmount);

    function lossParams()
        external
        view
        returns (uint128 currentCumulativeLoss, uint128 maxCumulativeLoss);

    function totalDebt()
        external
        view
        returns (uint128 currentTotalDebt, uint128 totalDebtLimit);

    /// @dev Address of the DegenNFT that gatekeeps account openings in whitelisted mode
    function degenNFT() external view returns (address);

    /// @dev Address of the underlying asset
    function underlying() external view returns (address);

    /// @dev Address of the blacklist helper or address(0), if underlying is not blacklistable
    function blacklistHelper() external view returns (address);

    /// @dev Whether the underlying of connected Credit Manager is blacklistable
    function isBlacklistableUnderlying() external view returns (bool);
}

interface ICreditFacadeV2 {
    /// @return maxBorrowedAmountPerBlock Maximal amount of new debt that can be taken per block
    /// @return isIncreaseDebtForbidden True if increasing debt is forbidden
    /// @return expirationDate Timestamp of the next expiration (for expirable Credit Facades only)
    function params()
        external
        view
        returns (
            uint128 maxBorrowedAmountPerBlock,
            bool isIncreaseDebtForbidden,
            uint40 expirationDate
        );
}