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// SPDX-License-Identifier: MIT

pragma solidity 0.8.24;

import "openzeppelin-contracts/contracts/token/ERC20/utils/SafeERC20.sol";
import "./Balancer/vault/IVault.sol";
import "./Balancer/vault/IFlashLoanRecipient.sol";

import "../../Interfaces/ILeverageZapper.sol";
import "../../Interfaces/IFlashLoanReceiver.sol";
import "../../Interfaces/IFlashLoanProvider.sol";

contract BalancerFlashLoan is IFlashLoanRecipient, IFlashLoanProvider {
    using SafeERC20 for IERC20;

    IVault private constant vault = IVault(0xBA12222222228d8Ba445958a75a0704d566BF2C8);
    IFlashLoanReceiver public receiver;

    function makeFlashLoan(IERC20 _token, uint256 _amount, Operation _operation, bytes calldata _params) external {
        IERC20[] memory tokens = new IERC20[](1);
        tokens[0] = _token;
        uint256[] memory amounts = new uint256[](1);
        amounts[0] = _amount;

        // Data for the callback receiveFlashLoan
        bytes memory userData;
        if (_operation == Operation.OpenTrove) {
            ILeverageZapper.OpenLeveragedTroveParams memory openTroveParams =
                abi.decode(_params, (ILeverageZapper.OpenLeveragedTroveParams));
            userData = abi.encode(_operation, openTroveParams);
        } else if (_operation == Operation.LeverUpTrove) {
            ILeverageZapper.LeverUpTroveParams memory leverUpTroveParams =
                abi.decode(_params, (ILeverageZapper.LeverUpTroveParams));
            userData = abi.encode(_operation, leverUpTroveParams);
        } else if (_operation == Operation.LeverDownTrove) {
            ILeverageZapper.LeverDownTroveParams memory leverDownTroveParams =
                abi.decode(_params, (ILeverageZapper.LeverDownTroveParams));
            userData = abi.encode(_operation, leverDownTroveParams);
        } else if (_operation == Operation.CloseTrove) {
            IZapper.CloseTroveParams memory closeTroveParams = abi.decode(_params, (IZapper.CloseTroveParams));
            userData = abi.encode(_operation, closeTroveParams);
        } else {
            revert("LZ: Wrong Operation");
        }

        // This will be used by the callback below no
        receiver = IFlashLoanReceiver(msg.sender);

        vault.flashLoan(this, tokens, amounts, userData);

        // Reset receiver
        receiver = IFlashLoanReceiver(address(0));
    }

    function receiveFlashLoan(
        IERC20[] calldata tokens,
        uint256[] calldata amounts,
        uint256[] calldata feeAmounts,
        bytes calldata userData
    ) external override {
        require(msg.sender == address(vault), "Caller is not Vault");
        require(address(receiver) != address(0), "Flash loan not properly initiated");

        // decode and operation
        Operation operation = abi.decode(userData[0:32], (Operation));

        if (operation == Operation.OpenTrove) {
            // Open
            // decode params
            ILeverageZapper.OpenLeveragedTroveParams memory openTroveParams =
                abi.decode(userData[32:], (ILeverageZapper.OpenLeveragedTroveParams));
            // Flash loan minus fees
            uint256 effectiveFlashLoanAmount = amounts[0] - feeAmounts[0];
            // We send only effective flash loan, keeping fees here
            tokens[0].safeTransfer(address(receiver), effectiveFlashLoanAmount);
            // Zapper callback
            receiver.receiveFlashLoanOnOpenLeveragedTrove(openTroveParams, effectiveFlashLoanAmount);
        } else if (operation == Operation.LeverUpTrove) {
            // Lever up
            // decode params
            ILeverageZapper.LeverUpTroveParams memory leverUpTroveParams =
                abi.decode(userData[32:], (ILeverageZapper.LeverUpTroveParams));
            // Flash loan minus fees
            uint256 effectiveFlashLoanAmount = amounts[0] - feeAmounts[0];
            // We send only effective flash loan, keeping fees here
            tokens[0].safeTransfer(address(receiver), effectiveFlashLoanAmount);
            // Zapper callback
            receiver.receiveFlashLoanOnLeverUpTrove(leverUpTroveParams, effectiveFlashLoanAmount);
        } else if (operation == Operation.LeverDownTrove) {
            // Lever down
            // decode params
            ILeverageZapper.LeverDownTroveParams memory leverDownTroveParams =
                abi.decode(userData[32:], (ILeverageZapper.LeverDownTroveParams));
            // Flash loan minus fees
            uint256 effectiveFlashLoanAmount = amounts[0] - feeAmounts[0];
            // We send only effective flash loan, keeping fees here
            tokens[0].safeTransfer(address(receiver), effectiveFlashLoanAmount);
            // Zapper callback
            receiver.receiveFlashLoanOnLeverDownTrove(leverDownTroveParams, effectiveFlashLoanAmount);
        } else if (operation == Operation.CloseTrove) {
            // Close trove
            // decode params
            IZapper.CloseTroveParams memory closeTroveParams = abi.decode(userData[32:], (IZapper.CloseTroveParams));
            // Flash loan minus fees
            uint256 effectiveFlashLoanAmount = amounts[0] - feeAmounts[0];
            // We send only effective flash loan, keeping fees here
            tokens[0].safeTransfer(address(receiver), effectiveFlashLoanAmount);
            // Zapper callback
            receiver.receiveFlashLoanOnCloseTroveFromCollateral(closeTroveParams, effectiveFlashLoanAmount);
        } else {
            revert("LZ: Wrong Operation");
        }

        // Return flash loan
        tokens[0].safeTransfer(address(vault), amounts[0] + feeAmounts[0]);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.3) (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../extensions/IERC20Permit.sol";
import "../../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using Address for address;

    /**
     * @dev Transfer `value` amount of `token` from the calling contract to `to`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    /**
     * @dev Transfer `value` amount of `token` from `from` to `to`, spending the approval given by `from` to the
     * calling contract. If `token` returns no value, non-reverting calls are assumed to be successful.
     */
    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    /**
     * @dev Increase the calling contract's allowance toward `spender` by `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 oldAllowance = token.allowance(address(this), spender);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, oldAllowance + value));
    }

    /**
     * @dev Decrease the calling contract's allowance toward `spender` by `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, oldAllowance - value));
        }
    }

    /**
     * @dev Set the calling contract's allowance toward `spender` to `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful. Meant to be used with tokens that require the approval
     * to be set to zero before setting it to a non-zero value, such as USDT.
     */
    function forceApprove(IERC20 token, address spender, uint256 value) internal {
        bytes memory approvalCall = abi.encodeWithSelector(token.approve.selector, spender, value);

        if (!_callOptionalReturnBool(token, approvalCall)) {
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, 0));
            _callOptionalReturn(token, approvalCall);
        }
    }

    /**
     * @dev Use a ERC-2612 signature to set the `owner` approval toward `spender` on `token`.
     * Revert on invalid signature.
     */
    function safePermit(
        IERC20Permit token,
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal {
        uint256 nonceBefore = token.nonces(owner);
        token.permit(owner, spender, value, deadline, v, r, s);
        uint256 nonceAfter = token.nonces(owner);
        require(nonceAfter == nonceBefore + 1, "SafeERC20: permit did not succeed");
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address-functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        require(returndata.length == 0 || abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     *
     * This is a variant of {_callOptionalReturn} that silents catches all reverts and returns a bool instead.
     */
    function _callOptionalReturnBool(IERC20 token, bytes memory data) private returns (bool) {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We cannot use {Address-functionCall} here since this should return false
        // and not revert is the subcall reverts.

        (bool success, bytes memory returndata) = address(token).call(data);
        return
            success && (returndata.length == 0 || abi.decode(returndata, (bool))) && Address.isContract(address(token));
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

import "openzeppelin-contracts/contracts/token/ERC20/IERC20.sol";
import "./IFlashLoanRecipient.sol";

pragma solidity >=0.7.0 <0.9.0;

/**
 * @dev Full external interface for the Vault core contract - no external or public methods exist in the contract that
 * don't override one of these declarations.
 */
interface IVault {
    // Flash Loans

    /**
     * @dev Performs a 'flash loan', sending tokens to `recipient`, executing the `receiveFlashLoan` hook on it,
     * and then reverting unless the tokens plus a proportional protocol fee have been returned.
     *
     * The `tokens` and `amounts` arrays must have the same length, and each entry in these indicates the loan amount
     * for each token contract. `tokens` must be sorted in ascending order.
     *
     * The 'userData' field is ignored by the Vault, and forwarded as-is to `recipient` as part of the
     * `receiveFlashLoan` call.
     *
     * Emits `FlashLoan` events.
     */
    function flashLoan(
        IFlashLoanRecipient recipient,
        IERC20[] memory tokens,
        uint256[] memory amounts,
        bytes memory userData
    ) external;

    /**
     * @dev Emitted for each individual flash loan performed by `flashLoan`.
     */
    event FlashLoan(IFlashLoanRecipient indexed recipient, IERC20 indexed token, uint256 amount, uint256 feeAmount);

    /**
     * @dev Returns the Vault's WETH instance.
     */
    //function WETH() external view returns (IWETH);
    // solhint-disable-previous-line func-name-mixedcase
}

// SPDX-License-Identifier: GPL-3.0-or-later
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity >=0.7.0 <0.9.0;

// Inspired by Aave Protocol's IFlashLoanReceiver.

import "openzeppelin-contracts/contracts/token/ERC20/IERC20.sol";

interface IFlashLoanRecipient {
    /**
     * @dev When `flashLoan` is called on the Vault, it invokes the `receiveFlashLoan` hook on the recipient.
     *
     * At the time of the call, the Vault will have transferred `amounts` for `tokens` to the recipient. Before this
     * call returns, the recipient must have transferred `amounts` plus `feeAmounts` for each token back to the
     * Vault, or else the entire flash loan will revert.
     *
     * `userData` is the same value passed in the `IVault.flashLoan` call.
     */
    function receiveFlashLoan(
        IERC20[] memory tokens,
        uint256[] memory amounts,
        uint256[] memory feeAmounts,
        bytes memory userData
    ) external;
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IZapper.sol";

interface ILeverageZapper is IZapper {
    struct OpenLeveragedTroveParams {
        address owner;
        uint256 ownerIndex;
        uint256 collAmount;
        uint256 flashLoanAmount;
        uint256 boldAmount;
        uint256 upperHint;
        uint256 lowerHint;
        uint256 annualInterestRate;
        address batchManager;
        uint256 maxUpfrontFee;
        address addManager;
        address removeManager;
        address receiver;
    }

    struct LeverUpTroveParams {
        uint256 troveId;
        uint256 flashLoanAmount;
        uint256 boldAmount;
        uint256 maxUpfrontFee;
    }

    struct LeverDownTroveParams {
        uint256 troveId;
        uint256 flashLoanAmount;
        uint256 minBoldAmount;
    }

    function openLeveragedTroveWithRawETH(OpenLeveragedTroveParams calldata _params) external payable;

    function leverUpTrove(LeverUpTroveParams calldata _params) external;

    function leverDownTrove(LeverDownTroveParams calldata _params) external;

    function leverageRatioToCollateralRatio(uint256 _inputRatio) external pure returns (uint256);
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IZapper.sol";
import "./ILeverageZapper.sol";

interface IFlashLoanReceiver {
    function receiveFlashLoanOnOpenLeveragedTrove(
        ILeverageZapper.OpenLeveragedTroveParams calldata _params,
        uint256 _effectiveFlashLoanAmount
    ) external;
    function receiveFlashLoanOnLeverUpTrove(
        ILeverageZapper.LeverUpTroveParams calldata _params,
        uint256 _effectiveFlashLoanAmount
    ) external;
    function receiveFlashLoanOnLeverDownTrove(
        ILeverageZapper.LeverDownTroveParams calldata _params,
        uint256 _effectiveFlashLoanAmount
    ) external;
    function receiveFlashLoanOnCloseTroveFromCollateral(
        IZapper.CloseTroveParams calldata _params,
        uint256 _effectiveFlashLoanAmount
    ) external;
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "openzeppelin-contracts/contracts/token/ERC20/IERC20.sol";
import "./ILeverageZapper.sol";
import "./IFlashLoanReceiver.sol";

interface IFlashLoanProvider {
    enum Operation {
        OpenTrove,
        CloseTrove,
        LeverUpTrove,
        LeverDownTrove
    }

    function receiver() external view returns (IFlashLoanReceiver);

    function makeFlashLoan(IERC20 _token, uint256 _amount, Operation _operation, bytes calldata userData) external;
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);

    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `from` to `to` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address from, address to, uint256 amount) external returns (bool);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.4) (token/ERC20/extensions/IERC20Permit.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on {IERC20-approve}, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 *
 * ==== Security Considerations
 *
 * There are two important considerations concerning the use of `permit`. The first is that a valid permit signature
 * expresses an allowance, and it should not be assumed to convey additional meaning. In particular, it should not be
 * considered as an intention to spend the allowance in any specific way. The second is that because permits have
 * built-in replay protection and can be submitted by anyone, they can be frontrun. A protocol that uses permits should
 * take this into consideration and allow a `permit` call to fail. Combining these two aspects, a pattern that may be
 * generally recommended is:
 *
 * ```solidity
 * function doThingWithPermit(..., uint256 value, uint256 deadline, uint8 v, bytes32 r, bytes32 s) public {
 *     try token.permit(msg.sender, address(this), value, deadline, v, r, s) {} catch {}
 *     doThing(..., value);
 * }
 *
 * function doThing(..., uint256 value) public {
 *     token.safeTransferFrom(msg.sender, address(this), value);
 *     ...
 * }
 * ```
 *
 * Observe that: 1) `msg.sender` is used as the owner, leaving no ambiguity as to the signer intent, and 2) the use of
 * `try/catch` allows the permit to fail and makes the code tolerant to frontrunning. (See also
 * {SafeERC20-safeTransferFrom}).
 *
 * Additionally, note that smart contract wallets (such as Argent or Safe) are not able to produce permit signatures, so
 * contracts should have entry points that don't rely on permit.
 */
interface IERC20Permit {
    /**
     * @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
     * given ``owner``'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     *
     * CAUTION: See Security Considerations above.
     */
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    /**
     * @dev Returns the current nonce for `owner`. This value must be
     * included whenever a signature is generated for {permit}.
     *
     * Every successful call to {permit} increases ``owner``'s nonce by one. This
     * prevents a signature from being used multiple times.
     */
    function nonces(address owner) external view returns (uint256);

    /**
     * @dev Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.
     */
    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view returns (bytes32);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     *
     * Furthermore, `isContract` will also return true if the target contract within
     * the same transaction is already scheduled for destruction by `SELFDESTRUCT`,
     * which only has an effect at the end of a transaction.
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://consensys.net/diligence/blog/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.8.0/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verify that a low level call to smart-contract was successful, and revert (either by bubbling
     * the revert reason or using the provided one) in case of unsuccessful call or if target was not a contract.
     *
     * _Available since v4.8._
     */
    function verifyCallResultFromTarget(
        address target,
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        if (success) {
            if (returndata.length == 0) {
                // only check isContract if the call was successful and the return data is empty
                // otherwise we already know that it was a contract
                require(isContract(target), "Address: call to non-contract");
            }
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    /**
     * @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason or using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    function _revert(bytes memory returndata, string memory errorMessage) private pure {
        // Look for revert reason and bubble it up if present
        if (returndata.length > 0) {
            // The easiest way to bubble the revert reason is using memory via assembly
            /// @solidity memory-safe-assembly
            assembly {
                let returndata_size := mload(returndata)
                revert(add(32, returndata), returndata_size)
            }
        } else {
            revert(errorMessage);
        }
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IFlashLoanProvider.sol";
import "./IExchange.sol";

interface IZapper {
    struct OpenTroveParams {
        address owner;
        uint256 ownerIndex;
        uint256 collAmount;
        uint256 boldAmount;
        uint256 upperHint;
        uint256 lowerHint;
        uint256 annualInterestRate;
        address batchManager;
        uint256 maxUpfrontFee;
        address addManager;
        address removeManager;
        address receiver;
    }

    struct CloseTroveParams {
        uint256 troveId;
        uint256 flashLoanAmount;
        address receiver;
    }

    function flashLoanProvider() external view returns (IFlashLoanProvider);

    function exchange() external view returns (IExchange);

    function openTroveWithRawETH(OpenTroveParams calldata _params) external payable returns (uint256);

    function closeTroveFromCollateral(CloseTroveParams calldata _params) external;
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

interface IExchange {
    function swapFromBold(uint256 _boldAmount, uint256 _minCollAmount) external;

    function swapToBold(uint256 _collAmount, uint256 _minBoldAmount) external returns (uint256);
}

{
  "remappings": [
    "openzeppelin/=lib/V2-gov/lib/openzeppelin-contracts/",
    "@chimera/=lib/V2-gov/lib/chimera/src/",
    "@ensdomains/=lib/V2-gov/lib/v4-core/node_modules/@ensdomains/",
    "@openzeppelin/=lib/V2-gov/lib/v4-core/lib/openzeppelin-contracts/",
    "@openzeppelin/contracts/=lib/V2-gov/lib/openzeppelin-contracts/contracts/",
    "Solady/=lib/Solady/src/",
    "V2-gov/=lib/V2-gov/",
    "chimera/=lib/V2-gov/lib/chimera/src/",
    "ds-test/=lib/openzeppelin-contracts/lib/forge-std/lib/ds-test/src/",
    "erc4626-tests/=lib/openzeppelin-contracts/lib/erc4626-tests/",
    "forge-gas-snapshot/=lib/V2-gov/lib/v4-core/lib/forge-gas-snapshot/src/",
    "forge-std/=lib/forge-std/src/",
    "hardhat/=lib/V2-gov/lib/v4-core/node_modules/hardhat/",
    "openzeppelin-contracts/=lib/openzeppelin-contracts/",
    "solmate/=lib/V2-gov/lib/v4-core/lib/solmate/src/",
    "v4-core/=lib/V2-gov/lib/v4-core/"
  ],
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "metadata": {
    "useLiteralContent": false,
    "bytecodeHash": "ipfs",
    "appendCBOR": true
  },
  "outputSelection": {
    "*": {
      "*": [
        "evm.bytecode",
        "evm.deployedBytecode",
        "devdoc",
        "userdoc",
        "metadata",
        "abi"
      ]
    }
  },
  "evmVersion": "cancun",
  "viaIR": false,
  "libraries": {}
}

[{"inputs":[{"internalType":"contract IERC20","name":"_token","type":"address"},{"internalType":"uint256","name":"_amount","type":"uint256"},{"internalType":"enum IFlashLoanProvider.Operation","name":"_operation","type":"uint8"},{"internalType":"bytes","name":"_params","type":"bytes"}],"name":"makeFlashLoan","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"contract IERC20[]","name":"tokens","type":"address[]"},{"internalType":"uint256[]","name":"amounts","type":"uint256[]"},{"internalType":"uint256[]","name":"feeAmounts","type":"uint256[]"},{"internalType":"bytes","name":"userData","type":"bytes"}],"name":"receiveFlashLoan","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"receiver","outputs":[{"internalType":"contract IFlashLoanReceiver","name":"","type":"address"}],"stateMutability":"view","type":"function"}]

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