// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Address.sol)

pragma solidity ^0.8.0;

/**
 * @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
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        assembly {
            size := extcodesize(account)
        }
        return size > 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://diligence.consensys.net/posts/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/v0.5.11/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 functionCall(target, data, "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");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResult(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) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResult(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) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason 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 {
            // 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

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/structs/EnumerableSet.sol)

pragma solidity ^0.8.0;

/**
 * @dev Library for managing
 * https://en.wikipedia.org/wiki/Set_(abstract_data_type)[sets] of primitive
 * types.
 *
 * Sets have the following properties:
 *
 * - Elements are added, removed, and checked for existence in constant time
 * (O(1)).
 * - Elements are enumerated in O(n). No guarantees are made on the ordering.
 *
 * ```
 * contract Example {
 *     // Add the library methods
 *     using EnumerableSet for EnumerableSet.AddressSet;
 *
 *     // Declare a set state variable
 *     EnumerableSet.AddressSet private mySet;
 * }
 * ```
 *
 * As of v3.3.0, sets of type `bytes32` (`Bytes32Set`), `address` (`AddressSet`)
 * and `uint256` (`UintSet`) are supported.
 */
library EnumerableSet {
    // To implement this library for multiple types with as little code
    // repetition as possible, we write it in terms of a generic Set type with
    // bytes32 values.
    // The Set implementation uses private functions, and user-facing
    // implementations (such as AddressSet) are just wrappers around the
    // underlying Set.
    // This means that we can only create new EnumerableSets for types that fit
    // in bytes32.

    struct Set {
        // Storage of set values
        bytes32[] _values;
        // Position of the value in the `values` array, plus 1 because index 0
        // means a value is not in the set.
        mapping(bytes32 => uint256) _indexes;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function _add(Set storage set, bytes32 value) private returns (bool) {
        if (!_contains(set, value)) {
            set._values.push(value);
            // The value is stored at length-1, but we add 1 to all indexes
            // and use 0 as a sentinel value
            set._indexes[value] = set._values.length;
            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function _remove(Set storage set, bytes32 value) private returns (bool) {
        // We read and store the value's index to prevent multiple reads from the same storage slot
        uint256 valueIndex = set._indexes[value];

        if (valueIndex != 0) {
            // Equivalent to contains(set, value)
            // To delete an element from the _values array in O(1), we swap the element to delete with the last one in
            // the array, and then remove the last element (sometimes called as 'swap and pop').
            // This modifies the order of the array, as noted in {at}.

            uint256 toDeleteIndex = valueIndex - 1;
            uint256 lastIndex = set._values.length - 1;

            if (lastIndex != toDeleteIndex) {
                bytes32 lastvalue = set._values[lastIndex];

                // Move the last value to the index where the value to delete is
                set._values[toDeleteIndex] = lastvalue;
                // Update the index for the moved value
                set._indexes[lastvalue] = valueIndex; // Replace lastvalue's index to valueIndex
            }

            // Delete the slot where the moved value was stored
            set._values.pop();

            // Delete the index for the deleted slot
            delete set._indexes[value];

            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function _contains(Set storage set, bytes32 value) private view returns (bool) {
        return set._indexes[value] != 0;
    }

    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function _length(Set storage set) private view returns (uint256) {
        return set._values.length;
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function _at(Set storage set, uint256 index) private view returns (bytes32) {
        return set._values[index];
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function _values(Set storage set) private view returns (bytes32[] memory) {
        return set._values;
    }

    // Bytes32Set

    struct Bytes32Set {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(Bytes32Set storage set, bytes32 value) internal returns (bool) {
        return _add(set._inner, value);
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(Bytes32Set storage set, bytes32 value) internal returns (bool) {
        return _remove(set._inner, value);
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(Bytes32Set storage set, bytes32 value) internal view returns (bool) {
        return _contains(set._inner, value);
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(Bytes32Set storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function at(Bytes32Set storage set, uint256 index) internal view returns (bytes32) {
        return _at(set._inner, index);
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function values(Bytes32Set storage set) internal view returns (bytes32[] memory) {
        return _values(set._inner);
    }

    // AddressSet

    struct AddressSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(AddressSet storage set, address value) internal returns (bool) {
        return _add(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(AddressSet storage set, address value) internal returns (bool) {
        return _remove(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(AddressSet storage set, address value) internal view returns (bool) {
        return _contains(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(AddressSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function at(AddressSet storage set, uint256 index) internal view returns (address) {
        return address(uint160(uint256(_at(set._inner, index))));
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function values(AddressSet storage set) internal view returns (address[] memory) {
        bytes32[] memory store = _values(set._inner);
        address[] memory result;

        assembly {
            result := store
        }

        return result;
    }

    // UintSet

    struct UintSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(UintSet storage set, uint256 value) internal returns (bool) {
        return _add(set._inner, bytes32(value));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(UintSet storage set, uint256 value) internal returns (bool) {
        return _remove(set._inner, bytes32(value));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(UintSet storage set, uint256 value) internal view returns (bool) {
        return _contains(set._inner, bytes32(value));
    }

    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function length(UintSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function at(UintSet storage set, uint256 index) internal view returns (uint256) {
        return uint256(_at(set._inner, index));
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function values(UintSet storage set) internal view returns (uint256[] memory) {
        bytes32[] memory store = _values(set._inner);
        uint256[] memory result;

        assembly {
            result := store
        }

        return result;
    }
}

// SPDX-License-Identifier: MIT
pragma solidity 0.8.3;

interface IAggregatorV3 {
    function decimals() external view returns (uint8);

    function description() external view returns (string memory);

    function version() external view returns (uint256);

    // getRoundData and latestRoundData should both raise "No data present"
    // if they do not have data to report, instead of returning unset values
    // which could be misinterpreted as actual reported values.
    function getRoundData(uint80 _roundId)
        external
        view
        returns (
            uint80 roundId,
            int256 answer,
            uint256 startedAt,
            uint256 updatedAt,
            uint80 answeredInRound
        );

    function latestRoundData()
        external
        view
        returns (
            uint80 roundId,
            int256 answer,
            uint256 startedAt,
            uint256 updatedAt,
            uint80 answeredInRound
        );
}

// SPDX-License-Identifier: MIT

pragma solidity 0.8.3;
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

interface CToken is IERC20 {
    function accrueInterest() external returns (uint256);

    function balanceOfUnderlying(address owner) external returns (uint256);

    function exchangeRateCurrent() external returns (uint256);

    function exchangeRateStored() external view returns (uint256);

    function mint() external payable; // For ETH

    function mint(uint256 mintAmount) external returns (uint256); // For ERC20

    function redeem(uint256 redeemTokens) external returns (uint256);

    function redeemUnderlying(uint256 redeemAmount) external returns (uint256);
}

interface Comptroller {
    function claimComp(address holder, address[] memory) external;

    function compAccrued(address holder) external view returns (uint256);
}

// SPDX-License-Identifier: MIT

//solhint-disable func-name-mixedcase, var-name-mixedcase
pragma solidity 0.8.3;

interface ICurveMetapool {
    function initialize(
        string memory _name,
        string memory _symbol,
        address _coin,
        uint256 _decimals,
        uint256 _A,
        uint256 _fee,
        address _admin
    ) external;

    function decimals() external view returns (uint256);

    function transfer(address _to, uint256 _value) external returns (bool);

    function transferFrom(
        address _from,
        address _to,
        uint256 _value
    ) external returns (bool);

    function approve(address _spender, uint256 _value) external returns (bool);

    function get_previous_balances() external view returns (uint256[2] memory);

    function get_balances() external view returns (uint256[2] memory);

    function get_twap_balances(
        uint256[2] memory _first_balances,
        uint256[2] memory _last_balances,
        uint256 _time_elapsed
    ) external view returns (uint256[2] memory);

    function get_price_cumulative_last() external view returns (uint256[2] memory);

    function admin_fee() external view returns (uint256);

    function A() external view returns (uint256);

    function A_precise() external view returns (uint256);

    function get_virtual_price() external view returns (uint256);

    function calc_token_amount(uint256[2] memory _amounts, bool _is_deposit) external view returns (uint256);

    function calc_token_amount(
        uint256[2] memory _amounts,
        bool _is_deposit,
        bool _previous
    ) external view returns (uint256);

    function add_liquidity(uint256[2] memory _amounts, uint256 _min_mint_amount) external returns (uint256);

    function add_liquidity(
        uint256[2] memory _amounts,
        uint256 _min_mint_amount,
        address _receiver
    ) external returns (uint256);

    function get_dy(
        int128 i,
        int128 j,
        uint256 dx
    ) external view returns (uint256);

    function get_dy(
        int128 i,
        int128 j,
        uint256 dx,
        uint256[2] memory _balances
    ) external view returns (uint256);

    function get_dy_underlying(
        int128 i,
        int128 j,
        uint256 dx
    ) external view returns (uint256);

    function get_dy_underlying(
        int128 i,
        int128 j,
        uint256 dx,
        uint256[2] memory _balances
    ) external view returns (uint256);

    function exchange(
        int128 i,
        int128 j,
        uint256 dx,
        uint256 min_dy
    ) external returns (uint256);

    function exchange(
        int128 i,
        int128 j,
        uint256 dx,
        uint256 min_dy,
        address _receiver
    ) external returns (uint256);

    function exchange_underlying(
        int128 i,
        int128 j,
        uint256 dx,
        uint256 min_dy
    ) external returns (uint256);

    function exchange_underlying(
        int128 i,
        int128 j,
        uint256 dx,
        uint256 min_dy,
        address _receiver
    ) external returns (uint256);

    function remove_liquidity(uint256 _burn_amount, uint256[2] memory _min_amounts)
        external
        returns (uint256[2] memory);

    function remove_liquidity(
        uint256 _burn_amount,
        uint256[2] memory _min_amounts,
        address _receiver
    ) external returns (uint256[2] memory);

    function remove_liquidity_imbalance(uint256[2] memory _amounts, uint256 _max_burn_amount)
        external
        returns (uint256);

    function remove_liquidity_imbalance(
        uint256[2] memory _amounts,
        uint256 _max_burn_amount,
        address _receiver
    ) external returns (uint256);

    function calc_withdraw_one_coin(uint256 _burn_amount, int128 i) external view returns (uint256);

    function calc_withdraw_one_coin(
        uint256 _burn_amount,
        int128 i,
        bool _previous
    ) external view returns (uint256);

    function remove_liquidity_one_coin(
        uint256 _burn_amount,
        int128 i,
        uint256 _min_received
    ) external returns (uint256);

    function remove_liquidity_one_coin(
        uint256 _burn_amount,
        int128 i,
        uint256 _min_received,
        address _receiver
    ) external returns (uint256);

    function ramp_A(uint256 _future_A, uint256 _future_time) external;

    function stop_ramp_A() external;

    function admin_balances(uint256 i) external view returns (uint256);

    function withdraw_admin_fees() external;

    function admin() external view returns (address);

    function coins(uint256 arg0) external view returns (address);

    function balances(uint256 arg0) external view returns (uint256);

    function fee() external view returns (uint256);

    function block_timestamp_last() external view returns (uint256);

    function initial_A() external view returns (uint256);

    function future_A() external view returns (uint256);

    function initial_A_time() external view returns (uint256);

    function future_A_time() external view returns (uint256);

    function name() external view returns (string memory);

    function symbol() external view returns (string memory);

    function balanceOf(address arg0) external view returns (uint256);

    function allowance(address arg0, address arg1) external view returns (uint256);

    function totalSupply() external view returns (uint256);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @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 `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, 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 `sender` to `recipient` 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 sender,
        address recipient,
        uint256 amount
    ) external returns (bool);

    /**
     * @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);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";

/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
interface IERC20Metadata is IERC20 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the symbol of the token.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the decimals places of the token.
     */
    function decimals() external view returns (uint8);
}

// SPDX-License-Identifier: MIT

pragma solidity 0.8.3;

import "@openzeppelin/contracts/token/ERC20/extensions/draft-IERC20Permit.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

interface IVUSD is IERC20, IERC20Permit {
    function burnFrom(address _user, uint256 _amount) external;

    function mint(address _to, uint256 _amount) external;

    function multiTransfer(address[] memory _recipients, uint256[] memory _amounts) external returns (bool);

    function updateMinter(address _newMinter) external;

    function updateTreasury(address _newTreasury) external;

    function governor() external view returns (address _governor);

    function minter() external view returns (address _minter);

    function treasury() external view returns (address _treasury);
}

// SPDX-License-Identifier: MIT

pragma solidity 0.8.3;

import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/utils/Context.sol";
import "@openzeppelin/contracts/utils/structs/EnumerableSet.sol";
import "./interfaces/chainlink/IAggregatorV3.sol";
import "./interfaces/compound/ICompound.sol";
import "./interfaces/curve/ICurveMetapool.sol";
import "./interfaces/IVUSD.sol";

/// @title Minter contract which will mint VUSD 1:1, less minting fee, with DAI, USDC or USDT.
contract Minter is Context, ReentrancyGuard {
    using SafeERC20 for IERC20;
    using EnumerableSet for EnumerableSet.AddressSet;

    string public constant NAME = "VUSD-Minter";
    string public constant VERSION = "1.3.0";

    IVUSD public immutable vusd;

    uint256 public mintingFee; // Default no fee
    uint256 public constant MAX_BPS = 10_000; // 10_000 = 100%
    uint256 public constant MINT_LIMIT = 50_000_000 * 10**18; // 50M VUSD
    uint256 private constant STABLE_PRICE = 100_000_000;
    uint256 private constant MAX_UINT_VALUE = type(uint256).max;
    uint256 public priceDeviationLimit = 400; // 4% based on BPS
    uint256 internal priceUpperBound;
    uint256 internal priceLowerBound;

    // Token => cToken mapping
    mapping(address => address) public cTokens;
    // Token => oracle mapping
    mapping(address => address) public oracles;

    address public constant CURVE_METAPOOL = 0x4dF9E1A764Fb8Df1113EC02fc9dc75963395b508;
    EnumerableSet.AddressSet private _whitelistedTokens;

    // Default whitelist token addresses
    address private constant DAI = 0x6B175474E89094C44Da98b954EedeAC495271d0F;
    address private constant USDC = 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48;

    // cToken addresses for default whitelisted tokens
    //solhint-disable const-name-snakecase
    address private constant cDAI = 0x5d3a536E4D6DbD6114cc1Ead35777bAB948E3643;
    address private constant cUSDC = 0x39AA39c021dfbaE8faC545936693aC917d5E7563;

    // Chainlink price oracle for default whitelisted tokens
    address private constant DAI_USD = 0xAed0c38402a5d19df6E4c03F4E2DceD6e29c1ee9;
    address private constant USDC_USD = 0x8fFfFfd4AfB6115b954Bd326cbe7B4BA576818f6;

    event UpdatedMintingFee(uint256 previousMintingFee, uint256 newMintingFee);
    event UpdatedPriceDeviationLimit(uint256 previousDeviationLimit, uint256 newDeviationLimit);

    constructor(address _vusd) {
        require(_vusd != address(0), "vusd-address-is-zero");
        vusd = IVUSD(_vusd);

        // Add token into the list, add oracle and cToken into the mapping and approve cToken to spend token
        _addToken(DAI, cDAI, DAI_USD);
        _addToken(USDC, cUSDC, USDC_USD);
        IERC20(_vusd).safeApprove(CURVE_METAPOOL, MAX_UINT_VALUE);
    }

    modifier onlyGovernor() {
        require(_msgSender() == governor(), "caller-is-not-the-governor");
        _;
    }

    ////////////////////////////// Only Governor //////////////////////////////
    /**
     * @notice Add token as whitelisted token for VUSD system
     * @dev Add token address in whitelistedTokens list and add cToken in mapping
     * @param _token address which we want to add in token list.
     * @param _cToken CToken address correspond to _token
     * @param _oracle Chainlink oracle address for token/USD feed
     */
    function addWhitelistedToken(
        address _token,
        address _cToken,
        address _oracle
    ) external onlyGovernor {
        require(_token != address(0), "token-address-is-zero");
        require(_cToken != address(0), "cToken-address-is-zero");
        require(_oracle != address(0), "oracle-address-is-zero");
        _addToken(_token, _cToken, _oracle);
    }

    /**
     * @notice Remove token from whitelisted tokens
     * @param _token address which we want to remove from token list.
     */
    function removeWhitelistedToken(address _token) external onlyGovernor {
        require(_whitelistedTokens.remove(_token), "remove-from-list-failed");
        IERC20(_token).safeApprove(cTokens[_token], 0);
        delete cTokens[_token];
        delete oracles[_token];
    }

    /**
     * @notice Mint request amount of VUSD and use minted VUSD to add liquidity in metapool
     * @dev Treasury will receive LP tokens of metapool liquidity
     * @param _amount Amount of VUSD to mint
     */
    function mintAndAddLiquidity(uint256 _amount) external onlyGovernor {
        uint256 _availableMintage = availableMintage();
        if (_amount > _availableMintage) {
            _amount = _availableMintage;
        }
        vusd.mint(address(this), _amount);
        ICurveMetapool(CURVE_METAPOOL).add_liquidity([_amount, 0], 1, treasury());
    }

    /// @notice Update minting fee
    function updateMintingFee(uint256 _newMintingFee) external onlyGovernor {
        require(_newMintingFee <= MAX_BPS, "minting-fee-limit-reached");
        require(mintingFee != _newMintingFee, "same-minting-fee");
        emit UpdatedMintingFee(mintingFee, _newMintingFee);
        mintingFee = _newMintingFee;
    }

    /// @notice Update price deviation limit
    function updatePriceDeviationLimit(uint256 _newDeviationLimit) external onlyGovernor {
        require(_newDeviationLimit <= MAX_BPS, "price-deviation-is-invalid");
        require(priceDeviationLimit != _newDeviationLimit, "same-price-deviation-limit");
        emit UpdatedPriceDeviationLimit(priceDeviationLimit, _newDeviationLimit);
        priceDeviationLimit = _newDeviationLimit;
    }

    ///////////////////////////////////////////////////////////////////////////

    /**
     * @notice Mint VUSD
     * @param _token Address of token being deposited
     * @param _amount Amount of _token
     */
    function mint(address _token, uint256 _amount) external nonReentrant {
        _mint(_token, _amount, _msgSender());
    }

    /**
     * @notice Mint VUSD
     * @param _token Address of token being deposited
     * @param _amount Amount of _token
     * @param _receiver Address of VUSD receiver
     */
    function mint(
        address _token,
        uint256 _amount,
        address _receiver
    ) external nonReentrant {
        _mint(_token, _amount, _receiver);
    }

    /**
     * @notice Calculate mintage for supported tokens.
     * @param _token Address of token which will be deposited for this mintage
     * @param _amount Amount of _token
     */
    function calculateMintage(address _token, uint256 _amount) external view returns (uint256 _mintReturn) {
        if (_whitelistedTokens.contains(_token)) {
            (uint256 _mintage, ) = _calculateMintage(_token, _amount);
            return _mintage;
        }
        // Return 0 for unsupported tokens.
        return 0;
    }

    /**
     * @notice Check whether minting is allowed or not.
     * @dev We are using chainlink oracle to check latest price and if price
     * is within allowed range then only minting is allowed.
     * @param _token Address of any of whitelisted token
     */
    function isMintingAllowed(address _token) external view returns (bool) {
        if (_whitelistedTokens.contains(_token)) {
            return _isMintingAllowed(_token);
        }
        return false;
    }

    /// @notice Returns whether given address is whitelisted or not
    function isWhitelistedToken(address _address) external view returns (bool) {
        return _whitelistedTokens.contains(_address);
    }

    /// @notice Return list of whitelisted tokens
    function whitelistedTokens() external view returns (address[] memory) {
        return _whitelistedTokens.values();
    }

    /// @notice Check available mintage based on mint limit
    function availableMintage() public view returns (uint256 _mintage) {
        return MINT_LIMIT - vusd.totalSupply();
    }

    /// @dev Treasury is defined in VUSD token contract only
    function treasury() public view returns (address) {
        return vusd.treasury();
    }

    /// @dev Governor is defined in VUSD token contract only
    function governor() public view returns (address) {
        return vusd.governor();
    }

    /**
     * @dev Add _token into the list, add _cToken in mapping and
     * approve cToken to spend token
     */
    function _addToken(
        address _token,
        address _cToken,
        address _oracle
    ) internal {
        require(_whitelistedTokens.add(_token), "add-in-list-failed");
        oracles[_token] = _oracle;
        cTokens[_token] = _cToken;
        IERC20(_token).safeApprove(_cToken, type(uint256).max);
    }

    /**
     * @notice Mint VUSD
     * @param _token Address of token being deposited
     * @param _amount Amount of _token
     * @param _receiver Address of VUSD receiver
     */
    function _mint(
        address _token,
        uint256 _amount,
        address _receiver
    ) internal {
        require(_whitelistedTokens.contains(_token), "token-is-not-supported");
        require(_isMintingAllowed(_token), "too-much-token-price-deviation");
        (uint256 _mintage, uint256 _actualAmount) = _calculateMintage(_token, _amount);
        require(_mintage != 0, "mint-limit-reached");
        IERC20(_token).safeTransferFrom(_msgSender(), address(this), _actualAmount);
        address _cToken = cTokens[_token];
        require(CToken(_cToken).mint(_actualAmount) == 0, "cToken-mint-failed");
        IERC20(_cToken).safeTransfer(treasury(), IERC20(_cToken).balanceOf(address(this)));
        vusd.mint(_receiver, _mintage);
    }

    /**
     * @notice Calculate mintage based on mintingFee, if any.
     * Also covert _token defined decimal amount to 18 decimal amount
     * @return _mintage VUSD mintage based on given input
     * @return _actualAmount Actual token amount used for _mintage
     */
    function _calculateMintage(address _token, uint256 _amount)
        internal
        view
        returns (uint256 _mintage, uint256 _actualAmount)
    {
        uint256 _decimals = IERC20Metadata(_token).decimals();
        uint256 _availableAmount = availableMintage() / 10**(18 - _decimals);
        _actualAmount = (_amount > _availableAmount) ? _availableAmount : _amount;
        _mintage = (mintingFee != 0) ? _actualAmount - ((_actualAmount * mintingFee) / MAX_BPS) : _actualAmount;
        // Convert final amount to 18 decimals
        _mintage = _mintage * 10**(18 - _decimals);
    }

    function _isMintingAllowed(address _token) internal view returns (bool) {
        address _oracle = oracles[_token];
        uint8 _oracleDecimal = IAggregatorV3(_oracle).decimals();
        uint256 _stablePrice = 10**_oracleDecimal;
        uint256 _deviationInPrice = (_stablePrice * priceDeviationLimit) / MAX_BPS;
        uint256 _priceUpperBound = _stablePrice + _deviationInPrice;
        uint256 _priceLowerBound = _stablePrice - _deviationInPrice;
        (, int256 _price, , , ) = IAggregatorV3(_oracle).latestRoundData();

        uint256 _latestPrice = uint256(_price);
        return _latestPrice <= _priceUpperBound && _latestPrice >= _priceLowerBound;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (security/ReentrancyGuard.sol)

pragma solidity ^0.8.0;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;

    uint256 private _status;

    constructor() {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and making it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;

        _;

        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

import "../IERC20.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;

    function safeTransfer(
        IERC20 token,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    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));
    }

    function safeIncreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    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");
            uint256 newAllowance = oldAllowance - value;
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
        }
    }

    /**
     * @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");
        if (returndata.length > 0) {
            // Return data is optional
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/draft-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.
 */
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].
     */
    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);
}

{
  "compilationTarget": {
    "contracts/Minter.sol": "Minter"
  },
  "evmVersion": "istanbul",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs",
    "useLiteralContent": true
  },
  "optimizer": {
    "enabled": false,
    "runs": 200
  },
  "remappings": []
}