1.sol

// SPDX-License-Identifier: AGPL-3.0-only
pragma solidity ^0.8.0;
library Counters {
    struct Counter {
        // This variable should never be directly accessed by users of the library: interactions must be restricted to
        // the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add
        // this feature: see https://github.com/ethereum/solidity/issues/4637
        uint256 _value; // default: 0
    }

    function current(Counter storage counter) internal view returns (uint256) {
        return counter._value;
    }

    function increment(Counter storage counter) internal {
        unchecked {
            counter._value += 1;
        }
    }

    function decrement(Counter storage counter) internal {
        uint256 value = counter._value;
        require(value > 0, "Counter: decrement overflow");
        unchecked {
            counter._value = value - 1;
        }
    }

    function reset(Counter storage counter) internal {
        counter._value = 0;
    }
}

abstract contract ERC20 {
    /*//////////////////////////////////////////////////////////////
                                 EVENTS
    //////////////////////////////////////////////////////////////*/

    event Transfer(address indexed from, address indexed to, uint256 amount);

    event Approval(address indexed owner, address indexed spender, uint256 amount);

    /*//////////////////////////////////////////////////////////////
                            METADATA STORAGE
    //////////////////////////////////////////////////////////////*/

    string public name;

    string public symbol;

    uint8 public immutable decimals;

    /*//////////////////////////////////////////////////////////////
                              ERC20 STORAGE
    //////////////////////////////////////////////////////////////*/

    uint256 public totalSupply;

    mapping(address => uint256) public balanceOf;

    mapping(address => mapping(address => uint256)) public allowance;

    /*//////////////////////////////////////////////////////////////
                            EIP-2612 STORAGE
    //////////////////////////////////////////////////////////////*/

    uint256 internal immutable INITIAL_CHAIN_ID;

    bytes32 internal immutable INITIAL_DOMAIN_SEPARATOR;

    mapping(address => uint256) public nonces;

    /*//////////////////////////////////////////////////////////////
                               CONSTRUCTOR
    //////////////////////////////////////////////////////////////*/

    constructor(
        string memory _name,
        string memory _symbol,
        uint8 _decimals
    ) {
        name = _name;
        symbol = _symbol;
        decimals = _decimals;

        INITIAL_CHAIN_ID = block.chainid;
        INITIAL_DOMAIN_SEPARATOR = computeDomainSeparator();
    }

    /*//////////////////////////////////////////////////////////////
                               ERC20 LOGIC
    //////////////////////////////////////////////////////////////*/



    /*//////////////////////////////////////////////////////////////
                             EIP-2612 LOGIC
    //////////////////////////////////////////////////////////////*/

    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) public virtual {
        require(deadline >= block.timestamp, "PERMIT_DEADLINE_EXPIRED");

        // Unchecked because the only math done is incrementing
        // the owner's nonce which cannot realistically overflow.
        unchecked {
            address recoveredAddress = ecrecover(
                keccak256(
                    abi.encodePacked(
                        "\x19\x01",
                        DOMAIN_SEPARATOR(),
                        keccak256(
                            abi.encode(
                                keccak256(
                                    "Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)"
                                ),
                                owner,
                                spender,
                                value,
                                nonces[owner]++,
                                deadline
                            )
                        )
                    )
                ),
                v,
                r,
                s
            );

            require(recoveredAddress != address(0) && recoveredAddress == owner, "INVALID_SIGNER");

            allowance[recoveredAddress][spender] = value;
        }

        emit Approval(owner, spender, value);
    }

    function DOMAIN_SEPARATOR() public view virtual returns (bytes32) {
        return block.chainid == INITIAL_CHAIN_ID ? INITIAL_DOMAIN_SEPARATOR : computeDomainSeparator();
    }

    function computeDomainSeparator() internal view virtual returns (bytes32) {
        return
            keccak256(
                abi.encode(
                    keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),
                    keccak256(bytes(name)),
                    keccak256("1"),
                    block.chainid,
                    address(this)
                )
            );
    }

    /*//////////////////////////////////////////////////////////////
                        INTERNAL MINT/BURN LOGIC
    //////////////////////////////////////////////////////////////*/

    function _mint(address to, uint256 amount) internal virtual {
        totalSupply += amount;

        // Cannot overflow because the sum of all user
        // balances can't exceed the max uint256 value.
        unchecked {
            balanceOf[to] += amount;
        }

        emit Transfer(address(0), to, amount);
    }

    function _burn(address from, uint256 amount) internal virtual {
        balanceOf[from] -= amount;

        // Cannot underflow because a user's balance
        // will never be larger than the total supply.
        unchecked {
            totalSupply -= amount;
        }

        emit Transfer(from, address(0), amount);
    }
}


contract VolatileToken is ERC20 {
    constructor(
        string memory _name,
        string memory _symbol,
        uint8 _decimals
    ) ERC20(_name, _symbol, _decimals) {}

    function mint(address to, uint256 amount) external {
        _mint(to, amount);
    }

    function burn(address from, uint256 amount) external {
        _burn(from, amount);
    }
}

/// @notice Safe ETH and ERC20 transfer library that gracefully handles missing return values.
/// @author Solmate (https://github.com/transmissions11/solmate/blob/main/src/utils/SafeTransferLib.sol)
/// @dev Use with caution! Some functions in this library knowingly create dirty bits at the destination of the free memory pointer.
/// @dev Note that none of the functions in this library check that a token has code at all! That responsibility is delegated to the caller.
library SafeTransferLib {
    /*//////////////////////////////////////////////////////////////
                             ETH OPERATIONS
    //////////////////////////////////////////////////////////////*/

    function safeTransferETH(address to, uint256 amount) internal {
        bool success;

        /// @solidity memory-safe-assembly
        assembly {
            // Transfer the ETH and store if it succeeded or not.
            success := call(gas(), to, amount, 0, 0, 0, 0)
        }

        require(success, "ETH_TRANSFER_FAILED");
    }

    /*//////////////////////////////////////////////////////////////
                            ERC20 OPERATIONS
    //////////////////////////////////////////////////////////////*/

    function safeTransferFrom(
        ERC20 token,
        address from,
        address to,
        uint256 amount
    ) internal {
        bool success;

        /// @solidity memory-safe-assembly
        assembly {
            // Get a pointer to some free memory.
            let freeMemoryPointer := mload(0x40)

            // Write the abi-encoded calldata into memory, beginning with the function selector.
            mstore(freeMemoryPointer, 0x23b872dd00000000000000000000000000000000000000000000000000000000)
            mstore(add(freeMemoryPointer, 4), from) // Append the "from" argument.
            mstore(add(freeMemoryPointer, 36), to) // Append the "to" argument.
            mstore(add(freeMemoryPointer, 68), amount) // Append the "amount" argument.

            success := and(
                // Set success to whether the call reverted, if not we check it either
                // returned exactly 1 (can't just be non-zero data), or had no return data.
                or(and(eq(mload(0), 1), gt(returndatasize(), 31)), iszero(returndatasize())),
                // We use 100 because the length of our calldata totals up like so: 4 + 32 * 3.
                // We use 0 and 32 to copy up to 32 bytes of return data into the scratch space.
                // Counterintuitively, this call must be positioned second to the or() call in the
                // surrounding and() call or else returndatasize() will be zero during the computation.
                call(gas(), token, 0, freeMemoryPointer, 100, 0, 32)
            )
        }

        require(success, "TRANSFER_FROM_FAILED");
    }

    function safeTransfer(
        ERC20 token,
        address to,
        uint256 amount
    ) internal {
        bool success;

        /// @solidity memory-safe-assembly
        assembly {
            // Get a pointer to some free memory.
            let freeMemoryPointer := mload(0x40)

            // Write the abi-encoded calldata into memory, beginning with the function selector.
            mstore(freeMemoryPointer, 0xa9059cbb00000000000000000000000000000000000000000000000000000000)
            mstore(add(freeMemoryPointer, 4), to) // Append the "to" argument.
            mstore(add(freeMemoryPointer, 36), amount) // Append the "amount" argument.

            success := and(
                // Set success to whether the call reverted, if not we check it either
                // returned exactly 1 (can't just be non-zero data), or had no return data.
                or(and(eq(mload(0), 1), gt(returndatasize(), 31)), iszero(returndatasize())),
                // We use 68 because the length of our calldata totals up like so: 4 + 32 * 2.
                // We use 0 and 32 to copy up to 32 bytes of return data into the scratch space.
                // Counterintuitively, this call must be positioned second to the or() call in the
                // surrounding and() call or else returndatasize() will be zero during the computation.
                call(gas(), token, 0, freeMemoryPointer, 68, 0, 32)
            )
        }

        require(success, "TRANSFER_FAILED");
    }

    function safeApprove(
        ERC20 token,
        address to,
        uint256 amount
    ) internal {
        bool success;

        /// @solidity memory-safe-assembly
        assembly {
            // Get a pointer to some free memory.
            let freeMemoryPointer := mload(0x40)

            // Write the abi-encoded calldata into memory, beginning with the function selector.
            mstore(freeMemoryPointer, 0x095ea7b300000000000000000000000000000000000000000000000000000000)
            mstore(add(freeMemoryPointer, 4), to) // Append the "to" argument.
            mstore(add(freeMemoryPointer, 36), amount) // Append the "amount" argument.

            success := and(
                // Set success to whether the call reverted, if not we check it either
                // returned exactly 1 (can't just be non-zero data), or had no return data.
                or(and(eq(mload(0), 1), gt(returndatasize(), 31)), iszero(returndatasize())),
                // We use 68 because the length of our calldata totals up like so: 4 + 32 * 2.
                // We use 0 and 32 to copy up to 32 bytes of return data into the scratch space.
                // Counterintuitively, this call must be positioned second to the or() call in the
                // surrounding and() call or else returndatasize() will be zero during the computation.
                call(gas(), token, 0, freeMemoryPointer, 68, 0, 32)
            )
        }

        require(success, "APPROVE_FAILED");
    }
}
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) {
        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly { codehash := extcodehash(account) }
        return (codehash != accountHash && codehash != 0x0);
    }

    /**
     * @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");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }
}
/**
 * @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 ERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
 library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}
library SafeERC20 {
    using SafeMath for uint256;
    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));
    }

    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'
        // solhint-disable-next-line max-line-length
        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).add(value);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
        _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.

        // A Solidity high level call has three parts:
        //  1. The target address is checked to verify it contains contract code
        //  2. The call itself is made, and success asserted
        //  3. The return value is decoded, which in turn checks the size of the returned data.
        // solhint-disable-next-line max-line-length
        require(address(token).isContract(), "SafeERC20: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = address(token).call(data);
        require(success, "SafeERC20: low-level call failed");

        if (returndata.length > 0) { // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}
interface IERC4626 {
    /*///////////////////////////////////////////////////////////////
                                Events
    //////////////////////////////////////////////////////////////*/

    event Deposit(address indexed from, address indexed to, uint256 amount, uint256 shares);
    event Withdraw(address indexed from, address indexed to, uint256 amount, uint256 shares);


    /*///////////////////////////////////////////////////////////////
                            Mutable Functions
    //////////////////////////////////////////////////////////////*/

    function deposit(uint256 amount, address to) external returns (uint256 shares);

    function mint(uint256 shares, address to) external returns (uint256 underlyingAmount);

    function withdraw(
        uint256 amount,
        address to,
        address from
    ) external returns (uint256 shares);

    function redeem(
        uint256 shares,
        address to,
        address from
    ) external returns (uint256 amount);

    /*///////////////////////////////////////////////////////////////
                            View Functions
    //////////////////////////////////////////////////////////////*/

    function totalAssets() external view returns (uint256);

    function assetsOf(address user) external view  returns (uint256);

    function assetsPerShare() external view returns (uint256);

    function maxDeposit(address) external returns (uint256);

    function maxMint(address) external returns (uint256);

    function maxRedeem(address user) external view returns (uint256);

    function maxWithdraw(address user) external view  returns (uint256);

    /**
      @notice Returns the amount of vault tokens that would be obtained if depositing a given amount of underlying tokens in a `deposit` call.
      @param underlyingAmount the input amount of underlying tokens
      @return shareAmount the corresponding amount of shares out from a deposit call with `underlyingAmount` in
     */
    function previewDeposit(uint256 underlyingAmount) external view returns (uint256 shareAmount);

    /**
      @notice Returns the amount of underlying tokens that would be deposited if minting a given amount of shares in a `mint` call.
      @param shareAmount the amount of shares from a mint call.
      @return underlyingAmount the amount of underlying tokens corresponding to the mint call
     */
    function previewMint(uint256 shareAmount) external view returns (uint256 underlyingAmount);

    /**
      @notice Returns the amount of vault tokens that would be burned if withdrawing a given amount of underlying tokens in a `withdraw` call.
      @param underlyingAmount the input amount of underlying tokens
      @return shareAmount the corresponding amount of shares out from a withdraw call with `underlyingAmount` in
     */
    function previewWithdraw(uint256 underlyingAmount) external view returns (uint256 shareAmount);

    /**
      @notice Returns the amount of underlying tokens that would be obtained if redeeming a given amount of shares in a `redeem` call.
      @param shareAmount the amount of shares from a redeem call.
      @return underlyingAmount the amount of underlying tokens corresponding to the redeem call
     */
    function previewRedeem(uint256 shareAmount) external view returns (uint256 underlyingAmount);
}

interface AggregatorV3Interface {
    function getRate(
        address srcToken,
        address dstToken,
        bool useWrappers
    ) 
    external view returns (
        uint256 weightedRate
        );
}
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);
}

/**
 * @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);
}

/*
 * @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;
    }
}

/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin guidelines: functions revert instead
 * of returning `false` on failure. This behavior is nonetheless conventional
 * and does not conflict with the expectations of ERC20 applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */

interface IWETH9 is IERC20 {

    function deposit() external payable;

    function withdraw(uint256 wad) external;

    function totalSupply() external view returns (uint256);

    function approve(address spender, uint256 amount) external returns (bool);

    function transfer(address to, uint256 amount) external returns (bool);

    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) external returns (bool);

    function balanceOf(address user) external view returns (uint);
}

/// Deposit, Withdraw, Mint, Redeem exists for Stable.
/// Fund & Defund exists for Volatility.
/// All reserve asset accounting (WETH) is done inside of Stable Vault. There is only one accounting.
/// Preserves 4626 expected interface (eg vault mint/burn operating on one underlying).
interface ICashier {
    function depositTo(address _token, address _to, uint256 _amount) external payable;
}

interface ICrosschainToken {
    function deposit(uint256 _amount) external;
    function coToken() external view returns (ERC20);
}
contract StableVault is ERC20, IERC4626 {
    using SafeERC20 for ERC20;
    using SafeERC20 for IWETH9;
    using SafeMath for uint256;
    mapping (address => uint256) public lastWithdrawTime;
    mapping (address => uint256) public lastDepositTime;
    mapping (address => uint256) public lastMintTime;
    mapping (address => uint256) public lastDefundTime;
    mapping (address => uint256) public lastRedeemTime;
    mapping (address => uint256) public lastFundTime;
    uint256 public constant depositFee = 100; // 0.1% 
    uint256 public constant withdrawFee = 9500; // 99.5%
    uint256 public constant maxFloatFee = 10000; // 100%
    uint256 public volatilityBuffer;
    IERC20 token;
    uint256 latestPrice;
    uint256 latestPriceTimestamp;
    address private owner;
    VolatileToken public immutable volatile;
    IWETH9 public immutable CPF;
    AggregatorV3Interface internal immutable priceFeed;
    constructor() ERC20("USD Pay", "USD-PC", 18) {
        volatile = new VolatileToken("External feeding", "WFOTA", 18);
        CPF = IWETH9(0xA3378bd30f9153aC12AFF64743841f4AFa29bC57);
        priceFeed = AggregatorV3Interface(0xfbD61B037C325b959c0F6A7e69D8f37770C2c550);
        token = IERC20(0xA3378bd30f9153aC12AFF64743841f4AFa29bC57);
        owner = msg.sender;
    }

    /*///////////////////////////////////////////////////////////////
                        DEPOSIT/WITHDRAWAL LOGIC
    //////////////////////////////////////////////////////////////*/

    modifier OnlyOwner() {
        require(msg.sender == owner);
        _;
    }

  
   function GetUserTokenBalance() public view returns(uint256){ 
       return token.balanceOf(msg.sender);// balancdOf function is already declared in ERC20 token function
   }
   
   
   function Approvetokens(uint256 _tokenamount) public returns(bool){
       token.approve(address(this), _tokenamount);
       return true;
   }
   
   
   function GetAllowance() public view returns(uint256){
       return token.allowance(msg.sender, address(this));
   }
   
   function AcceptPayment(uint256 _tokenamount) public returns(bool) {
       require(_tokenamount > GetAllowance(), "Please approve tokens before transferring");
       token.transfer(address(this), _tokenamount);
       return true;
   }
   
   
   function GetContractTokenBalance() public OnlyOwner view returns(uint256){
       return token.balanceOf(address(this));
   }
   

    /// @notice Stablecoin
    /// Give WETH amount, get STABLE amount
function deposit(uint256 wethIn, address to) public override returns (uint256 stableCoinAmount) {
    require(wethIn != 0, "ZERO_SHARES");
    require(wethIn >= 100 * 1e18, "DEPOSIT_AMOUNT_TOO_LOW");
    require(CPF.balanceOf(to) >= wethIn, "INSUFFICIENT_CPF_BALANCE");
    require(CPF.allowance(to, address(this)) >= wethIn, "CPF_ALLOWANCE_NOT_GRANTED");
    uint256 currentTime = block.timestamp;
    require(currentTime - lastDepositTime[to] >= 5 minutes, "DEPOSIT_LIMIT_REACHED");
    lastDepositTime[to] = currentTime;
    bool success = CPF.transferFrom(msg.sender, address(this), wethIn);
    require(success, "Transfer from CPF failed");
    if (!success) {
        // cancel transaction if transfer from CPF failed
        revert();
    }
    stableCoinAmount = previewDeposit(wethIn);
    require(stableCoinAmount != 0, "ZERO_SHARES");
    _mint(to, stableCoinAmount);
    emit Deposit(to, address(this), wethIn, stableCoinAmount);
    afterDeposit(wethIn);
}

function mint(uint256 stableCoinAmount, address to) public override returns (uint256 wethIn) {
    require(to != address(0), "Invalid address");
    require(stableCoinAmount > 0, "Stable coin amount must be greater than 0");
    require(stableCoinAmount >= 100 * 1e18, "MINT_AMOUNT_TOO_LOW");
    wethIn = previewMint(stableCoinAmount);
    require(wethIn > 0, "Preview mint failed");
    require(CPF.allowance(msg.sender, address(this)) >= wethIn, "Allowance is insufficient");
    uint256 currentTime = block.timestamp;
    require(currentTime - lastMintTime[msg.sender] >= 300, "Can only call mint once every 5 minutes");

    bool success = CPF.transferFrom(msg.sender, address(this), wethIn);
    require(success, "Transfer from CPF failed");
    if (!success) {
        // cancel transaction if transfer from CPF failed
        revert();
    }

    lastMintTime[msg.sender] = block.timestamp;
    _mint(to, stableCoinAmount);
    emit Deposit(to, address(this), wethIn, stableCoinAmount);
    afterDeposit(wethIn);
}

    /// @notice Stablecoin
    /// Withdraw from Vault underlying. Amount of WETH by burning equivalent amount of STABLECOIN
    function withdraw(
        uint256 amountReserve,
        address to,
        address from
    ) public override returns (uint256 wethOut) {
        require(to != address(0), "Invalid address");
        require(amountReserve >= 100 * 1e18, "Withdraw_AMOUNT_TOO_LOW");
        require(to != address(this), "Destination address cannot be this contract");
        require(amountReserve > 0, "Reserve amount must be greater than 0");
        uint256 allowed = allowance[from][msg.sender];
        if (msg.sender != from) {
            require(allowed != type(uint256).max, "Not enough allowance");
            allowance[from][msg.sender] = allowed - amountReserve;
        }
        uint256 currentTime = block.timestamp;
        require(currentTime - lastWithdrawTime[from] >= 1800, "WITHDRAW_LIMIT_REACHED");
        lastWithdrawTime[from] = currentTime;
        wethOut = previewWithdraw(amountReserve).mul(withdrawFee).div(maxFloatFee); 
        _burn(from, amountReserve);
        emit Withdraw(from, to, amountReserve, wethOut);
        require(CPF.transferFrom(address(this), msg.sender, wethOut), "Transfer from CPF failed");
    }


function redeem(
        uint256 amountStable,
        address to,
        address from
    ) public override returns (uint256 wethOut) {
        require(to != address(0), "Invalid address");
        require(wethOut >= 100 * 1e18, "redeem_AMOUNT_TOO_LOW");
        require(amountStable > 0, "Stable coin amount must be greater than 0");

        // Check if the last redeem was more than 30 minutes ago
         uint256 currentTime = block.timestamp;
        require(currentTime - lastRedeemTime[msg.sender] >= 1800, "WITHDRAW_LIMIT_REACHED");
        lastWithdrawTime[from] = currentTime;
        uint256 allowed = allowance[from][msg.sender];
        if (msg.sender != from) {
            require(allowed != type(uint256).max, "Not enough allowance");
            allowance[from][msg.sender] = allowed - amountStable;
        }
        require((wethOut = previewRedeem(amountStable)) != 0, "ZERO_ASSETS");
        wethOut = previewRedeem(amountStable).mul(withdrawFee).div(maxFloatFee);
        _burn(from, amountStable);
        emit Withdraw(from, to, wethOut, amountStable);
        require(CPF.transferFrom(address(this), msg.sender, wethOut), "Transfer from CPF failed");
    }

    /// @notice Volatility/Funding token
    /// Give amount of WETH, receive VolatilityToken
    function fund(uint256 volCoinAmount, address to) public returns (uint256 wethIn) {
        require(msg.sender == owner, "Only the owner can execute this function");
        require(to != address(0), "Invalid address: cannot deposit to the zero address");
        require(volCoinAmount >= 100 * 1e18, "VolatilityToken_AMOUNT_TOO_LOW");
        require(volCoinAmount > 0, "Invalid deposit amount: must be greater than zero");
        require(CPF.allowance(msg.sender, address(this)) >= volCoinAmount, "Not enough CPF allowed");
        uint256 currentTime = block.timestamp;
        require(currentTime - lastFundTime[msg.sender] >= 300, "FUND_LIMIT_REACHED");
        lastFundTime[msg.sender] = currentTime;
        require(CPF.transferFrom(msg.sender, address(this), wethIn = previewFund(volCoinAmount)), "Transfer from CPF failed");
        volatilityBuffer += wethIn;
        emit Deposit(msg.sender, to, wethIn, volCoinAmount);
}


    /// @notice Volatility/Funding token
    /// Redeem number of SHARES (VolToken) for WETH at current price (at loss or profit) + fees accrued
function defund(
    uint256 volCoinAmount,
    address to,
    address from
    ) public returns (uint256 wethOut) {
    require(msg.sender == owner, "Only the owner can execute this function");
    require(to != address(0), "Invalid recipient address: cannot withdraw to the zero address");
    require(volCoinAmount > 0, "Invalid withdrawal amount: must be greater than zero");
    require((wethOut = previewDefund(volCoinAmount)) != 0, "No assets to withdraw: check the amount and try again");
    uint256 currentTime = block.timestamp;
    require(currentTime - lastDefundTime[msg.sender] >= 300, "DEFUND_LIMIT_REACHED");
    lastDefundTime[msg.sender] = currentTime;
    volatile.burn(to, volCoinAmount);
    volatilityBuffer -= wethOut;
    emit Withdraw(from, to, wethOut, volCoinAmount);
}

    function previewFund(uint256 amount) public view returns (uint256 stableVaultShares) {
        uint256 price = getLatestPrice();
        require(price != 0, "Price cannot be 0");
        stableVaultShares = amount.mul(1e18).div(price);
        return stableVaultShares;
    }

    /// @notice Volatility token
    /// The only function that claims yield from Vault
    /// https://jacob-eliosoff.medium.com/a-cheesy-analogy-for-people-who-find-usm-confusing-1fd5e3d73a79
    function previewDefund(uint256 amount) public view returns (uint256 wethOut) {
        uint256 price = getLatestPrice();
        require(price != 0, "Price cannot be 0");
        uint256 sharesGrowth = amount.mul(volatilityBuffer).mul(latestPrice).div(volatile.totalSupply());
        wethOut = sharesGrowth.div(price).mul(1e18);
    }

    /// @notice Stablecoin
    /// Return how much STABLECOIN does user receive for AMOUNT of WETH
    function previewDeposit(uint256 amount) public view override returns (uint256 stableCoinAmount) {
        uint256 price = getLatestPrice();
        require(price != 0, "PRICE_IS_ZERO");
        return price.mul(amount).div(1e18);
    }

    /// @notice Stablecoin
    /// Return how much WETH is needed to receive AMOUNT of STABLECOIN
    function previewMint(uint256 amount) public view override returns (uint256 stableCoinAmount) {
        uint256 price = getLatestPrice();
        require(price != 0, "Price cannot be 0");
        stableCoinAmount = amount.mul(1e18).div(price);
        return stableCoinAmount;
    }

    /// @notice Stablecoin
    /// Return how much WETH to transfer by calculating equivalent amount of burn to given AMOUNT of WETH
    function previewRedeem(uint256 amount) public view override returns (uint256 wethOut) {
        uint256 price = getLatestPrice();
        require(price != 0, "Price cannot be 0");
        return amount.div(price).mul(1e18);
    }

    function previewWithdraw(uint256 amount) public view override returns (uint256 wethOut) {
         uint256 price = getLatestPrice();
        require(price != 0, "Price cannot be 0");
        return amount.div(price).mul(1e18); // AMOUNT * (ETH/USD)
    }


    /*///////////////////////////////////////////////////////////////
                         INTERNAL HOOKS LOGIC
    //////////////////////////////////////////////////////////////*/

    /// @notice Add fee from user WETH collateral to volatilityBuffer as FUNDers fee
    function afterDeposit(uint256 amount) internal {
        uint256 fee = (amount.mul(depositFee)).div(maxFloatFee);
        volatilityBuffer = volatilityBuffer.add(fee);
    }

    function beforeWithdraw(uint256 amount) internal {}

    /*///////////////////////////////////////////////////////////////
                        ACCOUNTING LOGIC
    //////////////////////////////////////////////////////////////*/

    function totalAssets() public view override returns (uint256) {
        return CPF.balanceOf(address(this));
    }

    function assetsOf(address user) public view override returns (uint256) {
        return balanceOf[user];
    }

    function volatileAssetsOf(address user) public view returns (uint256) {
        return volatile.balanceOf(user);
    }

    function assetsPerShare() public view override returns (uint256) {
        return previewRedeem(10**decimals);
    }

    function maxDeposit(address) public pure override returns (uint256) {
        return type(uint256).max;
    }

    function maxMint(address) public pure override returns (uint256) {
        return type(uint256).max;
    }

    function maxWithdraw(address user) public view override returns (uint256) {
        return assetsOf(user);
    }

    function maxRedeem(address user) public view override returns (uint256) {
        return balanceOf[user];
    }

    function getLatestPrice() public view returns (uint256) {
        (uint256 weightedRate) = priceFeed
            .getRate(0xA3378bd30f9153aC12AFF64743841f4AFa29bC57, 0xe9e7CEA3DedcA5984780Bafc599bD69ADd087D56, true);
    require(weightedRate != 0, "Price cannot be 0");
    return weightedRate;
    }

}