// 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 (last updated v4.8.0) (utils/cryptography/ECDSA.sol)

pragma solidity ^0.8.0;

import "../Strings.sol";

/**
 * @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
 *
 * These functions can be used to verify that a message was signed by the holder
 * of the private keys of a given address.
 */
library ECDSA {
    enum RecoverError {
        NoError,
        InvalidSignature,
        InvalidSignatureLength,
        InvalidSignatureS,
        InvalidSignatureV // Deprecated in v4.8
    }

    function _throwError(RecoverError error) private pure {
        if (error == RecoverError.NoError) {
            return; // no error: do nothing
        } else if (error == RecoverError.InvalidSignature) {
            revert("ECDSA: invalid signature");
        } else if (error == RecoverError.InvalidSignatureLength) {
            revert("ECDSA: invalid signature length");
        } else if (error == RecoverError.InvalidSignatureS) {
            revert("ECDSA: invalid signature 's' value");
        }
    }

    /**
     * @dev Returns the address that signed a hashed message (`hash`) with
     * `signature` or error string. This address can then be used for verification purposes.
     *
     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
     * this function rejects them by requiring the `s` value to be in the lower
     * half order, and the `v` value to be either 27 or 28.
     *
     * IMPORTANT: `hash` _must_ be the result of a hash operation for the
     * verification to be secure: it is possible to craft signatures that
     * recover to arbitrary addresses for non-hashed data. A safe way to ensure
     * this is by receiving a hash of the original message (which may otherwise
     * be too long), and then calling {toEthSignedMessageHash} on it.
     *
     * Documentation for signature generation:
     * - with https://web3js.readthedocs.io/en/v1.3.4/web3-eth-accounts.html#sign[Web3.js]
     * - with https://docs.ethers.io/v5/api/signer/#Signer-signMessage[ethers]
     *
     * _Available since v4.3._
     */
    function tryRecover(bytes32 hash, bytes memory signature) internal pure returns (address, RecoverError) {
        if (signature.length == 65) {
            bytes32 r;
            bytes32 s;
            uint8 v;
            // ecrecover takes the signature parameters, and the only way to get them
            // currently is to use assembly.
            /// @solidity memory-safe-assembly
            assembly {
                r := mload(add(signature, 0x20))
                s := mload(add(signature, 0x40))
                v := byte(0, mload(add(signature, 0x60)))
            }
            return tryRecover(hash, v, r, s);
        } else {
            return (address(0), RecoverError.InvalidSignatureLength);
        }
    }

    /**
     * @dev Returns the address that signed a hashed message (`hash`) with
     * `signature`. This address can then be used for verification purposes.
     *
     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
     * this function rejects them by requiring the `s` value to be in the lower
     * half order, and the `v` value to be either 27 or 28.
     *
     * IMPORTANT: `hash` _must_ be the result of a hash operation for the
     * verification to be secure: it is possible to craft signatures that
     * recover to arbitrary addresses for non-hashed data. A safe way to ensure
     * this is by receiving a hash of the original message (which may otherwise
     * be too long), and then calling {toEthSignedMessageHash} on it.
     */
    function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, signature);
        _throwError(error);
        return recovered;
    }

    /**
     * @dev Overload of {ECDSA-tryRecover} that receives the `r` and `vs` short-signature fields separately.
     *
     * See https://eips.ethereum.org/EIPS/eip-2098[EIP-2098 short signatures]
     *
     * _Available since v4.3._
     */
    function tryRecover(
        bytes32 hash,
        bytes32 r,
        bytes32 vs
    ) internal pure returns (address, RecoverError) {
        bytes32 s = vs & bytes32(0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff);
        uint8 v = uint8((uint256(vs) >> 255) + 27);
        return tryRecover(hash, v, r, s);
    }

    /**
     * @dev Overload of {ECDSA-recover} that receives the `r and `vs` short-signature fields separately.
     *
     * _Available since v4.2._
     */
    function recover(
        bytes32 hash,
        bytes32 r,
        bytes32 vs
    ) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, r, vs);
        _throwError(error);
        return recovered;
    }

    /**
     * @dev Overload of {ECDSA-tryRecover} that receives the `v`,
     * `r` and `s` signature fields separately.
     *
     * _Available since v4.3._
     */
    function tryRecover(
        bytes32 hash,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal pure returns (address, RecoverError) {
        // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
        // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
        // the valid range for s in (301): 0 < s < secp256k1n ÷ 2 + 1, and for v in (302): v ∈ {27, 28}. Most
        // signatures from current libraries generate a unique signature with an s-value in the lower half order.
        //
        // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
        // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
        // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
        // these malleable signatures as well.
        if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {
            return (address(0), RecoverError.InvalidSignatureS);
        }

        // If the signature is valid (and not malleable), return the signer address
        address signer = ecrecover(hash, v, r, s);
        if (signer == address(0)) {
            return (address(0), RecoverError.InvalidSignature);
        }

        return (signer, RecoverError.NoError);
    }

    /**
     * @dev Overload of {ECDSA-recover} that receives the `v`,
     * `r` and `s` signature fields separately.
     */
    function recover(
        bytes32 hash,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, v, r, s);
        _throwError(error);
        return recovered;
    }

    /**
     * @dev Returns an Ethereum Signed Message, created from a `hash`. This
     * produces hash corresponding to the one signed with the
     * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
     * JSON-RPC method as part of EIP-191.
     *
     * See {recover}.
     */
    function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
        // 32 is the length in bytes of hash,
        // enforced by the type signature above
        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
    }

    /**
     * @dev Returns an Ethereum Signed Message, created from `s`. This
     * produces hash corresponding to the one signed with the
     * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
     * JSON-RPC method as part of EIP-191.
     *
     * See {recover}.
     */
    function toEthSignedMessageHash(bytes memory s) internal pure returns (bytes32) {
        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n", Strings.toString(s.length), s));
    }

    /**
     * @dev Returns an Ethereum Signed Typed Data, created from a
     * `domainSeparator` and a `structHash`. This produces hash corresponding
     * to the one signed with the
     * https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`]
     * JSON-RPC method as part of EIP-712.
     *
     * See {recover}.
     */
    function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32) {
        return keccak256(abi.encodePacked("\x19\x01", domainSeparator, structHash));
    }
}

// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.19;

import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import {ECDSA} from "@openzeppelin/contracts/utils/cryptography/ECDSA.sol";
import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";
import {HelloBridgeStore} from "./HelloBridgeStore.sol";
/* -------------------------------------------------------------------------- */
/*                                   errors                                   */
/* -------------------------------------------------------------------------- */

error SignerNotWithdrawSigner();
error NoAmountToWithdraw();
error CannotBridgeToUnsupportedChain();
error Paused();
error NotPaused();
error ZeroAddress();

///@notice The owner will always be a multisig wallet.

/* -------------------------------------------------------------------------- */
/*                                 HelloBridge                                */
/* -------------------------------------------------------------------------- */
/**
 * @title A cross-chain bridge for HelloToken
 * @author 0xSimon
 * @notice It is recommended to use the provided UI to bridge your tokens from chain A to chain B
 * @dev Assumptions:
 *     - On chains that this contract is deployed to (besides the mainnet), the entire supply of HelloToken will be minted and sent to this contract.
 */
contract HelloBridge is Ownable {
    using ECDSA for bytes32;

    /* -------------------------------------------------------------------------- */
    /*                                   events                                   */
    /* -------------------------------------------------------------------------- */
    event Deposit(address indexed sender, uint256 amount, uint256 chainId);
    event Claim(address indexed sender, uint256 totalDepositedOnOtherChain, uint256 otherChainId);
    event SupportedChainChanged(uint256 chainID, bool isSupported);
    event SupportedChainsChanged(uint256[] chainIDs, bool isSupported);
    event WithdrawSigner1Changed(address signer);
    event WithdrawSigner2Changed(address signer);
    event PausedChanged(bool depositPaused, bool claimPaused);
    event BridgeStoreChanged(address store);

    /* -------------------------------------------------------------------------- */
    /*                                  constants                                 */
    /* -------------------------------------------------------------------------- */
    /**
     * @notice The HelloToken contract
     */
    IERC20 public immutable HELLO_TOKEN;

    /* -------------------------------------------------------------------------- */
    /*                                   states                                   */
    /* -------------------------------------------------------------------------- */
    /**
     * @notice The signer providing signatures for claiming tokens on the destination chain
     */
    address public withdrawSigner1;
    address public withdrawSigner2;

    /**
     * @notice Storage contract for deposits and withdrawals numbers
     */
    HelloBridgeStore public store;

    /**
     * @notice A mapping to store which destination chains are supported
     */
    mapping(uint256 => bool) public supportedChains;

    bool public depositPaused;
    bool public claimPaused;

    /**
     * @notice Deploys the contract and saves the HelloToken contract address
     *  @dev `msg.sender` is assigned to the owner, pay attention if this contract is deployed via another contract
     *  @param _helloToken The address of HelloToken
     */
    constructor(address _helloToken) {
        HELLO_TOKEN = IERC20(_helloToken);
    }

    /* -------------------------------------------------------------------------- */
    /*                                  external                                  */
    /* -------------------------------------------------------------------------- */
    /**
     * @notice Bridge HelloToken to another chain. HelloToken will be transferred to this contract.
     * @notice Ensure approvals for HelloToken has been set and the destination chain is supported.
     * @param amount Amount of HelloToken to bridge to another chain
     * @param chainId The chain ID of the destination chain
     * @dev Reverts if the destination chain is not supported
     */
    function sendToChain(uint256 amount, uint256 chainId) external {
        if (depositPaused) _revert(Paused.selector);

        // check chain
        if (!supportedChains[chainId]) _revert(CannotBridgeToUnsupportedChain.selector);

        // update state
        uint256 _currentDepsosit = store.totalCrossChainDeposits(msg.sender, chainId);
        store.setTotalCrossChainDeposits(msg.sender, chainId, _currentDepsosit + amount);

        // transfer tokens
        HELLO_TOKEN.transferFrom(msg.sender, address(this), amount);

        emit Deposit(msg.sender, amount, chainId);
    }

    /**
     * @notice Claims tokens deposited in the source chain. A signature is required.
     * @notice HelloToken will be transferred from this account to the caller.
     * @param totalDepositedOnOtherChain The total amount you have deposited in the source chain
     * @param otherChainId The chain ID of the source chain
     * @param signature The signature signed by `withdrawSigner`
     * @dev Reverts if there's no amount to claim.
     * @dev Reverts if the signature is invalid
     * @dev Assumptions:
     *     - `otherChainId` is supported, a user would not have been able to deposit if the path from `otherChainId` to this chain is not supported
     *     - `totalDepositedOnOtherChain` is checked on chain with ID `otherChainId` before a signature is generated for this transaction
     */
    function claimFromChain(
        uint256 totalDepositedOnOtherChain,
        uint256 otherChainId,
        bytes memory signature,
        bytes memory signature2
    ) external {
        if (claimPaused) _revert(Paused.selector);

        // note: this can never undeflow as the user would not have been able to withdraw if they had no balance
        uint256 amountToWithdraw =
            totalDepositedOnOtherChain - store.totalCrossChainWithdrawals(msg.sender, otherChainId);

        // check amount
        if (amountToWithdraw == 0) _revert(NoAmountToWithdraw.selector);

        // check signature
        bytes32 hash = keccak256(
            abi.encodePacked(msg.sender, totalDepositedOnOtherChain, otherChainId, block.chainid, address(this))
        );

        if (hash.toEthSignedMessageHash().recover(signature) != withdrawSigner1) {
            _revert(SignerNotWithdrawSigner.selector);
        }

        if (hash.toEthSignedMessageHash().recover(signature2) != withdrawSigner2) {
            _revert(SignerNotWithdrawSigner.selector);
        }

        // update state
        store.setTotalCrossChainWithdrawals(msg.sender, otherChainId, totalDepositedOnOtherChain);

        // transfer tokens
        HELLO_TOKEN.transfer(msg.sender, amountToWithdraw);

        emit Claim(msg.sender, totalDepositedOnOtherChain, otherChainId);
    }

    /* -------------------------------------------------------------------------- */
    /*                                   owners                                   */
    /* -------------------------------------------------------------------------- */
    /**
     * @notice Owner only - Updates the address of the withdrawal signer
     * @param _withdrawSigner Address of the withdrawal signer
     */
    function setWithdrawSigner(address _withdrawSigner) external onlyOwner {
        // check
        if (_withdrawSigner == address(0)) {
            _revert(ZeroAddress.selector);
        }

        // set
        withdrawSigner1 = _withdrawSigner;

        // emit
        emit WithdrawSigner1Changed(_withdrawSigner);
    }

    function setWithdrawSigner2(address _withdrawSigner2) external onlyOwner {
        // check
        if (_withdrawSigner2 == address(0)) {
            _revert(ZeroAddress.selector);
        }

        // set
        withdrawSigner2 = _withdrawSigner2;

        // emit
        emit WithdrawSigner2Changed(_withdrawSigner2);
    }

    /**
     * @notice Owner only - Updates a supported destination chain
     * @param chainId Chain ID of a destination chain
     * @param isSupported Whether the destination chain is supported
     */
    function setSupportedChain(uint256 chainId, bool isSupported) external onlyOwner {
        _setSupportedChain(chainId, isSupported);

        emit SupportedChainChanged(chainId, isSupported);
    }

    /**
     * @notice Owner only - Batch update supported destination chains
     * @param chainIds Chain IDs of the destination chains
     * @param isSupported Whether the destination chains are supported
     */
    function setSupportedChains(uint256[] calldata chainIds, bool isSupported) external onlyOwner {
        for (uint256 i; i < chainIds.length;) {
            _setSupportedChain(chainIds[i], isSupported);
            unchecked {
                ++i;
            }
        }

        emit SupportedChainsChanged(chainIds, isSupported);
    }

    /**
     * @notice Pause / unpause deposit & claim
     * @param depositPaused_ Whether to pause deposit
     * @param depositPaused_ Whether to pause claim
     */
    function setPaused(bool depositPaused_, bool claimPaused_) external onlyOwner {
        depositPaused = depositPaused_;
        claimPaused = claimPaused_;

        emit PausedChanged(depositPaused_, claimPaused_);
    }

    function setBridgeStore(address a_) external onlyOwner {
        // check
        if (a_ == address(0)) {
            _revert(ZeroAddress.selector);
        }

        // set
        store = HelloBridgeStore(a_);

        // emit
        emit BridgeStoreChanged(a_);
    }

    /**
     * @notice Migrates the bridge contract to another. Tokens in this contract will be transferred to the new contract.
     * @dev The new bridge contract should use the data stored in `store`.
     * @param bridgeAddress Address of the new contract
     */
    function migrateBridge(address bridgeAddress) external onlyOwner {
        // check zero
        if (bridgeAddress == address(0)) {
            _revert(ZeroAddress.selector);
        }

        // check paused
        if (!depositPaused || !claimPaused) {
            _revert(NotPaused.selector);
        }

        HELLO_TOKEN.transfer(bridgeAddress, HELLO_TOKEN.balanceOf(address(this)));
    }

    /* -------------------------------------------------------------------------- */
    /*                                  internal                                  */
    /* -------------------------------------------------------------------------- */
    function _setSupportedChain(uint256 chainId, bool isSupported) internal {
        supportedChains[chainId] = isSupported;
    }

    function _revert(bytes4 selector) internal pure {
        assembly {
            mstore(0x0, selector)
            revert(0x0, 0x04)
        }
    }
}

// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.19;

import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";

///@notice The contract is a storage contract for the bridge contract.
///@notice The owner will always be a multisig wallet.

/* -------------------------------------------------------------------------- */
/*                                   errors                                   */
/* -------------------------------------------------------------------------- */
error SignerNotWithdrawSigner();
error NoAmountToWithdraw();
error CannotBridgeToUnsupportedChain();
error Paused();
error NotPaused();
error ZeroAddress();

contract HelloBridgeStore is Ownable {
    /* -------------------------------------------------------------------------- */
    /*                                   errors                                   */
    /* -------------------------------------------------------------------------- */
    error ErrUnauthorized();
    error ErrZeroAddress();

    /* -------------------------------------------------------------------------- */
    /*                                   events                                   */
    /* -------------------------------------------------------------------------- */
    event BridgeContractChanged(address bridgeContract);

    /* -------------------------------------------------------------------------- */
    /*                                   states                                   */
    /* -------------------------------------------------------------------------- */
    /**
     * @notice A mapping that stores how much HelloToken a user has deposited to bridge to a destination chain
     * @dev Maps from userAddress -> chainID -> amount
     */
    mapping(address => mapping(uint256 => uint256)) public totalCrossChainDeposits;

    /**
     * @notice A mapping that stores how much HelloToken a user has withdrawn from a destination chain
     * @dev Maps from userAddress -> chainID -> amount
     */
    mapping(address => mapping(uint256 => uint256)) public totalCrossChainWithdrawals;

    /**
     * @notice The bridge contract associated with this storage contract.
     * This is the only contract authorized to update `totalCrossChainDeposits` & `totalCrossChainWithdrawals`
     */
    address public bridgeContract;

    /* -------------------------------------------------------------------------- */
    /*                                    owner                                   */
    /* -------------------------------------------------------------------------- */
    /**
     * @notice Updates the bridge contract associated with this storage contract
     */
    function setBridgeContract(address b_) external onlyOwner {
        if (b_ == address(0)) {
            revert ErrZeroAddress();
        }

        bridgeContract = b_;

        emit BridgeContractChanged(b_);
    }

    /* -------------------------------------------------------------------------- */
    /*                                  external                                  */
    /* -------------------------------------------------------------------------- */
    /**
     * @notice Updates totalCrossChainDeposits of a user to a destination chain
     * @param address_ The address to update
     * @param chainID_ The destination chainID of the deposit
     * @param amount_ The amount of token deposited
     */
    function setTotalCrossChainDeposits(address address_, uint256 chainID_, uint256 amount_) external {
        if (msg.sender != bridgeContract) {
            revert ErrUnauthorized();
        }

        totalCrossChainDeposits[address_][chainID_] = amount_;
    }

    /**
     * @notice Updates totalCrossChainWithdrawals of a user from a source chain
     * @param address_ The address to update
     * @param chainID_ The source chainID of the withdrawal
     * @param amount_ The amount of token withdrawn
     */
    function setTotalCrossChainWithdrawals(address address_, uint256 chainID_, uint256 amount_) external {
        if (msg.sender != bridgeContract) {
            revert ErrUnauthorized();
        }

        totalCrossChainWithdrawals[address_][chainID_] = amount_;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

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

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

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

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

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

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

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

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

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/math/Math.sol)

pragma solidity ^0.8.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    enum Rounding {
        Down, // Toward negative infinity
        Up, // Toward infinity
        Zero // Toward zero
    }

    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a > b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow.
        return (a & b) + (a ^ b) / 2;
    }

    /**
     * @dev Returns the ceiling of the division of two numbers.
     *
     * This differs from standard division with `/` in that it rounds up instead
     * of rounding down.
     */
    function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b - 1) / b can overflow on addition, so we distribute.
        return a == 0 ? 0 : (a - 1) / b + 1;
    }

    /**
     * @notice Calculates floor(x * y / denominator) with full precision. Throws if result overflows a uint256 or denominator == 0
     * @dev Original credit to Remco Bloemen under MIT license (https://xn--2-umb.com/21/muldiv)
     * with further edits by Uniswap Labs also under MIT license.
     */
    function mulDiv(
        uint256 x,
        uint256 y,
        uint256 denominator
    ) internal pure returns (uint256 result) {
        unchecked {
            // 512-bit multiply [prod1 prod0] = x * y. Compute the product mod 2^256 and mod 2^256 - 1, then use
            // use the Chinese Remainder Theorem to reconstruct the 512 bit result. The result is stored in two 256
            // variables such that product = prod1 * 2^256 + prod0.
            uint256 prod0; // Least significant 256 bits of the product
            uint256 prod1; // Most significant 256 bits of the product
            assembly {
                let mm := mulmod(x, y, not(0))
                prod0 := mul(x, y)
                prod1 := sub(sub(mm, prod0), lt(mm, prod0))
            }

            // Handle non-overflow cases, 256 by 256 division.
            if (prod1 == 0) {
                return prod0 / denominator;
            }

            // Make sure the result is less than 2^256. Also prevents denominator == 0.
            require(denominator > prod1);

            ///////////////////////////////////////////////
            // 512 by 256 division.
            ///////////////////////////////////////////////

            // Make division exact by subtracting the remainder from [prod1 prod0].
            uint256 remainder;
            assembly {
                // Compute remainder using mulmod.
                remainder := mulmod(x, y, denominator)

                // Subtract 256 bit number from 512 bit number.
                prod1 := sub(prod1, gt(remainder, prod0))
                prod0 := sub(prod0, remainder)
            }

            // Factor powers of two out of denominator and compute largest power of two divisor of denominator. Always >= 1.
            // See https://cs.stackexchange.com/q/138556/92363.

            // Does not overflow because the denominator cannot be zero at this stage in the function.
            uint256 twos = denominator & (~denominator + 1);
            assembly {
                // Divide denominator by twos.
                denominator := div(denominator, twos)

                // Divide [prod1 prod0] by twos.
                prod0 := div(prod0, twos)

                // Flip twos such that it is 2^256 / twos. If twos is zero, then it becomes one.
                twos := add(div(sub(0, twos), twos), 1)
            }

            // Shift in bits from prod1 into prod0.
            prod0 |= prod1 * twos;

            // Invert denominator mod 2^256. Now that denominator is an odd number, it has an inverse modulo 2^256 such
            // that denominator * inv = 1 mod 2^256. Compute the inverse by starting with a seed that is correct for
            // four bits. That is, denominator * inv = 1 mod 2^4.
            uint256 inverse = (3 * denominator) ^ 2;

            // Use the Newton-Raphson iteration to improve the precision. Thanks to Hensel's lifting lemma, this also works
            // in modular arithmetic, doubling the correct bits in each step.
            inverse *= 2 - denominator * inverse; // inverse mod 2^8
            inverse *= 2 - denominator * inverse; // inverse mod 2^16
            inverse *= 2 - denominator * inverse; // inverse mod 2^32
            inverse *= 2 - denominator * inverse; // inverse mod 2^64
            inverse *= 2 - denominator * inverse; // inverse mod 2^128
            inverse *= 2 - denominator * inverse; // inverse mod 2^256

            // Because the division is now exact we can divide by multiplying with the modular inverse of denominator.
            // This will give us the correct result modulo 2^256. Since the preconditions guarantee that the outcome is
            // less than 2^256, this is the final result. We don't need to compute the high bits of the result and prod1
            // is no longer required.
            result = prod0 * inverse;
            return result;
        }
    }

    /**
     * @notice Calculates x * y / denominator with full precision, following the selected rounding direction.
     */
    function mulDiv(
        uint256 x,
        uint256 y,
        uint256 denominator,
        Rounding rounding
    ) internal pure returns (uint256) {
        uint256 result = mulDiv(x, y, denominator);
        if (rounding == Rounding.Up && mulmod(x, y, denominator) > 0) {
            result += 1;
        }
        return result;
    }

    /**
     * @dev Returns the square root of a number. If the number is not a perfect square, the value is rounded down.
     *
     * Inspired by Henry S. Warren, Jr.'s "Hacker's Delight" (Chapter 11).
     */
    function sqrt(uint256 a) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }

        // For our first guess, we get the biggest power of 2 which is smaller than the square root of the target.
        //
        // We know that the "msb" (most significant bit) of our target number `a` is a power of 2 such that we have
        // `msb(a) <= a < 2*msb(a)`. This value can be written `msb(a)=2**k` with `k=log2(a)`.
        //
        // This can be rewritten `2**log2(a) <= a < 2**(log2(a) + 1)`
        // → `sqrt(2**k) <= sqrt(a) < sqrt(2**(k+1))`
        // → `2**(k/2) <= sqrt(a) < 2**((k+1)/2) <= 2**(k/2 + 1)`
        //
        // Consequently, `2**(log2(a) / 2)` is a good first approximation of `sqrt(a)` with at least 1 correct bit.
        uint256 result = 1 << (log2(a) >> 1);

        // At this point `result` is an estimation with one bit of precision. We know the true value is a uint128,
        // since it is the square root of a uint256. Newton's method converges quadratically (precision doubles at
        // every iteration). We thus need at most 7 iteration to turn our partial result with one bit of precision
        // into the expected uint128 result.
        unchecked {
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            return min(result, a / result);
        }
    }

    /**
     * @notice Calculates sqrt(a), following the selected rounding direction.
     */
    function sqrt(uint256 a, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = sqrt(a);
            return result + (rounding == Rounding.Up && result * result < a ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 2, rounded down, of a positive value.
     * Returns 0 if given 0.
     */
    function log2(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >> 128 > 0) {
                value >>= 128;
                result += 128;
            }
            if (value >> 64 > 0) {
                value >>= 64;
                result += 64;
            }
            if (value >> 32 > 0) {
                value >>= 32;
                result += 32;
            }
            if (value >> 16 > 0) {
                value >>= 16;
                result += 16;
            }
            if (value >> 8 > 0) {
                value >>= 8;
                result += 8;
            }
            if (value >> 4 > 0) {
                value >>= 4;
                result += 4;
            }
            if (value >> 2 > 0) {
                value >>= 2;
                result += 2;
            }
            if (value >> 1 > 0) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 2, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log2(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log2(value);
            return result + (rounding == Rounding.Up && 1 << result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 10, rounded down, of a positive value.
     * Returns 0 if given 0.
     */
    function log10(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >= 10**64) {
                value /= 10**64;
                result += 64;
            }
            if (value >= 10**32) {
                value /= 10**32;
                result += 32;
            }
            if (value >= 10**16) {
                value /= 10**16;
                result += 16;
            }
            if (value >= 10**8) {
                value /= 10**8;
                result += 8;
            }
            if (value >= 10**4) {
                value /= 10**4;
                result += 4;
            }
            if (value >= 10**2) {
                value /= 10**2;
                result += 2;
            }
            if (value >= 10**1) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 10, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log10(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log10(value);
            return result + (rounding == Rounding.Up && 10**result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 256, rounded down, of a positive value.
     * Returns 0 if given 0.
     *
     * Adding one to the result gives the number of pairs of hex symbols needed to represent `value` as a hex string.
     */
    function log256(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >> 128 > 0) {
                value >>= 128;
                result += 16;
            }
            if (value >> 64 > 0) {
                value >>= 64;
                result += 8;
            }
            if (value >> 32 > 0) {
                value >>= 32;
                result += 4;
            }
            if (value >> 16 > 0) {
                value >>= 16;
                result += 2;
            }
            if (value >> 8 > 0) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 10, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log256(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log256(value);
            return result + (rounding == Rounding.Up && 1 << (result * 8) < value ? 1 : 0);
        }
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/Strings.sol)

pragma solidity ^0.8.0;

import "./math/Math.sol";

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant _SYMBOLS = "0123456789abcdef";
    uint8 private constant _ADDRESS_LENGTH = 20;

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        unchecked {
            uint256 length = Math.log10(value) + 1;
            string memory buffer = new string(length);
            uint256 ptr;
            /// @solidity memory-safe-assembly
            assembly {
                ptr := add(buffer, add(32, length))
            }
            while (true) {
                ptr--;
                /// @solidity memory-safe-assembly
                assembly {
                    mstore8(ptr, byte(mod(value, 10), _SYMBOLS))
                }
                value /= 10;
                if (value == 0) break;
            }
            return buffer;
        }
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        unchecked {
            return toHexString(value, Math.log256(value) + 1);
        }
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = _SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }

    /**
     * @dev Converts an `address` with fixed length of 20 bytes to its not checksummed ASCII `string` hexadecimal representation.
     */
    function toHexString(address addr) internal pure returns (string memory) {
        return toHexString(uint256(uint160(addr)), _ADDRESS_LENGTH);
    }
}

{
  "compilationTarget": {
    "src/HelloBridge.sol": "HelloBridge"
  },
  "evmVersion": "paris",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": true,
    "runs": 1000000
  },
  "remappings": [
    ":@openzeppelin/contracts-upgradeable/=lib/openzeppelin-contracts-upgradeable/contracts/",
    ":@openzeppelin/contracts/=lib/openzeppelin-contracts/contracts/",
    ":closedsea/=lib/closedsea/src/",
    ":ds-test/=lib/forge-std/lib/ds-test/src/",
    ":erc4626-tests/=lib/closedsea/lib/openzeppelin-contracts/lib/erc4626-tests/",
    ":erc721a-upgradeable/=lib/closedsea/lib/erc721a-upgradeable/contracts/",
    ":erc721a/=lib/erc721a/contracts/",
    ":forge-std/=lib/forge-std/src/",
    ":openzeppelin-contracts-upgradeable/=lib/openzeppelin-contracts-upgradeable/",
    ":openzeppelin-contracts/=lib/openzeppelin-contracts/",
    ":operator-filter-registry/=lib/closedsea/lib/operator-filter-registry/",
    ":solmate/=lib/solmate/src/"
  ]
}