// SPDX-License-Identifier: Unlicense
/*
 * @title Solidity Bytes Arrays Utils
 * @author Gonçalo Sá <goncalo.sa@consensys.net>
 *
 * @dev Bytes tightly packed arrays utility library for ethereum contracts written in Solidity.
 *      The library lets you concatenate, slice and type cast bytes arrays both in memory and storage.
 */
pragma solidity >=0.8.0 <0.9.0;


library BytesLib {
    function concat(
        bytes memory _preBytes,
        bytes memory _postBytes
    )
    internal
    pure
    returns (bytes memory)
    {
        bytes memory tempBytes;

        assembly {
        // Get a location of some free memory and store it in tempBytes as
        // Solidity does for memory variables.
            tempBytes := mload(0x40)

        // Store the length of the first bytes array at the beginning of
        // the memory for tempBytes.
            let length := mload(_preBytes)
            mstore(tempBytes, length)

        // Maintain a memory counter for the current write location in the
        // temp bytes array by adding the 32 bytes for the array length to
        // the starting location.
            let mc := add(tempBytes, 0x20)
        // Stop copying when the memory counter reaches the length of the
        // first bytes array.
            let end := add(mc, length)

            for {
            // Initialize a copy counter to the start of the _preBytes data,
            // 32 bytes into its memory.
                let cc := add(_preBytes, 0x20)
            } lt(mc, end) {
            // Increase both counters by 32 bytes each iteration.
                mc := add(mc, 0x20)
                cc := add(cc, 0x20)
            } {
            // Write the _preBytes data into the tempBytes memory 32 bytes
            // at a time.
                mstore(mc, mload(cc))
            }

        // Add the length of _postBytes to the current length of tempBytes
        // and store it as the new length in the first 32 bytes of the
        // tempBytes memory.
            length := mload(_postBytes)
            mstore(tempBytes, add(length, mload(tempBytes)))

        // Move the memory counter back from a multiple of 0x20 to the
        // actual end of the _preBytes data.
            mc := end
        // Stop copying when the memory counter reaches the new combined
        // length of the arrays.
            end := add(mc, length)

            for {
                let cc := add(_postBytes, 0x20)
            } lt(mc, end) {
                mc := add(mc, 0x20)
                cc := add(cc, 0x20)
            } {
                mstore(mc, mload(cc))
            }

        // Update the free-memory pointer by padding our last write location
        // to 32 bytes: add 31 bytes to the end of tempBytes to move to the
        // next 32 byte block, then round down to the nearest multiple of
        // 32. If the sum of the length of the two arrays is zero then add
        // one before rounding down to leave a blank 32 bytes (the length block with 0).
            mstore(0x40, and(
            add(add(end, iszero(add(length, mload(_preBytes)))), 31),
            not(31) // Round down to the nearest 32 bytes.
            ))
        }

        return tempBytes;
    }

    function concatStorage(bytes storage _preBytes, bytes memory _postBytes) internal {
        assembly {
        // Read the first 32 bytes of _preBytes storage, which is the length
        // of the array. (We don't need to use the offset into the slot
        // because arrays use the entire slot.)
            let fslot := sload(_preBytes.slot)
        // Arrays of 31 bytes or less have an even value in their slot,
        // while longer arrays have an odd value. The actual length is
        // the slot divided by two for odd values, and the lowest order
        // byte divided by two for even values.
        // If the slot is even, bitwise and the slot with 255 and divide by
        // two to get the length. If the slot is odd, bitwise and the slot
        // with -1 and divide by two.
            let slength := div(and(fslot, sub(mul(0x100, iszero(and(fslot, 1))), 1)), 2)
            let mlength := mload(_postBytes)
            let newlength := add(slength, mlength)
        // slength can contain both the length and contents of the array
        // if length < 32 bytes so let's prepare for that
        // v. http://solidity.readthedocs.io/en/latest/miscellaneous.html#layout-of-state-variables-in-storage
            switch add(lt(slength, 32), lt(newlength, 32))
            case 2 {
            // Since the new array still fits in the slot, we just need to
            // update the contents of the slot.
            // uint256(bytes_storage) = uint256(bytes_storage) + uint256(bytes_memory) + new_length
                sstore(
                _preBytes.slot,
                // all the modifications to the slot are inside this
                // next block
                add(
                // we can just add to the slot contents because the
                // bytes we want to change are the LSBs
                fslot,
                add(
                mul(
                div(
                // load the bytes from memory
                mload(add(_postBytes, 0x20)),
                // zero all bytes to the right
                exp(0x100, sub(32, mlength))
                ),
                // and now shift left the number of bytes to
                // leave space for the length in the slot
                exp(0x100, sub(32, newlength))
                ),
                // increase length by the double of the memory
                // bytes length
                mul(mlength, 2)
                )
                )
                )
            }
            case 1 {
            // The stored value fits in the slot, but the combined value
            // will exceed it.
            // get the keccak hash to get the contents of the array
                mstore(0x0, _preBytes.slot)
                let sc := add(keccak256(0x0, 0x20), div(slength, 32))

            // save new length
                sstore(_preBytes.slot, add(mul(newlength, 2), 1))

            // The contents of the _postBytes array start 32 bytes into
            // the structure. Our first read should obtain the `submod`
            // bytes that can fit into the unused space in the last word
            // of the stored array. To get this, we read 32 bytes starting
            // from `submod`, so the data we read overlaps with the array
            // contents by `submod` bytes. Masking the lowest-order
            // `submod` bytes allows us to add that value directly to the
            // stored value.

                let submod := sub(32, slength)
                let mc := add(_postBytes, submod)
                let end := add(_postBytes, mlength)
                let mask := sub(exp(0x100, submod), 1)

                sstore(
                sc,
                add(
                and(
                fslot,
                0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff00
                ),
                and(mload(mc), mask)
                )
                )

                for {
                    mc := add(mc, 0x20)
                    sc := add(sc, 1)
                } lt(mc, end) {
                    sc := add(sc, 1)
                    mc := add(mc, 0x20)
                } {
                    sstore(sc, mload(mc))
                }

                mask := exp(0x100, sub(mc, end))

                sstore(sc, mul(div(mload(mc), mask), mask))
            }
            default {
            // get the keccak hash to get the contents of the array
                mstore(0x0, _preBytes.slot)
            // Start copying to the last used word of the stored array.
                let sc := add(keccak256(0x0, 0x20), div(slength, 32))

            // save new length
                sstore(_preBytes.slot, add(mul(newlength, 2), 1))

            // Copy over the first `submod` bytes of the new data as in
            // case 1 above.
                let slengthmod := mod(slength, 32)
                let mlengthmod := mod(mlength, 32)
                let submod := sub(32, slengthmod)
                let mc := add(_postBytes, submod)
                let end := add(_postBytes, mlength)
                let mask := sub(exp(0x100, submod), 1)

                sstore(sc, add(sload(sc), and(mload(mc), mask)))

                for {
                    sc := add(sc, 1)
                    mc := add(mc, 0x20)
                } lt(mc, end) {
                    sc := add(sc, 1)
                    mc := add(mc, 0x20)
                } {
                    sstore(sc, mload(mc))
                }

                mask := exp(0x100, sub(mc, end))

                sstore(sc, mul(div(mload(mc), mask), mask))
            }
        }
    }

    function slice(
        bytes memory _bytes,
        uint256 _start,
        uint256 _length
    )
    internal
    pure
    returns (bytes memory)
    {
        require(_length + 31 >= _length, "slice_overflow");
        require(_bytes.length >= _start + _length, "slice_outOfBounds");

        bytes memory tempBytes;

        assembly {
            switch iszero(_length)
            case 0 {
            // Get a location of some free memory and store it in tempBytes as
            // Solidity does for memory variables.
                tempBytes := mload(0x40)

            // The first word of the slice result is potentially a partial
            // word read from the original array. To read it, we calculate
            // the length of that partial word and start copying that many
            // bytes into the array. The first word we copy will start with
            // data we don't care about, but the last `lengthmod` bytes will
            // land at the beginning of the contents of the new array. When
            // we're done copying, we overwrite the full first word with
            // the actual length of the slice.
                let lengthmod := and(_length, 31)

            // The multiplication in the next line is necessary
            // because when slicing multiples of 32 bytes (lengthmod == 0)
            // the following copy loop was copying the origin's length
            // and then ending prematurely not copying everything it should.
                let mc := add(add(tempBytes, lengthmod), mul(0x20, iszero(lengthmod)))
                let end := add(mc, _length)

                for {
                // The multiplication in the next line has the same exact purpose
                // as the one above.
                    let cc := add(add(add(_bytes, lengthmod), mul(0x20, iszero(lengthmod))), _start)
                } lt(mc, end) {
                    mc := add(mc, 0x20)
                    cc := add(cc, 0x20)
                } {
                    mstore(mc, mload(cc))
                }

                mstore(tempBytes, _length)

            //update free-memory pointer
            //allocating the array padded to 32 bytes like the compiler does now
                mstore(0x40, and(add(mc, 31), not(31)))
            }
            //if we want a zero-length slice let's just return a zero-length array
            default {
                tempBytes := mload(0x40)
            //zero out the 32 bytes slice we are about to return
            //we need to do it because Solidity does not garbage collect
                mstore(tempBytes, 0)

                mstore(0x40, add(tempBytes, 0x20))
            }
        }

        return tempBytes;
    }

    function toAddress(bytes memory _bytes, uint256 _start) internal pure returns (address) {
        require(_bytes.length >= _start + 20, "toAddress_outOfBounds");
        address tempAddress;

        assembly {
            tempAddress := div(mload(add(add(_bytes, 0x20), _start)), 0x1000000000000000000000000)
        }

        return tempAddress;
    }

    function toUint8(bytes memory _bytes, uint256 _start) internal pure returns (uint8) {
        require(_bytes.length >= _start + 1 , "toUint8_outOfBounds");
        uint8 tempUint;

        assembly {
            tempUint := mload(add(add(_bytes, 0x1), _start))
        }

        return tempUint;
    }

    function toUint16(bytes memory _bytes, uint256 _start) internal pure returns (uint16) {
        require(_bytes.length >= _start + 2, "toUint16_outOfBounds");
        uint16 tempUint;

        assembly {
            tempUint := mload(add(add(_bytes, 0x2), _start))
        }

        return tempUint;
    }

    function toUint32(bytes memory _bytes, uint256 _start) internal pure returns (uint32) {
        require(_bytes.length >= _start + 4, "toUint32_outOfBounds");
        uint32 tempUint;

        assembly {
            tempUint := mload(add(add(_bytes, 0x4), _start))
        }

        return tempUint;
    }

    function toUint64(bytes memory _bytes, uint256 _start) internal pure returns (uint64) {
        require(_bytes.length >= _start + 8, "toUint64_outOfBounds");
        uint64 tempUint;

        assembly {
            tempUint := mload(add(add(_bytes, 0x8), _start))
        }

        return tempUint;
    }

    function toUint96(bytes memory _bytes, uint256 _start) internal pure returns (uint96) {
        require(_bytes.length >= _start + 12, "toUint96_outOfBounds");
        uint96 tempUint;

        assembly {
            tempUint := mload(add(add(_bytes, 0xc), _start))
        }

        return tempUint;
    }

    function toUint128(bytes memory _bytes, uint256 _start) internal pure returns (uint128) {
        require(_bytes.length >= _start + 16, "toUint128_outOfBounds");
        uint128 tempUint;

        assembly {
            tempUint := mload(add(add(_bytes, 0x10), _start))
        }

        return tempUint;
    }

    function toUint256(bytes memory _bytes, uint256 _start) internal pure returns (uint256) {
        require(_bytes.length >= _start + 32, "toUint256_outOfBounds");
        uint256 tempUint;

        assembly {
            tempUint := mload(add(add(_bytes, 0x20), _start))
        }

        return tempUint;
    }

    function toBytes32(bytes memory _bytes, uint256 _start) internal pure returns (bytes32) {
        require(_bytes.length >= _start + 32, "toBytes32_outOfBounds");
        bytes32 tempBytes32;

        assembly {
            tempBytes32 := mload(add(add(_bytes, 0x20), _start))
        }

        return tempBytes32;
    }

    function equal(bytes memory _preBytes, bytes memory _postBytes) internal pure returns (bool) {
        bool success = true;

        assembly {
            let length := mload(_preBytes)

        // if lengths don't match the arrays are not equal
            switch eq(length, mload(_postBytes))
            case 1 {
            // cb is a circuit breaker in the for loop since there's
            //  no said feature for inline assembly loops
            // cb = 1 - don't breaker
            // cb = 0 - break
                let cb := 1

                let mc := add(_preBytes, 0x20)
                let end := add(mc, length)

                for {
                    let cc := add(_postBytes, 0x20)
                // the next line is the loop condition:
                // while(uint256(mc < end) + cb == 2)
                } eq(add(lt(mc, end), cb), 2) {
                    mc := add(mc, 0x20)
                    cc := add(cc, 0x20)
                } {
                // if any of these checks fails then arrays are not equal
                    if iszero(eq(mload(mc), mload(cc))) {
                    // unsuccess:
                        success := 0
                        cb := 0
                    }
                }
            }
            default {
            // unsuccess:
                success := 0
            }
        }

        return success;
    }

    function equalStorage(
        bytes storage _preBytes,
        bytes memory _postBytes
    )
    internal
    view
    returns (bool)
    {
        bool success = true;

        assembly {
        // we know _preBytes_offset is 0
            let fslot := sload(_preBytes.slot)
        // Decode the length of the stored array like in concatStorage().
            let slength := div(and(fslot, sub(mul(0x100, iszero(and(fslot, 1))), 1)), 2)
            let mlength := mload(_postBytes)

        // if lengths don't match the arrays are not equal
            switch eq(slength, mlength)
            case 1 {
            // slength can contain both the length and contents of the array
            // if length < 32 bytes so let's prepare for that
            // v. http://solidity.readthedocs.io/en/latest/miscellaneous.html#layout-of-state-variables-in-storage
                if iszero(iszero(slength)) {
                    switch lt(slength, 32)
                    case 1 {
                    // blank the last byte which is the length
                        fslot := mul(div(fslot, 0x100), 0x100)

                        if iszero(eq(fslot, mload(add(_postBytes, 0x20)))) {
                        // unsuccess:
                            success := 0
                        }
                    }
                    default {
                    // cb is a circuit breaker in the for loop since there's
                    //  no said feature for inline assembly loops
                    // cb = 1 - don't breaker
                    // cb = 0 - break
                        let cb := 1

                    // get the keccak hash to get the contents of the array
                        mstore(0x0, _preBytes.slot)
                        let sc := keccak256(0x0, 0x20)

                        let mc := add(_postBytes, 0x20)
                        let end := add(mc, mlength)

                    // the next line is the loop condition:
                    // while(uint256(mc < end) + cb == 2)
                        for {} eq(add(lt(mc, end), cb), 2) {
                            sc := add(sc, 1)
                            mc := add(mc, 0x20)
                        } {
                            if iszero(eq(sload(sc), mload(mc))) {
                            // unsuccess:
                                success := 0
                                cb := 0
                            }
                        }
                    }
                }
            }
            default {
            // unsuccess:
                success := 0
            }
        }

        return success;
    }
}

// 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
import "@layerzerolabs/solidity-examples/contracts/lzApp/NonblockingLzApp.sol";
import "./abstract/ERC20BridgeRateLimiter.sol";

pragma solidity 0.8.17;

contract ERC20Bridge is NonblockingLzApp, ERC20BridgeRateLimiter {

    // Structs
    struct MintMessage {
        address to;
        uint amount;
    }

    // Events
    event MintMessageReceived(uint16 indexed srcChainId, address indexed to, uint amount);
    event BridgingInitiated(uint16 indexed targetChainId, address indexed to, uint amount);

    constructor(
        address _lzEndpoint,
        IERC20MintableBurnable _token,
        address _owner,
        uint _maxEpochLimit,
        uint _epochDuration,
        uint _epochLimit
    ) NonblockingLzApp(_lzEndpoint) ERC20BridgeRateLimiter(
        _token,
        _owner,
        _maxEpochLimit,
        _epochDuration,
        _epochLimit
    ) {}

    // @dev Helper to build MintMessage
    function buildBridgeMessage(address to, uint amount) private pure returns (bytes memory) {
        return abi.encode(
            MintMessage({
                to: to,
                amount: amount
            })
        );
    }

    // @notice Mints GNS bridged from the other side, can only be invoked by a trusted remote
    // @param payload message sent from the other side
    function _nonblockingLzReceive(
        uint16 srcChainId,
        bytes memory /* srcAddress */,
        uint64 /* nonce */,
        bytes memory payload
    ) internal override {
        MintMessage memory message = abi.decode(payload, (MintMessage));
        
        if(paused()){
            addPendingClaim(message.to, message.amount);
        }else{
            tryMint(message.to, message.amount);
        }
        
        emit MintMessageReceived(srcChainId, message.to, message.amount);
    }

    // @notice Burns GNS from caller, then sends a cross-chain message to the destination chain.
    // @param dstChainId The **LayerZero** destination chain ID.
    function bridgeTokens(uint16 dstChainId, uint amount) external payable whenNotPaused {
        require(msg.value != 0, "!fee");
        require(amount > 0, "!amount");

        address sender = _msgSender();
        tryBurn(sender, amount);

        _lzSend(
            dstChainId,
            buildBridgeMessage(sender, amount),
            payable(sender),  // refund address (LayerZero will refund any extra gas back to caller)
            address(0x0),     // unused
            bytes(""),        // unused
            msg.value         // native fee amount
        );

        emit BridgingInitiated(dstChainId, sender, amount);
    }

    // @notice Used by the frontend to estimate how much native token should be sent with bridgeTokens() for LayerZero fees.
    // @param dstChainId The **LayerZero** destination chain ID.
    function estimateNativeFee(
        uint16 dstChainId,
        address to,
        uint amount
    ) external view returns (uint nativeFee) {
        (nativeFee, ) = lzEndpoint.estimateFees(
            dstChainId,
            address(this),
            buildBridgeMessage(to, amount),
            false,
            bytes("")
        );
    }
}

//SPDX-License-Identifier: MIT
import "@openzeppelin/contracts/utils/math/Math.sol";

import "./../interfaces/IERC20MintableBurnable.sol";
import "./EpochBasedLimiter.sol";

pragma solidity 0.8.17;

abstract contract ERC20BridgeRateLimiter is EpochBasedLimiter {

    // Addresses
    IERC20MintableBurnable public token;

    // Pending claims
    struct PendingClaim {
        uint amount;
        uint claimTimestamp;
    }
    mapping(address => PendingClaim) public pendingClaims;

    // Events
    event Burned(address indexed from, uint amount);
    event Minted(address indexed to, uint amount);
    event PendingClaimUpdated(address indexed to, uint amount, uint claimTimestamp);
    event PendingClaimExecuted(address indexed to, uint amount);

    constructor(
        IERC20MintableBurnable _token,
        address _owner,
        uint _maxEpochLimit,
        uint _epochDuration,
        uint _epochLimit
    ) EpochBasedLimiter(
        _owner,
        _maxEpochLimit,
        _epochDuration,
        _epochLimit
    ) {
        require(address(_token) != address(0), "ADDRESS_0");
        token = _token;
    }

    // @dev Initiating the bridging. Throttled by epoch limit and blacklist.
    function tryBurn(address from, uint amount) internal whenNotPaused {
        require(amount <= epochLimit, "AMOUNT_TOO_HIGH");
        require(!blacklist[from], "BLACKLISTED");
        token.burn(from, amount);
        
        emit Burned(from, amount);
    }

    // @dev Executing the second part of the bridging. Throttled by epoch limit and blacklist.
    function tryMint(address to, uint amount) internal whenNotPaused {
        require(amount <= MAX_EPOCH_LIMIT, "AMOUNT_TOO_HIGH");
        require(!blacklist[to], "BLACKLISTED");
        
        tryUpdateEpoch();

        uint mintAmount = Math.min(
            amount,
            epochLimit - Math.min(epochLimit, currentEpochCount)
        );

        // If epoch limit reached, add to pending claims and emit event
        if (mintAmount < amount) {
            addPendingClaim(to, amount - mintAmount);
        }

        currentEpochCount += mintAmount;
        token.mint(to, mintAmount);

        emit Minted(to, mintAmount);
    }

    // @dev Add pending claim when throttled by epoch limit
    function addPendingClaim(address to, uint amount) internal {
        PendingClaim storage pendingClaim = pendingClaims[to];
        pendingClaim.amount += amount;
        pendingClaim.claimTimestamp = block.timestamp + epochDuration;

        emit PendingClaimUpdated(to, pendingClaim.amount, pendingClaim.claimTimestamp);
    }

    // @notice Executes pending claim for receiver. Throttled by epoch limit and blacklist.
    function executePendingClaim(address receiver) external whenNotPaused {
        PendingClaim storage pendingClaim = pendingClaims[receiver];

        require(pendingClaim.amount > 0, "NO_PENDING_CLAIM");
        require(pendingClaim.claimTimestamp <= block.timestamp, "TOO_EARLY");
        require(!blacklist[receiver], "RECEIVER_BLACKLISTED");

        tryUpdateEpoch();

        uint claimAmount = Math.min(
            pendingClaim.amount,
            epochLimit - Math.min(epochLimit, currentEpochCount)
        );

        pendingClaim.amount -= claimAmount;

        if (pendingClaim.amount > 0) {
            pendingClaim.claimTimestamp = block.timestamp + epochDuration;

            emit PendingClaimUpdated(
                receiver,
                pendingClaim.amount,
                pendingClaim.claimTimestamp
            );
        }

        currentEpochCount += claimAmount;
        token.mint(receiver, claimAmount);

        emit PendingClaimExecuted(receiver, claimAmount);
    }
}

//SPDX-License-Identifier: MIT
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/security/Pausable.sol";

import "./../interfaces/IEpochBasedLimiter.sol";

pragma solidity 0.8.17;

abstract contract EpochBasedLimiter is Ownable, Pausable, IEpochBasedLimiter {
    
    // Constants
    uint public constant MIN_EPOCH_DURATION = 30 minutes;
    uint public constant MAX_EPOCH_DURATION = 1 weeks;
    uint public immutable MAX_EPOCH_LIMIT;

    // Epoch params
    uint public epochDuration;
    uint public epochLimit;

    // Epoch state
    uint public currentEpoch;
    uint public currentEpochStart;
    uint public currentEpochCount;

    // Blacklist
    mapping(address => bool) public blacklist;

    // Events
    event EpochDurationUpdated(uint epochDuration);
    event EpochLimitUpdated(uint epochLimit);
    event EpochStarted(uint indexed epochId, uint epochStart);
    event Blacklisted(address indexed receiver, bool isBlacklisted);

    constructor(
        address _owner,
        uint _maxEpochLimit,
        uint _epochDuration,
        uint _epochLimit
    ) {
        require(
            _owner != address(0) &&
            _maxEpochLimit > 0 &&
            _epochDuration >= MIN_EPOCH_DURATION &&
            _epochDuration <= MAX_EPOCH_DURATION &&
            _epochLimit <= _maxEpochLimit,
            "WRONG_PARAMS"
        );

        MAX_EPOCH_LIMIT = _maxEpochLimit;

        epochDuration = _epochDuration;
        epochLimit = _epochLimit;

        currentEpoch = 1;
        currentEpochStart = block.timestamp;

        _transferOwnership(_owner);
    }

    // @notice Pause functions
    function pause() external onlyOwner {
        _pause();
    }

    function unpause() external onlyOwner {
        _unpause();
    }

    // @dev Updates duration of epoch in seconds
    function updateEpochDuration(uint _epochDuration) external onlyOwner {
        require(
            _epochDuration >= MIN_EPOCH_DURATION && _epochDuration <= MAX_EPOCH_DURATION,
            "INVALID_EPOCH_DURATION"
        );
        epochDuration = _epochDuration;

        emit EpochDurationUpdated(_epochDuration);
    }

    // @dev Update epoch limit
    function updateEpochLimit(uint _epochLimit) external onlyOwner {
        require(_epochLimit <= MAX_EPOCH_LIMIT, "INVALID_EPOCH_LIMIT");
        epochLimit = _epochLimit;

        emit EpochLimitUpdated(_epochLimit);
    }

    // @dev Adds address to blacklist. Prevents minting, burning, and using pending claims.
    function blacklistReceiver(address receiver, bool blacklisted) external onlyOwner {
        blacklist[receiver] = blacklisted;
        emit Blacklisted(receiver, blacklisted);
    }

    // @dev Tries to rotate epoch window
    function tryUpdateEpoch() public {
        if (block.timestamp >= currentEpochStart + epochDuration) {
            currentEpoch ++;
            currentEpochStart = block.timestamp;
            currentEpochCount = 0;
            
            emit EpochStarted(currentEpoch, currentEpochStart);
        }
    }
}

// SPDX-License-Identifier: MIT OR Apache-2.0
pragma solidity >=0.7.6;

library ExcessivelySafeCall {
    uint256 constant LOW_28_MASK =
    0x00000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffff;

    /// @notice Use when you _really_ really _really_ don't trust the called
    /// contract. This prevents the called contract from causing reversion of
    /// the caller in as many ways as we can.
    /// @dev The main difference between this and a solidity low-level call is
    /// that we limit the number of bytes that the callee can cause to be
    /// copied to caller memory. This prevents stupid things like malicious
    /// contracts returning 10,000,000 bytes causing a local OOG when copying
    /// to memory.
    /// @param _target The address to call
    /// @param _gas The amount of gas to forward to the remote contract
    /// @param _maxCopy The maximum number of bytes of returndata to copy
    /// to memory.
    /// @param _calldata The data to send to the remote contract
    /// @return success and returndata, as `.call()`. Returndata is capped to
    /// `_maxCopy` bytes.
    function excessivelySafeCall(
        address _target,
        uint256 _gas,
        uint16 _maxCopy,
        bytes memory _calldata
    ) internal returns (bool, bytes memory) {
        // set up for assembly call
        uint256 _toCopy;
        bool _success;
        bytes memory _returnData = new bytes(_maxCopy);
        // dispatch message to recipient
        // by assembly calling "handle" function
        // we call via assembly to avoid memcopying a very large returndata
        // returned by a malicious contract
        assembly {
            _success := call(
            _gas, // gas
            _target, // recipient
            0, // ether value
            add(_calldata, 0x20), // inloc
            mload(_calldata), // inlen
            0, // outloc
            0 // outlen
            )
        // limit our copy to 256 bytes
            _toCopy := returndatasize()
            if gt(_toCopy, _maxCopy) {
                _toCopy := _maxCopy
            }
        // Store the length of the copied bytes
            mstore(_returnData, _toCopy)
        // copy the bytes from returndata[0:_toCopy]
            returndatacopy(add(_returnData, 0x20), 0, _toCopy)
        }
        return (_success, _returnData);
    }

    /// @notice Use when you _really_ really _really_ don't trust the called
    /// contract. This prevents the called contract from causing reversion of
    /// the caller in as many ways as we can.
    /// @dev The main difference between this and a solidity low-level call is
    /// that we limit the number of bytes that the callee can cause to be
    /// copied to caller memory. This prevents stupid things like malicious
    /// contracts returning 10,000,000 bytes causing a local OOG when copying
    /// to memory.
    /// @param _target The address to call
    /// @param _gas The amount of gas to forward to the remote contract
    /// @param _maxCopy The maximum number of bytes of returndata to copy
    /// to memory.
    /// @param _calldata The data to send to the remote contract
    /// @return success and returndata, as `.call()`. Returndata is capped to
    /// `_maxCopy` bytes.
    function excessivelySafeStaticCall(
        address _target,
        uint256 _gas,
        uint16 _maxCopy,
        bytes memory _calldata
    ) internal view returns (bool, bytes memory) {
        // set up for assembly call
        uint256 _toCopy;
        bool _success;
        bytes memory _returnData = new bytes(_maxCopy);
        // dispatch message to recipient
        // by assembly calling "handle" function
        // we call via assembly to avoid memcopying a very large returndata
        // returned by a malicious contract
        assembly {
            _success := staticcall(
            _gas, // gas
            _target, // recipient
            add(_calldata, 0x20), // inloc
            mload(_calldata), // inlen
            0, // outloc
            0 // outlen
            )
        // limit our copy to 256 bytes
            _toCopy := returndatasize()
            if gt(_toCopy, _maxCopy) {
                _toCopy := _maxCopy
            }
        // Store the length of the copied bytes
            mstore(_returnData, _toCopy)
        // copy the bytes from returndata[0:_toCopy]
            returndatacopy(add(_returnData, 0x20), 0, _toCopy)
        }
        return (_success, _returnData);
    }

    /**
     * @notice Swaps function selectors in encoded contract calls
     * @dev Allows reuse of encoded calldata for functions with identical
     * argument types but different names. It simply swaps out the first 4 bytes
     * for the new selector. This function modifies memory in place, and should
     * only be used with caution.
     * @param _newSelector The new 4-byte selector
     * @param _buf The encoded contract args
     */
    function swapSelector(bytes4 _newSelector, bytes memory _buf)
    internal
    pure
    {
        require(_buf.length >= 4);
        uint256 _mask = LOW_28_MASK;
        assembly {
        // load the first word of
            let _word := mload(add(_buf, 0x20))
        // mask out the top 4 bytes
        // /x
            _word := and(_word, _mask)
            _word := or(_newSelector, _word)
            mstore(add(_buf, 0x20), _word)
        }
    }
}

//SPDX-License-Identifier: MIT
pragma solidity 0.8.17;

interface IERC20MintableBurnable {
    function burn(address from, uint amount) external;
    function mint(address to, uint amount) external;
}

//SPDX-License-Identifier: MIT
pragma solidity 0.8.17;

interface IEpochBasedLimiter {
    function epochLimit() external view returns (uint);
    function epochDuration() external view returns (uint);
    function currentEpoch() external view returns (uint);
    function currentEpochStart() external view returns (uint);
    function currentEpochCount() external view returns (uint);
    function tryUpdateEpoch() external;
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.5.0;

import "./ILayerZeroUserApplicationConfig.sol";

interface ILayerZeroEndpoint is ILayerZeroUserApplicationConfig {
    // @notice send a LayerZero message to the specified address at a LayerZero endpoint.
    // @param _dstChainId - the destination chain identifier
    // @param _destination - the address on destination chain (in bytes). address length/format may vary by chains
    // @param _payload - a custom bytes payload to send to the destination contract
    // @param _refundAddress - if the source transaction is cheaper than the amount of value passed, refund the additional amount to this address
    // @param _zroPaymentAddress - the address of the ZRO token holder who would pay for the transaction
    // @param _adapterParams - parameters for custom functionality. e.g. receive airdropped native gas from the relayer on destination
    function send(uint16 _dstChainId, bytes calldata _destination, bytes calldata _payload, address payable _refundAddress, address _zroPaymentAddress, bytes calldata _adapterParams) external payable;

    // @notice used by the messaging library to publish verified payload
    // @param _srcChainId - the source chain identifier
    // @param _srcAddress - the source contract (as bytes) at the source chain
    // @param _dstAddress - the address on destination chain
    // @param _nonce - the unbound message ordering nonce
    // @param _gasLimit - the gas limit for external contract execution
    // @param _payload - verified payload to send to the destination contract
    function receivePayload(uint16 _srcChainId, bytes calldata _srcAddress, address _dstAddress, uint64 _nonce, uint _gasLimit, bytes calldata _payload) external;

    // @notice get the inboundNonce of a lzApp from a source chain which could be EVM or non-EVM chain
    // @param _srcChainId - the source chain identifier
    // @param _srcAddress - the source chain contract address
    function getInboundNonce(uint16 _srcChainId, bytes calldata _srcAddress) external view returns (uint64);

    // @notice get the outboundNonce from this source chain which, consequently, is always an EVM
    // @param _srcAddress - the source chain contract address
    function getOutboundNonce(uint16 _dstChainId, address _srcAddress) external view returns (uint64);

    // @notice gets a quote in source native gas, for the amount that send() requires to pay for message delivery
    // @param _dstChainId - the destination chain identifier
    // @param _userApplication - the user app address on this EVM chain
    // @param _payload - the custom message to send over LayerZero
    // @param _payInZRO - if false, user app pays the protocol fee in native token
    // @param _adapterParam - parameters for the adapter service, e.g. send some dust native token to dstChain
    function estimateFees(uint16 _dstChainId, address _userApplication, bytes calldata _payload, bool _payInZRO, bytes calldata _adapterParam) external view returns (uint nativeFee, uint zroFee);

    // @notice get this Endpoint's immutable source identifier
    function getChainId() external view returns (uint16);

    // @notice the interface to retry failed message on this Endpoint destination
    // @param _srcChainId - the source chain identifier
    // @param _srcAddress - the source chain contract address
    // @param _payload - the payload to be retried
    function retryPayload(uint16 _srcChainId, bytes calldata _srcAddress, bytes calldata _payload) external;

    // @notice query if any STORED payload (message blocking) at the endpoint.
    // @param _srcChainId - the source chain identifier
    // @param _srcAddress - the source chain contract address
    function hasStoredPayload(uint16 _srcChainId, bytes calldata _srcAddress) external view returns (bool);

    // @notice query if the _libraryAddress is valid for sending msgs.
    // @param _userApplication - the user app address on this EVM chain
    function getSendLibraryAddress(address _userApplication) external view returns (address);

    // @notice query if the _libraryAddress is valid for receiving msgs.
    // @param _userApplication - the user app address on this EVM chain
    function getReceiveLibraryAddress(address _userApplication) external view returns (address);

    // @notice query if the non-reentrancy guard for send() is on
    // @return true if the guard is on. false otherwise
    function isSendingPayload() external view returns (bool);

    // @notice query if the non-reentrancy guard for receive() is on
    // @return true if the guard is on. false otherwise
    function isReceivingPayload() external view returns (bool);

    // @notice get the configuration of the LayerZero messaging library of the specified version
    // @param _version - messaging library version
    // @param _chainId - the chainId for the pending config change
    // @param _userApplication - the contract address of the user application
    // @param _configType - type of configuration. every messaging library has its own convention.
    function getConfig(uint16 _version, uint16 _chainId, address _userApplication, uint _configType) external view returns (bytes memory);

    // @notice get the send() LayerZero messaging library version
    // @param _userApplication - the contract address of the user application
    function getSendVersion(address _userApplication) external view returns (uint16);

    // @notice get the lzReceive() LayerZero messaging library version
    // @param _userApplication - the contract address of the user application
    function getReceiveVersion(address _userApplication) external view returns (uint16);
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.5.0;

interface ILayerZeroReceiver {
    // @notice LayerZero endpoint will invoke this function to deliver the message on the destination
    // @param _srcChainId - the source endpoint identifier
    // @param _srcAddress - the source sending contract address from the source chain
    // @param _nonce - the ordered message nonce
    // @param _payload - the signed payload is the UA bytes has encoded to be sent
    function lzReceive(uint16 _srcChainId, bytes calldata _srcAddress, uint64 _nonce, bytes calldata _payload) external;
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.5.0;

interface ILayerZeroUserApplicationConfig {
    // @notice set the configuration of the LayerZero messaging library of the specified version
    // @param _version - messaging library version
    // @param _chainId - the chainId for the pending config change
    // @param _configType - type of configuration. every messaging library has its own convention.
    // @param _config - configuration in the bytes. can encode arbitrary content.
    function setConfig(uint16 _version, uint16 _chainId, uint _configType, bytes calldata _config) external;

    // @notice set the send() LayerZero messaging library version to _version
    // @param _version - new messaging library version
    function setSendVersion(uint16 _version) external;

    // @notice set the lzReceive() LayerZero messaging library version to _version
    // @param _version - new messaging library version
    function setReceiveVersion(uint16 _version) external;

    // @notice Only when the UA needs to resume the message flow in blocking mode and clear the stored payload
    // @param _srcChainId - the chainId of the source chain
    // @param _srcAddress - the contract address of the source contract at the source chain
    function forceResumeReceive(uint16 _srcChainId, bytes calldata _srcAddress) external;
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/access/Ownable.sol";
import "../interfaces/ILayerZeroReceiver.sol";
import "../interfaces/ILayerZeroUserApplicationConfig.sol";
import "../interfaces/ILayerZeroEndpoint.sol";
import "../util/BytesLib.sol";

/*
 * a generic LzReceiver implementation
 */
abstract contract LzApp is Ownable, ILayerZeroReceiver, ILayerZeroUserApplicationConfig {
    using BytesLib for bytes;

    ILayerZeroEndpoint public immutable lzEndpoint;
    mapping(uint16 => bytes) public trustedRemoteLookup;
    mapping(uint16 => mapping(uint16 => uint)) public minDstGasLookup;
    address public precrime;

    event SetPrecrime(address precrime);
    event SetTrustedRemote(uint16 _remoteChainId, bytes _path);
    event SetTrustedRemoteAddress(uint16 _remoteChainId, bytes _remoteAddress);
    event SetMinDstGas(uint16 _dstChainId, uint16 _type, uint _minDstGas);

    constructor(address _endpoint) {
        lzEndpoint = ILayerZeroEndpoint(_endpoint);
    }

    function lzReceive(uint16 _srcChainId, bytes calldata _srcAddress, uint64 _nonce, bytes calldata _payload) public virtual override {
        // lzReceive must be called by the endpoint for security
        require(_msgSender() == address(lzEndpoint), "LzApp: invalid endpoint caller");

        bytes memory trustedRemote = trustedRemoteLookup[_srcChainId];
        // if will still block the message pathway from (srcChainId, srcAddress). should not receive message from untrusted remote.
        require(_srcAddress.length == trustedRemote.length && trustedRemote.length > 0 && keccak256(_srcAddress) == keccak256(trustedRemote), "LzApp: invalid source sending contract");

        _blockingLzReceive(_srcChainId, _srcAddress, _nonce, _payload);
    }

    // abstract function - the default behaviour of LayerZero is blocking. See: NonblockingLzApp if you dont need to enforce ordered messaging
    function _blockingLzReceive(uint16 _srcChainId, bytes memory _srcAddress, uint64 _nonce, bytes memory _payload) internal virtual;

    function _lzSend(uint16 _dstChainId, bytes memory _payload, address payable _refundAddress, address _zroPaymentAddress, bytes memory _adapterParams, uint _nativeFee) internal virtual {
        bytes memory trustedRemote = trustedRemoteLookup[_dstChainId];
        require(trustedRemote.length != 0, "LzApp: destination chain is not a trusted source");
        lzEndpoint.send{value: _nativeFee}(_dstChainId, trustedRemote, _payload, _refundAddress, _zroPaymentAddress, _adapterParams);
    }

    function _checkGasLimit(uint16 _dstChainId, uint16 _type, bytes memory _adapterParams, uint _extraGas) internal view virtual {
        uint providedGasLimit = _getGasLimit(_adapterParams);
        uint minGasLimit = minDstGasLookup[_dstChainId][_type] + _extraGas;
        require(minGasLimit > 0, "LzApp: minGasLimit not set");
        require(providedGasLimit >= minGasLimit, "LzApp: gas limit is too low");
    }

    function _getGasLimit(bytes memory _adapterParams) internal pure virtual returns (uint gasLimit) {
        require(_adapterParams.length >= 34, "LzApp: invalid adapterParams");
        assembly {
            gasLimit := mload(add(_adapterParams, 34))
        }
    }

    //---------------------------UserApplication config----------------------------------------
    function getConfig(uint16 _version, uint16 _chainId, address, uint _configType) external view returns (bytes memory) {
        return lzEndpoint.getConfig(_version, _chainId, address(this), _configType);
    }

    // generic config for LayerZero user Application
    function setConfig(uint16 _version, uint16 _chainId, uint _configType, bytes calldata _config) external override onlyOwner {
        lzEndpoint.setConfig(_version, _chainId, _configType, _config);
    }

    function setSendVersion(uint16 _version) external override onlyOwner {
        lzEndpoint.setSendVersion(_version);
    }

    function setReceiveVersion(uint16 _version) external override onlyOwner {
        lzEndpoint.setReceiveVersion(_version);
    }

    function forceResumeReceive(uint16 _srcChainId, bytes calldata _srcAddress) external override onlyOwner {
        lzEndpoint.forceResumeReceive(_srcChainId, _srcAddress);
    }

    // _path = abi.encodePacked(remoteAddress, localAddress)
    // this function set the trusted path for the cross-chain communication
    function setTrustedRemote(uint16 _srcChainId, bytes calldata _path) external onlyOwner {
        trustedRemoteLookup[_srcChainId] = _path;
        emit SetTrustedRemote(_srcChainId, _path);
    }

    function setTrustedRemoteAddress(uint16 _remoteChainId, bytes calldata _remoteAddress) external onlyOwner {
        trustedRemoteLookup[_remoteChainId] = abi.encodePacked(_remoteAddress, address(this));
        emit SetTrustedRemoteAddress(_remoteChainId, _remoteAddress);
    }

    function getTrustedRemoteAddress(uint16 _remoteChainId) external view returns (bytes memory) {
        bytes memory path = trustedRemoteLookup[_remoteChainId];
        require(path.length != 0, "LzApp: no trusted path record");
        return path.slice(0, path.length - 20); // the last 20 bytes should be address(this)
    }

    function setPrecrime(address _precrime) external onlyOwner {
        precrime = _precrime;
        emit SetPrecrime(_precrime);
    }

    function setMinDstGas(uint16 _dstChainId, uint16 _packetType, uint _minGas) external onlyOwner {
        require(_minGas > 0, "LzApp: invalid minGas");
        minDstGasLookup[_dstChainId][_packetType] = _minGas;
        emit SetMinDstGas(_dstChainId, _packetType, _minGas);
    }

    //--------------------------- VIEW FUNCTION ----------------------------------------
    function isTrustedRemote(uint16 _srcChainId, bytes calldata _srcAddress) external view returns (bool) {
        bytes memory trustedSource = trustedRemoteLookup[_srcChainId];
        return keccak256(trustedSource) == keccak256(_srcAddress);
    }
}

// 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

pragma solidity ^0.8.0;

import "./LzApp.sol";
import "../util/ExcessivelySafeCall.sol";

/*
 * the default LayerZero messaging behaviour is blocking, i.e. any failed message will block the channel
 * this abstract class try-catch all fail messages and store locally for future retry. hence, non-blocking
 * NOTE: if the srcAddress is not configured properly, it will still block the message pathway from (srcChainId, srcAddress)
 */
abstract contract NonblockingLzApp is LzApp {
    using ExcessivelySafeCall for address;

    constructor(address _endpoint) LzApp(_endpoint) {}

    mapping(uint16 => mapping(bytes => mapping(uint64 => bytes32))) public failedMessages;

    event MessageFailed(uint16 _srcChainId, bytes _srcAddress, uint64 _nonce, bytes _payload, bytes _reason);
    event RetryMessageSuccess(uint16 _srcChainId, bytes _srcAddress, uint64 _nonce, bytes32 _payloadHash);

    // overriding the virtual function in LzReceiver
    function _blockingLzReceive(uint16 _srcChainId, bytes memory _srcAddress, uint64 _nonce, bytes memory _payload) internal virtual override {
        (bool success, bytes memory reason) = address(this).excessivelySafeCall(gasleft(), 150, abi.encodeWithSelector(this.nonblockingLzReceive.selector, _srcChainId, _srcAddress, _nonce, _payload));
        // try-catch all errors/exceptions
        if (!success) {
            _storeFailedMessage(_srcChainId, _srcAddress, _nonce, _payload, reason);
        }
    }

    function _storeFailedMessage(uint16 _srcChainId, bytes memory _srcAddress, uint64 _nonce, bytes memory _payload, bytes memory _reason) internal virtual {
        failedMessages[_srcChainId][_srcAddress][_nonce] = keccak256(_payload);
        emit MessageFailed(_srcChainId, _srcAddress, _nonce, _payload, _reason);
    }

    function nonblockingLzReceive(uint16 _srcChainId, bytes calldata _srcAddress, uint64 _nonce, bytes calldata _payload) public virtual {
        // only internal transaction
        require(_msgSender() == address(this), "NonblockingLzApp: caller must be LzApp");
        _nonblockingLzReceive(_srcChainId, _srcAddress, _nonce, _payload);
    }

    //@notice override this function
    function _nonblockingLzReceive(uint16 _srcChainId, bytes memory _srcAddress, uint64 _nonce, bytes memory _payload) internal virtual;

    function retryMessage(uint16 _srcChainId, bytes calldata _srcAddress, uint64 _nonce, bytes calldata _payload) public payable virtual {
        // assert there is message to retry
        bytes32 payloadHash = failedMessages[_srcChainId][_srcAddress][_nonce];
        require(payloadHash != bytes32(0), "NonblockingLzApp: no stored message");
        require(keccak256(_payload) == payloadHash, "NonblockingLzApp: invalid payload");
        // clear the stored message
        failedMessages[_srcChainId][_srcAddress][_nonce] = bytes32(0);
        // execute the message. revert if it fails again
        _nonblockingLzReceive(_srcChainId, _srcAddress, _nonce, _payload);
        emit RetryMessageSuccess(_srcChainId, _srcAddress, _nonce, payloadHash);
    }
}

// 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 v4.7.0) (security/Pausable.sol)

pragma solidity ^0.8.0;

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

/**
 * @dev Contract module which allows children to implement an emergency stop
 * mechanism that can be triggered by an authorized account.
 *
 * This module is used through inheritance. It will make available the
 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
 * the functions of your contract. Note that they will not be pausable by
 * simply including this module, only once the modifiers are put in place.
 */
abstract contract Pausable is Context {
    /**
     * @dev Emitted when the pause is triggered by `account`.
     */
    event Paused(address account);

    /**
     * @dev Emitted when the pause is lifted by `account`.
     */
    event Unpaused(address account);

    bool private _paused;

    /**
     * @dev Initializes the contract in unpaused state.
     */
    constructor() {
        _paused = false;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    modifier whenNotPaused() {
        _requireNotPaused();
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        _requirePaused();
        _;
    }

    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     */
    function paused() public view virtual returns (bool) {
        return _paused;
    }

    /**
     * @dev Throws if the contract is paused.
     */
    function _requireNotPaused() internal view virtual {
        require(!paused(), "Pausable: paused");
    }

    /**
     * @dev Throws if the contract is not paused.
     */
    function _requirePaused() internal view virtual {
        require(paused(), "Pausable: not paused");
    }

    /**
     * @dev Triggers stopped state.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Returns to normal state.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
}

{
  "compilationTarget": {
    "contracts/ERC20Bridge.sol": "ERC20Bridge"
  },
  "evmVersion": "london",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": true,
    "runs": 1000
  },
  "remappings": []
}