// File: contracts/libs/common/ZeroCopySource.sol

// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;

/**
 * @dev Wrappers over decoding and deserialization operation from bytes into bassic types in Solidity for PolyNetwork cross chain utility.
 *
 * Decode into basic types in Solidity from bytes easily. It's designed to be used
 * for PolyNetwork cross chain application, and the decoding rules on Ethereum chain
 * and the encoding rule on other chains should be consistent, and . Here we
 * follow the underlying deserialization rule with implementation found here:
 * https://github.com/polynetwork/poly/blob/master/common/zero_copy_source.go
 *
 * Using this library instead of the unchecked serialization method can help reduce
 * the risk of serious bugs and handfule, so it's recommended to use it.
 *
 * Please note that risk can be minimized, yet not eliminated.
 */
library ZeroCopySource {
    /* @notice              Read next byte as boolean type starting at offset from buff
    *  @param buff          Source bytes array
    *  @param offset        The position from where we read the boolean value
    *  @return              The the read boolean value and new offset
    */
    function NextBool(bytes memory buff, uint256 offset) internal pure returns(bool, uint256) {
        require(offset + 1 <= buff.length && offset < offset + 1, "Offset exceeds limit");
        // byte === bytes1
        byte v;
        assembly{
            v := mload(add(add(buff, 0x20), offset))
        }
        bool value;
        if (v == 0x01) {
		    value = true;
    	} else if (v == 0x00) {
            value = false;
        } else {
            revert("NextBool value error");
        }
        return (value, offset + 1);
    }

    /* @notice              Read next byte starting at offset from buff
    *  @param buff          Source bytes array
    *  @param offset        The position from where we read the byte value
    *  @return              The read byte value and new offset
    */
    function NextByte(bytes memory buff, uint256 offset) internal pure returns (byte, uint256) {
        require(offset + 1 <= buff.length && offset < offset + 1, "NextByte, Offset exceeds maximum");
        byte v;
        assembly{
            v := mload(add(add(buff, 0x20), offset))
        }
        return (v, offset + 1);
    }

    /* @notice              Read next byte as uint8 starting at offset from buff
    *  @param buff          Source bytes array
    *  @param offset        The position from where we read the byte value
    *  @return              The read uint8 value and new offset
    */
    function NextUint8(bytes memory buff, uint256 offset) internal pure returns (uint8, uint256) {
        require(offset + 1 <= buff.length && offset < offset + 1, "NextUint8, Offset exceeds maximum");
        uint8 v;
        assembly{
            let tmpbytes := mload(0x40)
            let bvalue := mload(add(add(buff, 0x20), offset))
            mstore8(tmpbytes, byte(0, bvalue))
            mstore(0x40, add(tmpbytes, 0x01))
            v := mload(sub(tmpbytes, 0x1f))
        }
        return (v, offset + 1);
    }

    /* @notice              Read next two bytes as uint16 type starting from offset
    *  @param buff          Source bytes array
    *  @param offset        The position from where we read the uint16 value
    *  @return              The read uint16 value and updated offset
    */
    function NextUint16(bytes memory buff, uint256 offset) internal pure returns (uint16, uint256) {
        require(offset + 2 <= buff.length && offset < offset + 2, "NextUint16, offset exceeds maximum");

        uint16 v;
        assembly {
            let tmpbytes := mload(0x40)
            let bvalue := mload(add(add(buff, 0x20), offset))
            mstore8(tmpbytes, byte(0x01, bvalue))
            mstore8(add(tmpbytes, 0x01), byte(0, bvalue))
            mstore(0x40, add(tmpbytes, 0x02))
            v := mload(sub(tmpbytes, 0x1e))
        }
        return (v, offset + 2);
    }


    /* @notice              Read next four bytes as uint32 type starting from offset
    *  @param buff          Source bytes array
    *  @param offset        The position from where we read the uint32 value
    *  @return              The read uint32 value and updated offset
    */
    function NextUint32(bytes memory buff, uint256 offset) internal pure returns (uint32, uint256) {
        require(offset + 4 <= buff.length && offset < offset + 4, "NextUint32, offset exceeds maximum");
        uint32 v;
        assembly {
            let tmpbytes := mload(0x40)
            let byteLen := 0x04
            for {
                let tindex := 0x00
                let bindex := sub(byteLen, 0x01)
                let bvalue := mload(add(add(buff, 0x20), offset))
            } lt(tindex, byteLen) {
                tindex := add(tindex, 0x01)
                bindex := sub(bindex, 0x01)
            }{
                mstore8(add(tmpbytes, tindex), byte(bindex, bvalue))
            }
            mstore(0x40, add(tmpbytes, byteLen))
            v := mload(sub(tmpbytes, sub(0x20, byteLen)))
        }
        return (v, offset + 4);
    }

    /* @notice              Read next eight bytes as uint64 type starting from offset
    *  @param buff          Source bytes array
    *  @param offset        The position from where we read the uint64 value
    *  @return              The read uint64 value and updated offset
    */
    function NextUint64(bytes memory buff, uint256 offset) internal pure returns (uint64, uint256) {
        require(offset + 8 <= buff.length && offset < offset + 8, "NextUint64, offset exceeds maximum");
        uint64 v;
        assembly {
            let tmpbytes := mload(0x40)
            let byteLen := 0x08
            for {
                let tindex := 0x00
                let bindex := sub(byteLen, 0x01)
                let bvalue := mload(add(add(buff, 0x20), offset))
            } lt(tindex, byteLen) {
                tindex := add(tindex, 0x01)
                bindex := sub(bindex, 0x01)
            }{
                mstore8(add(tmpbytes, tindex), byte(bindex, bvalue))
            }
            mstore(0x40, add(tmpbytes, byteLen))
            v := mload(sub(tmpbytes, sub(0x20, byteLen)))
        }
        return (v, offset + 8);
    }

    /* @notice              Read next 32 bytes as uint256 type starting from offset,
                            there are limits considering the numerical limits in multi-chain
    *  @param buff          Source bytes array
    *  @param offset        The position from where we read the uint256 value
    *  @return              The read uint256 value and updated offset
    */
    function NextUint255(bytes memory buff, uint256 offset) internal pure returns (uint256, uint256) {
        require(offset + 32 <= buff.length && offset < offset + 32, "NextUint255, offset exceeds maximum");
        uint256 v;
        assembly {
            let tmpbytes := mload(0x40)
            let byteLen := 0x20
            for {
                let tindex := 0x00
                let bindex := sub(byteLen, 0x01)
                let bvalue := mload(add(add(buff, 0x20), offset))
            } lt(tindex, byteLen) {
                tindex := add(tindex, 0x01)
                bindex := sub(bindex, 0x01)
            }{
                mstore8(add(tmpbytes, tindex), byte(bindex, bvalue))
            }
            mstore(0x40, add(tmpbytes, byteLen))
            v := mload(tmpbytes)
        }
        require(v <= 0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff, "Value exceeds the range");
        return (v, offset + 32);
    }
    /* @notice              Read next variable bytes starting from offset,
                            the decoding rule coming from multi-chain
    *  @param buff          Source bytes array
    *  @param offset        The position from where we read the bytes value
    *  @return              The read variable bytes array value and updated offset
    */
    function NextVarBytes(bytes memory buff, uint256 offset) internal pure returns(bytes memory, uint256) {
        uint len;
        (len, offset) = NextVarUint(buff, offset);
        require(offset + len <= buff.length && offset < offset + len, "NextVarBytes, offset exceeds maximum");
        bytes memory tempBytes;
        assembly{
            switch iszero(len)
            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(len, 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, len)

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

                mstore(tempBytes, len)

                //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)

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

        return (tempBytes, offset + len);
    }
    /* @notice              Read next 32 bytes starting from offset,
    *  @param buff          Source bytes array
    *  @param offset        The position from where we read the bytes value
    *  @return              The read bytes32 value and updated offset
    */
    function NextHash(bytes memory buff, uint256 offset) internal pure returns (bytes32 , uint256) {
        require(offset + 32 <= buff.length && offset < offset + 32, "NextHash, offset exceeds maximum");
        bytes32 v;
        assembly {
            v := mload(add(buff, add(offset, 0x20)))
        }
        return (v, offset + 32);
    }

    /* @notice              Read next 20 bytes starting from offset,
    *  @param buff          Source bytes array
    *  @param offset        The position from where we read the bytes value
    *  @return              The read bytes20 value and updated offset
    */
    function NextBytes20(bytes memory buff, uint256 offset) internal pure returns (bytes20 , uint256) {
        require(offset + 20 <= buff.length && offset < offset + 20, "NextBytes20, offset exceeds maximum");
        bytes20 v;
        assembly {
            v := mload(add(buff, add(offset, 0x20)))
        }
        return (v, offset + 20);
    }

    function NextVarUint(bytes memory buff, uint256 offset) internal pure returns(uint, uint256) {
        byte v;
        (v, offset) = NextByte(buff, offset);

        uint value;
        if (v == 0xFD) {
            // return NextUint16(buff, offset);
            (value, offset) = NextUint16(buff, offset);
            require(value >= 0xFD && value <= 0xFFFF, "NextUint16, value outside range");
            return (value, offset);
        } else if (v == 0xFE) {
            // return NextUint32(buff, offset);
            (value, offset) = NextUint32(buff, offset);
            require(value > 0xFFFF && value <= 0xFFFFFFFF, "NextVarUint, value outside range");
            return (value, offset);
        } else if (v == 0xFF) {
            // return NextUint64(buff, offset);
            (value, offset) = NextUint64(buff, offset);
            require(value > 0xFFFFFFFF, "NextVarUint, value outside range");
            return (value, offset);
        } else{
            // return (uint8(v), offset);
            value = uint8(v);
            require(value < 0xFD, "NextVarUint, value outside range");
            return (value, offset);
        }
    }
}

// File: contracts/libs/common/ZeroCopySink.sol


pragma solidity 0.6.12;

/**
 * @dev Wrappers over encoding and serialization operation into bytes from bassic types in Solidity for PolyNetwork cross chain utility.
 *
 * Encode basic types in Solidity into bytes easily. It's designed to be used
 * for PolyNetwork cross chain application, and the encoding rules on Ethereum chain
 * and the decoding rules on other chains should be consistent. Here we
 * follow the underlying serialization rule with implementation found here:
 * https://github.com/polynetwork/poly/blob/master/common/zero_copy_sink.go
 *
 * Using this library instead of the unchecked serialization method can help reduce
 * the risk of serious bugs and handfule, so it's recommended to use it.
 *
 * Please note that risk can be minimized, yet not eliminated.
 */
library ZeroCopySink {
    /* @notice          Convert boolean value into bytes
    *  @param b         The boolean value
    *  @return          Converted bytes array
    */
    function WriteBool(bool b) internal pure returns (bytes memory) {
        bytes memory buff;
        assembly{
            buff := mload(0x40)
            mstore(buff, 1)
            switch iszero(b)
            case 1 {
                mstore(add(buff, 0x20), shl(248, 0x00))
                // mstore8(add(buff, 0x20), 0x00)
            }
            default {
                mstore(add(buff, 0x20), shl(248, 0x01))
                // mstore8(add(buff, 0x20), 0x01)
            }
            mstore(0x40, add(buff, 0x21))
        }
        return buff;
    }

    /* @notice          Convert byte value into bytes
    *  @param b         The byte value
    *  @return          Converted bytes array
    */
    function WriteByte(byte b) internal pure returns (bytes memory) {
        return WriteUint8(uint8(b));
    }

    /* @notice          Convert uint8 value into bytes
    *  @param v         The uint8 value
    *  @return          Converted bytes array
    */
    function WriteUint8(uint8 v) internal pure returns (bytes memory) {
        bytes memory buff;
        assembly{
            buff := mload(0x40)
            mstore(buff, 1)
            mstore(add(buff, 0x20), shl(248, v))
            // mstore(add(buff, 0x20), byte(0x1f, v))
            mstore(0x40, add(buff, 0x21))
        }
        return buff;
    }

    /* @notice          Convert uint16 value into bytes
    *  @param v         The uint16 value
    *  @return          Converted bytes array
    */
    function WriteUint16(uint16 v) internal pure returns (bytes memory) {
        bytes memory buff;

        assembly{
            buff := mload(0x40)
            let byteLen := 0x02
            mstore(buff, byteLen)
            for {
                let mindex := 0x00
                let vindex := 0x1f
            } lt(mindex, byteLen) {
                mindex := add(mindex, 0x01)
                vindex := sub(vindex, 0x01)
            }{
                mstore8(add(add(buff, 0x20), mindex), byte(vindex, v))
            }
            mstore(0x40, add(buff, 0x22))
        }
        return buff;
    }

    /* @notice          Convert uint32 value into bytes
    *  @param v         The uint32 value
    *  @return          Converted bytes array
    */
    function WriteUint32(uint32 v) internal pure returns(bytes memory) {
        bytes memory buff;
        assembly{
            buff := mload(0x40)
            let byteLen := 0x04
            mstore(buff, byteLen)
            for {
                let mindex := 0x00
                let vindex := 0x1f
            } lt(mindex, byteLen) {
                mindex := add(mindex, 0x01)
                vindex := sub(vindex, 0x01)
            }{
                mstore8(add(add(buff, 0x20), mindex), byte(vindex, v))
            }
            mstore(0x40, add(buff, 0x24))
        }
        return buff;
    }

    /* @notice          Convert uint64 value into bytes
    *  @param v         The uint64 value
    *  @return          Converted bytes array
    */
    function WriteUint64(uint64 v) internal pure returns(bytes memory) {
        bytes memory buff;

        assembly{
            buff := mload(0x40)
            let byteLen := 0x08
            mstore(buff, byteLen)
            for {
                let mindex := 0x00
                let vindex := 0x1f
            } lt(mindex, byteLen) {
                mindex := add(mindex, 0x01)
                vindex := sub(vindex, 0x01)
            }{
                mstore8(add(add(buff, 0x20), mindex), byte(vindex, v))
            }
            mstore(0x40, add(buff, 0x28))
        }
        return buff;
    }

    /* @notice          Convert limited uint256 value into bytes
    *  @param v         The uint256 value
    *  @return          Converted bytes array
    */
    function WriteUint255(uint256 v) internal pure returns (bytes memory) {
        require(v <= 0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff, "Value exceeds uint255 range");
        bytes memory buff;

        assembly{
            buff := mload(0x40)
            let byteLen := 0x20
            mstore(buff, byteLen)
            for {
                let mindex := 0x00
                let vindex := 0x1f
            } lt(mindex, byteLen) {
                mindex := add(mindex, 0x01)
                vindex := sub(vindex, 0x01)
            }{
                mstore8(add(add(buff, 0x20), mindex), byte(vindex, v))
            }
            mstore(0x40, add(buff, 0x40))
        }
        return buff;
    }

    /* @notice          Encode bytes format data into bytes
    *  @param data      The bytes array data
    *  @return          Encoded bytes array
    */
    function WriteVarBytes(bytes memory data) internal pure returns (bytes memory) {
        uint64 l = uint64(data.length);
        return abi.encodePacked(WriteVarUint(l), data);
    }

    function WriteVarUint(uint64 v) internal pure returns (bytes memory) {
        if (v < 0xFD){
    		return WriteUint8(uint8(v));
    	} else if (v <= 0xFFFF) {
    		return abi.encodePacked(WriteByte(0xFD), WriteUint16(uint16(v)));
    	} else if (v <= 0xFFFFFFFF) {
            return abi.encodePacked(WriteByte(0xFE), WriteUint32(uint32(v)));
    	} else {
    		return abi.encodePacked(WriteByte(0xFF), WriteUint64(uint64(v)));
    	}
    }
}

// File: contracts/libs/utils/ReentrancyGuard.sol


pragma solidity 0.6.12;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
contract ReentrancyGuard {
    bool private _notEntered;

    constructor () internal {
        // Storing an initial non-zero value makes deployment a bit more
        // expensive, but in exchange the refund on every call to nonReentrant
        // will be lower in amount. Since refunds are capped to a percetange of
        // the total transaction's gas, it is best to keep them low in cases
        // like this one, to increase the likelihood of the full refund coming
        // into effect.
        _notEntered = true;
    }

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

        // Any calls to nonReentrant after this point will fail
        _notEntered = false;

        _;

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

// File: contracts/libs/utils/Utils.sol


pragma solidity 0.6.12;

library Utils {

    /* @notice      Convert the bytes array to bytes32 type, the bytes array length must be 32
    *  @param _bs   Source bytes array
    *  @return      bytes32
    */
    function bytesToBytes32(bytes memory _bs) internal pure returns (bytes32 value) {
        require(_bs.length == 32, "bytes length is not 32.");
        assembly {
            // load 32 bytes from memory starting from position _bs + 0x20 since the first 0x20 bytes stores _bs length
            value := mload(add(_bs, 0x20))
        }
    }

    /* @notice      Convert bytes to uint256
    *  @param _b    Source bytes should have length of 32
    *  @return      uint256
    */
    function bytesToUint256(bytes memory _bs) internal pure returns (uint256 value) {
        require(_bs.length == 32, "bytes length is not 32.");
        assembly {
            // load 32 bytes from memory starting from position _bs + 32
            value := mload(add(_bs, 0x20))
        }
        require(value <= 0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff, "Value exceeds the range");
    }

    /* @notice      Convert uint256 to bytes
    *  @param _b    uint256 that needs to be converted
    *  @return      bytes
    */
    function uint256ToBytes(uint256 _value) internal pure returns (bytes memory bs) {
        require(_value <= 0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff, "Value exceeds the range");
        assembly {
            // Get a location of some free memory and store it in result as
            // Solidity does for memory variables.
            bs := mload(0x40)
            // Put 0x20 at the first word, the length of bytes for uint256 value
            mstore(bs, 0x20)
            //In the next word, put value in bytes format to the next 32 bytes
            mstore(add(bs, 0x20), _value)
            // Update the free-memory pointer by padding our last write location to 32 bytes
            mstore(0x40, add(bs, 0x40))
        }
    }

    /* @notice      Convert bytes to address
    *  @param _bs   Source bytes: bytes length must be 20
    *  @return      Converted address from source bytes
    */
    function bytesToAddress(bytes memory _bs) internal pure returns (address addr)
    {
        require(_bs.length == 20, "bytes length does not match address");
        assembly {
            // for _bs, first word store _bs.length, second word store _bs.value
            // load 32 bytes from mem[_bs+20], convert it into Uint160, meaning we take last 20 bytes as addr (address).
            addr := mload(add(_bs, 0x14))
        }

    }

    /* @notice      Convert address to bytes
    *  @param _addr Address need to be converted
    *  @return      Converted bytes from address
    */
    function addressToBytes(address _addr) internal pure returns (bytes memory bs){
        assembly {
            // Get a location of some free memory and store it in result as
            // Solidity does for memory variables.
            bs := mload(0x40)
            // Put 20 (address byte length) at the first word, the length of bytes for uint256 value
            mstore(bs, 0x14)
            // logical shift left _a by 12 bytes, change _a from right-aligned to left-aligned
            mstore(add(bs, 0x20), shl(96, _addr))
            // Update the free-memory pointer by padding our last write location to 32 bytes
            mstore(0x40, add(bs, 0x40))
       }
    }

    /* @notice          Do hash leaf as the multi-chain does
    *  @param _data     Data in bytes format
    *  @return          Hashed value in bytes32 format
    */
    function hashLeaf(bytes memory _data) internal pure returns (bytes32 result)  {
        result = sha256(abi.encodePacked(byte(0x0), _data));
    }

    /* @notice          Do hash children as the multi-chain does
    *  @param _l        Left node
    *  @param _r        Right node
    *  @return          Hashed value in bytes32 format
    */
    function hashChildren(bytes32 _l, bytes32  _r) internal pure returns (bytes32 result)  {
        result = sha256(abi.encodePacked(bytes1(0x01), _l, _r));
    }

    /* @notice              Compare if two bytes are equal, which are in storage and memory, seperately
                            Refer from https://github.com/summa-tx/bitcoin-spv/blob/master/solidity/contracts/BytesLib.sol#L368
    *  @param _preBytes     The bytes stored in storage
    *  @param _postBytes    The bytes stored in memory
    *  @return              Bool type indicating if they are equal
    */
    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)
            // 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)

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

    /* @notice              Slice the _bytes from _start index till the result has length of _length
                            Refer from https://github.com/summa-tx/bitcoin-spv/blob/master/solidity/contracts/BytesLib.sol#L246
    *  @param _bytes        The original bytes needs to be sliced
    *  @param _start        The index of _bytes for the start of sliced bytes
    *  @param _length       The index of _bytes for the end of sliced bytes
    *  @return              The sliced bytes
    */
    function slice(
        bytes memory _bytes,
        uint _start,
        uint _length
    )
        internal
        pure
        returns (bytes memory)
    {
        require(_bytes.length >= (_start + _length));

        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.
                // lengthmod <= _length % 32
                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)

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

        return tempBytes;
    }
    /* @notice              Check if the elements number of _signers within _keepers array is no less than _m
    *  @param _keepers      The array consists of serveral address
    *  @param _signers      Some specific addresses to be looked into
    *  @param _m            The number requirement paramter
    *  @return              True means containment, false meansdo do not contain.
    */
    function containMAddresses(address[] memory _keepers, address[] memory _signers, uint _m) internal pure returns (bool){
        uint m = 0;
        for(uint i = 0; i < _signers.length; i++){
            for (uint j = 0; j < _keepers.length; j++) {
                if (_signers[i] == _keepers[j]) {
                    m++;
                    delete _keepers[j];
                }
            }
        }
        return m >= _m;
    }

    /* @notice              TODO
    *  @param key
    *  @return
    */
    function compressMCPubKey(bytes memory key) internal pure returns (bytes memory newkey) {
         require(key.length >= 67, "key lenggh is too short");
         newkey = slice(key, 0, 35);
         if (uint8(key[66]) % 2 == 0){
             newkey[2] = byte(0x02);
         } else {
             newkey[2] = byte(0x03);
         }
         return newkey;
    }

    /**
     * @dev Returns true if `account` is a contract.
     *      Refer from https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/Address.sol#L18
     *
     * This test is non-exhaustive, and there may be false-negatives: during the
     * execution of a contract's constructor, its address will be reported as
     * not containing a contract.
     *
     * IMPORTANT: It is unsafe to assume that an address for which this
     * function returns false is an externally-owned account (EOA) and not a
     * contract.
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies in extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

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

// File: contracts/libs/math/SafeMath.sol


pragma solidity 0.6.12;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

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

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

        return c;
    }

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

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

        return c;
    }

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

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

        return c;
    }

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

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

// File: contracts/Wallet.sol


pragma solidity 0.6.12;

interface ERC20 {
    function approve(address spender, uint256 amount) external returns (bool);
    function transfer(address recipient, uint256 amount) external returns (bool);
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
    function balanceOf(address account) external view returns (uint256);
}

/// @title The Wallet contract for Switcheo TradeHub
/// @author Switcheo Network
/// @notice This contract faciliates deposits for Switcheo TradeHub.
/// @dev This contract is used together with the LockProxy contract to allow users
/// to deposit funds without requiring them to have ETH
contract Wallet {
    bool public isInitialized;
    address public creator;
    address public owner;
    bytes public swthAddress;

    function initialize(address _owner, bytes calldata _swthAddress) external {
        require(isInitialized == false, "Contract already initialized");
        isInitialized = true;
        creator = msg.sender;
        owner = _owner;
        swthAddress = _swthAddress;
    }

    /// @dev Allow this contract to receive Ethereum
    receive() external payable {}

    /// @dev Allow this contract to receive ERC223 tokens
    // An empty implementation is required so that the ERC223 token will not
    // throw an error on transfer
    function tokenFallback(address, uint, bytes calldata) external {}

    /// @dev send ETH from this contract to its creator
    function sendETHToCreator(uint256 _amount) external {
        require(msg.sender == creator, "Sender must be creator");
        // we use `call` here following the recommendation from
        // https://diligence.consensys.net/blog/2019/09/stop-using-soliditys-transfer-now/
        (bool success,  ) = creator.call{value: _amount}("");
        require(success, "Transfer failed");
    }

    /// @dev send tokens from this contract to its creator
    function sendERC20ToCreator(address _assetId, uint256 _amount) external {
        require(msg.sender == creator, "Sender must be creator");

        ERC20 token = ERC20(_assetId);
        _callOptionalReturn(
            token,
            abi.encodeWithSelector(
                token.transfer.selector,
                creator,
                _amount
            )
        );
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(ERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves.

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

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

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

    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `_isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function _isContract(address account) private view returns (bool) {
        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly { codehash := extcodehash(account) }
        return (codehash != accountHash && codehash != 0x0);
    }
}

// File: contracts/LockProxy.sol


pragma solidity 0.6.12;







interface CCM {
    function crossChain(uint64 _toChainId, bytes calldata _toContract, bytes calldata _method, bytes calldata _txData) external returns (bool);
}

interface CCMProxy {
    function getEthCrossChainManager() external view returns (address);
}

/// @title The LockProxy contract for Switcheo TradeHub
/// @author Switcheo Network
/// @notice This contract faciliates deposits and withdrawals to Switcheo TradeHub.
/// @dev The contract also allows for additional features in the future through "extension" contracts.
contract LockProxy is ReentrancyGuard {
    using SafeMath for uint256;

    // used for cross-chain addExtension and removeExtension methods
    struct ExtensionTxArgs {
        bytes extensionAddress;
    }

    // used for cross-chain registerAsset method
    struct RegisterAssetTxArgs {
        bytes assetHash;
        bytes nativeAssetHash;
    }

    // used for cross-chain lock and unlock methods
    struct TransferTxArgs {
        bytes fromAssetHash;
        bytes toAssetHash;
        bytes toAddress;
        uint256 amount;
        uint256 feeAmount;
        bytes feeAddress;
        bytes fromAddress;
        uint256 nonce;
    }

    // used to create a unique salt for wallet creation
    bytes public constant SALT_PREFIX = "switcheo-eth-wallet-factory-v1";
    address public constant ETH_ASSET_HASH = address(0);

    CCMProxy public ccmProxy;
    uint64 public counterpartChainId;
    uint256 public currentNonce = 0;

    // a mapping of assetHashes to the hash of
    // (associated proxy address on Switcheo TradeHub, associated asset hash on Switcheo TradeHub)
    mapping(address => bytes32) public registry;

    // a record of signed messages to prevent replay attacks
    mapping(bytes32 => bool) public seenMessages;

    // a mapping of extension contracts
    mapping(address => bool) public extensions;

    // a record of created wallets
    mapping(address => bool) public wallets;

    event LockEvent(
        address fromAssetHash,
        address fromAddress,
        uint64 toChainId,
        bytes toAssetHash,
        bytes toAddress,
        bytes txArgs
    );

    event UnlockEvent(
        address toAssetHash,
        address toAddress,
        uint256 amount,
        bytes txArgs
    );

    constructor(address _ccmProxyAddress, uint64 _counterpartChainId) public {
        require(_counterpartChainId > 0, "counterpartChainId cannot be zero");
        require(_ccmProxyAddress != address(0), "ccmProxyAddress cannot be empty");
        counterpartChainId = _counterpartChainId;
        ccmProxy = CCMProxy(_ccmProxyAddress);
    }

    modifier onlyManagerContract() {
        require(
            msg.sender == ccmProxy.getEthCrossChainManager(),
            "msg.sender is not CCM"
        );
        _;
    }

    /// @dev Allow this contract to receive Ethereum
    receive() external payable {}

    /// @dev Allow this contract to receive ERC223 tokens
    /// An empty implementation is required so that the ERC223 token will not
    /// throw an error on transfer, this is specific to ERC223 tokens which
    /// require this implementation, e.g. DGTX
    function tokenFallback(address, uint, bytes calldata) external {}

    /// @dev Calculate the wallet address for the given owner and Switcheo TradeHub address
    /// @param _ownerAddress the Ethereum address which the user has control over, i.e. can sign msgs with
    /// @param _swthAddress the hex value of the user's Switcheo TradeHub address
    /// @param _bytecodeHash the hash of the wallet contract's bytecode
    /// @return the wallet address
    function getWalletAddress(
        address _ownerAddress,
        bytes calldata _swthAddress,
        bytes32 _bytecodeHash
    )
        external
        view
        returns (address)
    {
        bytes32 salt = _getSalt(
            _ownerAddress,
            _swthAddress
        );

        bytes32 data = keccak256(
            abi.encodePacked(bytes1(0xff), address(this), salt, _bytecodeHash)
        );

        return address(bytes20(data << 96));
    }

    /// @dev Create the wallet for the given owner and Switcheo TradeHub address
    /// @param _ownerAddress the Ethereum address which the user has control over, i.e. can sign msgs with
    /// @param _swthAddress the hex value of the user's Switcheo TradeHub address
    /// @return true if success
    function createWallet(
        address _ownerAddress,
        bytes calldata _swthAddress
    )
        external
        nonReentrant
        returns (bool)
    {
        require(_ownerAddress != address(0), "Empty ownerAddress");
        require(_swthAddress.length != 0, "Empty swthAddress");

        bytes32 salt = _getSalt(
            _ownerAddress,
            _swthAddress
        );

        Wallet wallet = new Wallet{salt: salt}();
        wallet.initialize(_ownerAddress, _swthAddress);
        wallets[address(wallet)] = true;

        return true;
    }

    /// @dev Add a contract as an extension
    /// @param _argsBz the serialized ExtensionTxArgs
    /// @param _fromChainId the originating chainId
    /// @return true if success
    function addExtension(
        bytes calldata _argsBz,
        bytes calldata /* _fromContractAddr */,
        uint64 _fromChainId
    )
        external
        onlyManagerContract
        nonReentrant
        returns (bool)
    {
        require(_fromChainId == counterpartChainId, "Invalid chain ID");

        ExtensionTxArgs memory args = _deserializeExtensionTxArgs(_argsBz);
        address extensionAddress = Utils.bytesToAddress(args.extensionAddress);
        extensions[extensionAddress] = true;

        return true;
    }

    /// @dev Remove a contract from the extensions mapping
    /// @param _argsBz the serialized ExtensionTxArgs
    /// @param _fromChainId the originating chainId
    /// @return true if success
    function removeExtension(
        bytes calldata _argsBz,
        bytes calldata /* _fromContractAddr */,
        uint64 _fromChainId
    )
        external
        onlyManagerContract
        nonReentrant
        returns (bool)
    {
        require(_fromChainId == counterpartChainId, "Invalid chain ID");

        ExtensionTxArgs memory args = _deserializeExtensionTxArgs(_argsBz);
        address extensionAddress = Utils.bytesToAddress(args.extensionAddress);
        extensions[extensionAddress] = false;

        return true;
    }

    /// @dev Marks an asset as registered by mapping the asset's address to
    /// the specified _fromContractAddr and assetHash on Switcheo TradeHub
    /// @param _argsBz the serialized RegisterAssetTxArgs
    /// @param _fromContractAddr the associated contract address on Switcheo TradeHub
    /// @param _fromChainId the originating chainId
    /// @return true if success
    function registerAsset(
        bytes calldata _argsBz,
        bytes calldata _fromContractAddr,
        uint64 _fromChainId
    )
        external
        onlyManagerContract
        nonReentrant
        returns (bool)
    {
        require(_fromChainId == counterpartChainId, "Invalid chain ID");

        RegisterAssetTxArgs memory args = _deserializeRegisterAssetTxArgs(_argsBz);
        _markAssetAsRegistered(
            Utils.bytesToAddress(args.nativeAssetHash),
            _fromContractAddr,
            args.assetHash
        );

        return true;
    }

    /// @dev Performs a deposit from a Wallet contract
    /// @param _walletAddress address of the wallet contract, the wallet contract
    /// does not receive ETH in this call, but _walletAddress still needs to be payable
    /// since the wallet contract can receive ETH, there would be compile errors otherwise
    /// @param _assetHash the asset to deposit
    /// @param _targetProxyHash the associated proxy hash on Switcheo TradeHub
    /// @param _toAssetHash the associated asset hash on Switcheo TradeHub
    /// @param _feeAddress the hex version of the Switcheo TradeHub address to send the fee to
    /// @param _values[0]: amount, the number of tokens to deposit
    /// @param _values[1]: feeAmount, the number of tokens to be used as fees
    /// @param _values[2]: nonce, to prevent replay attacks
    /// @param _values[3]: callAmount, some tokens may burn an amount before transfer
    /// so we allow a callAmount to support these tokens
    /// @param _v: the v value of the wallet owner's signature
    /// @param _rs: the r, s values of the wallet owner's signature
    function lockFromWallet(
        address payable _walletAddress,
        address _assetHash,
        bytes calldata _targetProxyHash,
        bytes calldata _toAssetHash,
        bytes calldata _feeAddress,
        uint256[] calldata _values,
        uint8 _v,
        bytes32[] calldata _rs
    )
        external
        nonReentrant
        returns (bool)
    {
        require(wallets[_walletAddress], "Invalid wallet address");

        Wallet wallet = Wallet(_walletAddress);
        _validateLockFromWallet(
            wallet.owner(),
            _assetHash,
            _targetProxyHash,
            _toAssetHash,
            _feeAddress,
            _values,
            _v,
            _rs
        );

        // it is very important that this function validates the success of a transfer correctly
        // since, once this line is passed, the deposit is assumed to be successful
        // which will eventually result in the specified amount of tokens being minted for the
        // wallet.swthAddress on Switcheo TradeHub
        _transferInFromWallet(_walletAddress, _assetHash, _values[0], _values[3]);

        _lock(
            _assetHash,
            _targetProxyHash,
            _toAssetHash,
            wallet.swthAddress(),
            _values[0],
            _values[1],
            _feeAddress
        );

        return true;
    }

    /// @dev Performs a deposit
    /// @param _assetHash the asset to deposit
    /// @param _targetProxyHash the associated proxy hash on Switcheo TradeHub
    /// @param _toAddress the hex version of the Switcheo TradeHub address to deposit to
    /// @param _toAssetHash the associated asset hash on Switcheo TradeHub
    /// @param _feeAddress the hex version of the Switcheo TradeHub address to send the fee to
    /// @param _values[0]: amount, the number of tokens to deposit
    /// @param _values[1]: feeAmount, the number of tokens to be used as fees
    /// @param _values[2]: callAmount, some tokens may burn an amount before transfer
    /// so we allow a callAmount to support these tokens
    function lock(
        address _assetHash,
        bytes calldata _targetProxyHash,
        bytes calldata _toAddress,
        bytes calldata _toAssetHash,
        bytes calldata _feeAddress,
        uint256[] calldata _values
    )
        external
        payable
        nonReentrant
        returns (bool)
    {

        // it is very important that this function validates the success of a transfer correctly
        // since, once this line is passed, the deposit is assumed to be successful
        // which will eventually result in the specified amount of tokens being minted for the
        // _toAddress on Switcheo TradeHub
        _transferIn(_assetHash, _values[0], _values[2]);

        _lock(
            _assetHash,
            _targetProxyHash,
            _toAssetHash,
            _toAddress,
            _values[0],
            _values[1],
            _feeAddress
        );

        return true;
    }

    /// @dev Performs a withdrawal that was initiated on Switcheo TradeHub
    /// @param _argsBz the serialized TransferTxArgs
    /// @param _fromContractAddr the associated contract address on Switcheo TradeHub
    /// @param _fromChainId the originating chainId
    /// @return true if success
    function unlock(
        bytes calldata _argsBz,
        bytes calldata _fromContractAddr,
        uint64 _fromChainId
    )
        external
        onlyManagerContract
        nonReentrant
        returns (bool)
    {
        require(_fromChainId == counterpartChainId, "Invalid chain ID");

        TransferTxArgs memory args = _deserializeTransferTxArgs(_argsBz);
        require(args.fromAssetHash.length > 0, "Invalid fromAssetHash");
        require(args.toAssetHash.length == 20, "Invalid toAssetHash");

        address toAssetHash = Utils.bytesToAddress(args.toAssetHash);
        address toAddress = Utils.bytesToAddress(args.toAddress);

        _validateAssetRegistration(toAssetHash, _fromContractAddr, args.fromAssetHash);
        _transferOut(toAddress, toAssetHash, args.amount);

        emit UnlockEvent(toAssetHash, toAddress, args.amount, _argsBz);
        return true;
    }

    /// @dev Performs a transfer of funds, this is only callable by approved extension contracts
    /// the `nonReentrant` guard is intentionally not added to this function, to allow for more flexibility.
    /// The calling contract should be secure and have its own `nonReentrant` guard as needed.
    /// @param _receivingAddress the address to transfer to
    /// @param _assetHash the asset to transfer
    /// @param _amount the amount to transfer
    /// @return true if success
    function extensionTransfer(
        address _receivingAddress,
        address _assetHash,
        uint256 _amount
    )
        external
        returns (bool)
    {
        require(
            extensions[msg.sender] == true,
            "Invalid extension"
        );

        if (_assetHash == ETH_ASSET_HASH) {
            // we use `call` here since the _receivingAddress could be a contract
            // see https://diligence.consensys.net/blog/2019/09/stop-using-soliditys-transfer-now/
            // for more info
            (bool success,  ) = _receivingAddress.call{value: _amount}("");
            require(success, "Transfer failed");
            return true;
        }

        ERC20 token = ERC20(_assetHash);
        _callOptionalReturn(
            token,
            abi.encodeWithSelector(
                token.approve.selector,
                _receivingAddress,
                _amount
            )
        );

        return true;
    }

    /// @dev Marks an asset as registered by associating it to a specified Switcheo TradeHub proxy and asset hash
    /// @param _assetHash the address of the asset to mark
    /// @param _proxyAddress the associated proxy address on Switcheo TradeHub
    /// @param _toAssetHash the associated asset hash on Switcheo TradeHub
    function _markAssetAsRegistered(
        address _assetHash,
        bytes memory _proxyAddress,
        bytes memory _toAssetHash
    )
        private
    {
        require(_proxyAddress.length == 20, "Invalid proxyAddress");
        require(
            registry[_assetHash] == bytes32(0),
            "Asset already registered"
        );

        bytes32 value = keccak256(abi.encodePacked(
            _proxyAddress,
            _toAssetHash
        ));

        registry[_assetHash] = value;
    }

    /// @dev Validates that an asset's registration matches the given params
    /// @param _assetHash the address of the asset to check
    /// @param _proxyAddress the expected proxy address on Switcheo TradeHub
    /// @param _toAssetHash the expected asset hash on Switcheo TradeHub
    function _validateAssetRegistration(
        address _assetHash,
        bytes memory _proxyAddress,
        bytes memory _toAssetHash
    )
        private
        view
    {
        require(_proxyAddress.length == 20, "Invalid proxyAddress");
        bytes32 value = keccak256(abi.encodePacked(
            _proxyAddress,
            _toAssetHash
        ));
        require(registry[_assetHash] == value, "Asset not registered");
    }

    /// @dev validates the asset registration and calls the CCM contract
    function _lock(
        address _fromAssetHash,
        bytes memory _targetProxyHash,
        bytes memory _toAssetHash,
        bytes memory _toAddress,
        uint256 _amount,
        uint256 _feeAmount,
        bytes memory _feeAddress
    )
        private
    {
        require(_targetProxyHash.length == 20, "Invalid targetProxyHash");
        require(_toAssetHash.length > 0, "Empty toAssetHash");
        require(_toAddress.length > 0, "Empty toAddress");
        require(_amount > 0, "Amount must be more than zero");
        require(_feeAmount < _amount, "Fee amount cannot be greater than amount");

        _validateAssetRegistration(_fromAssetHash, _targetProxyHash, _toAssetHash);

        TransferTxArgs memory txArgs = TransferTxArgs({
            fromAssetHash: Utils.addressToBytes(_fromAssetHash),
            toAssetHash: _toAssetHash,
            toAddress: _toAddress,
            amount: _amount,
            feeAmount: _feeAmount,
            feeAddress: _feeAddress,
            fromAddress: abi.encodePacked(msg.sender),
            nonce: _getNextNonce()
        });

        bytes memory txData = _serializeTransferTxArgs(txArgs);
        CCM ccm = _getCcm();
        require(
            ccm.crossChain(counterpartChainId, _targetProxyHash, "unlock", txData),
            "EthCrossChainManager crossChain executed error!"
        );

        emit LockEvent(_fromAssetHash, msg.sender, counterpartChainId, _toAssetHash, _toAddress, txData);
    }

    /// @dev validate the signature for lockFromWallet
    function _validateLockFromWallet(
        address _walletOwner,
        address _assetHash,
        bytes memory _targetProxyHash,
        bytes memory _toAssetHash,
        bytes memory _feeAddress,
        uint256[] memory _values,
        uint8 _v,
        bytes32[] memory _rs
    )
        private
    {
        bytes32 message = keccak256(abi.encodePacked(
            "sendTokens",
            _assetHash,
            _targetProxyHash,
            _toAssetHash,
            _feeAddress,
            _values[0],
            _values[1],
            _values[2]
        ));

        require(seenMessages[message] == false, "Message already seen");
        seenMessages[message] = true;
        _validateSignature(message, _walletOwner, _v, _rs[0], _rs[1]);
    }

    /// @dev transfers funds from a Wallet contract into this contract
    /// the difference between this contract's before and after balance must equal _amount
    /// this is assumed to be sufficient in ensuring that the expected amount
    /// of funds were transferred in
    function _transferInFromWallet(
        address payable _walletAddress,
        address _assetHash,
        uint256 _amount,
        uint256 _callAmount
    )
        private
    {
        Wallet wallet = Wallet(_walletAddress);
        if (_assetHash == ETH_ASSET_HASH) {
            uint256 before = address(this).balance;

            wallet.sendETHToCreator(_callAmount);

            uint256 transferred = address(this).balance.sub(before);
            require(transferred == _amount, "ETH transferred does not match the expected amount");
            return;
        }

        ERC20 token = ERC20(_assetHash);
        uint256 before = token.balanceOf(address(this));

        wallet.sendERC20ToCreator(_assetHash, _callAmount);

        uint256 transferred = token.balanceOf(address(this)).sub(before);
        require(transferred == _amount, "Tokens transferred does not match the expected amount");
    }

    /// @dev transfers funds from an address into this contract
    /// for ETH transfers, we only check that msg.value == _amount, and _callAmount is ignored
    /// for token transfers, the difference between this contract's before and after balance must equal _amount
    /// these checks are assumed to be sufficient in ensuring that the expected amount
    /// of funds were transferred in
    function _transferIn(
        address _assetHash,
        uint256 _amount,
        uint256 _callAmount
    )
        private
    {
        if (_assetHash == ETH_ASSET_HASH) {
            require(msg.value == _amount, "ETH transferred does not match the expected amount");
            return;
        }

        ERC20 token = ERC20(_assetHash);
        uint256 before = token.balanceOf(address(this));
        _callOptionalReturn(
            token,
            abi.encodeWithSelector(
                token.transferFrom.selector,
                msg.sender,
                address(this),
                _callAmount
            )
        );
        uint256 transferred = token.balanceOf(address(this)).sub(before);
        require(transferred == _amount, "Tokens transferred does not match the expected amount");
    }

    /// @dev transfers funds from this contract to the _toAddress
    function _transferOut(
        address _toAddress,
        address _assetHash,
        uint256 _amount
    )
        private
    {
        if (_assetHash == ETH_ASSET_HASH) {
            // we use `call` here since the _receivingAddress could be a contract
            // see https://diligence.consensys.net/blog/2019/09/stop-using-soliditys-transfer-now/
            // for more info
            (bool success,  ) = _toAddress.call{value: _amount}("");
            require(success, "Transfer failed");
            return;
        }

        ERC20 token = ERC20(_assetHash);
        _callOptionalReturn(
            token,
            abi.encodeWithSelector(
                token.transfer.selector,
                _toAddress,
                _amount
            )
        );
    }

    /// @dev validates a signature against the specified user address
    function _validateSignature(
        bytes32 _message,
        address _user,
        uint8 _v,
        bytes32 _r,
        bytes32 _s
    )
        private
        pure
    {
        bytes32 prefixedMessage = keccak256(abi.encodePacked(
            "\x19Ethereum Signed Message:\n32",
            _message
        ));

        require(
            _user == ecrecover(prefixedMessage, _v, _r, _s),
            "Invalid signature"
        );
    }

    function _serializeTransferTxArgs(TransferTxArgs memory args) private pure returns (bytes memory) {
        bytes memory buff;
        buff = abi.encodePacked(
            ZeroCopySink.WriteVarBytes(args.fromAssetHash),
            ZeroCopySink.WriteVarBytes(args.toAssetHash),
            ZeroCopySink.WriteVarBytes(args.toAddress),
            ZeroCopySink.WriteUint255(args.amount),
            ZeroCopySink.WriteUint255(args.feeAmount),
            ZeroCopySink.WriteVarBytes(args.feeAddress),
            ZeroCopySink.WriteVarBytes(args.fromAddress),
            ZeroCopySink.WriteUint255(args.nonce)
        );
        return buff;
    }

    function _deserializeTransferTxArgs(bytes memory valueBz) private pure returns (TransferTxArgs memory) {
        TransferTxArgs memory args;
        uint256 off = 0;
        (args.fromAssetHash, off) = ZeroCopySource.NextVarBytes(valueBz, off);
        (args.toAssetHash, off) = ZeroCopySource.NextVarBytes(valueBz, off);
        (args.toAddress, off) = ZeroCopySource.NextVarBytes(valueBz, off);
        (args.amount, off) = ZeroCopySource.NextUint255(valueBz, off);
        return args;
    }

    function _deserializeRegisterAssetTxArgs(bytes memory valueBz) private pure returns (RegisterAssetTxArgs memory) {
        RegisterAssetTxArgs memory args;
        uint256 off = 0;
        (args.assetHash, off) = ZeroCopySource.NextVarBytes(valueBz, off);
        (args.nativeAssetHash, off) = ZeroCopySource.NextVarBytes(valueBz, off);
        return args;
    }

    function _deserializeExtensionTxArgs(bytes memory valueBz) private pure returns (ExtensionTxArgs memory) {
        ExtensionTxArgs memory args;
        uint256 off = 0;
        (args.extensionAddress, off) = ZeroCopySource.NextVarBytes(valueBz, off);
        return args;
    }

    function _getCcm() private view returns (CCM) {
      CCM ccm = CCM(ccmProxy.getEthCrossChainManager());
      return ccm;
    }

    function _getNextNonce() private returns (uint256) {
      currentNonce = currentNonce.add(1);
      return currentNonce;
    }

    function _getSalt(
        address _ownerAddress,
        bytes memory _swthAddress
    )
        private
        pure
        returns (bytes32)
    {
        return keccak256(abi.encodePacked(
            SALT_PREFIX,
            _ownerAddress,
            _swthAddress
        ));
    }


    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(ERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves.

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

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

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

    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `_isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function _isContract(address account) private view returns (bool) {
        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly { codehash := extcodehash(account) }
        return (codehash != accountHash && codehash != 0x0);
    }
}

// File: eth-contracts/contracts/core/cross_chain_manager/interface/IEthCrossChainManagerProxy.sol

pragma solidity ^0.5.0;

/**
 * @dev Interface of the EthCrossChainManagerProxy for business contract like LockProxy to obtain the reliable EthCrossChainManager contract hash.
 */
interface IEthCrossChainManagerProxy {
    function getEthCrossChainManager() external view returns (address);
}

// File: eth-contracts/contracts/core/cross_chain_manager/interface/IUpgradableECCM.sol

pragma solidity ^0.5.0;

/**
 * @dev Interface of upgradableECCM to make ECCM be upgradable, the implementation is in UpgradableECCM.sol
 */
interface IUpgradableECCM {
    function pause() external returns (bool);
    function unpause() external returns (bool);
    function paused() external view returns (bool);
    function upgradeToNew(address) external returns (bool);
    function isOwner() external view returns (bool);
    function setChainId(uint64 _newChainId) external returns (bool);
}

// File: eth-contracts/contracts/libs/GSN/Context.sol

pragma solidity ^0.5.0;

/*
 * @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 GSN 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.
 * Refer from https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/GSN/Context.sol
 */
contract Context {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    constructor () internal { }
    // solhint-disable-previous-line no-empty-blocks

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// File: eth-contracts/contracts/libs/lifecycle/Pausable.sol

pragma solidity ^0.5.0;


/**
 * @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.
 */
contract Pausable is Context {
    /**
     * @dev Emitted when the pause is triggered by a pauser (`account`).
     */
    event Paused(address account);

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

    bool private _paused;

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

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

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     */
    modifier whenNotPaused() {
        require(!_paused, "Pausable: paused");
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     */
    modifier whenPaused() {
        require(_paused, "Pausable: not paused");
        _;
    }

    /**
     * @dev Called to pause, triggers stopped state.
     */
    function _pause() internal whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Called to unpause, returns to normal state.
     */
    function _unpause() internal whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
}

// File: eth-contracts/contracts/libs/ownership/Ownable.sol

pragma solidity ^0.5.0;

/**
 * @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.
 *
 * 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.
 */
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 () internal {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

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

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(isOwner(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Returns true if the caller is the current owner.
     */
    function isOwner() public view returns (bool) {
        return _msgSender() == _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 onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = 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  onlyOwner {
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     */
    function _transferOwnership(address newOwner) internal {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

// File: eth-contracts/contracts/core/cross_chain_manager/upgrade/EthCrossChainManagerProxy.sol

pragma solidity ^0.5.0;





contract EthCrossChainManagerProxy is IEthCrossChainManagerProxy, Ownable, Pausable {
    address private EthCrossChainManagerAddr_;
    
    constructor(address _ethCrossChainManagerAddr) public {
        EthCrossChainManagerAddr_ = _ethCrossChainManagerAddr;
    }
    
    function pause() onlyOwner public returns (bool) {
        if (paused()) {
            return true;
        }
        _pause();
        return true;
    }
    function unpause() onlyOwner public returns (bool) {
        if (!paused()) {
            return true;
        }
        _unpause();
        return true;
    }
    function pauseEthCrossChainManager() onlyOwner whenNotPaused public returns (bool) {
        IUpgradableECCM eccm = IUpgradableECCM(EthCrossChainManagerAddr_);
        require(pause(), "pause EthCrossChainManagerProxy contract failed!");
        require(eccm.pause(), "pause EthCrossChainManager contract failed!");
    }
    function upgradeEthCrossChainManager(address _newEthCrossChainManagerAddr) onlyOwner whenPaused public returns (bool) {
        IUpgradableECCM eccm = IUpgradableECCM(EthCrossChainManagerAddr_);
        if (!eccm.paused()) {
            require(eccm.pause(), "Pause old EthCrossChainManager contract failed!");
        }
        require(eccm.upgradeToNew(_newEthCrossChainManagerAddr), "EthCrossChainManager upgradeToNew failed!");
        IUpgradableECCM neweccm = IUpgradableECCM(_newEthCrossChainManagerAddr);
        require(neweccm.isOwner(), "EthCrossChainManagerProxy is not owner of new EthCrossChainManager contract");
        EthCrossChainManagerAddr_ = _newEthCrossChainManagerAddr;
    }
    function unpauseEthCrossChainManager() onlyOwner whenPaused public returns (bool) {
        IUpgradableECCM eccm = IUpgradableECCM(EthCrossChainManagerAddr_);
        require(eccm.unpause(), "unpause EthCrossChainManager contract failed!");
        require(unpause(), "unpause EthCrossChainManagerProxy contract failed!");
    }
    function getEthCrossChainManager() whenNotPaused public view returns (address) {
        return EthCrossChainManagerAddr_;
    }
}

// File: eth-contracts/contracts/core/cross_chain_manager/interface/IEthCrossChainData.sol

pragma solidity ^0.5.0;

/**
 * @dev Interface of the EthCrossChainData contract, the implementation is in EthCrossChainData.sol
 */
interface IEthCrossChainData {
    function putCurEpochStartHeight(uint32 curEpochStartHeight) external returns (bool);
    function getCurEpochStartHeight() external view returns (uint32);
    function putCurEpochConPubKeyBytes(bytes calldata curEpochPkBytes) external returns (bool);
    function getCurEpochConPubKeyBytes() external view returns (bytes memory);
    function markFromChainTxExist(uint64 fromChainId, bytes32 fromChainTx) external returns (bool);
    function checkIfFromChainTxExist(uint64 fromChainId, bytes32 fromChainTx) external view returns (bool);
    function getEthTxHashIndex() external view returns (uint256);
    function putEthTxHash(bytes32 ethTxHash) external returns (bool);
    function putExtraData(bytes32 key1, bytes32 key2, bytes calldata value) external returns (bool);
    function getExtraData(bytes32 key1, bytes32 key2) external view returns (bytes memory);
    function transferOwnership(address newOwner) external;
    function pause() external returns (bool);
    function unpause() external returns (bool);
    function paused() external view returns (bool);
    // Not used currently by ECCM
    function getEthTxHash(uint256 ethTxHashIndex) external view returns (bytes32);
}
// File: eth-contracts/contracts/libs/GSN/Context.sol

pragma solidity ^0.5.0;

/*
 * @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 GSN 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.
 * Refer from https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/GSN/Context.sol
 */
contract Context {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    constructor () internal { }
    // solhint-disable-previous-line no-empty-blocks

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// File: eth-contracts/contracts/libs/lifecycle/Pausable.sol

pragma solidity ^0.5.0;


/**
 * @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.
 */
contract Pausable is Context {
    /**
     * @dev Emitted when the pause is triggered by a pauser (`account`).
     */
    event Paused(address account);

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

    bool private _paused;

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

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

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     */
    modifier whenNotPaused() {
        require(!_paused, "Pausable: paused");
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     */
    modifier whenPaused() {
        require(_paused, "Pausable: not paused");
        _;
    }

    /**
     * @dev Called to pause, triggers stopped state.
     */
    function _pause() internal whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Called to unpause, returns to normal state.
     */
    function _unpause() internal whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
}

// File: eth-contracts/contracts/libs/ownership/Ownable.sol

pragma solidity ^0.5.0;

/**
 * @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.
 *
 * 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.
 */
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 () internal {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

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

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(isOwner(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Returns true if the caller is the current owner.
     */
    function isOwner() public view returns (bool) {
        return _msgSender() == _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 onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = 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  onlyOwner {
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     */
    function _transferOwnership(address newOwner) internal {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

// File: eth-contracts/contracts/core/cross_chain_manager/data/EthCrossChainData.sol

pragma solidity ^0.5.0;




contract EthCrossChainData is IEthCrossChainData, Ownable, Pausable{
    /*
     Ethereum cross chain tx hash indexed by the automatically increased index.
     This map exists for the reason that Poly chain can verify the existence of 
     cross chain request tx coming from Ethereum
    */
    mapping(uint256 => bytes32) public EthToPolyTxHashMap;
    // This index records the current Map length
    uint256 public EthToPolyTxHashIndex;

    /* 
     When Poly chain switches the consensus epoch book keepers, the consensus peers public keys of Poly chain should be 
     changed into no-compressed version so that solidity smart contract can convert it to address type and 
     verify the signature derived from Poly chain account signature.
     ConKeepersPkBytes means Consensus book Keepers Public Key Bytes
    */
    bytes public ConKeepersPkBytes;
    
    // CurEpochStartHeight means Current Epoch Start Height of Poly chain block
    uint32 public CurEpochStartHeight;
    
    // Record the from chain txs that have been processed
    mapping(uint64 => mapping(bytes32 => bool)) FromChainTxExist;
    
    // Extra map for the usage of future potentially
    mapping(bytes32 => mapping(bytes32 => bytes)) public ExtraData;
    
    // Store Current Epoch Start Height of Poly chain block
    function putCurEpochStartHeight(uint32 curEpochStartHeight) public whenNotPaused onlyOwner returns (bool) {
        CurEpochStartHeight = curEpochStartHeight;
        return true;
    }

    // Get Current Epoch Start Height of Poly chain block
    function getCurEpochStartHeight() public view returns (uint32) {
        return CurEpochStartHeight;
    }

    // Store Consensus book Keepers Public Key Bytes
    function putCurEpochConPubKeyBytes(bytes memory curEpochPkBytes) public whenNotPaused onlyOwner returns (bool) {
        ConKeepersPkBytes = curEpochPkBytes;
        return true;
    }

    // Get Consensus book Keepers Public Key Bytes
    function getCurEpochConPubKeyBytes() public view returns (bytes memory) {
        return ConKeepersPkBytes;
    }

    // Mark from chain tx fromChainTx as exist or processed
    function markFromChainTxExist(uint64 fromChainId, bytes32 fromChainTx) public whenNotPaused onlyOwner returns (bool) {
        FromChainTxExist[fromChainId][fromChainTx] = true;
        return true;
    }

    // Check if from chain tx fromChainTx has been processed before
    function checkIfFromChainTxExist(uint64 fromChainId, bytes32 fromChainTx) public view returns (bool) {
        return FromChainTxExist[fromChainId][fromChainTx];
    }

    // Get current recorded index of cross chain txs requesting from Ethereum to other public chains
    // in order to help cross chain manager contract differenciate two cross chain tx requests
    function getEthTxHashIndex() public view returns (uint256) {
        return EthToPolyTxHashIndex;
    }

    // Store Ethereum cross chain tx hash, increase the index record by 1
    function putEthTxHash(bytes32 ethTxHash) public whenNotPaused onlyOwner returns (bool) {
        EthToPolyTxHashMap[EthToPolyTxHashIndex] = ethTxHash;
        EthToPolyTxHashIndex = EthToPolyTxHashIndex + 1;
        return true;
    }

    // Get Ethereum cross chain tx hash indexed by ethTxHashIndex
    function getEthTxHash(uint256 ethTxHashIndex) public view returns (bytes32) {
        return EthToPolyTxHashMap[ethTxHashIndex];
    }

    // Store extra data, which may be used in the future
    function putExtraData(bytes32 key1, bytes32 key2, bytes memory value) public whenNotPaused onlyOwner returns (bool) {
        ExtraData[key1][key2] = value;
        return true;
    }
    // Get extra data, which may be used in the future
    function getExtraData(bytes32 key1, bytes32 key2) public view returns (bytes memory) {
        return ExtraData[key1][key2];
    }
    
    function pause() onlyOwner whenNotPaused public returns (bool) {
        _pause();
        return true;
    }
    
    function unpause() onlyOwner whenPaused public returns (bool) {
        _unpause();
        return true;
    }
}