// Copyright 2021-2022, Offchain Labs, Inc.
// For license information, see https://github.com/OffchainLabs/nitro-contracts/blob/main/LICENSE
// SPDX-License-Identifier: BUSL-1.1

pragma solidity ^0.8.0;

struct GlobalState {
    bytes32[2] bytes32Vals;
    uint64[2] u64Vals;
}

library GlobalStateLib {
    uint16 internal constant BYTES32_VALS_NUM = 2;
    uint16 internal constant U64_VALS_NUM = 2;

    function hash(GlobalState memory state) internal pure returns (bytes32) {
        return
            keccak256(
                abi.encodePacked(
                    "Global state:",
                    state.bytes32Vals[0],
                    state.bytes32Vals[1],
                    state.u64Vals[0],
                    state.u64Vals[1]
                )
            );
    }

    function getBlockHash(GlobalState memory state) internal pure returns (bytes32) {
        return state.bytes32Vals[0];
    }

    function getSendRoot(GlobalState memory state) internal pure returns (bytes32) {
        return state.bytes32Vals[1];
    }

    function getInboxPosition(GlobalState memory state) internal pure returns (uint64) {
        return state.u64Vals[0];
    }

    function getPositionInMessage(GlobalState memory state) internal pure returns (uint64) {
        return state.u64Vals[1];
    }

    function isEmpty(GlobalState calldata state) internal pure returns (bool) {
        return (state.bytes32Vals[0] == bytes32(0) &&
            state.bytes32Vals[1] == bytes32(0) &&
            state.u64Vals[0] == 0 &&
            state.u64Vals[1] == 0);
    }
}