// 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;

import "./ValueStack.sol";
import "./Instructions.sol";
import "./StackFrame.sol";

enum MachineStatus {
    RUNNING,
    FINISHED,
    ERRORED,
    TOO_FAR
}

struct Machine {
    MachineStatus status;
    ValueStack valueStack;
    ValueStack internalStack;
    StackFrameWindow frameStack;
    bytes32 globalStateHash;
    uint32 moduleIdx;
    uint32 functionIdx;
    uint32 functionPc;
    bytes32 modulesRoot;
}

library MachineLib {
    using StackFrameLib for StackFrameWindow;
    using ValueStackLib for ValueStack;

    function hash(Machine memory mach) internal pure returns (bytes32) {
        // Warning: the non-running hashes are replicated in Challenge
        if (mach.status == MachineStatus.RUNNING) {
            return
                keccak256(
                    abi.encodePacked(
                        "Machine running:",
                        mach.valueStack.hash(),
                        mach.internalStack.hash(),
                        mach.frameStack.hash(),
                        mach.globalStateHash,
                        mach.moduleIdx,
                        mach.functionIdx,
                        mach.functionPc,
                        mach.modulesRoot
                    )
                );
        } else if (mach.status == MachineStatus.FINISHED) {
            return keccak256(abi.encodePacked("Machine finished:", mach.globalStateHash));
        } else if (mach.status == MachineStatus.ERRORED) {
            return keccak256(abi.encodePacked("Machine errored:"));
        } else if (mach.status == MachineStatus.TOO_FAR) {
            return keccak256(abi.encodePacked("Machine too far:"));
        } else {
            revert("BAD_MACH_STATUS");
        }
    }
}