bitburner-src/src/Infiltration/ui/GameTimer.tsx

import LinearProgress from '@material-ui/core/LinearProgress';
import React, { useState, useEffect } from 'react';
import { withStyles } from "@material-ui/core/styles";
import Grid from '@material-ui/core/Grid';

const TimerProgress = withStyles(() => ({
  bar: {
    transition: "none",
    backgroundColor: "#adff2f",
  },
}))(LinearProgress);

interface IProps {
    millis: number;
    onExpire: () => void;
}

export function GameTimer(props: IProps): React.ReactElement {
    const [v, setV] = useState(100);

    const tick = 200;
    useEffect(() => {
        const intervalId = setInterval(() => {
            setV(old => {
                if(old <= 0) props.onExpire();
                return old - tick / props.millis * 100;
            });
        }, tick);
        return () => {
            clearInterval(intervalId);
        }
    }, []);

    // https://stackoverflow.com/questions/55593367/disable-material-uis-linearprogress-animation
    // TODO(hydroflame): there's like a bug where it triggers the end before the
    // bar physically reaches the end
    return (<Grid item xs={12}>
        <TimerProgress variant="determinate" value={v} />
    </Grid>);
}