export class TimerService {
    K = 1000;
    INTERVAL = this.K;
    MINUTES = 25;
    TIME = this.MINUTES * this.K * 60;

    current = 0;
    time = this.TIME;

    toggle$ = new BehaviorSubject(true);
    remainingSeconds$ = this.toggle$.pipe(
        switchMap((running: boolean) => {
            return running ? timer(0, this.INTERVAL) : NEVER;
        }),
        map(this.toRemainingSeconds),
        takeWhile(t => t >= 0)
    );

    constructor() {}

    toMinutes(ms: number): number {
        return Math.floor(ms / this.K / 60);
    }

    toSeconds(ms: number): number {
        return Math.floor(ms / this.K) % 60;
    }

    toSecondsString(ms: number): string {
        const seconds = this.toSeconds(ms);
        return seconds < 10 ? `0${seconds}` : seconds.toString();
    }

    toMs(t: number): number {
        return t * this.INTERVAL;
    }

    currentInterval(): number {
        return this.time / this.INTERVAL;
    }

    toRemainingSeconds(t: number): number {
        return this.currentInterval() - t;
    }
}