/** Current time in milliseconds since the Unix epoch. */
export function nowMs(): number {
    return Date.now();
}

/** Normalize a date/time input to milliseconds since the Unix epoch. Returns `null` for unparseable or invalid values. */
export function toMs(input: Date | number | string | null | undefined): number | null {
    if (input === null || input === undefined) return null;
    if (input instanceof Date) return input.getTime();
    if (typeof input === 'string') {
        const parsed = new Date(input).getTime();
        return Number.isNaN(parsed) ? null : parsed;
    }
    // Reject NaN/±Infinity rather than passing them through as a "valid" timestamp.
    return Number.isFinite(input) ? Math.floor(input) : null;
}

/** Convert a millisecond timestamp to a `Date`. Returns `null` for `null`, `undefined`, or `NaN`. */
export function fromMs(ms: number | null | undefined): Date | null {
    if (ms === null || ms === undefined || Number.isNaN(ms)) return null;
    return new Date(ms);
}