const SECOND = 1;
const MINUTE = 60 * SECOND;
const HOUR = 60 * MINUTE;
const DAY = 24 * HOUR;

/**
 * "5d 12h 3m" — compact uptime display for the dashboard. We don't
 * use the existing `friendlyTime` helper because that one is tuned
 * for "how long ago" (past tense, single-unit), while uptime needs
 * multi-unit forward-looking output and to handle seconds-only
 * fresh-boot cases.
 */
export const formatUptime = (seconds: number): string =>
{
    if(!Number.isFinite(seconds) || seconds < 0) return '—';
    if(seconds < MINUTE) return `${ Math.floor(seconds) }s`;

    const d = Math.floor(seconds / DAY);
    const h = Math.floor((seconds % DAY) / HOUR);
    const m = Math.floor((seconds % HOUR) / MINUTE);

    if(d > 0) return `${ d }d ${ h }h ${ m }m`;
    if(h > 0) return `${ h }h ${ m }m`;

    return `${ m }m`;
};

/**
 * "5m ago", "2h ago", "3d ago" — past-tense relative formatter for
 * audit-log timestamps. Anything older than a day rolls to a fixed
 * date string so the log entries stay scannable even after a week.
 */
export const formatRelativePast = (timestampMs: number, nowMs: number = Date.now()): string =>
{
    if(!Number.isFinite(timestampMs) || timestampMs <= 0) return '—';

    const deltaSeconds = Math.max(0, Math.floor((nowMs - timestampMs) / 1000));

    if(deltaSeconds < 5) return 'now';
    if(deltaSeconds < MINUTE) return `${ deltaSeconds }s ago`;
    if(deltaSeconds < HOUR) return `${ Math.floor(deltaSeconds / MINUTE) }m ago`;
    if(deltaSeconds < DAY) return `${ Math.floor(deltaSeconds / HOUR) }h ago`;
    if(deltaSeconds < 7 * DAY) return `${ Math.floor(deltaSeconds / DAY) }d ago`;

    const date = new Date(timestampMs);

    return date.toISOString().slice(0, 10);
};

export const formatCompactNumber = (value: number): string =>
{
    if(!Number.isFinite(value)) return '—';

    const abs = Math.abs(value);

    if(abs >= 1_000_000) return `${ (value / 1_000_000).toFixed(abs >= 10_000_000 ? 0 : 1) }M`;
    if(abs >= 1_000) return `${ (value / 1_000).toFixed(abs >= 10_000 ? 0 : 1) }K`;

    return value.toString();
};