// Formatting of times, durations and labels.

const MIN = 60 * 1000;
const HOUR = 60 * MIN;
const DAY = 24 * HOUR;

// Compact age for list rows: "now", "4m", "3h", "2d".
export function age(iso, now = Date.now()) {
  const ms = Math.max(0, now - Date.parse(iso));
  if (ms < MIN) return 'now';
  if (ms < HOUR) return `${Math.floor(ms / MIN)}m`;
  if (ms < DAY) return `${Math.floor(ms / HOUR)}h`;
  return `${Math.floor(ms / DAY)}d`;
}

// "4 min ago", "3 h ago", "yesterday"-free: stays unambiguous at 3am.
export function ago(iso, now = Date.now()) {
  const a = age(iso, now);
  return a === 'now' ? 'just now' : `${a} ago`;
}

// Time remaining until iso, e.g. "1h 20m".
export function until(iso, now = Date.now()) {
  return duration(Date.parse(iso) - now);
}

export function duration(ms) {
  ms = Math.max(0, ms);
  if (ms < MIN) return '<1m';
  const d = Math.floor(ms / DAY);
  const h = Math.floor((ms % DAY) / HOUR);
  const m = Math.floor((ms % HOUR) / MIN);
  if (d) return h ? `${d}d ${h}h` : `${d}d`;
  if (h) return m ? `${h}h ${m}m` : `${h}h`;
  return `${m}m`;
}

const timeFmt = new Intl.DateTimeFormat(undefined, { hour: '2-digit', minute: '2-digit' });
const dayTimeFmt = new Intl.DateTimeFormat(undefined, {
  weekday: 'short', day: 'numeric', month: 'short', hour: '2-digit', minute: '2-digit',
});

// Local timestamp; the date is dropped when it is today.
export function when(iso) {
  const d = new Date(iso);
  const today = new Date();
  if (d.toDateString() === today.toDateString()) return timeFmt.format(d);
  return dayTimeFmt.format(d);
}

export function isFuture(iso) {
  return iso != null && Date.parse(iso) > Date.now();
}

// Local calendar dates, as the schedule stores them (YYYY-MM-DD).
export function isoDate(d) {
  const y = d.getFullYear();
  const m = String(d.getMonth() + 1).padStart(2, '0');
  const day = String(d.getDate()).padStart(2, '0');
  return `${y}-${m}-${day}`;
}

export function mondayOf(d) {
  const r = new Date(d.getFullYear(), d.getMonth(), d.getDate());
  r.setDate(r.getDate() - ((r.getDay() + 6) % 7));
  return r;
}

export function addDays(d, n) {
  const r = new Date(d);
  r.setDate(r.getDate() + n);
  return r;
}

// ISO 8601 week number.
export function isoWeek(d) {
  const t = new Date(Date.UTC(d.getFullYear(), d.getMonth(), d.getDate()));
  const day = t.getUTCDay() || 7;
  t.setUTCDate(t.getUTCDate() + 4 - day);
  const yearStart = new Date(Date.UTC(t.getUTCFullYear(), 0, 1));
  return Math.ceil(((t - yearStart) / DAY + 1) / 7);
}

export const STATUS_LABEL = {
  triggered: 'Triggered',
  acknowledged: 'Acknowledged',
  resolved: 'Resolved',
  snoozed: 'Snoozed',
  firing: 'Firing',
};

export function severityClass(sev) {
  const s = (sev || '').toLowerCase();
  if (s === 'critical' || s === 'page' || s === 'error') return 'sev-critical';
  if (s === 'warning' || s === 'warn') return 'sev-warning';
  if (s) return 'sev-info';
  return '';
}

// A one-line summary of the group labels, without the one the title already shows.
export function labelSummary(labels, skip = 'alertname') {
  return Object.entries(labels || {})
    .filter(([k]) => k !== skip)
    .map(([k, v]) => `${k}=${v}`)
    .join(' · ');
}

export function initial(name) {
  return (name || '?').trim().charAt(0) || '?';
}