/**
 * Formatting helpers. API timestamps are UTC ISO strings; dates render in UTC. All helpers accept `Num`
 * (Postgres aggregates can arrive as strings) and return the em-dash for missing values — never a fake number.
 */
import type { Num } from './types';

const nf0 = new Intl.NumberFormat('en-US', { maximumFractionDigits: 0 });
const nf1 = new Intl.NumberFormat('en-US', { maximumFractionDigits: 1 });
const nf2 = new Intl.NumberFormat('en-US', { maximumFractionDigits: 2 });
const nfCompact = new Intl.NumberFormat('en-US', { notation: 'compact', maximumFractionDigits: 1 });

export const DASH = '—';

/** Coerce `Num`/unknown to a finite number or null. */
export function num(v: unknown): number | null {
  if (v === null || v === undefined || v === '') return null;
  const n = typeof v === 'number' ? v : Number(v);
  return Number.isFinite(n) ? n : null;
}

export function fmtInt(v: Num | undefined | unknown): string {
  const n = num(v);
  return n === null ? DASH : nf0.format(n);
}
export function fmt1(v: Num | undefined | unknown): string {
  const n = num(v);
  return n === null ? DASH : nf1.format(n);
}
export function fmt2(v: Num | undefined | unknown): string {
  const n = num(v);
  return n === null ? DASH : nf2.format(n);
}
export function fmtCompact(v: Num | undefined | unknown): string {
  const n = num(v);
  return n === null ? DASH : nfCompact.format(n);
}

/** Parameter counts: 7e9 → "7B", 1.8e12 → "1.8T", 350e6 → "350M". */
export function fmtParams(v: Num | undefined | unknown): string {
  const n = num(v);
  if (n === null) return DASH;
  if (n >= 1e12) return `${trim(n / 1e12)}T`;
  if (n >= 1e9) return `${trim(n / 1e9)}B`;
  if (n >= 1e6) return `${trim(n / 1e6)}M`;
  if (n >= 1e3) return `${trim(n / 1e3)}K`;
  return nf0.format(n);
}
/** Token windows: 128000 → "128K", 1000000 → "1M", 200000 → "200K". */
export function fmtTokens(v: Num | undefined | unknown): string {
  const n = num(v);
  if (n === null) return DASH;
  if (n >= 1e6) return `${trim(n / 1e6)}M`;
  if (n >= 1e3) return `${trim(n / 1e3)}K`;
  return nf0.format(n);
}
function trim(x: number): string {
  const r = Math.round(x * 100) / 100;
  return r % 1 === 0 ? String(r) : String(Number(r.toFixed(r < 10 ? 2 : 1)));
}

/** USD per 1M tokens: 3 → "$3.00", 0.075 → "$0.075", 15 → "$15.00". */
export function fmtUsdPerM(v: Num | undefined | unknown, withUnit = false): string {
  const n = num(v);
  if (n === null) return DASH;
  let s: string;
  if (n === 0) s = '$0';
  else if (n < 0.01) s = `$${n.toFixed(4).replace(/0+$/, '')}`;
  else if (n < 1) s = `$${n.toFixed(3).replace(/0$/, '')}`;
  else s = `$${nf2.format(n)}`;
  return withUnit ? `${s} / 1M` : s;
}
export function fmtUsd(v: Num | undefined | unknown): string {
  const n = num(v);
  return n === null ? DASH : `$${nf0.format(n)}`;
}
export function fmtPct(v: Num | undefined | unknown, digits = 1): string {
  const n = num(v);
  return n === null ? DASH : `${n.toFixed(digits)}%`;
}
export function fmtGb(v: Num | undefined | unknown, digits = 0): string {
  const n = num(v);
  return n === null ? DASH : `${digits ? n.toFixed(digits) : nf0.format(n)} GB`;
}
export function fmtBytes(v: Num | undefined | unknown): string {
  const n = num(v);
  if (n === null) return DASH;
  if (n >= 1e12) return `${(n / 1e12).toFixed(2)} TB`;
  if (n >= 1e9) return `${(n / 1e9).toFixed(1)} GB`;
  if (n >= 1e6) return `${(n / 1e6).toFixed(0)} MB`;
  if (n >= 1e3) return `${(n / 1e3).toFixed(0)} kB`;
  return `${n} B`;
}
export function fmtScore(v: Num | undefined | unknown): string {
  const n = num(v);
  if (n === null) return DASH;
  return Number.isInteger(n) ? nf0.format(n) : nf2.format(n);
}

/** ISO date (YYYY-MM-DD, YYYY-MM or full timestamp) → "11 Sept 2026" / "Sept 2026" / "2026" (UTC). */
export function fmtDate(v: string | null | undefined): string {
  if (!v) return DASH;
  if (/^\d{4}$/.test(v)) return v;
  if (/^\d{4}-\d{2}$/.test(v)) return fmtMonth(v);
  const d = new Date(v.length === 10 ? `${v}T00:00:00Z` : v);
  if (Number.isNaN(d.getTime())) return v;
  return d.toLocaleDateString('en-GB', { year: 'numeric', month: 'short', day: 'numeric', timeZone: 'UTC' });
}
export function fmtMonth(v: string | null | undefined): string {
  if (!v) return DASH;
  const m = /^(\d{4})-(\d{2})/.exec(v);
  if (!m) return fmtDate(v);
  const d = new Date(Date.UTC(Number(m[1]), Number(m[2]) - 1, 1));
  return d.toLocaleDateString('en-GB', { year: 'numeric', month: 'short', timeZone: 'UTC' });
}
export function fmtDateTime(v: string | null | undefined): string {
  if (!v) return DASH;
  const d = new Date(v);
  if (Number.isNaN(d.getTime())) return DASH;
  return `${d.toLocaleDateString('en-GB', { year: 'numeric', month: 'short', day: 'numeric', timeZone: 'UTC' })} ${d.toLocaleTimeString('en-GB', { hour: '2-digit', minute: '2-digit', timeZone: 'UTC' })} UTC`;
}
export function fmtAgo(v: string | null | undefined, now: number = Date.now()): string {
  if (!v) return 'unavailable';
  const t = new Date(v).getTime();
  if (Number.isNaN(t)) return 'unavailable';
  const s = Math.max(0, Math.round((now - t) / 1000));
  if (s < 60) return 'just now';
  const m = Math.round(s / 60);
  if (m < 60) return `${m} min ago`;
  const h = Math.round(m / 60);
  if (h < 48) return `${h} h ago`;
  const d = Math.round(h / 24);
  if (d < 60) return `${d} d ago`;
  return fmtDate(v);
}
export function fmtYear(v: string | null | undefined): string {
  return v && /^\d{4}/.test(v) ? v.slice(0, 4) : DASH;
}
export function fmtDuration(seconds: Num | undefined | unknown): string {
  const n = num(seconds);
  if (n === null) return DASH;
  if (n < 60) return `${n}s`;
  if (n < 3600) return `${Math.round(n / 60)} min`;
  if (n < 86400) return `${Math.round(n / 3600)} h`;
  return `${Math.round(n / 86400)} d`;
}

/** Signed delta: +3.2% / −1.8% (relative change between two values). Null when either side is missing or the base is 0. */
export function fmtDeltaPct(from: Num | undefined | unknown, to: Num | undefined | unknown, digits = 1): string | null {
  const a = num(from);
  const b = num(to);
  if (a === null || b === null || a === 0) return null;
  const d = ((b - a) / Math.abs(a)) * 100;
  const sign = d > 0 ? '+' : d < 0 ? '−' : '';
  return `${sign}${Math.abs(d).toFixed(digits)}%`;
}
/** Signed integer: +12 / −3 / 0. */
export function fmtSigned(v: Num | undefined | unknown): string {
  const n = num(v);
  if (n === null) return DASH;
  return n > 0 ? `+${nf0.format(n)}` : n < 0 ? `−${nf0.format(Math.abs(n))}` : '0';
}
/** Host of a URL without `www.` — for compact source labels. */
export function hostOf(url: string | null | undefined): string | null {
  if (!url) return null;
  try {
    return new URL(url).hostname.replace(/^www\./, '');
  } catch {
    return null;
  }
}

export function titleCase(s: string | null | undefined): string {
  if (!s) return DASH;
  return s.replace(/[_-]+/g, ' ').replace(/\b\w/g, (c) => c.toUpperCase());
}
/** Event type / predicate constant → words: NEW_MODEL → "New model", fine_tuned_from → "fine-tuned from". */
export function humanize(s: string | null | undefined): string {
  if (!s) return DASH;
  const w = s.toLowerCase().replace(/_/g, ' ');
  return w.charAt(0).toUpperCase() + w.slice(1);
}
export function plural(n: number, one: string, many = `${one}s`): string {
  return n === 1 ? one : many;
}

/** Render any attribute value for a spec table (never JSON-dumps a primitive). */
export function fmtValue(v: unknown, key?: string): string {
  if (v === null || v === undefined || v === '') return DASH;
  if (typeof v === 'boolean') return v ? 'Yes' : 'No';
  if (Array.isArray(v)) return v.length ? v.map((x) => (typeof x === 'object' && x ? JSON.stringify(x) : String(x))).join(', ') : DASH;
  if (typeof v === 'number') {
    if (key && /parameter_count/.test(key)) return fmtParams(v);
    if (key && /(context_length|max_output_tokens)/.test(key)) return `${fmtTokens(v)} tokens`;
    if (key && /memory_gb|file_size_gb/.test(key)) return fmtGb(v, v % 1 ? 1 : 0);
    if (key && /bandwidth_gbs/.test(key)) return `${fmtInt(v)} GB/s`;
    if (key && /tdp_watts/.test(key)) return `${fmtInt(v)} W`;
    if (key && /tflops/.test(key)) return `${fmt1(v)} TFLOPS`;
    if (key && /price_usd/.test(key)) return fmtUsd(v);
    return Number.isInteger(v) ? nf0.format(v) : nf2.format(v);
  }
  if (typeof v === 'string') {
    if (key && /(_date|_at|cutoff)$/.test(key) && /^\d{4}(-\d{2})?(-\d{2})?/.test(v)) return fmtDate(v);
    return v;
  }
  return JSON.stringify(v);
}