/** Date presets for Ad Tracker. Data ends at yesterday unless preset is «Hoy». */

export type RangePreset =
  | 'today'
  | 'yesterday'
  | 'last_7d'
  | 'last_14d'
  | 'last_28d'
  | 'last_30d'
  | 'this_week'
  | 'last_week'
  | 'this_month'
  | 'last_month'
  | 'custom';

export type DateRange = { since: string; until: string; label: string };

const QUICK: { id: RangePreset; label: string }[] = [
  { id: 'today', label: 'Hoy' },
  { id: 'yesterday', label: 'Ayer' },
  { id: 'last_7d', label: '7 días' },
  { id: 'last_14d', label: '14 días' },
  { id: 'last_28d', label: '28 días' },
  { id: 'last_30d', label: '30 días' },
  { id: 'this_week', label: 'Esta semana' },
  { id: 'last_week', label: 'Semana pasada' },
  { id: 'this_month', label: 'Este mes' },
  { id: 'last_month', label: 'Mes pasado' },
];

export { QUICK as AD_TRACKER_PRESETS };

function iso(d: Date): string {
  return d.toISOString().slice(0, 10);
}

/** UTC calendar day for «today». */
export function utcToday(now = new Date()): Date {
  return new Date(
    Date.UTC(now.getUTCFullYear(), now.getUTCMonth(), now.getUTCDate())
  );
}

/** UTC calendar day for «yesterday». */
export function utcYesterday(now = new Date()): Date {
  const d = utcToday(now);
  d.setUTCDate(d.getUTCDate() - 1);
  return d;
}

export function isoToday(now = new Date()): string {
  return iso(utcToday(now));
}

export function isoYesterday(now = new Date()): string {
  return iso(utcYesterday(now));
}

/**
 * Max date allowed in the picker / default until.
 * Only «Hoy» may include today; everything else ends at yesterday.
 */
export function maxDataDate(preset: RangePreset, now = new Date()): string {
  return preset === 'today' ? isoToday(now) : isoYesterday(now);
}

function startOfWeekMon(d: Date): Date {
  const x = new Date(Date.UTC(d.getUTCFullYear(), d.getUTCMonth(), d.getUTCDate()));
  const day = x.getUTCDay();
  const diff = day === 0 ? -6 : 1 - day;
  x.setUTCDate(x.getUTCDate() + diff);
  return x;
}

const MONTHS_ES = [
  'ene',
  'feb',
  'mar',
  'abr',
  'may',
  'jun',
  'jul',
  'ago',
  'sep',
  'oct',
  'nov',
  'dic',
];

export function formatRangeLabel(since: string, until: string): string {
  const a = since.split('-').map(Number);
  const b = until.split('-').map(Number);
  if (a.length !== 3 || b.length !== 3) return `${since} - ${until}`;
  return `${a[2]} ${MONTHS_ES[a[1] - 1]} ${a[0]} - ${b[2]} ${MONTHS_ES[b[1] - 1]} ${b[0]}`;
}

function parseIsoDay(s: string): Date | null {
  if (!/^\d{4}-\d{2}-\d{2}$/.test(s)) return null;
  const d = new Date(s + 'T00:00:00Z');
  return Number.isNaN(d.getTime()) ? null : d;
}

/**
 * Resolve a date range.
 * All presets except «today» end at yesterday (ads warehouse lag).
 * Custom ranges are clamped so until ≤ yesterday.
 */
export function resolveAdRange(
  preset: RangePreset,
  custom?: { since?: string; until?: string },
  now = new Date()
): DateRange {
  const today = utcToday(now);
  const yesterday = utcYesterday(now);
  /** Anchor end for non-today presets. */
  const end = yesterday;

  let since = new Date(end);
  let until = new Date(end);

  switch (preset) {
    case 'today':
      since = new Date(today);
      until = new Date(today);
      break;
    case 'yesterday':
      since = new Date(yesterday);
      until = new Date(yesterday);
      break;
    case 'last_7d':
      since = new Date(end);
      since.setUTCDate(since.getUTCDate() - 6);
      until = new Date(end);
      break;
    case 'last_14d':
      since = new Date(end);
      since.setUTCDate(since.getUTCDate() - 13);
      until = new Date(end);
      break;
    case 'last_28d':
      since = new Date(end);
      since.setUTCDate(since.getUTCDate() - 27);
      until = new Date(end);
      break;
    case 'last_30d':
      since = new Date(end);
      since.setUTCDate(since.getUTCDate() - 29);
      until = new Date(end);
      break;
    case 'this_week':
      since = startOfWeekMon(today);
      until = new Date(end);
      if (since.getTime() > until.getTime()) {
        since = new Date(until);
      }
      break;
    case 'last_week': {
      const thisMon = startOfWeekMon(today);
      until = new Date(thisMon);
      until.setUTCDate(until.getUTCDate() - 1);
      since = startOfWeekMon(until);
      break;
    }
    case 'this_month':
      since = new Date(Date.UTC(today.getUTCFullYear(), today.getUTCMonth(), 1));
      until = new Date(end);
      if (since.getTime() > until.getTime()) {
        // 1st of month = today → no complete days yet; show yesterday of prev month
        since = new Date(until);
      }
      break;
    case 'last_month': {
      const firstThis = new Date(
        Date.UTC(today.getUTCFullYear(), today.getUTCMonth(), 1)
      );
      until = new Date(firstThis);
      until.setUTCDate(until.getUTCDate() - 1);
      since = new Date(Date.UTC(until.getUTCFullYear(), until.getUTCMonth(), 1));
      break;
    }
    case 'custom': {
      const maxUntil = yesterday;
      let s = parseIsoDay(custom?.since || '') || new Date(end);
      let u = parseIsoDay(custom?.until || '') || new Date(end);
      // Clamp: never past yesterday for custom
      if (u.getTime() > maxUntil.getTime()) u = new Date(maxUntil);
      if (s.getTime() > u.getTime()) s = new Date(u);
      since = s;
      until = u;
      break;
    }
  }

  const s = iso(since);
  const u = iso(until);
  return { since: s, until: u, label: formatRangeLabel(s, u) };
}

export function normalizePlatform(p?: string): 'meta' | 'google' | 'other' {
  const x = (p || '').toLowerCase();
  if (
    x.includes('meta') ||
    x.includes('facebook') ||
    x.includes('instagram') ||
    x === 'fb' ||
    x === 'ig'
  ) {
    return 'meta';
  }
  if (x.includes('google') || x.includes('adwords') || x === 'gads') {
    return 'google';
  }
  return 'other';
}