/**
 * Presets de rango de fecha compartidos (Ventas, y reutilizables por otras
 * vistas). El rango elegido se persiste en localStorage para que al volver a
 * la pantalla se restaure, igual que los presets de la agenda.
 */

export type DatePreset = 'hoy' | 'ayer' | 'semana' | 'mes' | 'mes_pasado' | 'custom';

export interface DateRange {
  start: string;
  end: string;
}

export const DATE_PRESETS: { value: DatePreset; label: string }[] = [
  { value: 'hoy', label: 'Hoy' },
  { value: 'ayer', label: 'Ayer' },
  { value: 'semana', label: 'Esta semana' },
  { value: 'mes', label: 'Este mes' },
  { value: 'mes_pasado', label: 'Mes pasado' },
  { value: 'custom', label: 'Rango personalizado' },
];

export const isoDate = (d: Date): string => {
  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 const rangeForPreset = (preset: DatePreset, today = new Date()): DateRange => {
  const t = new Date(today.getFullYear(), today.getMonth(), today.getDate());
  switch (preset) {
    case 'hoy':
      return { start: isoDate(t), end: isoDate(t) };
    case 'ayer': {
      const y = new Date(t);
      y.setDate(y.getDate() - 1);
      return { start: isoDate(y), end: isoDate(y) };
    }
    case 'semana': {
      // Semana en curso, de lunes a domingo
      const dow = (t.getDay() + 6) % 7; // 0 = lunes
      const monday = new Date(t);
      monday.setDate(t.getDate() - dow);
      const sunday = new Date(monday);
      sunday.setDate(monday.getDate() + 6);
      return { start: isoDate(monday), end: isoDate(sunday) };
    }
    case 'mes': {
      const first = new Date(t.getFullYear(), t.getMonth(), 1);
      const last = new Date(t.getFullYear(), t.getMonth() + 1, 0);
      return { start: isoDate(first), end: isoDate(last) };
    }
    case 'mes_pasado': {
      const first = new Date(t.getFullYear(), t.getMonth() - 1, 1);
      const last = new Date(t.getFullYear(), t.getMonth(), 0);
      return { start: isoDate(first), end: isoDate(last) };
    }
    default:
      return { start: isoDate(t), end: isoDate(t) };
  }
};

export interface DateFilterPrefs extends DateRange {
  preset: DatePreset;
}

export const readDateFilterPrefs = (key: string): DateFilterPrefs | null => {
  try {
    const raw = localStorage.getItem(key);
    if (!raw) return null;
    const parsed = JSON.parse(raw) as Partial<DateFilterPrefs>;
    if (!parsed || typeof parsed.start !== 'string' || typeof parsed.end !== 'string') return null;
    const preset = (DATE_PRESETS.some((p) => p.value === parsed.preset) ? parsed.preset : 'custom') as DatePreset;
    return { preset, start: parsed.start, end: parsed.end };
  } catch {
    return null;
  }
};

export const writeDateFilterPrefs = (key: string, prefs: DateFilterPrefs): void => {
  try {
    localStorage.setItem(key, JSON.stringify(prefs));
  } catch {
    // localStorage no disponible: se mantiene solo en memoria
  }
};