import { useRegionStore } from '~/stores/region'

/**
 * 🌍 useFormatter Composable
 *
 * Provides locale-aware formatting utilities for numbers, currencies, dates,
 * and percentages. Uses the active region configuration from the RegionStore
 * to determine the appropriate locale, currency, and timezone.
 *
 * Falls back to 'en-EU' locale and 'EUR' currency if no region is configured.
 */
export function useFormatter() {
  const regionStore = useRegionStore()

  /**
   * Format a number according to the active locale.
   * Example: 1234567.89 → "1,234,567.89" (en) or "1 234 567,89" (hu)
   */
  function formatNumber(value: number, options?: Intl.NumberFormatOptions): string {
    const locale = regionStore.activeLocale || 'en-EU'
    try {
      return new Intl.NumberFormat(locale, options).format(value)
    } catch {
      return new Intl.NumberFormat('en-EU', options).format(value)
    }
  }

  /**
   * Format a currency value according to the active region's currency and locale.
   * Example: 1234.50 → "€1,234.50" (EUR/en) or "3 456 Ft" (HUF/hu)
   */
  function formatCurrency(
    value: number,
    currency?: string,
    options?: Intl.NumberFormatOptions,
  ): string {
    const locale = regionStore.activeLocale || 'en-EU'
    const curr = currency || regionStore.activeCurrency || 'EUR'
    try {
      return new Intl.NumberFormat(locale, {
        style: 'currency',
        currency: curr,
        minimumFractionDigits: 2,
        maximumFractionDigits: 2,
        ...options,
      }).format(value)
    } catch {
      return `${value.toFixed(2)} ${curr}`
    }
  }

  /**
   * Format a date according to the active locale and timezone.
   * Example: 2026-06-24 → "24/06/2026" (en-GB) or "2026. 06. 24." (hu-HU)
   */
  function formatDate(
    date: Date | string | number,
    options?: Intl.DateTimeFormatOptions,
  ): string {
    const locale = regionStore.activeLocale || 'en-EU'
    const timezone = regionStore.activeTimezone || 'Europe/Brussels'
    const d = typeof date === 'string' || typeof date === 'number' ? new Date(date) : date

    try {
      return new Intl.DateTimeFormat(locale, {
        timezone,
        year: 'numeric',
        month: '2-digit',
        day: '2-digit',
        ...options,
      }).format(d)
    } catch {
      return d.toLocaleDateString('en-GB')
    }
  }

  /**
   * Format a datetime with time according to the active locale and timezone.
   * Example: "2026-06-24T14:30:00Z" → "24/06/2026, 16:30" (hu-HU/Budapest)
   */
  function formatDateTime(
    date: Date | string | number,
    options?: Intl.DateTimeFormatOptions,
  ): string {
    const locale = regionStore.activeLocale || 'en-EU'
    const timezone = regionStore.activeTimezone || 'Europe/Brussels'
    const d = typeof date === 'string' || typeof date === 'number' ? new Date(date) : date

    try {
      return new Intl.DateTimeFormat(locale, {
        timezone,
        year: 'numeric',
        month: '2-digit',
        day: '2-digit',
        hour: '2-digit',
        minute: '2-digit',
        ...options,
      }).format(d)
    } catch {
      return d.toLocaleString('en-GB')
    }
  }

  /**
   * Format a percentage value.
   * Example: 27 → "27%" or 27.5 → "27,5%" (hu)
   */
  function formatPercent(
    value: number,
    options?: Intl.NumberFormatOptions,
  ): string {
    const locale = regionStore.activeLocale || 'en-EU'
    try {
      return new Intl.NumberFormat(locale, {
        style: 'percent',
        minimumFractionDigits: 0,
        maximumFractionDigits: 1,
        ...options,
      }).format(value / 100)
    } catch {
      return `${value}%`
    }
  }

  /**
   * Calculate price including VAT for the active region.
   * VAT rate comes from the active region's default_vat_rate.
   */
  function calculatePriceWithVat(
    netPrice: number,
    vatRate?: number,
  ): { net: number; vat: number; gross: number; vatRate: number } {
    const rate = vatRate ?? regionStore.activeVatRate ?? 0
    const vat = netPrice * (rate / 100)
    const gross = netPrice + vat
    return { net: netPrice, vat, gross, vatRate: rate }
  }

  /**
   * Format a price range with VAT breakdown.
   * Example: (100, 27) → "Net: €100.00 | VAT: €27.00 (27%) | Gross: €127.00"
   */
  function formatPriceWithVat(
    netPrice: number,
    vatRate?: number,
    currency?: string,
  ): string {
    const { net, vat, gross, vatRate: rate } = calculatePriceWithVat(netPrice, vatRate)
    const curr = currency || regionStore.activeCurrency || 'EUR'
    return `Net: ${formatCurrency(net, curr)} | VAT: ${formatCurrency(vat, curr)} (${rate}%) | Gross: ${formatCurrency(gross, curr)}`
  }

  return {
    formatNumber,
    formatCurrency,
    formatDate,
    formatDateTime,
    formatPercent,
    calculatePriceWithVat,
    formatPriceWithVat,
  }
}