import { texts } from '@/texts'

const EMPTY_VALUE = '—'

/** Product display timezone — keeps SSR (Docker UTC) and client (Iran) text identical. */
export const DISPLAY_TIME_ZONE = 'Asia/Tehran'

const PERSIAN_DIGITS = ['۰', '۱', '۲', '۳', '۴', '۵', '۶', '۷', '۸', '۹'] as const

/** Normalize Western digits and grouping to Persian digits for stable SSR/client output. */
export function toPersianDigits(value: string): string {
  return value.replace(/\d/g, (digit) => PERSIAN_DIGITS[Number(digit)])
}

const defaultDateTimeOptions: Intl.DateTimeFormatOptions = {
  dateStyle: 'medium',
  timeStyle: 'short',
  timeZone: DISPLAY_TIME_ZONE,
}

function dayKeyInTimeZone(date: Date, timeZone: string): string | null {
  const parts = new Intl.DateTimeFormat('en-CA', {
    timeZone,
    year: 'numeric',
    month: '2-digit',
    day: '2-digit',
  }).formatToParts(date)

  const year = parts.find((part) => part.type === 'year')?.value
  const month = parts.find((part) => part.type === 'month')?.value
  const day = parts.find((part) => part.type === 'day')?.value

  if (!year || !month || !day) return null

  return `${year}-${month}-${day}`
}

export function formatPersianDate(
  value: unknown,
  options: Intl.DateTimeFormatOptions = defaultDateTimeOptions,
  fallback = EMPTY_VALUE
): string {
  if (!value || (typeof value !== 'string' && !(value instanceof Date))) return fallback

  const date = value instanceof Date ? value : new Date(value)

  return Number.isFinite(date.getTime())
    ? new Intl.DateTimeFormat('fa-IR', { timeZone: DISPLAY_TIME_ZONE, ...options }).format(date)
    : fallback
}

/** Local calendar day key (YYYY-MM-DD) in the product display timezone. */
export function toLocalDayKey(value: string | Date, timeZone = DISPLAY_TIME_ZONE): string | null {
  const date = value instanceof Date ? value : new Date(value)

  if (!Number.isFinite(date.getTime())) return null

  return dayKeyInTimeZone(date, timeZone)
}

/** Telegram-style day label: امروز / فردا / دیروز / full Persian date. */
export function formatChatDayLabel(value: string | Date, now = new Date()): string {
  const date = value instanceof Date ? value : new Date(value)

  if (!Number.isFinite(date.getTime())) return EMPTY_VALUE

  const todayKey = toLocalDayKey(now)
  const dayKey = toLocalDayKey(date)

  if (!todayKey || !dayKey) return EMPTY_VALUE

  if (dayKey === todayKey) return texts.common.today

  const tomorrow = new Date(now)

  tomorrow.setDate(tomorrow.getDate() + 1)
  if (dayKey === toLocalDayKey(tomorrow)) return texts.common.tomorrow

  const yesterday = new Date(now)

  yesterday.setDate(yesterday.getDate() - 1)
  if (dayKey === toLocalDayKey(yesterday)) return texts.common.yesterday

  return formatPersianDate(date, { dateStyle: 'medium' })
}

/** e.g. `امروز ۱۸:۰۰ تا ۲۰:۳۰` for home category preview rows. */
export function formatEventDayTimeRange(startsAt: string | Date, endsAt: string | Date, now = new Date()): string {
  const day = formatChatDayLabel(startsAt, now)
  const from = formatPersianDate(startsAt, { hour: '2-digit', minute: '2-digit' })
  const to = formatPersianDate(endsAt, { hour: '2-digit', minute: '2-digit' })

  return `${day} ${from} تا ${to}`
}

export function formatIranianMobile(value: unknown, fallback = EMPTY_VALUE): string {
  if (typeof value !== 'string' || value.length === 0) return fallback

  return value.startsWith('98') && value.length === 12 ? `0${value.slice(2)}` : value
}

export function truncateValue(value: unknown, maxLength = 80, fallback = EMPTY_VALUE): string {
  if (typeof value !== 'string' || value.trim().length === 0) return fallback

  return value.length > maxLength ? `${value.slice(0, maxLength)}…` : value
}

/** Relative Persian time for review/activity timestamps (e.g. «۲ روز پیش»). */
export function formatRelativeTimePersian(value: unknown, now = new Date(), fallback = EMPTY_VALUE): string {
  if (!value || (typeof value !== 'string' && !(value instanceof Date))) return fallback

  const date = value instanceof Date ? value : new Date(value)

  if (!Number.isFinite(date.getTime())) return fallback

  const diffMs = Math.max(0, now.getTime() - date.getTime())
  const diffMinutes = Math.floor(diffMs / 60_000)

  if (diffMinutes < 1) return texts.common.justNow
  if (diffMinutes < 60) {
    return texts.common.minutesAgo.replace('{count}', toPersianDigits(String(diffMinutes)))
  }

  const diffHours = Math.floor(diffMinutes / 60)

  if (diffHours < 24) {
    return texts.common.hoursAgo.replace('{count}', toPersianDigits(String(diffHours)))
  }

  const diffDays = Math.floor(diffHours / 24)

  if (diffDays < 7) {
    return texts.common.daysAgo.replace('{count}', toPersianDigits(String(diffDays)))
  }

  const diffWeeks = Math.floor(diffDays / 7)

  if (diffWeeks < 5) {
    return texts.common.weeksAgo.replace('{count}', toPersianDigits(String(diffWeeks)))
  }

  return formatPersianDate(date, { dateStyle: 'medium' })
}