import { isPublicEventSlug } from '@/lib/routing/eventRoute'

export const EVENT_SLUG_MAX_LENGTH = 220
export const EVENT_SLUG_FALLBACK = 'event'

/** Previous wizard default: `event-` + first 8 chars of a UUID. */
const RANDOM_PLACEHOLDER_SLUG = /^event-[0-9a-f]{8}$/i

// Same single-pass map as backend/src/modules/events/event-slug.util.ts.
const PERSIAN_TRANSLIT_FROM = 'ابپتثجچحخدذرزژسشصضطظعغفقکگلمنوهیآأإئءؤةيك '
const PERSIAN_TRANSLIT_TO = 'abptsjchxdzrzjsssztzaqfqkglmnvhyaaaeaotyk-'
const PERSIAN_DIGITS = '۰۱۲۳۴۵۶۷۸۹'

export function slugifyEventTitle(title: string): string {
  const trimmed = title.trim()

  if (!trimmed) return ''

  let withLatinDigits = ''

  for (const char of trimmed) {
    const digit = PERSIAN_DIGITS.indexOf(char)

    withLatinDigits += digit === -1 ? char : String(digit)
  }

  let raw = ''

  for (const char of withLatinDigits) {
    const index = PERSIAN_TRANSLIT_FROM.indexOf(char)

    raw += index === -1 ? char : PERSIAN_TRANSLIT_TO[index]
  }

  const slug = raw
    .toLowerCase()
    .replace(/[^a-z0-9]+/g, '-')
    .replace(/-+/g, '-')
    .replace(/(^-+|-+$)/g, '')
    .slice(0, EVENT_SLUG_MAX_LENGTH)
    .replace(/-+$/g, '')

  if (!slug || !isPublicEventSlug(slug)) return EVENT_SLUG_FALLBACK

  return slug
}

/**
 * True when the slug field should keep tracking the title: empty, leftover
 * random placeholder, or still equal to the slug generated from `title`.
 */
export function shouldAutogenerateEventSlug(currentSlug: string, title: string): boolean {
  const slug = currentSlug.trim()

  if (!slug) return true
  if (RANDOM_PLACEHOLDER_SLUG.test(slug)) return true

  return slug === slugifyEventTitle(title)
}