export interface TwitchTarget {
  kind: 'video' | 'channel' | 'clip'
  id: string
}

// Twitch-Pfade, die keine Kanalnamen sind
const RESERVED_PATHS = new Set([
  'directory', 'downloads', 'drops', 'friends', 'inventory', 'jobs', 'messages',
  'moderator', 'notifications', 'p', 'payments', 'popout', 'products', 'settings',
  'subscriptions', 'turbo', 'videos', 'wallet', 'broadcast', 'search', 'activate',
])

export function getTwitchTarget(href: string): TwitchTarget | null {
  try {
    const url = new URL(href)
    const host = url.hostname.replace(/^(www\.|m\.)/, '')

    // clips.twitch.tv/{slug}
    if (host === 'clips.twitch.tv') {
      const slug = url.pathname.split('/').filter(Boolean)[0]
      return slug ? { kind: 'clip', id: slug } : null
    }

    if (host !== 'twitch.tv') return null
    const seg = url.pathname.split('/').filter(Boolean)

    // twitch.tv/videos/{id}
    if (seg[0] === 'videos' && /^\d+$/.test(seg[1] ?? '')) {
      return { kind: 'video', id: seg[1]! }
    }
    // twitch.tv/{channel}/clip/{slug}
    if (seg.length === 3 && seg[1] === 'clip') {
      return { kind: 'clip', id: seg[2]! }
    }
    // twitch.tv/{channel}
    if (seg.length === 1 && /^[\w]{2,25}$/.test(seg[0]!) && !RESERVED_PATHS.has(seg[0]!.toLowerCase())) {
      return { kind: 'channel', id: seg[0]! }
    }
    return null
  }
  catch {
    return null
  }
}

export function serializeTwitchTarget(t: TwitchTarget | null): string | null {
  return t ? `${t.kind}:${t.id}` : null
}

export function parseTwitchTarget(value: string): TwitchTarget | null {
  const i = value.indexOf(':')
  if (i < 0) return null
  const kind = value.slice(0, i)
  const id = value.slice(i + 1)
  if ((kind !== 'video' && kind !== 'channel' && kind !== 'clip') || !id) return null
  return { kind, id }
}

// Twitch-Embeds brauchen zwingend ?parent=<Hostname der einbettenden Seite>
export function twitchEmbedUrl(target: TwitchTarget | string | null, parent: string): string | null {
  const t = typeof target === 'string' ? parseTwitchTarget(target) : target
  if (!t) return null
  const p = `parent=${encodeURIComponent(parent)}`
  const id = encodeURIComponent(t.id)
  if (t.kind === 'clip') return `https://clips.twitch.tv/embed?clip=${id}&${p}&autoplay=false`
  if (t.kind === 'channel') return `https://player.twitch.tv/?channel=${id}&${p}`
  return `https://player.twitch.tv/?video=${id}&${p}&autoplay=false`
}