export interface AppNotification {
  id: number
  uploadId: string
  commentId: number
  isRead: boolean
  isMention: boolean
  createdAt: string
  actorName: string
  actorColor: string | null
  content: string
  uploadType: 'image' | 'video' | 'audio' | 'youtube' | 'twitch' | 'link'
  url: string
  thumbUrl: string | null
}

export function useNotifications() {
  const notifications = useState<AppNotification[]>('notifications:list', () => [])
  const unreadCount = useState<number>('notifications:unread', () => 0)

  const unreadUploadIds = computed(() =>
    new Set(notifications.value.filter(n => !n.isRead).map(n => n.uploadId)),
  )

  async function fetchAll() {
    const data = await $fetch<{ notifications: AppNotification[], unreadCount: number }>('/api/notifications')
    notifications.value = data.notifications
    unreadCount.value = data.unreadCount
  }

  function addLive(notification: AppNotification, count?: number) {
    const existing = notifications.value.some(n => n.uploadId === notification.uploadId && !n.isRead)
    notifications.value = [notification, ...notifications.value.filter(n => n.uploadId !== notification.uploadId)].slice(0, 30)
    unreadCount.value = count ?? (unreadCount.value + (existing ? 0 : 1))
  }

  async function markAllRead() {
    if (!unreadCount.value) return
    unreadCount.value = 0
    notifications.value = notifications.value.map(n => ({ ...n, isRead: true }))
    await $fetch('/api/notifications/read', { method: 'POST' })
  }

  async function markRead(id: number) {
    const target = notifications.value.find(n => n.id === id)
    notifications.value = notifications.value.filter(n => target ? n.uploadId !== target.uploadId : n.id !== id)
    if (target && !target.isRead) {
      unreadCount.value = Math.max(0, unreadCount.value - 1)
    }
    await $fetch(`/api/notifications/${id}/read`, { method: 'POST' })
  }

  function reset() {
    notifications.value = []
    unreadCount.value = 0
  }

  return { notifications, unreadCount, unreadUploadIds, fetchAll, addLive, markAllRead, markRead, reset }
}