'use client'

import { useEffect, useRef } from 'react'
import useSWRInfinite from 'swr/infinite'
import { debounce } from 'lodash-es'
import { useTranslation } from 'react-i18next'
import AppCard from './AppCard'
import NewAppCard from './NewAppCard'
import type { AppListResponse } from '@/models/app'
import { fetchAppList } from '@/service/apps'
import { useSelector } from '@/context/app-context'
import { NEED_REFRESH_APP_LIST_KEY } from '@/config'

const getKey = (pageIndex: number, previousPageData: AppListResponse) => {
  if (!pageIndex || previousPageData.has_more)
    return { url: 'apps', params: { page: pageIndex + 1, limit: 30 } }
  return null
}

const Apps = () => {
  const { t } = useTranslation()
  const { data, isLoading, setSize, mutate } = useSWRInfinite(getKey, fetchAppList, { revalidateFirstPage: false })
  const loadingStateRef = useRef(false)
  const pageContainerRef = useSelector(state => state.pageContainerRef)
  const anchorRef = useRef<HTMLAnchorElement>(null)

  useEffect(() => {
    document.title = `${t('app.title')} -  Dify`
    if (localStorage.getItem(NEED_REFRESH_APP_LIST_KEY) === '1') {
      localStorage.removeItem(NEED_REFRESH_APP_LIST_KEY)
      mutate()
    }
  }, [])

  useEffect(() => {
    loadingStateRef.current = isLoading
  }, [isLoading])

  useEffect(() => {
    const onScroll = debounce(() => {
      if (!loadingStateRef.current) {
        const { scrollTop, clientHeight } = pageContainerRef.current!
        const anchorOffset = anchorRef.current!.offsetTop
        if (anchorOffset - scrollTop - clientHeight < 100)
          setSize(size => size + 1)
      }
    }, 50)

    pageContainerRef.current?.addEventListener('scroll', onScroll)
    return () => pageContainerRef.current?.removeEventListener('scroll', onScroll)
  }, [])

  return (
    <nav className='grid content-start grid-cols-1 gap-4 px-12 pt-8 sm:grid-cols-2 md:grid-cols-3 lg:grid-cols-4 grow shrink-0'>
      {data?.map(({ data: apps }) => apps.map(app => (
        <AppCard key={app.id} app={app} onRefresh={mutate} />
      )))}
      <NewAppCard ref={anchorRef} onSuccess={mutate} />
    </nav>
  )
}

export default Apps
