import { useState, useEffect, useRef, useCallback } from 'react'
import Link from 'next/link'
import HeadTag from '../../components/HeadTag'
import Loader from '../../components/Loader'
import api from '../../utils/api'
import '../../public/css/pages/users.css'
import { API_URL } from '../../utils/config/config'

const Users = () => {
  let pageUsers = 1

  const [inputSearch, setInputSearch] = useState('')
  const [usersData, setUsersData] = useState({ totalItems: 0, hasMore: true, rows: [] })
  const [isLoadingUsers, setLoadingUsers] = useState(true)

  // Récupère les users si la recherche change
  useEffect(() => {
    pageUsers = 1
    getUsersData().then((data) => setUsersData(data))
  }, [inputSearch])

  const getUsersData = async () => {
    setLoadingUsers(true)
    const { data } = await api.get(`/users?page=${pageUsers}&limit=15&search=${inputSearch}`)
    setLoadingUsers(false)
    return data
  }

  const handleSearchChange = (event) => {
    setInputSearch(event.target.value)
  }

  // Permet la pagination au scroll
  const observer = useRef()
  const lastUserCardRef = useCallback((node) => {
    if (isLoadingUsers) return
    if (observer.current) observer.current.disconnect()
    observer.current = new window.IntersectionObserver((entries) => {
      if (entries[0].isIntersecting && usersData.hasMore) {
        pageUsers += 1
        getUsersData().then((data) => {
          setUsersData((oldData) => {
            return {
              totalItems: data.totalItems,
              hasMore: data.hasMore,
              rows: [...oldData.rows, ...data.rows]
            }
          })
        })
      }
    }, { threshold: 1 })
    if (node) observer.current.observe(node)
  }, [isLoadingUsers, usersData.hasMore])

  return (
    <>
      <HeadTag
        title='Utilisateurs'
        description='Liste des utilisateurs.'
      />

      <div className='container text-center'>
        <div className='row justify-content-center'>
          <div className='col-24'>
            <h1 style={{ marginBottom: 0, paddingTop: '20px' }}>Utilisateurs</h1>
            <p style={{ marginTop: '5px' }}>La liste des utilisateurs - Total de {usersData.totalItems} utilisateurs :</p>
          </div>
        </div>

        <div className='Users__search-container row justify-content-center'>
          <input value={inputSearch} onChange={handleSearchChange} type='search' className='Users__form-control Users__search-input' name='search' id='search' placeholder='🔎 Rechercher...' />
        </div>

        <div className='row justify-content-center'>
          {usersData.rows.map((user, index) => {
            // Si c'est le dernier élément
            if (usersData.rows.length === index + 1) {
              return (
                <div ref={lastUserCardRef} key={user.id} className='UserCard col-sm-24 col-md-10 col-xl-7'>
                  <Link href='/users/[name]' as={`/users/${user.name}`}>
                    <div className='UserCard__container'>
                      <img className='UserCard__logo' src={API_URL + user.logo} alt={user.name} />
                      <h2 className='UserCard__name'>{user.name}</h2>
                    </div>
                  </Link>
                </div>
              )
            }
            return (
              <div key={user.id} className='UserCard col-sm-24 col-md-10 col-xl-7'>
                <Link href='/users/[name]' as={`/users/${user.name}`}>
                  <div className='UserCard__container'>
                    <img className='UserCard__logo' src={API_URL + user.logo} alt={user.name} />
                    <h2 className='UserCard__name'>{user.name}</h2>
                  </div>
                </Link>
              </div>
            )
          })}
        </div>

        {isLoadingUsers && <Loader />}
      </div>
    </>
  )
}

export default Users