import { useState, useEffect, useRef, useCallback } from 'react'
import { useRouter } from 'next/router'
import FunctionCard from '../FunctionCard/FunctionCard'
import Loader from '../Loader'
import api from '../../utils/api'
import useAPI from '../../hooks/useAPI'
import './FunctionsList.css'

let pageFunctions = 1
const FunctionsList = props => {
  const { categoryId } = useRouter().query

  // State de recherche et de catégories
  const [, categories] = useAPI('/categories')
  const [inputSearch, setInputSearch] = useState({
    search: '',
    selectedCategory: categoryId || '0'
  })

  // State pour afficher les fonctions
  const [functionsData, setFunctionsData] = useState({
    hasMore: true,
    rows: []
  })
  const [isLoadingFunctions, setLoadingFunctions] = useState(true)

  // Récupère la catégorie avec la query categoryId
  useEffect(() => {
    if (categoryId) {
      handleChange({ target: { name: 'selectedCategory', value: categoryId } })
    }
  }, [categoryId])

  // Récupère les fonctions si la catégorie/recherche change
  useEffect(() => {
    pageFunctions = 1
    getFunctionsData().then(data => setFunctionsData(data))
  }, [inputSearch])

  // Permet la pagination au scroll
  const observer = useRef()
  const lastFunctionCardRef = useCallback(
    node => {
      if (isLoadingFunctions) return
      if (observer.current) observer.current.disconnect()
      observer.current = new window.IntersectionObserver(
        entries => {
          if (entries[0].isIntersecting && functionsData.hasMore) {
            pageFunctions += 1
            getFunctionsData().then(data => {
              setFunctionsData(oldData => {
                return {
                  hasMore: data.hasMore,
                  rows: [...oldData.rows, ...data.rows]
                }
              })
            })
          }
        },
        { threshold: 1 }
      )
      if (node) observer.current.observe(node)
    },
    [isLoadingFunctions, functionsData.hasMore]
  )

  const getFunctionsData = async () => {
    setLoadingFunctions(true)
    const URL = `${
      props.isAdmin ? '/admin/functions' : '/functions'
    }?page=${pageFunctions}&limit=10&categoryId=${
      inputSearch.selectedCategory
    }&search=${inputSearch.search}`
    const { data } = await api.get(URL, {
      headers: {
        ...(props.isAdmin &&
          props.token != null && { Authorization: props.token })
      }
    })
    setLoadingFunctions(false)
    return data
  }

  const handleChange = event => {
    const inputSearchNew = { ...inputSearch }
    inputSearchNew[event.target.name] = event.target.value
    setInputSearch(inputSearchNew)
  }

  return (
    <div className='container text-center'>
      <div className='row justify-content-center'>{props.children}</div>

      <div className='Functions__search-container row justify-content-center'>
        <select
          name='selectedCategory'
          value={inputSearch.selectedCategory}
          onChange={handleChange}
          className='Functions__select Functions__form-control'
        >
          <option value='0'>Toutes catégories</option>
          {categories.map(category => (
            <option
              key={category.id}
              value={category.id}
              className='Functions__select-option'
              style={{ backgroundColor: category.color }}
            >
              {category.name}
            </option>
          ))}
        </select>
        <input
          value={inputSearch.search}
          onChange={handleChange}
          type='search'
          className='Functions__form-control Functions__search-input'
          name='search'
          id='search'
          placeholder='🔎 Rechercher...'
        />
      </div>

      <div className='row justify-content-center'>
        {functionsData.rows.map((currentFunction, index) => {
          // Si c'est le dernier élément
          if (functionsData.rows.length === index + 1) {
            return (
              <FunctionCard
                isAdmin={props.isAdmin}
                key={currentFunction.id}
                ref={lastFunctionCardRef}
                {...currentFunction}
              />
            )
          }
          return (
            <FunctionCard
              isAdmin={props.isAdmin}
              key={currentFunction.id}
              {...currentFunction}
            />
          )
        })}
      </div>
      {isLoadingFunctions && <Loader />}
    </div>
  )
}

export default FunctionsList