import { useState, useEffect, useContext, useRef, useCallback } from 'react'
import Link from 'next/link'
import { UserContext } from '../../../contexts/UserContext'
import CommentCard from '../CommentCard/CommentCard'
import Loader from '../../Loader'
import api from '../../../utils/api'
import './FunctionComments.css'

const FunctionComments = ({ functionId }) => {
  // State pour poster un commentaire
  const { isAuth, user } = useContext(UserContext)
  const [inputState, setInputState] = useState({})

  // State pour afficher les commentaires
  const [commentsData, setCommentsData] = useState({ hasMore: true, rows: [] })
  const [isLoadingComments, setLoadingComments] = useState(true)
  const [pageComments, setPageComments] = useState(1)

  // Récupère les commentaires si la page change
  useEffect(() => {
    getCommentsData().then((data) => setCommentsData({
      hasMore: data.hasMore,
      rows: [...commentsData.rows, ...data.rows]
    }))
  }, [pageComments])

  // Permet la pagination au scroll
  const observer = useRef()
  const lastCommentCardRef = useCallback((node) => {
    if (isLoadingComments) return
    if (observer.current) observer.current.disconnect()
    observer.current = new window.IntersectionObserver((entries) => {
      if (entries[0].isIntersecting && commentsData.hasMore) {
        setPageComments(pageComments + 1)
      }
    }, { threshold: 1 })
    if (node) observer.current.observe(node)
  }, [isLoadingComments, commentsData.hasMore])

  const getCommentsData = async () => {
    setLoadingComments(true)
    const { data } = await api.get(`/comments/${functionId}/?page=${pageComments}&limit=10`)
    setLoadingComments(false)
    return data
  }

  const handleChange = (event) => {
    const inputStateNew = { ...inputState }
    inputStateNew[event.target.name] = event.target.value
    setInputState(inputStateNew)
  }

  const handleSubmit = async (event) => {
    setLoadingComments(true)
    event.preventDefault()
    const token = user.token
    if (isAuth && token != null && inputState.commentPost != null) {
      try {
        const response = await api.post(`/comments/${functionId}`, { message: inputState.commentPost }, { headers: { Authorization: token } })
        const comment = { ...response.data, user: { name: user.name, logo: user.logo } }
        setCommentsData({ hasMore: commentsData.hasMore, rows: [comment, ...commentsData.rows] })
        setInputState({ commentPost: '' })
      } catch { }
    }
    setLoadingComments(false)
  }

  return (
    <>
      <div className='FunctionComments__post container-fluid'>
        <div className='row FunctionComments__row'>
          <div className='col-24'>
            {
              (isAuth)
                ? (
                  <form onSubmit={handleSubmit}>
                    <div className='form-group FunctionComments__post-group'>
                      <label className='form-label' htmlFor='commentPost'>Ajouter un commentaire :</label>
                      <textarea className='FunctionComments__textarea form-control' value={inputState.commentPost} onChange={handleChange} name='commentPost' id='commentPost' placeholder="Idée d'amélioration, avis, remarque, partage d'expérience personnel, ... (Markdown autorisé)" />
                    </div>
                    <div className='form-group' style={{ marginTop: '0.7em' }}>
                      <button type='submit' className='btn btn-dark'>Envoyer</button>
                    </div>
                  </form>
                )
                : (
                  <p className='text-center'>
                                      Vous devez être <Link href='/users/login'><a>connecté</a></Link> pour poster un commentaire.
                  </p>
                )
            }
          </div>
        </div>
      </div>
      <div className='container-fluid'>
        {isLoadingComments &&
          <div className='row justify-content-center'>
            <Loader />
          </div>}
        <div className='row justify-content-center'>
          {commentsData.rows.map((comment, index) => {
            // Si c'est le dernier élément
            if (commentsData.rows.length === index + 1) {
              return <CommentCard key={comment.id} ref={lastCommentCardRef} {...comment} manageComment={{ setCommentsData, commentsData, setLoadingComments }} />
            }
            return <CommentCard key={comment.id} {...comment} manageComment={{ setCommentsData, commentsData, setLoadingComments }} />
          })}
        </div>
      </div>
    </>
  )
}

export default FunctionComments