import React, { useState, useEffect } from 'react'
import fetch from 'unfetch'

import SubjectView from '../components/subjectView'
import QuestionView from '../components/questionView'
import LoadingIndicator from '../components/LoadingIndicator'

import styles from './index.module.css'
import constants from '../constants.json'

const views = {
  subject: 'SUBJECT',
  question: 'QUESTION'
}

// TODO:
// Add question on subjects view
// question.data editor
// save data to server / load it from there
//   save: save question count and subj count
//   save deleted/removed questions ?
// edit \n-s in questions / answers
// Load data: generate key / save keys as cookie and list?
// Upload data: save to new / save to same as loaded

export default function Index (props) {
  const [data, setData] = useState(null)
  const [view, setView] = useState(views.subject)
  const [error, setError] = useState(null)

  const setIndexes = (d) => {
    d.Subjects.forEach((subj, i) => {
      subj.ind = i
      subj.Questions.forEach((question, j) => {
        question.ind = j
      })
    })
    return d
  }

  useEffect(() => {
    console.info('Fetching data')
    fetch(`${constants.apiUrl}data.json`)
      .then((resp) => {
        if (resp && resp.ok) {
          return resp.json()
        } else {
          console.error('Error while fetching data')
          setError('Error while fetching data')
        }
      })
      .then((resp) => {
        if (data) {
          console.warn('Tried to refetch data when it was still set!')
        } else {
          setData(setIndexes(resp))
        }
      })
      .catch((e) => {
        console.log(e)
        console.error('Error while fetching data')
        setError('Error while fetching data')
      })
  }, [])

  if (error) {
    return (
      <div>
        {error}
      </div>
    )
  }

  const deleteQuestion = (subjInd, questionInd) => {
    data.Subjects[subjInd].Questions.splice(questionInd, 1)

    setData({
      ...setIndexes(data)
    })
  }

  const onChange = (subjInd, questionInd, newVal) => {
    data.Subjects[subjInd].Questions[questionInd] = newVal
    setData({
      ...data
    })
  }

  const renderView = () => {
    if (view === views.subject) {
      return (
        <SubjectView
          onChange={onChange}
          data={data}
          deleteQuestion={deleteQuestion}
        />
      )
    } else if (view === views.question) {
      return (
        <QuestionView
          onChange={onChange}
          data={data}
          deleteQuestion={deleteQuestion}
        />
      )
    } else {
      return (
        <div>
          No view!
        </div>
      )
    }
  }

  const downloadFile = async (data) => {
    const json = JSON.stringify(data)
    const blob = new Blob([json], { type: 'application/json' }) // eslint-disable-line
    const href = await URL.createObjectURL(blob)
    const link = document.createElement('a')
    link.href = href
    link.download = 'data.json'
    document.body.appendChild(link)
    link.click()
    document.body.removeChild(link)
  }

  if (!data) {
    return (
      <LoadingIndicator />
    )
  }

  return (
    <div>
      <div className={styles.optionsButtonContainer}>
        <span
          onClick={() => {

          }}
        >
          Load data
        </span>
        <span
          onClick={() => {

          }}
        >
          Upload data
        </span>
        <span
          onClick={() => {
            downloadFile(data)
          }}
        >
          Download data
        </span>
      </div>
      <div className={styles.viewButtonContainer}>
        <span
          onClick={() => { setView(views.subject) }}>
            Subject view
        </span>
        <span
          onClick={() => { setView(views.question) }}>
            Question view
        </span>
      </div>
      {renderView()}
    </div>
  )
}