import React, { useContext, useState, useRef, useEffect } from 'react'
import useSWR from 'swr'

import { WizardContext } from '../context/wizardStore'

import Form from 'react-bootstrap/Form'
import Button from 'react-bootstrap/Button'

import { DateUtils } from 'react-day-picker'
import DayPickerInput from 'react-day-picker/DayPickerInput'

import Required from './required'
import { dateFormat } from '../helpers/date'
import { getNextSmaller, getNextBigger } from '../helpers/array'

const fetcher = (path) => fetch(path).then((r) => r.json())

export default function DateSelect() {
  const { state, onChange } = useContext(WizardContext)
  const [range, setRange] = useState({ form: null, to: null })
  const { data: daysBooked, error: fetchBookedOnError } = useSWR(
    '/api/daysbooked',
    fetcher
  )
  const prevBookedDay = getNextSmaller(
    daysBooked,
    dateFormat(range.from || range.to)
  )
  const nextBookedDay = getNextBigger(
    daysBooked,
    dateFormat(range.from || range.to)
  )

  const fromRef = useRef()
  const toRef = useRef()

  function dayBooked(day) {
    return daysBooked && daysBooked.includes(dateFormat(day))
  }

  function dayDisabled(day) {
    return (
      DateUtils.isPastDay(day) ||
      dayBooked(day) ||
      (prevBookedDay && day < new Date(prevBookedDay)) ||
      (nextBookedDay && day > new Date(nextBookedDay))
    )
  }

  function parseDate(value) {
    return new Date(value)
  }

  useEffect(() => {
    toRef.current?.getInput().focus()
  }, [range.from])

  const { from, to } = range
  const disabledDays = [dayDisabled]
  const modifiers = {
    dayBooked,
    start: from,
    end: to,
  }

  if (fetchBookedOnError) {
    return (
      <div>
        Entschuldige, aber die Buchungszeiten konnten nicht geladen werden.
        Versuchen Sie es später nochmals.
      </div>
    )
  }

  return (
    <Form.Group>
      <Form.Label component="legend" style={{ display: 'block' }}>
        Datum <Required />
      </Form.Label>
      <Form.Group>
        <DayPickerInput
          ref={fromRef}
          component={Form.Control}
          value={from}
          placeholder="Von"
          formatDate={dateFormat}
          parseDate={parseDate}
          dayPickerProps={{
            className: 'Selectable',
            selectedDays: [from, { from, to }],
            disabledDays,
            modifiers,
            numberOfMonths: 1,
          }}
          onDayChange={(from) => setRange({ ...range, from })}
        />
        <Form.Label className="px-2">bis</Form.Label>
        <DayPickerInput
          ref={toRef}
          component={Form.Control}
          inputProps={{ disabled: !from }}
          value={to}
          placeholder="Bis"
          formatDate={dateFormat}
          parseDate={parseDate}
          dayPickerProps={{
            className: 'Selectable',
            selectedDays: [from, { from, to }],
            disabledDays,
            modifiers,
            numberOfMonths: 1,
            month: from,
            fromMonth: from,
          }}
          onDayChange={(to) => setRange({ ...range, to })}
        />
        <Button
          className="ml-2"
          variant="outline-secondary"
          onClick={() => setRange({})}
        >
          Zurücksetzen
        </Button>
      </Form.Group>
    </Form.Group>
  )
}