import React, { useState, useRef, useEffect } from 'react'
import cx from 'classnames'
import { useRouter } from 'next/router'
import { ThumbsdownIcon, ThumbsupIcon } from '@primer/octicons-react'

import { useTranslation } from '@/languages/components/useTranslation'
import { Link } from '@/frame/components/Link'
import { sendEvent } from '@/events/components/events'
import { EventType } from '../types'

import styles from './Survey.module.scss'

enum ViewState {
  START = 'START',
  END = 'END',
}

enum VoteState {
  YES = 'YES',
  NO = 'NO',
}

type EventData = {
  vote: boolean
  token?: string
  comment?: string
  email?: string
}

export const Survey = () => {
  const { asPath, locale } = useRouter()
  const { t } = useTranslation('survey')
  const [state, setState] = useState<ViewState>(ViewState.START)
  const [voteState, setVoteState] = useState<VoteState | null>(null)
  const [isEmailError, setIsEmailError] = useState(false)
  const formRef = useRef<HTMLFormElement>(null)
  const [comment, setComment] = useState('')
  const [email, setEmail] = useState('')
  const [token, setToken] = useState('')

  useEffect(() => {
    // Always reset the form if navigating to a new page because what
    // you might have said or started to say belongs exclusively to
    // to the page you started on.
    setState(ViewState.START)
    setVoteState(null)
  }, [asPath])

  useEffect(() => {
    // After the form is submitted we need to manually set the focus since we
    // remove the form inputs after submit.  The privacy policy link is the
    // next focusable element in the footer so we focus that.
    if (state === ViewState.END) {
      document
        .querySelector<HTMLAnchorElement>(
          `footer a[href="/${locale}/site-policy/privacy-policies/github-privacy-statement"]`,
        )
        ?.focus()
    }
  }, [state])

  function vote(userVote: VoteState) {
    return () => {
      trackEvent(getEventData(userVote === VoteState.YES))
      setVoteState(userVote)
    }
  }

  // Though we set `type="email"` on the email address input which gives us browser
  // validation of the field, that has accessibility issues (e.g. some screen
  // readers won't read the error message) so we need to do manual validation
  // ourselves.
  useEffect(() => {
    const emailRegex = /[^@\s.][^@\s]*@\[?[a-z0-9.-]+\]?\.\[?[a-z0-9.-]+\]?/i
    if (!email.trim() || emailRegex.test(email)) {
      setIsEmailError(false)
    } else {
      setIsEmailError(true)
    }
  }, [email])

  function submit(evt: React.FormEvent) {
    evt.preventDefault()
    if (voteState === null) return

    trackEvent(getEventData(voteState === VoteState.YES))
    completeSurvey()
  }

  function completeSurvey() {
    setState(ViewState.END)
    setIsEmailError(false)
    setComment('')
  }

  function getEventData(voteValue: boolean): EventData {
    return {
      vote: voteValue,
      comment,
      email,
      token,
    }
  }

  return (
    <form
      className={cx(styles.underlineLinks, 'f5')}
      onSubmit={submit}
      ref={formRef}
      data-testid="survey-form"
      aria-live="polite"
    >
      <h3 id="survey-title" className="f4 mb-3">{t`able_to_find`}</h3>

      {/* Honeypot: token isn't a real field */}
      <input
        type="text"
        className="d-none"
        name="survey-token"
        value={token}
        onChange={(event) => setToken(event.target.value)}
      />

      {state !== ViewState.END && (
        <div className="mb-2" role="radiogroup" aria-labelledby="survey-title">
          <input
            className={cx(styles.visuallyHidden, styles.customRadio)}
            id="survey-yes"
            type="radio"
            name="survey-vote"
            value="Y"
            aria-label={t`yes`}
            onChange={vote(VoteState.YES)}
            checked={voteState === VoteState.YES}
          />
          <label
            className={cx(
              'btn mr-1',
              voteState === VoteState.YES && 'color-fg-on-emphasis color-bg-success-emphasis',
            )}
            htmlFor="survey-yes"
          >
            <ThumbsupIcon
              size={16}
              className={voteState === VoteState.YES ? 'color-fg-on-emphasis' : 'color-fg-muted'}
            />{' '}
            {t`yes`}
          </label>
          <input
            className={cx(styles.visuallyHidden, styles.customRadio)}
            id="survey-no"
            type="radio"
            name="survey-vote"
            value="N"
            aria-label={t`no`}
            onChange={vote(VoteState.NO)}
            checked={voteState === VoteState.NO}
          />
          <label
            className={cx(
              'btn',
              voteState === VoteState.NO && 'color-fg-on-emphasis color-bg-danger-emphasis',
            )}
            htmlFor="survey-no"
          >
            <ThumbsdownIcon
              size={16}
              className={voteState === VoteState.NO ? 'color-fg-on-emphasis' : 'color-fg-muted'}
            />{' '}
            {t`no`}
          </label>
        </div>
      )}

      {state === ViewState.START && voteState && (
        <p
          role="status"
          className="color-fg-muted f6 mb-3"
          data-testid="survey-end"
        >{t`feedback`}</p>
      )}

      {state === ViewState.START && voteState && (
        <>
          <p className="mb-3">
            <label className="d-block mb-1 f6" htmlFor="survey-comment">
              <span>{t`additional_feedback`}</span>
            </label>
            <textarea
              className="form-control input-sm width-full"
              name="survey-comment"
              id="survey-comment"
              value={comment}
              onChange={(event) => setComment(event.target.value)}
            ></textarea>
          </p>

          <div className={cx('form-group', isEmailError && email.trim().length > 3 ? 'warn' : '')}>
            <label className="d-block mb-1 f6" htmlFor="survey-email">
              {t`email_label`}
            </label>
            <input
              type="email"
              className="form-control input-sm width-full color-bg-transparent"
              name="survey-email"
              id="survey-email"
              value={email}
              onChange={(event) => setEmail(event.target.value)}
              aria-invalid={isEmailError}
              {...(isEmailError ? { 'aria-describedby': 'email-input-validation' } : {})}
            />
            {isEmailError && email.trim().length > 3 && (
              <p className="note warning" id="email-input-validation">
                {t`email_validation`}
              </p>
            )}
          </div>

          <span
            className="f6 color-fg-muted"
            dangerouslySetInnerHTML={{ __html: t`not_support` }}
          ></span>
          <div className="d-flex flex-justify-end flex-items-center mt-3">
            <button
              type="button"
              className="btn btn-sm btn-invisible mr-3"
              onClick={() => {
                completeSurvey()
              }}
            >
              {t`cancel`}
            </button>
            <button disabled={isEmailError} type="submit" className="btn btn-sm">
              {t`send`}
            </button>
          </div>
        </>
      )}

      {state === ViewState.END && (
        <p role="status" className="color-fg-muted f6" data-testid="survey-end">{t`feedback`}</p>
      )}

      <Link
        className="f6"
        href={`/${locale}/site-policy/privacy-policies/github-privacy-statement`}
        target="_blank"
      >
        {t`privacy_policy`}
      </Link>
    </form>
  )
}

function trackEvent(eventData: EventData) {
  // Nota bene: convert empty strings to undefined
  return sendEvent({
    type: EventType.survey,
    survey_token: eventData.token || undefined, // Honeypot
    survey_vote: eventData.vote,
    survey_comment: eventData.comment || undefined,
    survey_email: eventData.email || undefined,
  })
}