import m from 'mithril'
import { decode } from 'html-entities'
import twemoji from 'twemoji'
import render from 'mithril-node-render'

import fetchRemote from './fetchRemote'
import { youtubeKey } from './constants'
import { replaceAsync } from './utils'

export async function cleanMarkup (html) {
  if (!html) {
    return Promise.resolve('')
  }

  html = html.normalize('NFC') // normalize unicode

  html = twemoji.parse(html, { ext: '.svg', folder: 'svg' })

  // replace HTML entities with decimal entities
  /* eslint-disable no-control-regex */
  html = html.replace(/\xA0/g, ' ')
  html = html.replace(/ /ig, ' ')
  html = html.replace(/ /ig, ' ')
  html = html.replace(/[\u000C\u007F]/g, '') // remove invalid token (formfeed and u007F)
  /* eslint-enable no-control-regex */

  // fix some tags
  html = html.replace(/<u>/ig, '<span style="text-decoration: underline">')
  html = html.replace(/<\/u>/ig, '</span>')
  html = html.replace(/<s>/ig, '<span style="text-decoration: line-through">')
  html = html.replace(/<\/s>/ig, '</span>')
  html = html.replace(/<span style="font-variant-caps:small-caps">/ig, '<span class="smcp">')

  html = html.replace(/<p>\s*/ig, '<p>')
  html = html.replace(/\s*<\/p>/ig, '</p>')

  // html = fixParagraphIndent(html)

  html = fixDoubleSpacing(html)

  // fix floating blockquote tags
  html = html.replace('<blockquote style="margin: 10px 0px; box-sizing:border-box; -moz-box-sizing:border-box;margin-right:25px; padding: 15px;background-color: #F7F7F7;border: 1px solid #AAA;width: 50%;float:left;box-shadow: 5px 5px 0px #EEE;">', '<blockquote class="left_insert">')
  html = html.replace('<blockquote style="margin: 10px 0px; box-sizing:border-box; -moz-box-sizing:border-box;margin-left:25px; padding: 15px;background-color: #F7F7F7;border: 1px solid #AAA;width: 50%;float:right;box-shadow: 5px 5px 0px #EEE;">', '<blockquote class="right_insert">')

  // add alt attributes to images that don't have them
  const imageEmbed = /<img src="(.*?)" \/>/g
  html = await replaceAsync(html, imageEmbed, (match, src) => render(m('img', { src: decode(src, { level: 'xml' }), alt: 'Image' }), { strict: true }))

  // Fix links pointing to pages on fimfiction
  // Example: <a href="/user/djazz" rel="nofollow">djazz</a>
  const matchLink = /(<a .?href=")(.+?)(".+?>)/g
  html = html.replace(matchLink, (match, head, url, tail) => {
    if (url.substring(0, 1) !== '#' && url.substring(0, 2) !== '//' && url.substring(0, 4) !== 'http' && url.substring(0, 1) === '/') {
      url = 'https://fimfiction.net' + url
    }

    return head + url + tail
  })

  const cache = new Map()
  const query = new Map()
  let completeCount = 0

  const matchYouTube = /<p><a class="embed" href="https:\/\/www\.youtube\.com\/watch\?v=(.*?)">.*?<\/a><\/p>/g
  for (let ma; (ma = matchYouTube.exec(html));) {
    const youtubeId = ma[1].match(/^[^&]+/)[0]
    cache.set(youtubeId, null)
    query.set(decode(ma[1], { level: 'xml' }), youtubeId)
  }

  const matchSoundCloud = /<p><a class="embed" href="(https:\/\/soundcloud\.com\/.*?)">.*?<\/a><\/p>/g
  html = await replaceAsync(html, matchSoundCloud, (match, url) => {
    return render(m('.soundcloud.leftalign', [
      'SoundCloud: ', m('a', { href: decode(url, { level: 'xml' }), rel: 'nofollow' }, url.replace('https://soundcloud.com/', '').replace(/[-_]/g, ' ').replace('/', ' - ').replace(/ {2}/g, ' '))
    ]), { strict: true })
  })

  if (cache.size === 0) {
    return html
  } else {
    return getYoutubeInfo([...cache.keys()])
  }

  async function getYoutubeInfo (ids) {
    return fetchRemote('https://www.googleapis.com/youtube/v3/videos?id=' + ids + '&part=snippet&maxResults=50&key=' + youtubeKey).then(async (raw) => {
      let data = []
      try {
        data = JSON.parse(raw).items
      } catch (e) {
        console.error('Error parsing Youtube API response:', e)
      }
      if (!data) {
        data = []
      }
      data.forEach((video) => {
        console.log('Adding Youtube video ' + video.id + ' to cache')
        cache.set(video.id, video.snippet)
        completeCount++
      })
      if (completeCount === cache.size || data.length === 0) {
        html = await replaceAsync(html, matchYouTube, replaceYouTube)
      }
      return html
    })
  }

  function replaceYouTube (match, queryString) {
    queryString = decode(queryString, { level: 'xml' })
    const youtubeId = query.get(queryString)
    let thumbnail = 'https://img.youtube.com/vi/' + youtubeId + '/hqdefault.jpg'
    const youtubeUrl = 'https://youtube.com/watch?v=' + queryString
    let title = 'Youtube Video'
    let caption = ''
    const data = cache.get(youtubeId)

    if (data) {
      thumbnail = (data.thumbnails.standard || data.thumbnails.high || data.thumbnails.medium || data.thumbnails.default).url
      title = data.title
      caption = data.title + ' on YouTube'
    } else {
      return Promise.resolve(match)
    }
    return render(m('figure.youtube', [
      m('a', { href: youtubeUrl, rel: 'nofollow' },
        m('img', { src: thumbnail, alt: title })
      ),
      m('figcaption', m('a', { href: youtubeUrl, rel: 'nofollow' }, caption))
    ]), { strict: true })
  }
}

export function fixDoubleSpacing (html) {
  // from FimFictionConverter by Nyerguds
  html = html.replace(/\s\s+/g, ' ')
  // push spaces to the closed side of tags
  html = html.replace(/\s+(<[a-z][^>]*>)\s+/g, ' $1')
  html = html.replace(/\s+(<\/[a-z][^>]*>)\s+/g, '$1 ')
  return html
}

export function fixParagraphIndent (html) {
  // from FimFictionConverter by Nyerguds
  const fixIndent = 2
  if (fixIndent > 0) {
    // only trigger indenting when finding as many whitespace characters in a row as indicated by the FixIndent setting.

    // Add indented class, with the search keeping into account that there could be opening tags behind the p tag.
    html = html.replace(new RegExp('<p>((<([^>]+)>)*)\\s{' + fixIndent + '}\\s*', 'g'), '<p class="indented">$1')
    html = html.replace(new RegExp('<p class="(((?!indented)[^>])*)">((<([^>]+)>)*)\\s{' + fixIndent + '}\\s*', 'g'), '<p class="indented $1">$3')

    // Cleanup of remaining start whitespace in already indented paragraphs:
    html = html.replace(/<p([^>]*)>((<[^>]+>)*)\\s+/g, '<p$1>$2')
  }
  return html
}