const request = require('request')
const cheerio = require('cheerio')

/**
 * @typedef lastPost
 * @prop {string} txt post body
 * @prop {string} id post id
 * @prop {string} link post link
 * @prop {string} time timestamp
 */
/**
 * get facebook fan page last post
 * @param {string} pageid facebook fan page id
 * @return {Promise<lastPost>}
 */
const getLastPost = async (pageid = '') => {
  if (typeof pageid !== 'string' || pageid.trim().length === 0) return null
  pageid = pageid.trim()
  console.log('access facebook fan page :::: ' + pageid)
  let page = await new Promise((resolve) => {
    request({
      baseUrl: 'https://www.facebook.com',
      url: `/${encodeURIComponent(pageid)}/posts`,
      method: 'get',
      headers: {
        'User-Agent': 'Mozilla/5.0 (X11; Linux x86_64; rv:62.0) Gecko/20100101 Firefox/62.0'
      }
    }, (err, res, body) => {
      if (err) {
        resolve(null)
        return
      }
      if (body && typeof body !== 'string' && !(body instanceof String)) {
        resolve(null)
        return
      }
      resolve(body)
    })
  })
  if (page === null) return null
  let $ = cheerio.load(page, {
    lowerCaseTags: true,
    lowerCaseAttributeNames: true
  })

  let posts = []

  $('div.userContentWrapper').each((i, el) => {
    let t = cheerio.load(el)
    let timeEl = t('abbr')
    let time = timeEl.attr('data-utime')
    let link = timeEl.parent().attr('href')
    let p = t('div.userContent')
    let txt = p.text() || ''
    let id = p.first().attr('id')

    if (!id) {
      if (/[\?|&]id\=(\d+)/.test(link)) { // eslint-disable-line
        let m = link.match(/[\?|&]story_fbid\=(\d+)/) // eslint-disable-line
        if (m !== null && m.length > 1) {
          id = m[1]
        }
      } else if (/\/posts\/(\d+)/.test(link)) {
        let m = link.match(/\/posts\/(\d+)/)
        if (m !== null && m.length > 1) {
          id = m[1]
        }
      } else if (/\/photos\/.+?\/(\d+)/.test(link)) {
        let m = link.match(/\/photos\/.+?\/(\d+)/)
        if (m !== null && m.length > 1) {
          id = m[1]
        }
      } else if (/\/videos\/(\d+)/.test(link)) {
        let m = link.match(/\/videos\/(\d+)/)
        if (m !== null && m.length > 1) {
          id = m[1]
        }
      }
    }
    // console.log(time, link, txt, id)
    if (!time || !link || !id) return null
    let tmp = {
      txt,
      id,
      link,
      time
    }
    posts.push(tmp)
    el = null
    t = null
  })
  $ = null
  if (posts.length === 0) return null
  posts.sort((a, b) => {
    return b.time - a.time
  })
  let post = posts[0]
  post.link = `https://www.facebook.com/${post.link.replace(/^\//, '')}`
  return post
}

module.exports = {
  getLastPost
}