const http = require('http')
const ical = require('ical')

function createEventEntry (event) {
  const entry = document.createElement('div')
  const formatDate = Intl.DateTimeFormat('fr', { dateStyle: 'long', timeStyle: 'short' }).format
  const header = document.createElement('h3')

  header.textContent = formatDate(event.date) + ' | ' + event.summary

  entry.className = 'event-entry'
  entry.setAttribute('entry-time', event.date.getTime())
  entry.appendChild(header)

  return entry
}

function sortEvents (events) {
  const sorted = []

  /* First extract the events. */
  Object.values(events).forEach(event => {
    if (event.type === 'VEVENT') {
      sorted.push({
        date: event.start,
        location: event.location,
        summary: event.summary
      })
    }
  })

  /* Then sort them out. */
  // TODO: Useless here. Should be done on callbacks below
  return sorted.sort((a, b) => { return a.date < b.date })
}

function loadEvents (cb) {
  http.request({
    //    host: 'www.ti-nuage.fr',
    host: 'test-www.ti-nuage.fr',
    path: '/donnees/calendrier.php'
  }, function (response) {
    let str = ''

    response.on('data', function (chunk) {
      str += chunk
    })

    response.on('end', function () {
      const events = sortEvents(ical.parseICS(str))
      cb(events)
    })
  }).end()
}

module.exports = {

  fill: function (target) {
    loadEvents(events => {
      events.forEach(event => {
        target.appendChild(createEventEntry(event))
      })
    })
  },

  mergeWithNews: function (target) {
    const blogEntries = target.getElementsByClassName('blog-entry')
    const entries = {}

    for (let i = 0; i < blogEntries.length; ++i) {
      const item = blogEntries.item(i)
      entries[item.getAttribute('entry-time')] = item
    }

    loadEvents(events => {
      target.innerHTML = ''

      /* Merge events with blog entries */
      events.forEach(event => {
        entries[event.date.getTime()] = createEventEntry(event)
      })

      /* Sort and only keep entries up to the next 30 days */
      const limitTime = Date.now() + (30 * 24 * 60 * 60 * 1000)
      const times = Object.keys(entries).sort(function (a, b) { return a < b })

      for (let i = times.length; i--;) {
        if (times[i] > limitTime) {
          times.splice(i, 1)
        }
      }

      /* Finally display only the first six entries */
      times.splice(5, times.length)
      times.forEach(time => {
        target.appendChild(entries[time])
      })
    })
  }
}