const fs = require('fs')
const path = require('path')
const c = require('canvas')
const EventEmitter = require('events').EventEmitter

const config = require(path.join(__dirname, 'config.js'))
const request = require(path.join(__dirname, 'request.js'))

function pz (z) {
  if (z < 10) {
    return '0' + z
  }
  return z
}

function dateFormat (date, yr) {
  return (yr ? (date.getDate() + '/' + (date.getMonth() + 1) + '/' + date.getFullYear() + ' ') : '') +
         pz(date.getHours()) + ':' + pz(date.getMinutes())
}

class Drawer {
  constructor () {
    this.canvas = c.createCanvas(config.calendar.schedule.width, config.calendar.schedule.height)
    this.ctx = this.canvas.getContext('2d')
  }

  async draw (cal) {
    let ctx = this.ctx
    let font = config.calendar.schedule.font
    let fontColor = config.calendar.schedule.fontColor

    ctx.clearRect(0, 0, this.canvas.width, this.canvas.height)

    ctx.fillStyle = config.calendar.schedule.background
    ctx.fillRect(5, 5, this.canvas.width - 10, this.canvas.height - 10)

    let added = 0

    for (let i in cal.events) {
      let ev = cal.events[i]

      if (i > 5) break // Can't fit so many on here :P
      if (ev.eventStartTime < Date.now() || ev.eventEndTime < Date.now()) continue

      ctx.fillStyle = fontColor
      let y = (i * 60) + 30

      // Write event name
      let evn = ev.eventName
      if (evn.length > 14) {
        evn = evn.substring(0, 14) + '…'
      }

      ctx.font = '26px ' + font
      ctx.fillText(evn, 10, y)

      // Write event description
      ctx.font = '16px ' + font
      ctx.fillText(ev.description, 10, y + 20)

      // Write event time
      let time = dateFormat(ev.eventStartTime)
      ctx.font = '26px ' + font
      let tlen = ctx.measureText(time).width
      ctx.fillText(time, (this.canvas.width - 10) - tlen, y)

      // Draw line under text
      ctx.strokeStyle = 'rgba(0,0,0,0.5)'
      ctx.beginPath()
      ctx.lineTo(10, y + 20 + 12)
      ctx.lineTo(this.canvas.width - 10, y + 20 + 12)
      ctx.stroke()
      added++
    }

    if (added === 0) {
      ctx.fillStyle = fontColor
      ctx.font = '26px ' + font
      ctx.fillText('No events scheduled.', 10, 35)
    }

    await this.toFile()
  }

  toFile () {
    const out = fs.createWriteStream(path.join(process.env.PWD, 'liq', 'schedule.png'))
    const stream = this.canvas.createPNGStream()
    stream.pipe(out)

    return new Promise((resolve, reject) => {
      out.on('finish', resolve)
      out.on('error', reject)
    })
  }
}

class Calendar extends EventEmitter {
  constructor (conf) {
    super()
    this.events = []

    this.config = conf

    this.drawer = new Drawer()

    this.started = []
    this.timers = { a: null, b: null, c: null }
  }

  update () {
    this.drawer.draw(this).then(() => this.emit('reload'))
  }

  startTimers () {
    // Initial run
    this.calendarFetch().then(
      (e) => this.update(),
      (e) => console.error('Calendar fetch failed!', e.stack)
    )

    // Set timers
    this.timers = {
      a: setInterval(() => this.calendarFetch().catch((e) => console.error('Calendar fetch failed!', e.stack)), this.config.interval * 1000),
      b: setInterval(() => this.runners(), 60 * 1000),
      c: setInterval(() => this.update(), 120 * 1000)
    }
  }

  stopTimers () {
    clearInterval(this.timers.a)
    clearInterval(this.timers.b)
    clearInterval(this.timers.c)
  }

  static sortStartTime (a, b) {
    return a.eventStartTime - b.eventEndTime
  }

  static prettifyEvent (item) {
    let ev = {
      id: item.id,
      htmlLink: item.htmlLink,
      created: new Date(item.created),
      updated: new Date(item.updated),

      title: item.summary.replace(/\n/g, ' '),
      location: item.location,
      description: (item.description || '').replace(/\n/g, ' '),

      start: new Date(item.start.dateTime || item.start.date),
      end: new Date(item.end.dateTime || item.end.date),
      sequence: item.sequence
    }

    ev.length = (ev.end.getTime() - ev.start.getTime()) / 1000

    return ev
  }

  async calendarFetch () {
    const timeFrame = this.config.timeFrame
    const cUrl = this.config.calendar
    const apiKey = this.config.googleKey

    let now = Date.now()
    let url = 'https://www.googleapis.com/calendar/v3/calendars/' + encodeURIComponent(cUrl) + '/events?key=' + apiKey +
          '&timeMin=' + (new Date(now - 10 * 60 * 1000).toISOString()) +
          '&timeMax=' + (new Date(now + timeFrame * 1000).toISOString()) + '&singleEvents=true'

    let data = await request.GET(url)
    data = JSON.parse(data)
    now = Date.now()

    if (!data.items) return
    let results = []

    for (let i = 0; i < data.items.length; i++) {
      let item = Calendar.prettifyEvent(data.items[i])

      if (now < item.end.getTime()) {
        let desc = item.description
        let scr = null
        if (desc.indexOf('$:') !== -1) {
          let a = desc.split('$:')
          desc = a[0].trim()
          scr = a[1].trim()
        }

        results.push({
          id: item.id,
          eventName: item.title,
          eventStartTime: item.start,
          eventEndTime: item.end,
          description: desc,
          descriptor: scr
        })
      }
    }

    console.log(`[schedule] Calendar fetched successfully!`)

    this.events = results.sort(Calendar.sortStartTime)
    this.emit('events', this.events)
  }

  runners () {
    for (let i in this.events) {
      let ev = this.events[i]
      if (!ev.descriptor) continue
      if (ev.eventStartTime < Date.now() && ev.eventEndTime > Date.now()) {
        if (this.started.indexOf(ev.id) !== -1) continue
        console.log(`[schedule] Starting event ${ev.eventName}..`)

        this.started.push(ev.id)
        this.emit('event-start', ev)
      }
    }
  }
}

module.exports = Calendar