const connectSession = require('connect-redis')
const rateLimit = require("express-rate-limit")
const validemail = require('email-validator')
const session = require('express-session')
const bodyParser = require('body-parser')
const nodemailer = require('nodemailer')
const nunjucks = require('nunjucks')
const passport = require('passport')
const express = require('express')
const request = require('request')
const sqlite3 = require('sqlite3')
const sqlite = require('sqlite')
const xml2js = require('xml2js')
const crypto = require('crypto')
const WebSocket = require('ws')
const redis = require('redis')
const path = require('path')
const toml = require('toml')
const http = require('http')
const URL = require('url').URL
const fs = require('fs')

require('express-async-errors')

const SessionStore = connectSession(session)

const util = require('util')
const get = util.promisify(request.get)

const dev = process.env.NODE_ENV === 'development'

// Load Configuration
const filename = path.join(__dirname, 'config.toml')

let config
const cache = { _updated: 0, streamers: {}, viewers: {}, live: [] }

try {
  config = toml.parse(fs.readFileSync(filename))
} catch (e) {
  console.error(e)
  process.exit(1)
}

config = Object.assign({
  Streaming: {
    port: '9322',
    database: 'streaming.db',
    streamServer: 'https://tv.icynet.eu/live/',
    serverHost: 'icynet.eu',
    publishAddress: 'rtmp://{host}:1935/hls-live/{streamer}',
    secret: 'changeme'
  },
  Auth: {
    strategy: 'passport-oauth2',
    callbackURL: 'http://localhost:5000/auth/_callback/',
    clientID: '1',
    clientSecret: 'changeme'
  },
  Email: {
    enabled: false,
    from: 'no-reply@icynet.eu',
    host: '',
    port: 587,
    secure: false,
    baseURL: 'http://localhost:9321/',
    auth: {
      user: '',
      pass: '',
    },
    tls: {
      rejectUnauthorized: false,
    },
  }
}, config)

// Constants
const port = parseInt(config.Streaming.port, 10)
const streamServer = config.Streaming.streamServer
const streamServerHost = config.Streaming.serverHost
const streamAppName = streamServer.match(/\/([\w-_]+)\/$/)[1]

// Database
const dbPromise = sqlite.open({
  filename: path.join(process.cwd(), config.Streaming.database),
  driver: sqlite3.cached.Database
})

// Setup server
const app = express()
const server = http.createServer(app)
const wss = new WebSocket.Server({ clientTracking: false, noServer: true })

// Rate limits
const emlLimiter = rateLimit({
  windowMs: 1000 * 60 * 60,
  max: 16,
  message: 'Too many subscription attempts from this IP address. Try again in an hour.'
})

// Authentication
const Strategy = require(config.Auth.strategy)
const strategyConfig = Object.assign({}, config.Auth)
if (!strategyConfig.provider) strategyConfig.provider = strategyConfig.strategy.replace('passport-', '')
passport.use(new Strategy(strategyConfig, function (accessToken, refreshToken, profile, done) {
  process.nextTick(function () {
    return done(null, profile)
  })
}))

// Email
let emailTransport;
if (config.Email.enabled) {
  emailTransport = nodemailer.createTransport({
    ...config.Email,
    pool: true,
  })
}

const notifQueue = []
const notifHistory = {}

function now() {
  return Math.floor(Date.now() / 1000)
}

function key() {
  return crypto.randomBytes(32).toString('hex').slice(0, 32)
}

async function sendEmailPush(channel) {
  if (!emailTransport) {
    return
  }

  // Don't re-send notifications within an hour if a channel happens to go live again
  if (notifHistory[channel] && notifHistory[channel] > now() - 3600) {
    return
  }
  notifHistory[channel] = now()

  const db = await dbPromise
  const data = await db.get('SELECT name FROM channels WHERE id = ?', channel)
  if (!data) {
    return;
  }

  const subs = await db.all('SELECT email,unsubkey FROM emailsub WHERE uuid = ? AND active = 1', channel);
  for (const sub of subs) {
    const unsubURL = config.Email.baseURL + 'unsubscribe/' + sub.unsubkey
    const watchURL = config.Email.baseURL + 'watch/' + data.name
    emailTransport.sendMail({
      from: config.Email.from,
      to: sub.email,
      subject: `🔴 ${data.name} has gone LIVE on IcyTV!`,
      text: `${data.name} has gone LIVE on IcyTV!\nWatch now: ${watchURL}`
        + `\n\nUnsubscribe from ${data.name}: ${unsubURL}`,
      html: `<h1>${data.name} has gone LIVE on IcyTV!</h1><p>Watch now: `
        + `<a href="${watchURL}" target="_blank" rel="nofollow">${watchURL}</a>`
        + `</p><br/><p>Unsubscribe from ${data.name}: `
        + `<a href="${unsubURL}" target="_blank" rel="nofollow">${unsubURL}</a></p>`,
    }).catch(e => console.error(e))
  }
}

async function subscribeToChannel(channel, email) {
  if (!emailTransport) {
    return
  }

  const db = await dbPromise
  const data = await db.get('SELECT id FROM channels WHERE name = ?', channel)
  if (!data) {
    throw new Error('Invalid channel!')
  }

  const exists = await db.get('SELECT * FROM emailsub WHERE email = ? AND uuid = ?', [email, data.id])
  if (exists) {
    throw new Error('A subscription already exists for this email address.')
  }

  // New verification email
  const activateKey = key()
  const unsubKey = key()
  const activateURL = config.Email.baseURL + 'email/' + activateKey
  await db.run('INSERT INTO emailsub (unsubkey, activatekey, email, uuid, active, created_at) VALUES '
    + '(?, ?, ?, ?, 0, ?)', [unsubKey, activateKey, email, data.id, now()])

  await emailTransport.sendMail({
    from: config.Email.from,
    to: email,
    subject: `Confirm IcyTV subscription to channel ${channel}`,
    text: `Confirm your subscription\n\nClick here to subscribe to ${channel}: ${activateURL} `
      + `\n\nIf you did not subscribe to ${channel} on IcyTV, please ignore this email `
      + `\nand no further action is required on your part. If these emails persist, please `
      + `\ncontact us via abuse@icynet.eu and we'll be sure to help you.`,
    html: `<h1>Confirm your subscription</h1><p>Click here to subscribe to ${channel}: `
      + `<a href="${activateURL}" target="_blank" rel="nofollow">${activateURL}</a>`
      + `</p><br/><p>If you did not subscribe to ${channel} on IcyTV, please ignore this email `
      + `and no further action is required on your part. If these emails persist, please contact us via `
      + `<a href="mailto:abuse@icynet.eu">abuse@icynet.eu</a> and we'll be sure to help you.</p>`,
  })
}

async function unsubscribe(key) {
  const db = await dbPromise
  await db.run('DELETE FROM emailsub WHERE unsubkey = ?', key)
}

async function activateSubscription(key) {
  const db = await dbPromise
  await db.run('UPDATE emailsub SET active = 1 WHERE activatekey = ?', key)
}

passport.serializeUser(function (user, done) {
  done(null, user)
})

passport.deserializeUser(function (user, done) {
  done(null, user)
})

app.enable('trust proxy', 1)

app.use(bodyParser.urlencoded({ extended: false }))
app.use(bodyParser.json())

app.disable('x-powered-by')

nunjucks.configure('templates', {
  autoescape: true,
  express: app
})

const sessionParser = session({
  key: 'Streamserver Session',
  secret: config.Streaming.secret,
  resave: false,
  saveUninitialized: true,
  store: new SessionStore({ client: redis.createClient() }),
  cookie: {
    secure: !dev,
    maxAge: 2678400000 // 1 month
  }
})

app.use(sessionParser)

app.use(passport.initialize())
app.use(passport.session())

app.use((req, res, next) => {
  if (!req.session.csrf) {
    req.session.csrf = key()
  }
  next()
})

// Parse stream metrics from the stat.xml file
async function pullMetrics (uuid) {
  const statPath = streamServer + 'stat'
  if (!cache.stats || cache._updated < Date.now() - 5000) {
    const { body } = await get(statPath)
    const rip = await xml2js.parseStringPromise(body)
    if (!rip.rtmp.server) throw new Error('Invalid response from server.')

    // Autofind the correct server
    const rtmpserver = rip.rtmp.server[0].application
    let rtmpapp
    for (const i in rtmpserver) {
      if (rtmpserver[i].name[0] !== streamAppName) continue
      rtmpapp = rtmpserver[i]
    }

    if (!rtmpapp) throw new Error('Invalid response from server.')

    cache.stats = rtmpapp.live
    cache._updated = Date.now()
  }

  // Extract applicable stream data
  let forUser
  for (const i in cache.stats) {
    if (!cache.stats[i].stream) continue
    if (cache.stats[i].stream[0].name[0] !== uuid) continue
    forUser = cache.stats[i].stream[0]
  }

  if (!forUser) return null

  // Generic data object
  const data = {
    time: forUser.time[0],
    bytes: forUser.bytes_in[0],
    video: null,
    audio: null
  }

  // Add video metadata, if applicable
  if (forUser.meta[0].video[0] !== '') {
    data.video = {
      width: forUser.meta[0].video[0].width[0],
      height: forUser.meta[0].video[0].height[0],
      frame_rate: forUser.meta[0].video[0].frame_rate[0],
      codec: forUser.meta[0].video[0].codec[0]
    }
  }

  // Add audio metadata, if applicable
  if (forUser.meta[0].audio[0] !== '') {
    data.audio = {
      sample_rate: forUser.meta[0].audio[0].sample_rate[0],
      channels: forUser.meta[0].audio[0].channels[0],
      codec: forUser.meta[0].audio[0].codec[0]
    }
  }

  return data
}

// Handle requests from nginx-rtmp-module

app.post('/publish', async (req, res) => {
  if (!req.body.name) throw new Error('Invalid request.')
  const db = await dbPromise

  // Validate stream key
  const streamer = await db.get('SELECT * FROM channels WHERE key=?', req.body.name)

  if (!streamer) throw new Error('Invalid stream key.')
  console.log('=> Streamer %s has started streaming!', streamer.name)

  // Generate real publish address for the server
  const publishAddress = config.Streaming.publishAddress
    .replace('{streamer}', streamer.name)
    .replace('{host}', '127.0.0.1')

  // Set channel streaming status
  db.run('UPDATE channels SET live_at=? WHERE id=?', Date.now(), streamer.id)
  cache.live.push(streamer.name)

  // Send notifications
  if (!notifQueue.includes(streamer.id)) {
    notifQueue.push(streamer.id)
  }

  // Redirect the streaming server to the target
  res.set('Location', publishAddress)
  res.status(302)
  res.end()
})

app.post('/publish_done', async (req, res) => {
  if (!req.body.name) throw new Error('Invalid request.')

  const db = await dbPromise
  const chan = await db.get('SELECT * FROM channels WHERE key = ?', req.body.name)
  console.log('<= Streamer %s has stopped streaming!', chan.name)

  try { delete cache.viewers[chan.name] } catch (e) {}
  if (cache.live.indexOf(chan.name) !== -1) cache.live.splice(cache.live.indexOf(chan.name), 1)

  db.run('UPDATE channels SET live_at=NULL, last_stream=? WHERE key=?', Date.now(), chan.key)

  res.send('OK')
})

// Front-end server
// OAuth2 authenticator
app.get('/login', passport.authenticate(strategyConfig.provider, Object.assign({}, strategyConfig.authOptions || {})))

app.get('/auth/_callback', passport.authenticate(strategyConfig.provider, { failureRedirect: '/' }), async (req, res) => {
  dev && console.log(req.user.username, 'logged in')
  // Get user from database
  const db = await dbPromise
  const user = await db.get('SELECT * FROM signed_users WHERE uuid=?', req.user.uuid)
  if (!user) {
    await db.run('INSERT INTO signed_users (uuid,name) VALUES (?,?)', req.user.uuid, req.user.username)
  }

  // Lets see if this user is a streamer
  const streamer = await db.get('SELECT * FROM channels WHERE user_uuid = ?', req.user.uuid)
  if (streamer) cache.streamers[req.user.uuid] = streamer

  res.redirect('/')
})

app.get('/logout', (req, res) => {
  req.logout()
  res.redirect('/')
})

function authed (req, res, next) {
  if (req.isAuthenticated() && req.isStreamer) return next()
  res.jsonp({ error: 'Unauthorized' })
}

// Views

app.use('/dist', express.static(path.join(__dirname, 'dist'), { maxAge: dev ? 0 : 2678400000 }))
app.use(async function (req, res, next) {
  req.isStreamer = false
  if (!req.isAuthenticated()) return next()

  res.locals.user = req.user

  if (!cache.streamers[req.user.uuid]) {
    const db = await dbPromise
    const streamer = await db.get('SELECT * FROM channels WHERE user_uuid = ?', req.user.uuid)
    if (streamer) cache.streamers[req.user.uuid] = streamer
  }

  if (cache.streamers[req.user.uuid]) {
    req.isStreamer = true
    return next()
  }

  next()
})

// Index
app.get('/', (req, res) => {
  res.render('index.html', { streamer: req.isStreamer })
})

// Dashboard
app.get('/dashboard', authed, (req, res) => {
  const stream = cache.streamers[req.user.uuid]
  res.render('dashboard.html', { server: 'rtmp://' + streamServerHost + '/live/' })
})

// Stats
app.get('/dashboard/stats', authed, async (req, res) => {
  const stream = cache.streamers[req.user.uuid]
  let data

  try {
    data = await pullMetrics(stream.key)
  } catch (e) {
    return res.jsonp({ error: e.message })
  }

  if (!data) return res.jsonp({ error: 'No data was returned.' })
  res.jsonp(data)
})

// Data
app.get('/dashboard/data', authed, async (req, res) => {
  const stream = cache.streamers[req.user.uuid]
  let data

  const db = await dbPromise

  try {
    data = await db.get('SELECT * FROM channels WHERE key=?', stream.key)
  } catch (e) {
    return res.jsonp({ error: 'Unauthorized' })
  }

  if (!data) return res.jsonp({ error: 'Unauthorized' })

  res.jsonp({
    name: data.name,
    key: stream.key,
    uuid: req.user.uuid,
    live: data.live_at != null,
    live_at: new Date(parseInt(data.live_at, 10)),
    last_stream: new Date(parseInt(data.last_stream, 10))
  })
})

// Get links
app.get('/dashboard/link', authed, async (req, res) => {
  const user = req.user.uuid

  const db = await dbPromise
  const links = await db.all('SELECT * FROM link WHERE uuid = ?', user)

  res.jsonp(links)
})

// Add link URL
app.post('/dashboard/link', authed, async (req, res) => {
  const user = req.user.uuid
  const name = req.body.name
  const url = req.body.url

  if (name == null || url == null) return res.jsonp({ error: 'Missing parameters!' })
  if (name.length > 120) return res.jsonp({ error: 'Only 120 characters are allowed in the name.' })
  if (name.length < 3) return res.jsonp({ error: 'Minimum name length is 3 characters.' })
  if (name.indexOf('<') !== -1 || name.indexOf('>') !== -1 ||
    url.indexOf('<') !== -1 || url.indexOf('>') !== -1) return res.jsonp({ error: 'HTML tags are forbidden!' })

  // Validate URL
  const a = new URL(url)
  if (a.protocol === '' || a.host === '') return res.jsonp({ error: 'Invalid URL!' })

  // Checks
  const db = await dbPromise
  const links = await db.all('SELECT * FROM link WHERE uuid = ?', user)
  if (links.length > 10) return res.jsonp({ error: 'You can currently only add up to 10 links!' })

  const link = await db.get('SELECT * FROM link WHERE url = ? AND uuid = ?', url, user)
  if (link) return res.jsonp({ error: 'This URL already exists!' })

  // Add
  await db.run('INSERT INTO link (name,url,uuid) VALUES (?,?,?)', name, url, user)
  res.jsonp({ success: true })
})

// Remove link URL
app.post('/dashboard/link/delete', authed, async (req, res) => {
  const user = req.user.uuid

  if (req.body.name == null && req.body.url == null) return res.jsonp({ error: 'Missing parameters!' })

  // Check
  const db = await dbPromise
  let link = await db.get('SELECT * FROM link WHERE url = ? AND uuid = ?', req.body.url, user)
  if (!link) {
    link = await db.get('SELECT * FROM link WHERE name = ? AND uuid = ?', req.body.name, user)
  }

  if (!link) return res.jsonp({ error: 'Invalid link parameter!' })

  // Delete
  await db.run('DELETE FROM link WHERE id = ?', link.id)
  res.jsonp({ success: true })
})

// Player
app.get('/watch/:name', (req, res) => {
  res.render('player.html', {
    name: req.params.name,
    server: streamServer,
    csrf: req.session.csrf,
    email: emailTransport != null,
  })
})

app.get('/player/:name', (req, res) => {
  res.redirect('/watch/' + req.params.name)
})

// Public data
app.get('/api/channel/:name', async (req, res) => {
  const name = req.params.name
  const db = await dbPromise
  const data = await db.get('SELECT user_uuid,name,live_at,last_stream,chat_channel FROM channels WHERE name=?', name)
  if (!data) return res.jsonp({ error: 'No such channel!' })
  const links = await db.all('SELECT name,url FROM link WHERE uuid = ?', data.user_uuid)

  delete data.user_uuid
  data.live = data.live_at != null
  data.live_at = new Date(parseInt(data.live_at, 10))
  data.last_stream = new Date(parseInt(data.last_stream, 10))
  data.links = links || []
  data.viewers = Object.keys(cache.viewers[name] || {}).length
  data.source = streamServer + name + '.m3u8'

  res.jsonp(data)
})

app.post('/api/email/:channel', emlLimiter, async (req, res) => {
  if (!emailTransport) {
    return res.json({ message: 'Email transport is disabled.' })
  }

  const csrf = req.body.csrf
  if (!csrf || !req.session.csrf || req.session.csrf !== csrf) {
    return res.status(400).json({error: true, message: 'Illegal request!'})
  }

  const email = req.body.email
  if (!email || !validemail.validate(email)) {
    return res.status(400).json({error: true, message: 'Invalid email address!'})
  }

  try {
    await subscribeToChannel(req.params.channel, email)
  } catch (e) {
    return res.status(400).json({error: true, message: e.message})
  }
  res.json({ message: 'Confirmation email has been sent!' })
})

app.get('/email/:key', async (req, res) => {
  if (!emailTransport) {
    return res.redirect('/?activated=false')
  }
  await activateSubscription(req.params.key)
  res.redirect('/?activated=true')
})

app.get('/unsubscribe/:key', async (req, res) => {
  if (!emailTransport) {
    return res.redirect('/?unsubscribe=false')
  }
  await unsubscribe(req.params.key)
  res.redirect('/?unsubscribe=true')
})

// Error handler
app.use((error, req, res, next) => {
  if (dev) console.error(error.stack)
  res.send(error.message)
})

// Socket Server
wss.on('connection', (ws, request, client) => {
  let userId = request.session.id
  let username = 'A Friendly Guest'
  const myChannels = []

  if (request.user) {
    userId = request.user.uuid
    username = request.user.username
  }

  dev && console.log(userId, 'connected')
  ws.on('message', (msg) => {
    dev && console.log(userId, 'said', msg)
    const is = msg.toString().trim().split(' ')
    const chan = is[1]
    if (!chan) return
    switch (is[0]) {
      case 'watch':
        dev && console.log('adding watcher', userId, 'to channel', chan)
        if (cache.live.indexOf(chan) !== -1) {
          if (!cache.viewers[chan]) cache.viewers[chan] = {}
          cache.viewers[chan][userId] = username
          if (myChannels.indexOf(chan) === -1) myChannels.push(chan)
        }
        break
      case 'stop':
        dev && console.log('removing watcher', userId, 'from channel', chan)
        if (cache.live.indexOf(chan) !== -1) {
          if (cache.viewers[chan] && cache.viewers[chan][userId]) delete cache.viewers[chan][userId]
          if (myChannels.indexOf(chan) !== -1) myChannels.splice(myChannels.indexOf(chan), 1)
        }
        break
      case 'viewers':
        if (cache.viewers[chan] != null) ws.send('viewlist ' + Object.values(cache.viewers[chan]).join(','))
        break
    }
  })

  ws.on('close', () => {
    dev && console.log(userId, 'disconnected')
    for (const i in myChannels) {
      const chan = myChannels[i]
      const viewers = cache.viewers[chan]
      if (viewers && viewers[userId]) delete cache.viewers[chan][userId]
    }
  })

  ws.on('error', (e) => {
    dev && console.error('Socket error:', e)
  })
})

// Handle upgrade, parse included session
server.on('upgrade', (request, socket, head) => {
  sessionParser(request, {}, () => {
    if (!request.session || !request.session.id) return socket.destroy()
    if (request.session && request.session.passport) {
      request.user = request.session.passport.user
    }

    wss.handleUpgrade(request, socket, head, function (ws) {
      wss.emit('connection', ws, request)
    })
  })
})

// Stream start notifications pump
function notify() {
  const channel = notifQueue.pop()
  if (channel) {
    sendEmailPush(channel).catch(e => console.error(e))
  }
  setTimeout(notify, notifQueue.length ? 1000 : 5000)
}

// Start server
const host = dev ? '0.0.0.0' : '127.0.0.1'
server.listen(port, host, () => {
  // Get currently live channels, for example, when server restarted while someone was live
  (async function () {
    const db = await dbPromise
    await db.migrate()

    const allLive = await db.all('SELECT name FROM channels WHERE live_at IS NOT NULL')

    for (const i in allLive) {
      cache.live.push(allLive[i].name)
    }

    console.log(`=> Found ${cache.live.length} channels still live`)
  })().catch(e => console.error(e.stack))

  console.log('Listening on %s:%d', host, port)
  console.log('Authentication module: %s (%s)', strategyConfig.strategy, strategyConfig.provider)

  notify()
})