const express = require('express')
const session = require('express-session')
const bodyParser = require('body-parser')
const request = require('request')
const nunjucks = require('nunjucks')
const sqlite = require('sqlite')
const xml2js = require('xml2js')
const path = require('path')
const toml = require('toml')
const fs = require('fs')
const uuid = require('uuid/v4')

require('express-async-errors')

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

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

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

let config
let cache = { _updated: 0, streamers: {} }

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': {
    'Server': 'http://localhost:8282',
    'Redirect': 'http://localhost:5000/auth/_callback/'
  },
  'OAuth2': {
    'ClientID': '1',
    'ClientSecret': 'changeme'
  }
}, config)

// Constants
const oauthAuth = '{server}/oauth2/authorize?response_type=code&state={state}&redirect_uri={redirect}&client_id={client}&scope=image'
const port = parseInt(config['Streaming']['Port'])
const streamServer = config['Streaming']['StreamServer']
const streamServerHost = config['Streaming']['ServerHost']
const authServer = config['Auth']['Server']
const oauthRedirect = config['Auth']['Redirect']
const oauthId = config['OAuth2']['ClientID'].toString()
const oauthSecret = config['OAuth2']['ClientSecret']
const streamAppName = streamServer.match(/\/([\w-_]+)\/$/)[1]

function teval (str, obj) {
  let res = str + ''
  for (let key in obj) {
    if (res.indexOf('{' + key + '}') === -1) continue
    res = res.replace('{' + key + '}', obj[key])
  }
  return res
}

// Database
const dbPromise = Promise.resolve()
  .then(() => sqlite.open(path.join(process.cwd(), config['Streaming']['Database']), { Promise, cache: true }))
  .then(db => db.migrate())

// Setup server
let app = express()

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
})

app.use(session({
  secret: config['Streaming']['Secret'],
  resave: false,
  saveUninitialized: true,
  cookie: {
    secure: !dev,
    maxAge: 2678400000 // 1 month
  }
}))

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

    // Autofind the correct server
    let rtmpserver = rip.rtmp.server[0].application
    let rtmpapp
    for (let 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 (let 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
  let 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.')
  let db = await dbPromise

  // Validate stream key
  let 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
  let 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)

  // 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.')

  let db = await dbPromise
  db.run('UPDATE channels SET live_at=NULL, last_stream=? WHERE key=?', Date.now(), req.body.name)

  res.send('OK')
})

// Front-end server
// OAuth2 authenticator
app.get('/login', async (req, res) => {
  if (req.session.user) return res.redirect('/')
  req.session.state = uuid()
  res.redirect(teval(oauthAuth, { state: req.session.state, redirect: oauthRedirect, client: oauthId, server: authServer }))
})

app.get('/auth/_callback', async (req, res) => {
  let state = req.session.state
  if (!state) throw new Error('Something went wrong!')

  let code = req.query.code
  let provState = req.query.state
  if (!code || state !== provState) throw new Error('Something went wrong!')
  delete req.session.state

  // Aquire token
  let { body } = await post(authServer + '/oauth2/token', {
    form: {
      grant_type: 'authorization_code',
      code: code,
      redirect_uri: oauthRedirect,
      client_id: oauthId,
      client_secret: oauthSecret
    },
    auth: {
      user: oauthId,
      pass: oauthSecret
    }
  })

  if (!body) throw new Error('Could not obtain access token!')
  try {
    body = JSON.parse(body)
  } catch (e) {
    console.error(e, body)
    throw new Error('Authorization server gave us an invalid response!')
  }

  if (body['error']) {
    throw new Error(body['error'] + ': ' + body['error_description'])
  }

  let token = body.access_token

  // Get user information
  let { body: bodyNew } = await get(authServer + '/oauth2/user', { auth: { bearer: token } })
  try {
    bodyNew = JSON.parse(bodyNew)
  } catch (e) {
    console.error(e, bodyNew)
    throw new Error('Authorization server gave us an invalid response for user!')
  }

  // Get user from database
  let db = await dbPromise
  let user = await db.get('SELECT * FROM signed_users WHERE uuid=?', bodyNew.uuid)
  if (!user) {
    await db.run('INSERT INTO signed_users (uuid,name) VALUES (?,?)', bodyNew.uuid, bodyNew.username)
  }

  req.session.login = bodyNew.uuid
  req.session.username = bodyNew.username

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

  res.redirect('/')
})

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

// 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.session.login) return next()

  res.locals.session = { uuid: req.session.login, username: req.session.username }

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

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

// Dashboard
app.get('/dashboard', (req, res, next) => {
  if (!req.isStreamer) return next(new Error('Unauthorized'))
  let stream = cache.streamers[req.session.login]
  res.render('dashboard.html', { stream: stream.key, server: 'rtmp://' + streamServerHost + '/live/' })
})

// Stats
app.get('/dashboard/stats', async (req, res) => {
  if (!req.isStreamer) return res.jsonp({ error: 'Unauthorized' })
  let stream = cache.streamers[req.session.login]
  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', async (req, res) => {
  if (!req.isStreamer) return res.jsonp({ error: 'Unauthorized' })
  let stream = cache.streamers[req.session.login]
  let data

  let 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.session.login,
    'live': data.live_at != null,
    'live_at': new Date(parseInt(data.live_at)),
    'last_stream': new Date(parseInt(data.last_stream))
  })
})

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

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

// Public data
app.get('/api/channel/:name', async (req, res) => {
  let name = req.params.name
  let db = await dbPromise
  let data = await db.get('SELECT name,live_at,last_stream FROM channels WHERE name=?', name)
  if (!data) return res.jsonp({ error: 'No such channel!' })
  data.live = data.live_at != null
  data.live_at = new Date(parseInt(data.live_at))
  data.last_stream = new Date(parseInt(data.last_stream))
  res.jsonp(data)
})

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

// Start server
const host = dev ? '0.0.0.0' : '127.0.0.1'
app.listen(port, host, () => console.log('Listening on %s:%d', host, port))