app.js

require('dotenv').config()

const express = require('express')
const path = require('path')
const redis = require('redis')
const bcrypt = require('bcrypt')
const session = require('express-session')
const { promisify } = require('util')
const { formatDistance } = require('date-fns')


const RedisStore = require('connect-redis')(session)
const app = express()
const client = redis.createClient(process.env.REDIS_URL)

const ahget = promisify(client.hget).bind(client)
const asmembers = promisify(client.smembers).bind(client)
const ahkeys = promisify(client.hkeys).bind(client)
const aincr = promisify(client.incr).bind(client)
const alrange = promisify(client.lrange).bind(client)

app.use(express.urlencoded({ extended: true }))
app.use(
  session({
    store: new RedisStore({ client: client }),
    resave: true,
    saveUninitialized: true,
    cookie: {
      maxAge: 36000000,
      httpOnly: false,
      secure: false,
    },
    secret: process.env.API_KEY,
  })
)

app.set('view engine', 'pug')
app.set('views', path.join(__dirname, 'views'))

app.get('/', async (req, res) => {
  if (req.session.userid) {

    const currentUserName = await ahget(`user:${req.session.userid}`, 'username')
    const following = await asmembers(`following:${currentUserName}`)
    const users = await ahkeys('users')

    const timeline = []
    const posts = await alrange(`timeline:${currentUserName}`, 0, 100)

    for (post of posts) {
      const timestamp = await ahget(`post:${post}`, 'timestamp')
      const timeString = formatDistance(new Date(), new Date(parseInt(timestamp)))

      timeline.push({
        message: await ahget(`post:${post}`, 'message'),
        author: await ahget(`post:${post}`, 'username'),
        timeString: timeString,
      })
    }


    res.render('dashboard', {
      users: users.filter(user => user !== currentUserName && following.indexOf(user) === -1),
      currentUserName,
      timeline,
    })
  } else {
    res.render('login')
  }
})

app.post('/', (req, res) => {
  const { username, password } = req.body
  if (!username || !password) {
    res.render('error', {
      message: 'Please set both username and password',
    })
    return
  }

  console.log(req.body, username, password)

  client.hget('users', username, (err, userid) => {
    if (!userid) {
      //user does not exist, signup procedure
      client.incr('userid', async (err, userid) => {
        client.hset('users', username, userid)

        const saltRounds = 10
        const hash = await bcrypt.hash(password, saltRounds)

        client.hset(`user:${userid}`, 'hash', hash, 'username', username)

        saveSessionAndRenderDashboard(userid)
      })
    } else {
      //user exists, login procedure
      client.hget(`user:${userid}`, 'hash', async (err, hash) => {
        const result = await bcrypt.compare(password, hash)
        if (result) {
          saveSessionAndRenderDashboard(userid)
        } else {
          res.render('error', {
            message: 'Incorrect password',
          })
          return
        }
      })
    }
  })

  const saveSessionAndRenderDashboard = userid => {
    req.session.userid = userid
    req.session.save()
    res.redirect('/')
  }
})

app.get('/post', (req,res) => {
  if (req.session.userid) {
    res.render('post')
  } else {
    res.render('login')
  }
})

app.post('/post', async (req,res) => {
  if(!req.session.userid) {
    res.render('login')
    return
  }

  const { message } = req.body
  const currentUserName = await ahget(`user:${req.session.userid}`, 'username')
  const postid = await aincr('postid')
  client.hmset(
    `post:${postid}`,
    'userid',
    req.session.userid,
    'username',
    currentUserName,
    'message',
    message,
    'timestamp',
    Date.now()
  )
  client.lpush(`timeline:${currentUserName}`, postid)
  
  const followers = await asmembers(`followers:${currentUserName}`)
  for (follower of followers) {
    client.lpush(`timeline:${follower}`, postid)
  }

  res.redirect('/')
})

app.post('/follow', (req, res) => {
  if(!req.session.userid) {
    res.render('login')
    return
  }

  const { username } = req.body

  client.hget(
    `user:${req.session.userid}`,
    'username',
    (err, currentUserName) => {
      client.sadd(`following:${currentUserName}`, username)
      client.sadd(`followers:${username}`, currentUserName)
    },
  )

  res.redirect('/')
})

app.listen(process.env.PORT, () => {
  console.log(`Server listening on port ${process.env.PORT}... `)
})