const bcrypt = require('bcrypt')
const sqlite3 = require('sqlite3').verbose()
const uuidv4 = require('uuid/v4')
const { parse } = require('querystring')
const passStrength = require('owasp-password-strength-test')
const he = require('he') // Encodes HTML attributes

passStrength.config({
  minLength: 8
})

const saltRounds = 10
const expiryTime = 24 * 60 * 60 // For sessions - expires in 24 hours
const codeExpiryTime = 30 * 60 // For verification codes - expires in 30 minutes

let https = true // Just to make sure - determines whether cookies have the Secure; option

exports.setHTTPS = function (ishttps) { // Called from index.js
  https = ishttps
}

const db = new sqlite3.Database('secrets/database.db', (err) => {
  if (err) {
    console.error(err.message)
  }
  console.log('Connected to the database.')
})

async function querySingle (sql, params = []) {
  return await new Promise((resolve, reject) => {
    db.get(sql, params, (err, result) => {
      if (err) {
        console.log('Error running sql: ' + sql)
        console.log(err)
        reject(err)
      } else {
        resolve(result)
      }
    })
  })
}

async function queryAll (sql, params = []) {
  return await new Promise((resolve, reject) => {
    db.all(sql, params, (err, result) => {
      if (err) {
        console.log('Error running sql: ' + sql)
        console.log(err)
        reject(err)
      } else {
        resolve(result)
      }
    })
  })
}

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

exports.createUser = async function (discordID, username, password) {
  let match = await querySingle('SELECT DISTINCT * FROM users WHERE username=?', [username])
  if (match) {
    return { status: 'error', reason: 'An account with that username exists!' }
  }
  match = await querySingle('SELECT DISTINCT * FROM users WHERE discordID=?', [discordID])
  if (match) {
    return { status: 'error', reason: "There's already an account linked to that Discord account!\nTry resetting your password on the login page." }
  }
  const tested = passStrength.test(password)
  if (tested.strong) {
    const hashedPassword = await bcrypt.hash(password, saltRounds)
    await querySingle('INSERT INTO users VALUES (?,?,?)', [discordID, username, hashedPassword])
    return { status: 'success' }
  } else {
    return { status: 'error', reason: tested.errors.join('\n') }
  }
}

exports.login = async function (username, password) {
  const match = await querySingle('SELECT DISTINCT * FROM users WHERE username=?', [username])
  if (!match) {
    return { status: 'error', reason: "That account doesn't exist!" }
  } else {
    const correctPassword = await bcrypt.compare(password, match.hashedPassword)
    if (correctPassword) {
      const sessionID = uuidv4()
      const expiresAt = unixTime() + expiryTime
      await querySingle('INSERT INTO sessions VALUES (?,?,?)', [match.discordID, sessionID, unixTime() + expiryTime])
      return { status: 'success', sessionID: sessionID, expires: expiresAt }
    } else {
      return { status: 'error', reason: 'Incorrect password!' }
    }
  }
}

exports.checkSession = async function (sessionID) {
  const time = unixTime()
  querySingle('DELETE FROM sessions WHERE NOT expires > ?', [time]) // Clean the database (not awaited because it's not urgent)
  const match = await querySingle('SELECT DISTINCT * FROM sessions WHERE sessionID=? AND expires > ?', [sessionID, time])
  if (!match) {
    return false
  } else {
    if (exports.getUsername(match.discordID)) { // Check if user exists
      return match.discordID
    } else {
      return false
    }
  }
}

exports.logout = async function (discordID) {
  await querySingle('DELETE FROM sessions WHERE discordID=?', [discordID])
}

exports.getUsername = async function (discordID) {
  const match = await querySingle('SELECT DISTINCT username FROM users WHERE discordID=?', [discordID])
  if (match) {
    return match.username
  } else {
    return false
  }
}

exports.createVerificationCode = async function (discordID) {
  const time = unixTime()
  querySingle('DELETE FROM verificationcodes WHERE NOT expires > ?', [time]) // Clean the database (not awaited because it's not urgent)
  const match = await querySingle('SELECT DISTINCT code FROM verificationcodes WHERE discordID=? AND expires > ?', [discordID, time])
  if (match) {
    return match.code
  } else {
    const generatedCode = uuidv4().slice(0, 8) + 'a' + uuidv4().slice(9, 10) // Puts an "a" into it so it isn't stored as a number. I know that this makes 2 UUIDs.
    await querySingle('INSERT INTO verificationcodes VALUES (?,?,?)', [discordID, generatedCode, time + codeExpiryTime])
    return generatedCode
  }
}

exports.checkVerificationCode = async function (code) {
  const time = unixTime()
  querySingle('DELETE FROM verificationcodes WHERE NOT expires > ?', [time]) // Clean the database (not awaited because it's not urgent)
  const match = await querySingle('SELECT DISTINCT discordID FROM verificationcodes WHERE code=? AND expires > ?', [code, time])
  if (match) {
    return match.discordID
  } else {
    return false
  }
}

async function setup () {
  await querySingle('CREATE TABLE IF NOT EXISTS users (discordID TEXT, username STRING, hashedPassword STRING)')
  await querySingle('CREATE TABLE IF NOT EXISTS sessions (discordID TEXT, sessionID STRING, expires INT)')
  await querySingle('CREATE TABLE IF NOT EXISTS webhooks (serverID TEXT, webhookID TEXT, token STRING)')
  await querySingle('CREATE TABLE IF NOT EXISTS verificationcodes (discordID TEXT, code STRING, expires INT)')
}

setup()

exports.checkAuth = async function (req, res, noRedirect) {
  const cookies = req.headers.cookie

  const cookiedict = {} // https://stackoverflow.com/questions/3393854/get-and-set-a-single-cookie-with-node-js-http-server

  cookies && cookies.split(';').forEach(function (cookie) {
    var parts = cookie.split('=')
    cookiedict[parts.shift().trim()] = decodeURI(parts.join('='))
  })

  if (cookiedict.sessionID) {
    if (cookiedict.sessionID === 'guest') {
      return ['guest', cookiedict.guestUsername]
    } else {
      const session = await exports.checkSession(cookiedict.sessionID)
      if (session) {
        return session
      } else {
        if (!noRedirect) {
          res.writeHead(303, { Location: '/login.html?redirect=' + encodeURIComponent(req.url) })
          res.end()
        }
        return false
      }
    }
  } else {
    if (!noRedirect) {
      res.writeHead(303, { Location: '/login.html?redirect=' + encodeURIComponent(req.url) })
      res.end()
    }
    return false
  }
}

exports.handleLoginRegister = async function (req, res, body) {
  if (req.url === '/login') {
    const params = parse(body)
    if (params.username && params.password) {
      const result = await exports.login(params.username, params.password)
      if (result.status === 'success') {
        if (params.redirect) {
          res.writeHead(303, { 'Set-Cookie': 'sessionID=' + result.sessionID + '; SameSite=Strict; ' + (https ? 'Secure;' : '') + ' Expires=' + new Date(result.expires * 1000), Location: params.redirect + '#end', 'Content-Type': 'text/html' })
          res.write('Logged in! Click <a href="' + he.encode(params.redirect) + '">here</a> to continue.')
        } else {
          res.writeHead(303, { 'Set-Cookie': 'sessionID=' + result.sessionID + '; SameSite=Strict; ' + (https ? 'Secure;' : '') + ' Expires=' + new Date(result.expires * 1000), Location: '/server/', 'Content-Type': 'text/html' })
          res.write('Logged in! Click <a href="/server/">here</a> to continue.')
        }
        res.write('test')
        res.end()
      } else {
        res.writeHead(303, { Location: '/login.html?errortext=' + encodeURIComponent(result.reason), 'Content-Type': 'text/html' })
        res.write('test')
        res.end()
      }
    }
  } else if (req.url === '/guest') {
    const params = parse(body)
    if (params.username !== '') {
      res.writeHead(303, { 'Set-Cookie': ['guestUsername=' + encodeURIComponent(params.username), 'sessionID=guest; SameSite=Strict; ' + (https ? 'Secure;' : '')], Location: '/server/', 'Content-Type': 'text/html' })
      res.write('Logged as a guest! Click <a href="/server/">here</a> to continue.')
    } else {
      res.writeHead(303, { Location: '/guest.html?errortext=Please+input+a+username', 'Content-Type': 'text/html' })
      res.write('Please input a username')
      res.end()
    }
  } else if (req.url === '/register') {
    const params = parse(body)
    if (params.username && params.password && params.confirm && params.token) {
      if (params.confirm !== params.password) {
        res.writeHead(303, { Location: "/register.html?errortext=Password+confirmation+doesn't+match+password!", 'Content-Type': 'text/html' })
        res.end()
        return
      }
      const id = await exports.checkVerificationCode(params.token)
      if (!id) {
        res.writeHead(303, { Location: '/register.html?errortext=Invalid+verification+code!%0AType+%5Econnect+on+a+server+with+the+Discross+bot.', 'Content-Type': 'text/html' })
        res.end()
        return
      }
      const result = await exports.createUser(id, params.username, params.password)
      if (result.status === 'success') {
        res.writeHead(303, { Location: '/login.html' })
        res.end()
      } else {
        res.writeHead(303, { Location: '/register.html?errortext=' + encodeURIComponent(result.reason) })
        res.end()
      }
    } else {
      res.writeHead(303, { Location: '/register.html?errortext=Please+fill+in+all+boxes!' })
      res.end()
    }
  } else if (req.url === '/forgot') {
    const params = parse(body)
    if (params.token) {
      const id = await exports.checkVerificationCode(params.token)
      if (!id) {
        res.writeHead(303, { Location: '/forgot.html?errortext=Invalid+verification+code!%0AType+%5Econnect+on+a+server+with+the+Discross+bot.' })
        res.end()
        return
      }
      querySingle('DELETE FROM users WHERE discordID = ?', [id])
      querySingle('DELETE FROM sessions WHERE discordID = ?', [id])
      querySingle('DELETE FROM verificationcodes WHERE discordID = ?', [id])
      res.writeHead(303, { Location: '/register.html' })
      res.end()
    } else {
      res.writeHead(303, { Location: '/forgot.html?errortext=Please+fill+the+code!' })
      res.end()
    }
  }
}

exports.dbQuerySingle = querySingle

exports.dbQueryAll = queryAll