evilsoft · November 5, 2017 21:05 · Nov 5, 2017
diff --git a/login.js b/login.js
@@ -0,0 +1,39 @@
+const { validateUser } = require('../data/users')
+
+const {
+  compose, curry, objOf
+} = require('crocks')
+
+module.exports = ({ config, express, jwt, knex }) => {
+  const { jwtSecret } = config
+  const router = express.Router()
+
+  const setCookie = res => payload => {
+    res.cookie('token', jwt.sign(payload, jwtSecret))
+    res.redirect('/')
+  }
+
+  const render = curry(
+    (res, locals) => res.render('login', locals)
+  )
+
+  router.get('/', (req, res) => {
+    render(res, {})
+  })
+
+  router.post('/', (req, res) => {
+    const { body } = req
+
+    validateUser({ knex }, body)
+      .fork(
+        compose(render(res), objOf('flash')),
+        setCookie(res)
+      )
+  })
+
+  router.get('/logout', (req, res) => {
+    res.redirect('/')
+  })
+
+  return router
+}
diff --git a/users.js b/users.js
@@ -0,0 +1,83 @@
+const Async = require('crocks/Async')
+const ReaderT = require('crocks/Reader/ReaderT')
+
+const crypto = require('crypto')
+
+const assign = require('crocks/helpers/assign')
+const assoc = require('crocks/helpers/assoc')
+const B = require('crocks/combinators/composeB')
+const curry = require('crocks/helpers/curry')
+const K = require('crocks/combinators/constant')
+const head = require('crocks/Maybe/head')
+const map = require('crocks/pointfree/map')
+const maybeToAsync = require('crocks/Async/maybeToAsync')
+const safe = require('crocks/Maybe/safe')
+
+const AsyncReader = ReaderT(Async)
+const { ask, liftFn } = AsyncReader
+const { fromPromise } = Async
+
+const table = 'users'
+const unique = [ 'email', 'userName' ]
+
+// liftQuery :: (a -> Promise b e) -> AsyncReader Object (Async e b)
+const liftQuery = fn =>
+  ask()
+    .chain(liftFn(fromPromise(fn)))
+
+// mergeEnv :: Object -> Object
+const mergeEnv =
+  assign({ table, unique })
+
+// maybeEqual :: a -> a -> Maybe a
+const maybeEqual = curry(
+  x => safe(y => y === x)
+)
+
+// hash :: Object -> String
+const hash = ({ salt='', data }) =>
+  crypto.createHash('md5')
+    .update(data.concat(salt), 'utf8')
+    .digest('hex')
+
+// hashPassword :: Record -> Object
+const hashPassword = rec => {
+  const { password: data, salt } = rec
+  return assoc('password', hash({ data, salt }), rec)
+}
+
+// compareHashed :: String -> Object -> Object
+const compareHashed = curry(
+  (hashed, { password, id }) =>
+    B(map(K({ id })), maybeEqual(password))(hashed)
+)
+
+// getCreds :: Creds -> AsyncReader Object (Async e [ Record ])
+const getCreds = ({ username }) =>
+  liftQuery(({ knex, table }) =>
+    knex(table)
+      .select([ 'id', 'password', 'salt' ])
+      .where({ userName: username })
+      .orWhere({ email: username })
+  )
+
+// validatePassword :: Object -> Record -> Async e Record
+const validatePassword = curry(
+  (creds, rec) => {
+    const { salt, id, password: hashed } = rec
+    const { password } = creds
+
+    return Async.of(hashPassword({ id, salt, password }))
+      .chain(maybeToAsync('Invalid Credentials', compareHashed(hashed)))
+  }
+)
+
+// validateUser :: Object -> Creds -> Async e Record
+exports.validateUser = curry(
+  (env, creds) =>
+    AsyncReader.of(creds)
+      .chain(getCreds)
+      .chain(liftFn(maybeToAsync('Invalid Credentials',  head)))
+      .chain(liftFn(validatePassword(creds)))
+      .runWith(mergeEnv(env))
+)