From a40c4825996c90d107901b0d71162f9356f1395a Mon Sep 17 00:00:00 2001
From: Joris Guyonvarch
Date: Sun, 19 Jul 2015 20:24:54 +0200
Subject: Showing login token error message in the UI

---
 public/javascripts/elmLauncher.js | 11 ++++++++++-
 src/client/Main.elm               | 15 ++++++++++++---
 src/client/Update.elm             |  4 ++++
 src/server/Application.hs         | 11 ++++++++---
 4 files changed, 34 insertions(+), 7 deletions(-)

diff --git a/public/javascripts/elmLauncher.js b/public/javascripts/elmLauncher.js
index 52b1087..c4a00b3 100644
--- a/public/javascripts/elmLauncher.js
+++ b/public/javascripts/elmLauncher.js
@@ -1 +1,10 @@
-Elm.fullscreen(Elm.Main);
+Elm.fullscreen(Elm.Main, {
+  signInError: getParameterByName('signInError')
+});
+
+function getParameterByName(name) {
+  name = name.replace(/[\[]/, "\\[").replace(/[\]]/, "\\]");
+  var regex = new RegExp("[\\?&]" + name + "=([^&#]*)"),
+      results = regex.exec(location.search);
+  return results && decodeURIComponent(results[1].replace(/\+/g, " "));
+}
diff --git a/src/client/Main.elm b/src/client/Main.elm
index e79fe2b..519360a 100644
--- a/src/client/Main.elm
+++ b/src/client/Main.elm
@@ -15,6 +15,7 @@ import Model exposing (Model, initialModel)
 import Model.Payment exposing (Payments, paymentsDecoder)
 
 import Update exposing (Action(..), actions, updateModel)
+import Update.SignIn exposing (..)
 
 import View.Page exposing (renderPage)
 
@@ -28,13 +29,21 @@ main = Signal.map renderPage model
 model : Signal Model
 model = Signal.foldp updateModel initialModel actions.signal
 
+-------------------------
+
+port signInError : Maybe String
+
 ---------------------------------------
 
 port fetchPayments : Task Http.Error ()
 port fetchPayments =
-  getPayments
-    |> flip Task.andThen reportSuccess
-    |> flip Task.onError reportError
+  case signInError of
+    Just msg ->
+      Signal.send actions.address (SignInError msg)
+    Nothing ->
+      getPayments
+        |> flip Task.andThen reportSuccess
+        |> flip Task.onError reportError
 
 reportSuccess : Payments -> Task x ()
 reportSuccess payments = Signal.send actions.address (UpdatePayments payments)
diff --git a/src/client/Update.elm b/src/client/Update.elm
index 1d0fe95..508ee2f 100644
--- a/src/client/Update.elm
+++ b/src/client/Update.elm
@@ -14,6 +14,7 @@ import Update.SignIn exposing (..)
 type Action =
   NoOp
   | SignIn
+  | SignInError String
   | UpdateSignIn SignInAction
   | UpdatePayments Payments
 
@@ -27,6 +28,9 @@ updateModel action model =
       model
     SignIn ->
       { model | view <- SignInView initSignIn }
+    SignInError msg ->
+      let signIn = { initSignIn | result <- Just (Err msg) }
+      in  { model | view <- SignInView signIn }
     UpdateSignIn signInAction ->
       case model.view of
         SignInView signIn ->
diff --git a/src/server/Application.hs b/src/server/Application.hs
index 739fe33..7e93fe1 100644
--- a/src/server/Application.hs
+++ b/src/server/Application.hs
@@ -23,6 +23,7 @@ import Control.Monad.IO.Class (liftIO)
 
 import Data.Text (Text)
 import qualified Data.Text as T
+import qualified Data.Text.Lazy as TL
 import qualified Data.Text.Encoding as TE
 import Data.String (fromString)
 import Data.Time.Clock (getCurrentTime, diffUTCTime)
@@ -109,18 +110,22 @@ validateSignInAction token = do
     Just signIn ->
       if signInIsUsed . entityVal $ signIn
         then
-          errorResponse "The token has already been used."
+          redirectError "The token has already been used."
         else
           let diffTime = now `diffUTCTime` (signInCreation . entityVal $ signIn)
           in  if diffTime > 2 * 60 -- 2 minutes
                 then
-                  errorResponse "The token has expired."
+                  redirectError "The token has expired."
                 else do
                   LoginSession.put (signInEmail . entityVal $ signIn)
                   liftIO . runDb . signInTokenToUsed . entityKey $ signIn
                   redirect "/"
     Nothing ->
-      errorResponse "The token is invalid."
+      redirectError "The token is invalid."
+
+redirectError :: Text -> ActionM ()
+redirectError msg =
+  redirect . TL.fromStrict . T.concat $ ["/?signInError=", msg]
 
 signOutAction :: ActionM ()
 signOutAction = do
-- 
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