fix: Warn on session data decoding error. (#884)

Warn users when decoding their session has failed, with useful information on how to report the problem and reset the session
MTES-MCT · Jan 8, 2025 · 2601218 · 2601218
1 parent f8ffbcd
commit 2601218
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Showing 4 changed files with 78 additions and 53 deletions.
diff --git a/src/Data/Session.elm b/src/Data/Session.elm
@@ -7,8 +7,9 @@ module Data.Session exposing
     , authenticated
     , checkComparedSimulations
     , closeNotification
+    , decodeRawStore
+    , defaultStore
     , deleteBookmark
-    , deserializeStore
     , getUser
     , isAuthenticated
     , logout
@@ -80,6 +81,7 @@ type alias EnabledSections =
 type Notification
     = GenericError String String
     | GenericInfo String String
+    | StoreDecodingError Decode.Error
 
 
 closeNotification : Notification -> Session -> Session
@@ -97,6 +99,11 @@ notifyError title error ({ notifications } as session) =
     { session | notifications = notifications ++ [ GenericError title error ] }
 
 
+notifyStoreDecodingError : Decode.Error -> Session -> Session
+notifyStoreDecodingError error ({ notifications } as session) =
+    { session | notifications = notifications ++ [ StoreDecodingError error ] }
+
+
 
 -- Boomarks
 
@@ -219,13 +226,9 @@ selectNoBookmarks =
     updateStore (\store -> { store | comparedSimulations = Set.empty })
 
 
-
--- Store
---
--- A serializable data structure holding session information you want to share
--- across browser restarts, typically in localStorage.
-
-
+{-| A serializable data structure holding session information you want to share
+across browser restarts, typically in localStorage.
+-}
 type alias Store =
     { auth : Auth
     , bookmarks : List Bookmark
@@ -289,26 +292,14 @@ getUser { store } =
             Nothing
 
 
-deserializeStore : String -> Store
-deserializeStore =
-    Decode.decodeString decodeStore
-        -- FIXME: this should return a `Result String Store` so we could inform
-        -- users something went wrong while decoding their data (eg. so they can
-        -- report the issue).
-        -- Meanwhile, if you ever need to debug JSON decode errors from session
-        -- store, uncomment these lines.
-        -- >> (\res ->
-        --         case res of
-        --             Ok r ->
-        --                 Ok r
-        --             Err err ->
-        --                 let
-        --                     _ =
-        --                         Debug.log "deserializeStore error" err
-        --                 in
-        --                 Err err
-        --    )
-        >> Result.withDefault defaultStore
+decodeRawStore : String -> Session -> Session
+decodeRawStore rawStore session =
+    case Decode.decodeString decodeStore rawStore of
+        Err error ->
+            session |> notifyStoreDecodingError error
+
+        Ok store ->
+            { session | store = store }
 
 
 serializeStore : Store -> String

diff --git a/src/Main.elm b/src/Main.elm
@@ -88,6 +88,7 @@ type Msg
     | OpenMobileNavigation
     | ReleasesReceived (WebData (List Github.Release))
     | ReloadPage
+    | ResetSessionStore
     | StatsMsg Stats.Msg
     | StoreChanged String
     | SwitchVersion String
@@ -137,30 +138,27 @@ init flags requestedUrl navKey =
 
 setupSession : Nav.Key -> Flags -> Db -> Session
 setupSession navKey flags db =
-    let
-        store =
-            Session.deserializeStore flags.rawStore
-    in
-    { clientUrl = flags.clientUrl
-    , currentVersion = Request.Version.Unknown
-    , db = db
-    , enabledSections = flags.enabledSections
-    , matomo = flags.matomo
-    , navKey = navKey
-    , notifications = []
-    , queries =
-        { food = FoodQuery.empty
-        , object = ObjectQuery.default
-        , textile =
-            db.textile.examples
-                |> Example.findByName "Tshirt coton (150g) - Majorant par défaut"
-                |> Result.map .query
-                |> Result.withDefault TextileQuery.default
-        , veli = ObjectQuery.default
+    Session.decodeRawStore flags.rawStore
+        { clientUrl = flags.clientUrl
+        , currentVersion = Request.Version.Unknown
+        , db = db
+        , enabledSections = flags.enabledSections
+        , matomo = flags.matomo
+        , navKey = navKey
+        , notifications = []
+        , queries =
+            { food = FoodQuery.empty
+            , object = ObjectQuery.default
+            , textile =
+                db.textile.examples
+                    |> Example.findByName "Tshirt coton (150g) - Majorant par défaut"
+                    |> Result.map .query
+                    |> Result.withDefault TextileQuery.default
+            , veli = ObjectQuery.default
+            }
+        , releases = RemoteData.NotAsked
+        , store = Session.defaultStore
         }
-    , releases = RemoteData.NotAsked
-    , store = store
-    }
 
 
 setRoute : Url -> ( Model, Cmd Msg ) -> ( Model, Cmd Msg )
@@ -353,11 +351,22 @@ update rawMsg ({ state } as model) =
                 ( StoreChanged json, currentPage ) ->
                     ( { model
                         | state =
-                            currentPage |> Loaded { session | store = Session.deserializeStore json }
+                            currentPage
+                                |> Loaded (session |> Session.decodeRawStore json)
                       }
                     , Cmd.none
                     )
 
+                ( ResetSessionStore, currentPage ) ->
+                    let
+                        newSession =
+                            { session | notifications = [], store = Session.defaultStore }
+                                |> Session.notifyInfo "Session" "La session a été réinitialisée."
+                    in
+                    ( { model | state = currentPage |> Loaded newSession }
+                    , newSession.store |> Session.serializeStore |> Ports.saveStore
+                    )
+
                 -- Version switch
                 ( SwitchVersion version, _ ) ->
                     ( model
@@ -478,6 +487,7 @@ view { mobileNavigationOpened, state } =
                         LoadUrl
                         ReloadPage
                         CloseNotification
+                        ResetSessionStore
                         SwitchVersion
 
                 mapMsg msg ( title, content ) =

diff --git a/src/Views/Alert.elm b/src/Views/Alert.elm
@@ -26,6 +26,7 @@ type Level
     = Danger
     | Info
     | Success
+    | Warning
 
 
 icon : Level -> Html msg
@@ -40,6 +41,9 @@ icon level =
         Success ->
             span [ class "me-1" ] [ Icon.checkCircle ]
 
+        Warning ->
+            span [ class "me-1" ] [ Icon.warning ]
+
 
 httpError : Http.Error -> Html msg
 httpError error =
@@ -125,3 +129,6 @@ levelToClass level =
 
         Success ->
             "success"
+
+        Warning ->
+            "warning"
diff --git a/src/Views/Page.elm b/src/Views/Page.elm
@@ -15,6 +15,7 @@ import Data.Session as Session exposing (Session)
 import Html exposing (..)
 import Html.Attributes exposing (..)
 import Html.Events exposing (..)
+import Json.Decode as Decode
 import RemoteData
 import Request.Version as Version exposing (Version(..))
 import Route
@@ -53,6 +54,7 @@ type alias Config msg =
     , loadUrl : String -> msg
     , reloadPage : msg
     , closeNotification : Session.Notification -> msg
+    , resetSessionStore : msg
     , switchVersion : String -> msg
     , activePage : ActivePage
     }
@@ -436,7 +438,7 @@ notificationListView ({ session } as config) =
 
 
 notificationView : Config msg -> Session.Notification -> Html msg
-notificationView { closeNotification } notification =
+notificationView { closeNotification, resetSessionStore } notification =
     -- TODO:
     -- - absolute positionning
     case notification of
@@ -456,6 +458,21 @@ notificationView { closeNotification } notification =
                 , content = [ text message ]
                 }
 
+        Session.StoreDecodingError decodeError ->
+            Alert.simple
+                { level = Alert.Warning
+                , title = Just "Erreur de récupération de session"
+                , close = Nothing
+                , content =
+                    [ p [] [ text "Votre précédente session n'a pas pu être récupérée, elle doit donc être réinitialisée." ]
+                    , p [] [ button [ class "btn btn-primary", onClick resetSessionStore ] [ text "D’accord, réinitialiser la session" ] ]
+                    , details []
+                        [ summary [] [ text "Afficher les détails techniques de l'erreur" ]
+                        , pre [] [ text <| Decode.errorToString decodeError ]
+                        ]
+                    ]
+                }
+
 
 notFound : Html msg
 notFound =