Add part5

advanced/part5/src/Session.elm

@@ -0,0 +1,98 @@
+port module Session
+    exposing
+        ( Session
+        , changes
+        , cred
+        , decode
+        , login
+        , logout
+        , navKey
+        , viewer
+        )
+
+import Browser.Navigation as Nav
+import Json.Decode as Decode exposing (Decoder)
+import Json.Decode.Pipeline exposing (custom, required)
+import Json.Encode as Encode exposing (Value)
+import Profile exposing (Profile)
+import Time
+import Viewer exposing (Viewer)
+import Viewer.Cred as Cred exposing (Cred)
+
+
+
+-- TYPES
+
+
+type Session
+    = Session Internals
+
+
+type alias Internals =
+    { navKey : Nav.Key
+    , viewer : Maybe Viewer
+    }
+
+
+
+-- INFO
+
+
+viewer : Session -> Maybe Viewer
+viewer (Session info) =
+    info.viewer
+
+
+cred : Session -> Maybe Cred
+cred (Session info) =
+    Maybe.map Viewer.cred info.viewer
+
+
+navKey : Session -> Nav.Key
+navKey (Session info) =
+    info.navKey
+
+
+
+-- LOGIN
+
+
+login : Viewer -> Cmd msg
+login newViewer =
+    Viewer.encode newViewer
+        |> Encode.encode 0
+        |> Just
+        |> storeSession
+
+
+
+-- LOGOUT
+
+
+logout : Cmd msg
+logout =
+    storeSession Nothing
+
+
+port storeSession : Maybe String -> Cmd msg
+
+
+
+-- CHANGES
+
+
+changes : (Session -> msg) -> Nav.Key -> Sub msg
+changes toMsg key =
+    onSessionChange (decode key)
+        |> Sub.map toMsg
+
+
+port onSessionChange : (Value -> msg) -> Sub msg
+
+
+decode : Nav.Key -> Value -> Session
+decode key value =
+    Session
+        { viewer = Result.toMaybe (Decode.decodeValue Viewer.decoder value)
+        , navKey = key
+        }