Handle invalid stored myPlex tokens.

User has an option to `Sign In` or `Ignore` the prompt.

fixes plexinc/roku-client#210

Plex/source/MyPlexManager.brs

@@ -214,6 +214,16 @@ Sub mpProcessAccountResponse(event)
         Debug("Failed to validate myPlex token: ResponseCode=" + responseCode)
         if val(responseCode) >= 400 and val(responseCode) < 500 then
             m.Disconnect()
+
+            ' Set the reauth flag and a dialog to continue or cancel reauth
+            MyPlexManager().reauth = true
+            dlg = createBaseDialog()
+            dlg.Title = "Please sign in again. Your credentials have expired."
+            dlg.Text = " "
+            dlg.SetButton("sign_in", "Sign In")
+            dlg.SetButton("ignore", "Ignore")
+            dlg.HandleButton = mpDialogHandleButton
+            dlg.Show(true)
         else
             m.SetOffline()
         end if
@@ -484,3 +494,8 @@ sub mpSetOffline()
     ' reset registry user
     RegInitializeUser()
 end sub
+
+Function mpDialogHandleButton(command, data) As Boolean
+    if command <> "sign_in" then MyPlexManager().reauth = false
+    return true
+End Function

Plex/source/MyPlexPinScreen.brs

@@ -20,7 +20,7 @@ Function createMyPlexPinScreen(viewController As Object) As Object
     screen.AddParagraph("This screen will automatically update once your Roku player has been linked to your Plex account.")
 
     screen.AddButton(0, "get a new code")
-    screen.AddButton(1, "back")
+    screen.AddButton(1, "cancel")
 
     ' Set standard screen properties/methods
     obj.Screen = screen

Plex/source/ViewController.brs

@@ -110,6 +110,15 @@ Function GetViewController()
 End Function
 
 Function vcCreateHomeScreen() as dynamic
+    ' Show the PIN screen if we have been flagged for reauth
+    if MyPlexManager().reauth = true then
+        MyPlexManager().reauth = false
+        screen = createMyPlexPinScreen(m)
+        m.InitializeOtherScreen(screen, invalid)
+        screen.Show()
+        return invalid
+    end if
+
     ' show the user list on startup for multi-user homes or if the last user is protected
     isProtectedUser = (MyPlexManager().Protected = true and NOT(MyPlexManager().PinAuthenticated = true))
     isMultiUserHome = (MyPlexManager().homeUsers.count() > 1)