Add part3

advanced/part3/src/Route.elm

@@ -0,0 +1,107 @@
+module Route exposing (Route(..), fromUrl, href, replaceUrl)
+
+import Article.Slug as Slug exposing (Slug)
+import Browser.Navigation as Nav
+import Html exposing (Attribute)
+import Html.Attributes as Attr
+import Profile exposing (Profile)
+import Url exposing (Url)
+import Url.Parser as Parser exposing ((</>), Parser, oneOf, s, string)
+import Username exposing (Username)
+
+
+
+-- ROUTING
+
+
+type Route
+    = Home
+    | Root
+    | Login
+    | Logout
+    | Register
+    | Settings
+    | Article Slug
+    | Profile Username
+    | NewArticle
+    | EditArticle Slug
+
+
+parser : Parser (Route -> a) a
+parser =
+    oneOf
+        [ Parser.map Home Parser.top
+        , Parser.map Login (s "login")
+        , Parser.map Logout (s "logout")
+        , Parser.map Settings (s "settings")
+        , Parser.map Profile (s "profile" </> Username.urlParser)
+        , Parser.map Register (s "register")
+        , Parser.map Article (s "article" </> Slug.urlParser)
+        , Parser.map NewArticle (s "editor")
+        , Parser.map EditArticle (s "editor" </> Slug.urlParser)
+        ]
+
+
+
+-- PUBLIC HELPERS
+
+
+href : Route -> Attribute msg
+href targetRoute =
+    Attr.href (routeToString targetRoute)
+
+
+replaceUrl : Nav.Key -> Route -> Cmd msg
+replaceUrl key route =
+    Nav.replaceUrl key (routeToString route)
+
+
+fromUrl : Url -> Maybe Route
+fromUrl url =
+    -- The RealWorld spec treats the fragment like a path.
+    -- This makes it *literally* the path, so we can proceed
+    -- with parsing as if it had been a normal path all along.
+    { url | path = Maybe.withDefault "" url.fragment, fragment = Nothing }
+        |> Parser.parse parser
+
+
+
+-- INTERNAL
+
+
+routeToString : Route -> String
+routeToString page =
+    let
+        pieces =
+            case page of
+                Home ->
+                    []
+
+                Root ->
+                    []
+
+                Login ->
+                    [ "login" ]
+
+                Logout ->
+                    [ "logout" ]
+
+                Register ->
+                    [ "register" ]
+
+                Settings ->
+                    [ "settings" ]
+
+                Article slug ->
+                    [ "article", Slug.toString slug ]
+
+                Profile username ->
+                    [ "profile", Username.toString username ]
+
+                NewArticle ->
+                    [ "editor" ]
+
+                EditArticle slug ->
+                    [ "editor", Slug.toString slug ]
+    in
+    "#/" ++ String.join "/" pieces