Switch to json encoded meta data

Instead of parsing a comma separated list of photo urls, we retrieve a
json array of meta data (url, title, size).

src/PhotoGroove.elm

@@ -5,6 +5,8 @@ import Html exposing (Html, button, div, h1, h3, img, input, label, text)
 import Html.Attributes exposing (..)
 import Html.Events exposing (onClick)
 import Http
+import Json.Decode as D exposing (Decoder)
+import Json.Decode.Pipeline as D
 import Random
 
 
@@ -21,7 +23,18 @@ type alias Model =
 
 
 type alias Photo =
-    { url : String }
+    { url : String
+    , size : Int
+    , title : String
+    }
+
+
+photoDecoder : Decoder Photo
+photoDecoder =
+    D.succeed Photo
+        |> D.required "url" D.string
+        |> D.required "size" D.int
+        |> D.optional "title" D.string "(untitled)"
 
 
 type ThumbnailSize
@@ -41,7 +54,7 @@ initialCommand : Cmd Message
 initialCommand =
     Http.get
         { url = "list"
-        , expect = Http.expectString GotPhotos
+        , expect = Http.expectJson GotPhotos (D.list photoDecoder)
         }
 
 
@@ -129,7 +142,7 @@ type Message
     | ClickedSurpriseMe
     | ClickedSize ThumbnailSize
     | GotRandomPhoto Photo
-    | GotPhotos (Result Http.Error String)
+    | GotPhotos (Result Http.Error (List Photo))
 
 
 update : Message -> Model -> ( Model, Cmd Message )
@@ -160,17 +173,11 @@ update msg model =
         GotRandomPhoto photo ->
             ( { model | status = selectUrl photo.url model.status }, Cmd.none )
 
-        GotPhotos (Ok str) ->
-            case String.split "," str of
-                (x :: _) as urls ->
-                    let
-                        photos =
-                            List.map Photo urls
-                    in
-                    ( { model | status = Loaded photos x }, Cmd.none )
+        GotPhotos (Ok ((firstPhoto :: _) as photos)) ->
+            ( { model | status = Loaded photos firstPhoto.url }, Cmd.none )
 
-                [] ->
-                    ( { model | status = Errored ("No photos: " ++ str) }, Cmd.none )
+        GotPhotos (Ok []) ->
+            ( { model | status = Errored "No photos!" }, Cmd.none )
 
         GotPhotos (Err httpError) ->
             ( { model | status = Errored <| ("Failed to load photos: " ++ httpErrorToString httpError) }, Cmd.none )