Add JSON-LD schema

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/service/metadata/event.ex

@@ -2,14 +2,17 @@ defimpl Mobilizon.Service.Metadata, for: Mobilizon.Events.Event do
   alias Phoenix.HTML
   alias Phoenix.HTML.Tag
   alias Mobilizon.Events.Event
+  alias MobilizonWeb.JsonLD.ObjectView
 
   def build_tags(%Event{} = event) do
     event
     |> do_build_tags()
     |> Enum.map(&HTML.safe_to_string/1)
     |> Enum.reduce("", fn tag, acc -> acc <> tag end)
+    |> Kernel.<>(build_json_ld_schema(event))
   end
 
+  # Build OpenGraph & Twitter Tags
   defp do_build_tags(%Event{} = event) do
     [
       Tag.tag(:meta, property: "og:title", content: event.title),
@@ -21,4 +24,11 @@ defimpl Mobilizon.Service.Metadata, for: Mobilizon.Events.Event do
       Tag.tag(:meta, property: "twitter:card", content: "summary_large_image")
     ]
   end
+
+  # Insert JSON-LD schema by hand because Tag.content_tag wants to escape it
+  defp build_json_ld_schema(%Event{} = event) do
+    "<script type=\"application\/ld+json\">" <>
+      (ObjectView.render("event.json", %{event: event})
+       |> Jason.encode!()) <> "</script>"
+  end
 end