Redirect properly to correct endpoint depending on content-type

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

lib/service/metadata/event.ex

@@ -0,0 +1,24 @@
+defimpl Mobilizon.Service.Metadata, for: Mobilizon.Events.Event do
+  alias Phoenix.HTML
+  alias Phoenix.HTML.Tag
+  alias Mobilizon.Events.Event
+
+  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)
+  end
+
+  defp do_build_tags(%Event{} = event) do
+    [
+      Tag.tag(:meta, property: "og:title", content: event.title),
+      Tag.tag(:meta, property: "og:url", content: event.url),
+      Tag.tag(:meta, property: "og:description", content: event.description),
+      Tag.tag(:meta, property: "og:type", content: "website"),
+      Tag.tag(:meta, property: "og:image", content: event.thumbnail),
+      Tag.tag(:meta, property: "og:image", content: event.large_image),
+      Tag.tag(:meta, property: "twitter:card", content: "summary_large_image")
+    ]
+  end
+end