Add basic metadata to opengraph preview

Also refactor datetime & address utils

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

lib/service/metadata/event.ex

@@ -1,19 +1,22 @@
 defimpl Mobilizon.Service.Metadata, for: Mobilizon.Events.Event do
   alias Phoenix.HTML
   alias Phoenix.HTML.Tag
+  alias Mobilizon.Addresses.Address
   alias Mobilizon.Events.Event
   alias Mobilizon.Web.JsonLD.ObjectView
-  import Mobilizon.Service.Metadata.Utils, only: [process_description: 2, strip_tags: 1]
+
+  import Mobilizon.Service.Metadata.Utils,
+    only: [process_description: 2, strip_tags: 1, datetime_to_string: 2, render_address: 1]
 
   def build_tags(%Event{} = event, locale \\ "en") do
-    event = Map.put(event, :description, process_description(event.description, locale))
+    formatted_description = description(event, locale)
 
     tags = [
       Tag.content_tag(:title, event.title <> " - Mobilizon"),
-      Tag.tag(:meta, name: "description", content: event.description),
+      Tag.tag(:meta, name: "description", content: process_description(event.description, locale)),
       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:description", content: formatted_description),
       Tag.tag(:meta, property: "og:type", content: "website"),
       # Tell Search Engines what's the origin
       Tag.tag(:link, rel: "canonical", href: event.url)
@@ -45,4 +48,25 @@ defimpl Mobilizon.Service.Metadata, for: Mobilizon.Events.Event do
     |> ObjectView.render(%{event: %{event | title: strip_tags(title)}})
     |> Jason.encode!()
   end
+
+  defp description(
+         %Event{
+           description: description,
+           begins_on: begins_on,
+           physical_address: %Address{} = address
+         },
+         locale
+       ) do
+    "#{datetime_to_string(begins_on, locale)} - #{render_address(address)} - #{process_description(description, locale)}"
+  end
+
+  defp description(
+         %Event{
+           description: description,
+           begins_on: begins_on
+         },
+         locale
+       ) do
+    "#{datetime_to_string(begins_on, locale)} - #{process_description(description, locale)}"
+  end
 end

lib/service/metadata/utils.ex

@@ -3,6 +3,7 @@ defmodule Mobilizon.Service.Metadata.Utils do
   Tools to convert tags to string.
   """
 
+  alias Mobilizon.Service.{Address, DateTime}
   alias Mobilizon.Service.Formatter.HTML, as: HTMLFormatter
   alias Phoenix.HTML
   import Mobilizon.Web.Gettext
@@ -52,6 +53,9 @@ defmodule Mobilizon.Service.Metadata.Utils do
     gettext("The event organizer didn't add any description.")
   end
 
+  defdelegate datetime_to_string(datetime, locale \\ "en", format \\ :medium), to: DateTime
+  defdelegate render_address(address), to: Address
+
   defp maybe_slice(description, limit) do
     if String.length(description) > limit do
       description