add opengraph meta

lib/philomena_web/controllers/api/json/oembed_controller.ex

@@ -67,6 +67,6 @@ defmodule PhilomenaWeb.Api.Json.OembedController do
   defp artist_tags(tags) do
     tags
     |> Enum.filter(& &1.namespace == "artist")
-    |> Enum.map_join(", ", & &1.name)
+    |> Enum.map_join(", ", & &1.name_in_namespace)
   end
 end

lib/philomena_web/templates/layout/_opengraph.html.slime

@@ -0,0 +1,41 @@
+meta name="generator" content="philomena"
+meta name="theme-color" 
+meta name="format-detection" content="telephone=no"
+meta name="robots" content="noindex, nofollow"
+
+= if !is_nil(@conn.assigns.image) and @conn.assigns.image.__meta__.state == :loaded do
+  - image = @conn.assigns.image
+  - filtered = ImageView.filter_or_spoiler_hits?(@conn, image)
+
+  meta name="description" content="##{image.id} - Derpibooru"
+  meta name="keywords" content=image.tag_list_cache
+  meta name="og:title" content="##{image.id} - Derpibooru"
+  meta name="og:url" content=Routes.image_url(@conn, :show, image)
+
+  = for tag <- artist_tags(image.tags) do
+    meta property="dc:creator" content=tag.name_in_namespace
+
+  = if image.source_url not in [nil, ""] do
+    meta propery="foaf:primaryTopic" content=image.source_url
+
+  link rel="alternate" type="application/json+oembed" href=Routes.api_json_oembed_url(@conn, :index, url: Routes.image_path(@conn, :show, image)) title="oEmbed JSON Profile"
+
+  = cond do
+    - image.image_mime_type == "video/webm" and !filtered ->
+      meta name="og:type" content="video.other"
+      meta name="og:image" content=ImageView.thumb_url(image, false, :rendered)
+      meta name="og:video" content=Imageview.thumb_url(image, false, :full)
+
+    - image.image_mime_type == "image/svg+xml" and !filtered ->
+      meta name="og:type" content="video.other"
+      meta name="og:image" content=ImageView.thumb_url(image, false, :rendered)
+
+    - !filtered ->
+      meta name="og:type" content="website"
+      meta name="og:image" content=ImageView.thumb_url(image, false, :full)
+
+    - true ->
+      meta name="og:type" content="website"
+
+- else
+  meta name="description" content="Derpibooru is a linear imagebooru which lets you share, find and discover new art and media surrounding the show My Little Pony: Friendship is Magic"

lib/philomena_web/templates/layout/app.html.slime

@@ -19,6 +19,7 @@ html lang="en"
     meta name="robots" content="noindex, nofollow"
     = csrf_meta_tag()
     script type="text/javascript" src=Routes.static_path(@conn, "/js/app.js") async="async"
+    = render PhilomenaWeb.LayoutView, "_opengraph.html", assigns
   body data-theme="default"
     = render PhilomenaWeb.LayoutView, "_burger.html", assigns
     #container class=container_class(@current_user)

lib/philomena_web/views/image_view.ex

@@ -72,7 +72,7 @@ defmodule PhilomenaWeb.ImageView do
     format =
       image.image_format
       |> String.downcase()
-      |> thumb_format()
+      |> thumb_format(name)
 
     id_fragment =
       if deleted and show_hidden do
@@ -93,7 +93,7 @@ defmodule PhilomenaWeb.ImageView do
     format =
       image.image_format
       |> String.downcase()
-      |> thumb_format()
+      |> thumb_format(nil)
 
     "#{root}/#{view}/#{year}/#{month}/#{day}/#{filename}.#{format}"
   end
@@ -136,8 +136,9 @@ defmodule PhilomenaWeb.ImageView do
     conn.assigns.current_user.anonymous_by_default
   end
 
-  defp thumb_format("svg"), do: "png"
-  defp thumb_format(format), do: format
+  defp thumb_format("svg", _name), do: "png"
+  defp thumb_format(_, :rendered), do: "png"
+  defp thumb_format(format, _name), do: format
 
   defp image_filter_data(image) do
     %{

lib/philomena_web/views/layout_view.ex

@@ -1,6 +1,8 @@
 defmodule PhilomenaWeb.LayoutView do
   use PhilomenaWeb, :view
 
+  alias PhilomenaWeb.ImageView
+
   def layout_class(conn) do
     conn.assigns[:layout_class] || "layout--narrow"
   end
@@ -71,4 +73,7 @@ defmodule PhilomenaWeb.LayoutView do
 
   def stylesheet_path(conn, _user),
     do: Routes.static_path(conn, "/css/default.css")
+
+  def artist_tags(tags),
+    do: Enum.filter(tags, & &1.namespace == "artist")
 end