Fix title & meta

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

lib/mobilizon_web/views/page_view.ex

@@ -7,6 +7,7 @@ defmodule MobilizonWeb.PageView do
   alias Mobilizon.Service.ActivityPub.{Converter, Utils}
   alias Mobilizon.Service.Metadata
   alias Mobilizon.Service.MetadataUtils
+  alias Mobilizon.Service.Metadata.Instance
 
   def render("actor.activity-json", %{conn: %{assigns: %{object: actor}}}) do
     public_key = Utils.pem_to_public_key_pem(actor.keys)
@@ -80,6 +81,8 @@ defmodule MobilizonWeb.PageView do
 
   def render("index.html", _assigns) do
     with {:ok, index_content} <- File.read(index_file_path()) do
+      tags = Instance.build_tags() |> MetadataUtils.stringify_tags()
+      index_content = String.replace(index_content, "<!--server-generated-meta-->", tags)
       {:safe, index_content}
     end
   end

lib/service/metadata/instance.ex

@@ -0,0 +1,46 @@
+defmodule Mobilizon.Service.Metadata.Instance do
+  @moduledoc """
+  Generates metadata for every other page that isn't event/actor/comment
+  """
+
+  alias Phoenix.HTML
+  alias Phoenix.HTML.Tag
+  alias Mobilizon.Config
+  alias MobilizonWeb.Endpoint
+
+  def build_tags() do
+    description = process_description(Config.instance_description())
+    title = "#{Config.instance_name()} - Mobilizon"
+
+    instance_json_ld = """
+    <script type="application/ld+json">{
+    "@context": "http://schema.org",
+    "@type": "WebSite",
+    "name": "#{title}",
+    "url": "#{Endpoint.url()}",
+    "potentialAction": {
+    "@type": "SearchAction",
+    "target": "#{Endpoint.url()}/search/{search_term}",
+    "query-input": "required name=search_term"
+    }
+    }</script>
+    """
+
+    [
+      Tag.content_tag(:title, title),
+      Tag.tag(:meta, name: "description", content: description),
+      Tag.tag(:meta, property: "og:title", content: title),
+      Tag.tag(:meta, property: "og:url", content: Endpoint.url()),
+      Tag.tag(:meta, property: "og:description", content: description),
+      Tag.tag(:meta, property: "og:type", content: "website"),
+      HTML.raw(instance_json_ld)
+    ]
+  end
+
+  defp process_description(description) do
+    description
+    |> HtmlSanitizeEx.strip_tags()
+    |> String.slice(0..200)
+    |> (&"#{&1}…").()
+  end
+end