Add invisible tags to TwAPI output.

lib/pleroma/web/twitter_api/representers/activity_representer.ex

 defmodule Pleroma.Web.TwitterAPI.Representers.ActivityRepresenter do
   use Pleroma.Web.TwitterAPI.Representers.BaseRepresenter
   alias Pleroma.Web.TwitterAPI.Representers.{UserRepresenter, ObjectRepresenter}
-  alias Pleroma.{Activity, User}
+  alias Pleroma.{Activity, User, Formatter}
   alias Calendar.Strftime
   alias Pleroma.Web.TwitterAPI.TwitterAPI
 
@@ -72,6 +72,18 @@ def to_map(%Activity{data: %{"type" => "Follow", "published" => created_at, "obj
     }
   end
 
+  def content_with_tags(content, tags) do
+    tags = tags || []
+    text_content = HtmlSanitizeEx.strip_tags(content)
+    found_tags = Formatter.parse_tags(text_content)
+    |> Enum.map(fn ({_, tag}) -> tag end)
+
+    missing_tags = tags -- found_tags
+    |> Enum.map(&"##{&1}")
+
+    Enum.join([content | missing_tags], "<br>\n")
+  end
+
   def to_map(%Activity{data: %{"object" => %{"content" => content} = object}} = activity, %{user: user} = opts) do
     created_at = object["published"] |> date_to_asctime
     like_count = object["like_count"] || 0
@@ -88,6 +100,8 @@ def to_map(%Activity{data: %{"object" => %{"content" => content} = object}} = ac
 
     conversation_id = conversation_id(activity)
 
+    content = content_with_tags(content, object["tag"])
+
     %{
       "id" => activity.id,
       "user" => UserRepresenter.to_map(user, opts),

test/support/httpoison_mock.ex

@@ -23,7 +23,7 @@ def get("https://social.heldscal.la/.well-known/webfinger", [Accept: "applicatio
       body: File.read!("test/fixtures/httpoison_mock/https___social.heldscal.la_user_23211.xml")
     }}
   end
-  
+
   def get("https://social.heldscal.la/.well-known/webfinger", [Accept: "application/xrd+xml"], [params: [resource: "https://social.heldscal.la/user/29191"]]) do
     {:ok, %Response{
       status_code: 200,

test/web/twitter_api/representers/activity_representer_test.exs

@@ -67,7 +67,7 @@ test "an activity" do
       }
     }
 
-    content_html = "Some content mentioning <a href='#{mentioned_user.ap_id}'>@shp</shp>"
+    content_html = "Some #content mentioning <a href='#{mentioned_user.ap_id}'>@shp</shp>"
     content = HtmlSanitizeEx.strip_tags(content_html)
     date = DateTime.from_naive!(~N[2016-05-24 13:26:08.003], "Etc/UTC") |> DateTime.to_iso8601
 
@@ -94,7 +94,8 @@ test "an activity" do
           ],
           "like_count" => 5,
           "announcement_count" => 3,
-          "context" => "2hu"
+          "context" => "2hu",
+          "tag" => ["nsfw", "content"]
         },
         "published" => date,
         "context" => "2hu"
@@ -107,8 +108,8 @@ test "an activity" do
       "user" => UserRepresenter.to_map(user, %{for: follower}),
       "is_local" => true,
       "attentions" => [],
-      "statusnet_html" => content_html,
-      "text" => content,
+      "statusnet_html" => content_html <> "<br>\n#nsfw",
+      "text" => content <> "\n#nsfw",
       "is_post_verb" => true,
       "created_at" => "Tue May 24 13:26:08 +0000 2016",
       "in_reply_to_status_id" => 213123,