Add gab rewrite policy

lib/pleroma/web/activity_pub/mrf/gab_rewrite_policy.ex

@@ -0,0 +1,46 @@
+defmodule Pleroma.Web.ActivityPub.MRF.GABRewritePolicy do
+  @moduledoc "Adds stupid quotes to gab users"
+  @behaviour Pleroma.Web.ActivityPub.MRF
+  @domain "gab.com"
+  @appends [
+    "Sent from AOL Mobile Mail",
+    "John had surgery Friday and he's with the lord now.",
+    "Lovely pics as alway, Janice. I have terminal brain cancer.",
+    "DISCUSTING",
+    "I DID NOT POST THAT! SOMEONE HAS HACKED MY ACCOUNT",
+    "LOVE ETHYL",
+    "Just got back from the doctor. I have Ebola. See you at church on Sunday!",
+    "ADULT ONLY",
+    "Are you my grandson?",
+    "http://m.facebook.com",
+    "WISH GOD WOULD TAKE ME.",
+    "YOU SURE ARE A LONG BABY",
+    "REFURBISHD +OK?",
+    "THIS EMAIL IS INTENDED FOR THE RECIPIENT ONLY. PLEASE THINK ABOUT THE ENVIRONMENT BEFORE YOU PRINT THIS MESSAGE",
+    "AC/DC is my favourite band",
+    "BRAD'S WIFE!",
+    "Order corn!",
+    "Yim yum",
+    "My 49 year old son, Shane, died this morning.",
+    "I called Mr uber",
+    "Coconut oil.",
+    "price for apple sauce at walmart",
+    "no SWEARING on my timeline!"
+  ]
+
+  def add(%{"object" => %{"content" => content}} = object) do
+    put_in(object, ["object", "content"], content <> " " <> Enum.random(@appends))
+  end
+
+  @impl true
+  def filter(%{"type" => "Create", "actor" => actor} = object) do
+    actor_info = URI.parse(actor)
+    if String.contains?(actor_info.host, @domain) do
+      {:ok, add(object)}
+    else
+      {:ok, object}
+    end
+  end
+
+  def filter(object), do: {:ok, object}
+end