fixes #96: add tag blacklist

config/tag.json

@@ -0,0 +1,20 @@
+{
+  "blacklist": [
+    "tagme",
+    "tag me",
+    "not tagged",
+    "no tag",
+    "notag",
+    "notags",
+    "upvotes galore",
+    "downvotes galore",
+    "wall of faves",
+    "drama in the comments",
+    "drama in comments",
+    "tag needed",
+    "paywall",
+    "cringeworthy",
+    "solo oc",
+    "tag your shit"
+  ]
+}

lib/philomena/images/tag_validator.ex

@@ -1,4 +1,5 @@
 defmodule Philomena.Images.TagValidator do
+  alias Philomena.Servers.Config
   import Ecto.Changeset
 
   @safe_rating MapSet.new(["safe"])
@@ -19,6 +20,7 @@ defmodule Philomena.Images.TagValidator do
 
     changeset
     |> validate_number_of_tags(tag_set, 3)
+    |> validate_bad_words(tag_set)
     |> validate_has_rating(rating_set)
     |> validate_safe(rating_set)
     |> validate_sexual_exclusion(rating_set)
@@ -50,6 +52,19 @@ defmodule Philomena.Images.TagValidator do
     end
   end
 
+  def validate_bad_words(changeset, tag_set) do
+    bad_words = MapSet.new(Config.get(:tag)["blacklist"])
+    intersection = MapSet.intersection(tag_set, bad_words)
+
+    cond do
+      MapSet.size(intersection) > 0 ->
+        Enum.reduce(intersection, changeset, &add_error(&2, :tag_input, "contains forbidden tag `#{&1}'"))
+
+      true ->
+        changeset
+    end
+  end
+
   defp validate_has_rating(changeset, %{safe: s, sexual: x, horror: h, gross: g})
        when s == @empty and x == @empty and h == @empty and g == @empty do
     changeset