Add permitted_uses to image kind config

This means we don't have to hardcode the fact that only default images are allowed to be embedded in govspeak. If we later have other kinds of images which are allowed to be embedded in govspeak, that could be represented in config too.

The permitted_uses array could be used in future for other situations where only some kinds of images are allowed to be used in a particular circumstance - for example in featured images, lead images, person images, etc.

app/helpers/govspeak_helper.rb

@@ -48,7 +48,7 @@ def govspeak_html_attachment_to_html(html_attachment)
 
   def prepare_images(images)
     images
-      .select { |image| image.image_data&.image_kind == "default" }
+      .select { |image| image.image_data&.image_kind_config&.permits? "govspeak_embed" }
       .select { |image| image.image_data&.all_asset_variants_uploaded? }
       .map do |image|
       {

config/image_kinds.yml

@@ -3,6 +3,8 @@ default:
   display_name: "Default (960 by 640)"
   valid_width: 960
   valid_height: 640
+  permitted_uses:
+    - govspeak_embed
   versions:
     - name: s960
       width: 960

lib/whitehall/image_kinds.rb

@@ -19,23 +19,28 @@ def resize_to_fill
   end
 
   class ImageKind
-    attr_reader :name, :display_name, :valid_width, :valid_height, :versions
+    attr_reader :name, :display_name, :valid_width, :valid_height, :permitted_uses, :versions
 
     def initialize(name, config)
       @name = name
       @display_name = config.fetch("display_name")
       @valid_width = config.fetch("valid_width")
       @valid_height = config.fetch("valid_height")
+      @permitted_uses = config.fetch("permitted_uses")
       @versions = config.fetch("versions").map { |version_config| ImageVersion.new(version_config) }.freeze
     end
 
     def deconstruct_keys(_keys)
-      { name:, display_name:, valid_width:, valid_height:, versions: }
+      { name:, display_name:, valid_width:, valid_height:, permitted_uses:, versions: }
     end
 
     def version_names
       versions.map(&:name)
     end
+
+    def permits?(use_case)
+      permitted_uses.include?(use_case)
+    end
   end
 
   class ImageKinds

test/unit/app/helpers/govspeak_helper_test.rb

@@ -197,11 +197,19 @@ def edition_with_attachment(body:)
     refute_select_within_html html, ".image.embedded"
   end
 
-  test "should ignore images with non-default image kinds" do
+  test "should ignore images with image kinds which do not permit use in govspeak embeds" do
     embed_code = "[Image: minister-of-funk.960x640.jpg]"
     body = "#Heading\n\n#{embed_code}\n\n##Subheading"
     image = build(:image)
-    image.image_data.image_kind = "some_non_default_image_kind"
+    image_data = image.image_data
+    def image_data.image_kind_config = Whitehall::ImageKind.new(
+      "some name",
+      "display_name" => "some display name",
+      "valid_width" => 0,
+      "valid_height" => 0,
+      "permitted_uses" => [],
+      "versions" => [],
+    )
     document = build(:published_news_article, images: [image], body:)
 
     html = govspeak_edition_to_html(document)

test/unit/app/validators/image_validator_test.rb

@@ -37,6 +37,7 @@ def image_kind_config
         Whitehall::ImageKind.new(
           "some image kind",
           "display_name" => "some image kind display name",
+          "permitted_uses" => [],
           "valid_width" => 50,
           "valid_height" => 33,
           "versions" => [],

test/unit/lib/image_kinds_test.rb

@@ -7,6 +7,7 @@ class ImageKindsTest < ActiveSupport::TestCase
         "display_name" => "default display name",
         "valid_width" => 1,
         "valid_height" => 2,
+        "permitted_uses" => [],
         "versions" => [
           {
             "name" => "some name",
@@ -42,6 +43,7 @@ class ImageKindsTest < ActiveSupport::TestCase
         "display_name" => "default display name",
         "valid_width" => 0,
         "valid_height" => 0,
+        "permitted_uses" => [],
         "versions" => %w[a b c d e f g].map do
           {
             "name" => _1,
@@ -55,6 +57,22 @@ class ImageKindsTest < ActiveSupport::TestCase
     assert_equal %w[a b c d e f g], result["default"].version_names
   end
 
+  test "#permits? checks if use cases are permitted" do
+    image_kind = Whitehall::ImageKind.new(
+      "default",
+      "display_name" => "default display name",
+      "valid_width" => 0,
+      "valid_height" => 0,
+      "permitted_uses" => %w[use_case_1 use_case_2 use_case_3],
+      "versions" => [],
+    )
+    assert_equal(true, image_kind.permits?("use_case_1"))
+    assert_equal(true, image_kind.permits?("use_case_2"))
+    assert_equal(true, image_kind.permits?("use_case_3"))
+    assert_equal(false, image_kind.permits?("use_case_4"))
+    assert_equal(false, image_kind.permits?("use_case_5"))
+  end
+
   test "raises errors when given invalid config" do
     # Missing display_name / valid_width / valid_height / versions keys
     assert_raise(KeyError, "key not found") { Whitehall::ImageKinds.build_image_kinds("default" => {}) }