Make image_kind an attribute of ImageData

This will allow users to choose from a list of image kinds, when models
permit more than one kind of image.

The ImageKind mixin still creates an image_kind method as a fallback for
models which don't have an image_kind attribute (such as
FeaturedImageData)

app/controllers/admin/edition_images_controller.rb

@@ -93,6 +93,6 @@ def enforce_permissions!
   end
 
   def image_params
-    params.fetch(:image, {}).permit(image_data: [:file])
+    params.fetch(:image, {}).permit(image_data: %i[file image_kind])
   end
 end

app/models/concerns/edition/images.rb

@@ -39,6 +39,10 @@ def allows_image_attachments?
     true
   end
 
+  def permitted_image_kinds
+    Whitehall.image_kinds.values_at("default")
+  end
+
 private
 
   def no_substantive_attributes?(attrs)

app/models/concerns/image_kind.rb

@@ -3,7 +3,7 @@ module ImageKind
 
   included do
     def image_kind
-      "default"
+      attributes.fetch(:image_kind, "default")
     end
 
     def image_kind_config

app/views/admin/edition_images/_image_upload.html.erb

@@ -15,6 +15,21 @@
     accept: "image/png, image/jpeg, image/gif, image/svg+xml",
   } %>
 
+  <% if @edition.permitted_image_kinds.size == 1 %>
+    <%= hidden_field_tag("image[image_data][image_kind]", @edition.permitted_image_kinds.first.name) %>
+  <% else %>
+    <%= render "govuk_publishing_components/components/radio", {
+      heading: "What kind of image is this?",
+      name: "image[image_data][image_kind]",
+      items: @edition.permitted_image_kinds.map do |image_kind|
+        {
+          value: image_kind.name,
+          text: image_kind.display_name,
+        }
+      end,
+    } %>
+  <% end %>
+
    <%= render "govuk_publishing_components/components/details", {
       title: "You must use an SVG for charts and diagrams",
     } do %>

db/migrate/20241105092100_add_image_kind_to_image_data.rb

@@ -0,0 +1,5 @@
+class AddImageKindToImageData < ActiveRecord::Migration[7.1]
+  def change
+    add_column :image_data, :image_kind, :string, default: "default", null: false
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.1].define(version: 2024_10_15_123028) do
+ActiveRecord::Schema[7.1].define(version: 2024_11_05_092100) do
   create_table "assets", charset: "utf8mb3", force: :cascade do |t|
     t.string "asset_manager_id", null: false
     t.string "variant", null: false
@@ -666,6 +666,7 @@
     t.string "carrierwave_image"
     t.datetime "created_at", precision: nil
     t.datetime "updated_at", precision: nil
+    t.string "image_kind", default: "default", null: false
   end
 
   create_table "images", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|