Present hero images inside landing page blocks

app/presenters/publishing_api/landing_page_presenter.rb

@@ -4,6 +4,8 @@ class LandingPagePresenter
 
     attr_reader :update_type
 
+    IMAGE_PATTERN = /^\[Image:\s*(.*?)\s*\]/
+
     def initialize(item, update_type: nil)
       @item = item
       @update_type = update_type || default_update_type(item)
@@ -50,10 +52,75 @@ def details
       body = YAML.load(item.body, permitted_classes: [Date])
               .merge(PayloadBuilder::Attachments.for(item))
       extends_slug = body.delete("extends")
-      return body unless extends_slug
+      if extends_slug
+        extends = Document.find_by(slug: extends_slug).latest_edition
+        extends_body = YAML.load(extends.body, permitted_classes: [Date])
+        body.reverse_merge!(extends_body)
+      end
+
+      recursively_expand_images(body.deep_symbolize_keys)
+    end
+
+    def recursively_expand_images(input)
+      case input
+      in { type: "hero", image: { sources: { desktop:, tablet:, mobile: } }, **rest }
+        {
+          type: "hero",
+          image: present_hero_image(desktop, tablet, mobile),
+          **recursively_expand_images(rest),
+        }
+      in Hash => h
+        h.transform_values { recursively_expand_images(_1) }
+      in Array => a
+        a.map { recursively_expand_images(_1) }
+      else
+        input
+      end
+    end
+
+    def present_hero_image(desktop, tablet, mobile)
+      images = find_images(desktop, tablet, mobile)
+      return { errors: ["Some image expressions weren't correctly formatted, or images could not be found"] } if images.any?(&:nil?)
+      return { errors: ["Some image variants hadn't finished uploading"] } unless images.map(&:image_data).all?(&:all_asset_variants_uploaded?)
 
-      extends = Document.find_by(slug: extends_slug).latest_edition
-      YAML.load(extends.body, permitted_classes: [Date]).merge(body)
+      desktop_image, tablet_image, mobile_image = images
+
+      {
+        alt: present_alt_text(images),
+        sources: {
+          desktop: desktop_image.url(:hero_desktop_1x),
+          desktop_2x: desktop_image.url(:hero_desktop_2x),
+          tablet: tablet_image.url(:hero_tablet_1x),
+          tablet_2x: tablet_image.url(:hero_tablet_2x),
+          mobile: mobile_image.url(:hero_mobile_1x),
+          mobile_2x: mobile_image.url(:hero_mobile_2x),
+        },
+      }
+    end
+
+    def find_images(*image_expressions)
+      image_expressions.map do |image_expression|
+        match = IMAGE_PATTERN.match(image_expression)
+        if match.nil?
+          nil
+        else
+          image_id = match.captures.first
+          item.images.find { _1.filename == image_id }
+        end
+      end
+    end
+
+    def present_alt_text(images)
+      unique_alt_text = images.map(&:alt_text).compact.uniq
+      case unique_alt_text
+      in []
+        nil
+      in [alt_text]
+        alt_text
+      in Array
+        warn("Different images had different alt text, using the first option")
+        unique_alt_text.first
+      end
     end
   end
 end

test/factories/image_data.rb

@@ -23,6 +23,26 @@
     end
   end
 
+  factory :hero_image_data, class: ImageData do
+    file { image_fixture_file }
+
+    image_kind { "hero_desktop" }
+
+    after(:build) do |image_data|
+      image_data.assets << build(:asset, asset_manager_id: "asset_manager_id_original", variant: Asset.variants[:original], filename: image_data.filename)
+      variants = %W[#{image_data.image_kind}_2x #{image_data.image_kind}_1x]
+      variants.each do |variant|
+        image_data.assets << build(:asset, asset_manager_id: "asset_manager_id_#{variant}", variant: Asset.variants[variant], filename: "#{variant}_#{image_data.filename}")
+      end
+
+      # Defining this method is a bit of a hack, but with FactoryBot created model,
+      # the file_url method just returns nil, which makes it less useful for testing
+      def image_data.file_url(variant)
+        "http://asset-manager/#{assets.find_by(variant:).asset_manager_id}"
+      end
+    end
+  end
+
   factory :image_data, parent: :generic_image_data, traits: [:jpg]
   factory :image_data_for_svg, parent: :generic_image_data, traits: [:svg]
   factory :image_data_with_no_assets, parent: :generic_image_data

test/unit/app/presenters/publishing_api/landing_page_presenter_test.rb

@@ -117,4 +117,132 @@ class PublishingApi::LandingPagePresenterTest < ActiveSupport::TestCase
 
     assert_equal expected_details, presented_content[:details].deep_stringify_keys
   end
+
+  test "it recursively expands images in the body" do
+    body = <<~YAML
+      blocks:
+      - type: hero
+        image:
+          sources:
+            desktop: "[Image: hero_image_desktop_2x.png]"
+            tablet: "[Image: hero_image_tablet_2x.png]"
+            mobile: "[Image: hero_image_mobile_2x.png]"
+        hero_content:
+          blocks:
+          - type: govspeak
+            content: "some content"
+      - type: grid_container
+        blocks:
+        - type: hero
+          image:
+            sources:
+              desktop: "[Image: hero_image_desktop_2x.png]"
+              tablet: "[Image: hero_image_tablet_2x.png]"
+              mobile: "[Image: hero_image_mobile_2x.png]"
+          hero_content:
+            blocks:
+            - type: govspeak
+              content: "some content"
+    YAML
+
+    landing_page = create(
+      :landing_page,
+      document: create(:document, id: 12_346, slug: "/landing-page/with-images"),
+      body:,
+      title: "Landing Page title",
+      summary: "Landing Page summary",
+      first_published_at: @first_published_at = Time.zone.now,
+      updated_at: 1.year.ago,
+      images: [
+        build(:image, image_data: build(:hero_image_data, image_kind: "hero_desktop", file: upload_fixture("hero_image_desktop_2x.png", "image/png"))),
+        build(:image, image_data: build(:hero_image_data, image_kind: "hero_tablet", file: upload_fixture("hero_image_tablet_2x.png", "image/png"))),
+        build(:image, image_data: build(:hero_image_data, image_kind: "hero_mobile", file: upload_fixture("hero_image_mobile_2x.png", "image/png"))),
+      ],
+    )
+
+    presented_landing_page = PublishingApi::LandingPagePresenter.new(landing_page)
+    presented_content = I18n.with_locale("en") { presented_landing_page.content }
+
+    assert_pattern do
+      presented_content[:details].deep_symbolize_keys => {
+      blocks: [
+        {
+          type: "hero",
+          image: {
+            sources: {
+              desktop_2x: "http://asset-manager/asset_manager_id_hero_desktop_2x",
+              desktop: "http://asset-manager/asset_manager_id_hero_desktop_1x",
+              tablet_2x: "http://asset-manager/asset_manager_id_hero_tablet_2x",
+              tablet: "http://asset-manager/asset_manager_id_hero_tablet_1x",
+              mobile_2x: "http://asset-manager/asset_manager_id_hero_mobile_2x",
+              mobile: "http://asset-manager/asset_manager_id_hero_mobile_1x",
+            }
+          },
+          hero_content: {
+            blocks: [ { type: "govspeak", content: String } ]
+          }
+        },
+        {
+          type: "grid_container",
+          blocks: [{
+            type: "hero",
+            image: {
+              sources: {
+                desktop_2x: "http://asset-manager/asset_manager_id_hero_desktop_2x",
+                desktop: "http://asset-manager/asset_manager_id_hero_desktop_1x",
+                tablet_2x: "http://asset-manager/asset_manager_id_hero_tablet_2x",
+                tablet: "http://asset-manager/asset_manager_id_hero_tablet_1x",
+                mobile_2x: "http://asset-manager/asset_manager_id_hero_mobile_2x",
+                mobile: "http://asset-manager/asset_manager_id_hero_mobile_1x",
+              }
+            },
+            hero_content: {
+              blocks: [ { type: "govspeak", content: String } ]
+            }
+          }],
+        },
+      ]}
+    end
+  end
+
+  test "it presents errors if files are not found" do
+    body = <<~YAML
+      blocks:
+      - type: hero
+        image:
+          sources:
+            desktop: "[Image: non-existent-file.jpg]"
+            tablet: "[Image: non-existent-file.jpg]"
+            mobile: "[Image: non-existent-file.jpg]"
+    YAML
+
+    landing_page = create(
+      :landing_page,
+      document: create(:document, id: 12_346, slug: "/landing-page/with-images"),
+      body:,
+      title: "Landing Page title",
+      summary: "Landing Page summary",
+      first_published_at: @first_published_at = Time.zone.now,
+      updated_at: 1.year.ago,
+      images: [],
+    )
+
+    presented_landing_page = PublishingApi::LandingPagePresenter.new(landing_page)
+    presented_content = I18n.with_locale("en") { presented_landing_page.content }
+    details = presented_content[:details].deep_symbolize_keys
+
+    assert_pattern do
+      details =>
+      {
+        blocks: [
+          {
+            type: "hero",
+            image: {
+               errors: ["Some image expressions weren't correctly formatted, or images could not be found"],
+            }
+          },
+        ],
+      }
+    end
+  end
 end