Expand images when presenting landing pages

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)
@@ -49,11 +51,60 @@ def document_type
     def details
       body = YAML.load(item.body, permitted_classes: [Date])
               .merge(PayloadBuilder::Attachments.for(item))
+
+      body = recursively_expand_images(body)
+
       extends_slug = body.delete("extends")
       return body unless extends_slug
 
       extends = Document.find_by(slug: extends_slug).latest_edition
       YAML.load(extends.body, permitted_classes: [Date]).merge(body)
     end
+
+    def recursively_expand_images(input)
+      case input
+      in String => s if s =~ IMAGE_PATTERN
+        image_id = IMAGE_PATTERN.match(s).captures.first
+        image = item.images.find { _1.filename == image_id }
+        present_image(image, s)
+      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_image(image, pattern)
+      return { errors: ["Image not found for pattern #{pattern}"] } if image.nil?
+
+      result = {
+        id: image.filename,
+        image_kind: image.image_data.image_kind,
+        alt_text: image.alt_text,
+        url: image.url,
+        caption: image.caption,
+        created_at: image.created_at,
+        updated_at: image.updated_at,
+      }
+
+      if image.image_data.all_asset_variants_uploaded?
+        result[:versions] = present_image_versions(image)
+      else
+        result[:errors] = ["Image versions have not finished uploading"]
+      end
+
+      result
+    end
+
+    def present_image_versions(image)
+      image.image_data.image_kind_config.versions.map do |v|
+        {
+          name: v.name,
+          url: image.url(v.name),
+        }
+      end
+    end
   end
 end

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

@@ -117,4 +117,105 @@ 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:
+          - "[Image: big-cheese.960x640.jpg]"
+          - "[Image: minister-of-funk.960x640.jpg]"
+      - type: grid_container
+        blocks:
+        - type: hero
+          image:
+            sources:
+            - "[Image: big-cheese.960x640.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: [
+        build(:image, image_data: build(:image_data, file: upload_fixture("big-cheese.960x640.jpg", "image/jpg"))),
+        build(:image, image_data: build(:image_data, file: upload_fixture("minister-of-funk.960x640.jpg", "image/jpg"))),
+      ],
+    )
+
+    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: [
+              { id: "big-cheese.960x640.jpg", image_kind: "default", versions: Array },
+              { id: "minister-of-funk.960x640.jpg", image_kind: "default", versions: Array },
+            ]
+          }
+        },
+        {
+          type: "grid_container",
+          blocks: [{
+            type: "hero",
+            image: {
+              sources: [
+                { id: "big-cheese.960x640.jpg", image_kind: "default", versions: Array },
+              ]
+            }
+          }],
+        },
+      ]}
+    end
+  end
+
+  test "it presents errors if files are not found" do
+    body = <<~YAML
+      blocks:
+      - type: hero
+        image:
+          sources:
+          - "[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: {
+              sources: [
+                { errors: ["Image not found for pattern [Image: non-existent-file.jpg]"] },
+              ]
+            }
+          },
+        ],
+      }
+    end
+  end
 end