Iterate interactors following feedback

Following feedback on the first draft of interactors for images this
makes a number of changes:

- Changes the class naming to be suffixed with interactor. As these are
  mostly named with verbs this is a bit weird as it sounds like they
  create an interactor, however it is consistent with most other app
  level naming patterns.
- Makes clearer the properties in play on a context by delegating each
  of them to context in the interactor class.
- Drops using an update_context method to set context at the end of an
  interactor and instead uses an approach where context properties are
  set in the call method.
- Run an interactor in an explicit transaction rather than using the
  `Edition.find_and_lock_current` method. Since we're setting
  context.edition we'd still have a line of code so we don't really
  benefit from the yield.
- Uses a suggestion from Ben to define each instance variable we use
  from a result in a controller, by using values_at method on the result
  object (once converted to a hash)
- Rather than checking on failure of a result check on a particular
  problem, such as issues.

app/controllers/images_controller.rb

@@ -7,20 +7,24 @@ def index
   end
 
   def create
-    result = Images::Create.call(params: params, user: current_user)
-    if result.failure?
+    result = Images::CreateInteractor.call(params: params, user: current_user)
+    edition, image_revision, issues = result.to_h.values_at(:edition,
+                                                            :image_revision,
+                                                            :issues)
+
+    if issues
       flash.now["alert_with_items"] = {
         "title" => I18n.t!("images.index.flashes.upload_requirements"),
-        "items" => result.issues.items,
+        "items" => issues.items,
       }
 
       render :index,
-             assigns: { edition: result.edition },
+             assigns: { edition: edition },
              layout: rendering_context,
              status: :unprocessable_entity
     else
-      redirect_to crop_image_path(result.edition.document,
-                                  result.image_revision.image_id,
+      redirect_to crop_image_path(edition.document,
+                                  image_revision.image_id,
                                   wizard: "upload")
     end
   end
@@ -32,9 +36,10 @@ def crop
   end
 
   def update_crop
-    result = Images::UpdateCrop.call(params: params, user: current_user)
-    redirect_to edit_image_path(result.edition.document,
-                                result.image_revision.image_id,
+    result = Images::UpdateCropInteractor.call(params: params, user: current_user)
+    edition, image_revision = result.to_h.values_at(:edition, :image_revision)
+    redirect_to edit_image_path(edition.document,
+                                image_revision.image_id,
                                 wizard: params[:wizard])
   end
 
@@ -45,49 +50,51 @@ def edit
   end
 
   def update
-    result = Images::Update.call(params: params, user: current_user)
+    result = Images::UpdateInteractor.call(params: params, user: current_user)
+
+    edition, image_revision, issues, lead_selected, lead_removed =
+      result.to_h.values_at(:edition,
+                            :image_revision,
+                            :issues,
+                            :selected_lead_image,
+                            :removed_lead_image)
 
-    if result.failure?
+    if issues
       flash.now["alert_with_items"] = {
         "title" => I18n.t!("images.edit.flashes.requirements"),
-        "items" => result.issues.items,
+        "items" => issues.items,
       }
 
       render :edit,
-             assigns: { edition: result.edition,
-                        image_revision: result.image_revision,
-                        issues: result.issues },
+             assigns: { edition: edition,
+                        image_revision: image_revision,
+                        issues: issues },
              layout: rendering_context,
              status: :unprocessable_entity
+    elsif lead_selected
+      redirect_to document_path(edition.document),
+                  notice: t("documents.show.flashes.lead_image.selected", file: image_revision.filename)
+    elsif lead_removed
+      redirect_to images_path(edition.document),
+                  notice: t("images.index.flashes.lead_image.removed", file: image_revision.filename)
     else
-      document = result.edition.document
-
-      if result.updater.selected_lead_image?
-        redirect_to document_path(document),
-                    notice: t("documents.show.flashes.lead_image.selected",
-                              file: result.image_revision.filename)
-      elsif result.updater.removed_lead_image?
-        redirect_to images_path(document),
-                    notice: t("images.index.flashes.lead_image.removed",
-                              file: result.image_revision.filename)
-      else
-        redirect_to images_path(document)
-      end
+      redirect_to images_path(edition.document)
     end
   end
 
   def destroy
-    result = Images::Destroy.call(params: params, user: current_user)
-    document = result.edition.document
-
-    if result.updater.removed_lead_image?
-      redirect_to images_path(document),
+    result = Images::DestroyInteractor.call(params: params, user: current_user)
+    edition, image_revision, removed_lead = result.to_h.values_at(:edition,
+                                                                  :image_revision,
+                                                                  :removed_lead_image)
+    if removed_lead
+      redirect_to images_path(edition.document),
                   notice: t("images.index.flashes.lead_image.deleted",
-                            file: result.image_revision.filename)
+                            file: image_revision.filename)
     else
-      redirect_to images_path(document),
+      redirect_to images_path(edition.document),
                   notice: t("images.index.flashes.deleted",
-                            file: result.image_revision.filename)
+                            file: image_revision.filename)
     end
   end
 

app/interactors/images/create_interactor.rb

@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+class Images::CreateInteractor
+  include Interactor
+  delegate :params,
+           :user,
+           :edition,
+           :image_revision,
+           :issues,
+           to: :context
+
+  def initialize(params:, user:)
+    super
+  end
+
+  def call
+    Edition.transaction do
+      context.edition = Edition.lock.find_current(document: params[:document])
+      check_for_issues(params[:image])
+
+      context.image_revision = upload_image(params[:image])
+      update_edition
+    end
+  end
+
+private
+
+  def check_for_issues(image_params)
+    issues = Requirements::ImageUploadChecker.new(image_params).issues
+    context.fail!(issues: issues) if issues.any?
+  end
+
+  def upload_image(image_params)
+    ImageUploadService.new(image_params, edition.revision).call(user)
+  end
+
+  def update_edition
+    Versioning::RevisionUpdater.new(edition.revision, user).tap do |updater|
+      updater.update_image(image_revision, false)
+      edition.assign_revision(updater.next_revision, user).save!
+    end
+  end
+end

app/interactors/images/destroy_interactor.rb

@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+class Images::DestroyInteractor
+  include Interactor
+  delegate :params,
+           :user,
+           :edition,
+           :image_revision,
+           :removed_lead_image,
+           to: :context
+
+  def initialize(params:, user:)
+    super
+  end
+
+  def call
+    Edition.transaction do
+      context.edition = Edition.lock.find_current(document: params[:document])
+      context.image_revision = edition.image_revisions.find_by!(image_id: params[:image_id])
+
+      updater = remove_image(image_revision)
+      create_timeline_entry
+      update_preview
+
+      context.removed_lead_image = updater.removed_lead_image?
+    end
+  end
+
+private
+
+  def remove_image(image_revision)
+    Versioning::RevisionUpdater.new(edition.revision, user).tap do |updater|
+      updater.remove_image(image_revision)
+      edition.assign_revision(updater.next_revision, user).save!
+    end
+  end
+
+  def create_timeline_entry
+    TimelineEntry.create_for_revision(entry_type: :image_deleted, edition: edition)
+  end
+
+  def update_preview
+    PreviewService.new(edition).try_create_preview
+  end
+end