🎁 Add action to re-split PDF

For applications that have already installed IiifPrint, you'll need to
manually add the following to your `config/routes.rb` file:

```ruby
mount IiifPrint::Engine, at: '/'
```

Related to:

- #292
- #294

Co-authored-by: LaRita Robinson <[email protected]>

app/controllers/iiif_print/split_pdfs_controller.rb

@@ -0,0 +1,38 @@
+module IiifPrint
+  # Responsible for coordinating the request to resplit a PDF.
+  class SplitPdfsController < ApplicationController
+    before_action :authenticate_user!
+
+    def create
+      @file_set = FileSet.where(id: params[:file_set_id]).first
+      authorize_create_split_request!(@file_set)
+      IiifPrint::Jobs::RequestSplitPdfJob.perform_later(file_set: @file_set, user: current_user)
+      respond_to do |wants|
+        wants.html { redirect_to polymorphic_path([main_app, @file_set]), flash: t("iiif_print.file_set.split_submitted", id: @file_set.id) }
+        wants.json { render json: { id: @file_set.id, to_param: @file_set.to_param }, status: :ok }
+      end
+    end
+
+    private
+
+    ##
+    # @param file_set [FileSet]
+    def authorize_create_split_request!(file_set)
+      # NOTE: Duplicates logic of Hyrax: https://github.com/samvera/hyrax/blob/b334e186e77691d7da8ed59ff27f091be1c2a700/app/controllers/hyrax/file_sets_controller.rb#L234-L241
+      #
+      # Namely if we don't have a file_set we need not proceed.
+      raise CanCan::AccessDenied unless file_set
+
+      ##
+      # Rely on CanCan's authorize! method.  We could add the :split_pdf action to the ability
+      # class.  But we're pigging backing on the idea that you can do this if you can edit the work.
+      authorize!(:edit, file_set)
+      raise "Expected #{file_set.class} ID=#{file_set.id} #to_param=#{file_set.to_param} to be a PDF.  Instead found mime_type of #{file_set.mime_type}." unless file_set.pdf?
+
+      work = IiifPrint.parent_for(file_set)
+      raise WorkNotConfiguredToSplitFileSetError.new(file_set: file_set, work: work) unless work&.iiif_print_config&.pdf_splitter_job&.presence
+
+      true
+    end
+  end
+end

app/views/hyrax/file_sets/_show_actions.html.erb

@@ -0,0 +1,23 @@
+<div class="form-actions">
+  <% if Hyrax.config.analytics? %>
+    <% # turbolinks needs to be turned off or the page will use the cache and the %>
+    <% # analytics graph will not show unless the page is refreshed. %>
+    <%= link_to t('.analytics'), @presenter.stats_path, id: 'stats', class: 'btn btn-default', data: { turbolinks: false } %>
+  <% end %>
+
+  <% if @presenter.editor? && !workflow_restriction?(@presenter) %>
+      <%= link_to t(".edit_this", type: @presenter.human_readable_type), edit_polymorphic_path([main_app, @presenter]),
+                  class: 'btn btn-default' %>
+      <%= link_to t(".delete_this", type: @presenter.human_readable_type), [main_app, @presenter],
+                  class: 'btn btn-danger', data: { confirm: t(".confirm_delete_this", type: @presenter.human_readable_type) },
+                  method: :delete %>
+  <% end %>
+
+  <% if @presenter.editor? && @presenter.pdf? %>
+    <%= link_to t("iiif_print.file_set.split_this"), split_pdf_path(@presenter),
+     class: 'btn btn-default', data: { confirm: t("iiif_print.file_set.confirm_split_this") },
+     method: :post %>
+  <% end %>
+
+  <%= render 'social_media' %>
+</div>

config/locales/iiif_print.en.yml

@@ -52,6 +52,10 @@ en:
         label: 'Place of publication'
       publication_title:
         label: 'Publication'
+    file_set:
+      split_this: 'Split PDF into multiple images.'
+      confirm_split_this: 'Split PDF into multiple images.'
+      split_submitted: 'Submitted PDF splitting job for FileSet ID=%{id}.'
     newspapers_search:
       title:                    'Search Newspapers'
       text:                     'Use this form to search for full-text newspaper content.'

config/routes.rb

@@ -0,0 +1,3 @@
+IiifPrint::Engine.routes.draw do
+  post "split_pdfs/:file_set_id" => "split_pdfs#create", as: :split_pdf
+end

lib/generators/iiif_print/install_generator.rb

@@ -22,6 +22,14 @@ def catalog_controller_configuration
       generate 'iiif_print:catalog_controller'
     end
 
+    def install_routes
+      return if IO.read('config/routes.rb').include?('mount IiifPrint::Engine')
+
+      inject_into_file 'config/routes.rb', after: /mount Hyrax::Engine\s*\n/ do
+        "  mount IiifPrint::Engine, at: '/'\n"\
+      end
+    end
+
     def inject_configuration
       copy_file 'config/initializers/iiif_print.rb'
     end

lib/iiif_print/errors.rb

@@ -9,4 +9,13 @@ class DataError < IiifPrintError
 
   class MissingFileError < IiifPrintError
   end
+
+  class WorkNotConfiguredToSplitFileSetError < IiifPrintError
+    def initialize(file_set:, work:)
+      message = "Expected that we would be splitting #{file_set.class} ID=#{file_set&.id} #to_param=#{file_set&.to_param} " \
+                "for work #{work.class} ID=#{work&.id} #to_param=#{work&.to_param}.  " \
+                "However it was not configured for PDF splitting."
+      super(message)
+    end
+  end
 end

lib/iiif_print/jobs/request_split_pdf_job.rb

@@ -0,0 +1,38 @@
+module IiifPrint
+  module Jobs
+    ##
+    # Encapsulates logic for cleanup when the PDF is destroyed after pdf splitting into child works
+    class RequestSplitPdfJob < IiifPrint::Jobs::ApplicationJob
+      ##
+      # @param file_set [FileSet]
+      # @param user [User]
+      # rubocop:disable Metrics/MethodLength
+      def perform(file_set:, user:)
+        return true if file_set.pdf?
+
+        work = IiifPrint.parent_for(file_set)
+
+        # Woe is ye who changes the configuration of the model, thus removing the splitting.
+        raise WorkNotConfiguredToSplitFileSetError.new(work: work, file_set: file_set) unless work&.iiif_print_config&.pdf_splitter_job&.presence
+
+        # clean up any existing spawned child works of this file_set
+        IiifPrint::SplitPdfs::DestroyPdfChildWorksService.conditionally_destroy_spawned_children_of(
+          file_set: file_set,
+          work: work
+        )
+
+        location = Hyrax::WorkingDirectory.find_or_retrieve(file_set.files.first.id, file_set.id)
+
+        # submit a job to split pdf into child works
+        work.iiif_print_config.pdf_splitter_job.perform_later(
+          file_set,
+          [location],
+          user,
+          work.admin_set_id,
+          0 # A no longer used parameter; but we need to preserve the method signature (for now)
+        )
+      end
+      # rubocop:enable Metrics/MethodLength
+    end
+  end
+end