add documents preview endpoint

app/controllers/api/submission_documents_controller.rb

@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+module Api
+  class SubmissionDocumentsController < ApiBaseController
+    load_and_authorize_resource :submission
+
+    def index
+      documents =
+        if @submission.submitters.all?(&:completed_at?)
+          last_submitter = @submission.submitters.max_by(&:completed_at)
+
+          if last_submitter.documents_attachments.blank?
+            last_submitter.documents_attachments = Submissions::EnsureResultGenerated.call(submitter)
+          end
+
+          last_submitter.documents_attachments
+        else
+          values_hash = Submissions::GeneratePreviewAttachments.build_values_hash(@submission)
+
+          if @submission.preview_documents.present? &&
+             @submission.preview_documents.all? { |s| s.metadata['values_hash'] == values_hash }
+            @submission.preview_documents
+          else
+            ApplicationRecord.no_touching do
+              @submission.preview_documents.each(&:destroy)
+            end
+
+            Submissions::GeneratePreviewAttachments.call(@submission, values_hash:)
+          end
+        end
+
+      ActiveRecord::Associations::Preloader.new(
+        records: documents,
+        associations: [:blob]
+      ).call
+
+      render json: {
+        id: @submission.id,
+        documents: documents.map do |attachment|
+          { name: attachment.filename.base, url: ActiveStorage::Blob.proxy_url(attachment.blob) }
+        end
+      }
+    end
+  end
+end

app/models/submission.rb

@@ -55,6 +55,8 @@ class Submission < ApplicationRecord
   has_one_attached :audit_trail
   has_one_attached :combined_document
 
+  has_many_attached :preview_documents
+
   has_many :template_schema_documents,
            ->(e) { where(uuid: (e.template_schema.presence || e.template.schema).pluck('attachment_uuid')) },
            through: :template, source: :documents_attachments

config/routes.rb

@@ -34,6 +34,7 @@ Rails.application.routes.draw do
     resources :submitter_form_views, only: %i[create]
     resources :submitters, only: %i[index show update]
     resources :submissions, only: %i[index show create destroy] do
+      resources :documents, only: %i[index], controller: 'submission_documents'
       collection do
         resources :init, only: %i[create], controller: 'submissions'
         resources :emails, only: %i[create], controller: 'submissions', as: :submissions_emails

lib/submissions/generate_preview_attachments.rb

@@ -0,0 +1,96 @@
+# frozen_string_literal: true
+
+module Submissions
+  module GeneratePreviewAttachments
+    module_function
+
+    # rubocop:disable Metrics
+    def call(submission, values_hash: nil)
+      values_hash ||= build_values_hash(submission)
+
+      with_signature_id = submission.account.account_configs
+                                    .exists?(key: AccountConfig::WITH_SIGNATURE_ID, value: true)
+
+      is_flatten =
+        submission.account.account_configs
+                  .find_or_initialize_by(key: AccountConfig::FLATTEN_RESULT_PDF_KEY).value != false
+
+      pdfs_index = GenerateResultAttachments.build_pdfs_index(submission, flatten: is_flatten)
+
+      submission.submitters.where(completed_at: nil).preload(attachments_attachments: :blob).each do |submitter|
+        GenerateResultAttachments.fill_submitter_fields(submitter, submission.account, pdfs_index,
+                                                        with_signature_id:, is_flatten:)
+      end
+
+      template = submission.template
+
+      image_pdfs = []
+      original_documents = template.documents.preload(:blob)
+
+      result_attachments =
+        submission.template_schema.map do |item|
+          pdf = pdfs_index[item['attachment_uuid']]
+
+          if original_documents.find { |a| a.uuid == item['attachment_uuid'] }.image?
+            pdf = GenerateResultAttachments.normalize_image_pdf(pdf)
+
+            image_pdfs << pdf
+          end
+
+          build_pdf_attachment(pdf:, submission:,
+                               uuid: item['attachment_uuid'],
+                               values_hash:,
+                               name: item['name'])
+        end
+
+      return ApplicationRecord.no_touching { result_attachments.map { |e| e.tap(&:save!) } } if image_pdfs.size < 2
+
+      images_pdf =
+        image_pdfs.each_with_object(HexaPDF::Document.new) do |pdf, doc|
+          pdf.pages.each { |page| doc.pages << doc.import(page) }
+        end
+
+      images_pdf = GenerateResultAttachments.normalize_image_pdf(images_pdf)
+
+      images_pdf_attachment =
+        build_pdf_attachment(
+          pdf: images_pdf,
+          submission:,
+          uuid: GenerateResultAttachments.images_pdf_uuid(original_documents.select(&:image?)),
+          values_hash:,
+          name: template.name
+        )
+
+      ApplicationRecord.no_touching do
+        (result_attachments + [images_pdf_attachment]).map { |e| e.tap(&:save!) }
+      end
+    end
+
+    def build_values_hash(submission)
+      submission.submitters.reduce({}) { |acc, s| acc.merge(s.values) }.hash
+    end
+
+    def build_pdf_attachment(pdf:, submission:, uuid:, name:, values_hash:)
+      io = StringIO.new
+
+      begin
+        pdf.write(io, incremental: true, validate: false)
+      rescue HexaPDF::MalformedPDFError => e
+        Rollbar.error(e) if defined?(Rollbar)
+
+        pdf.write(io, incremental: false, validate: false)
+      end
+
+      ActiveStorage::Attachment.new(
+        blob: ActiveStorage::Blob.create_and_upload!(io: io.tap(&:rewind), filename: "#{name}.pdf"),
+        metadata: { original_uuid: uuid,
+                    values_hash:,
+                    analyzed: true,
+                    sha256: Base64.urlsafe_encode64(Digest::SHA256.digest(io.string)) },
+        name: 'preview_documents',
+        record: submission
+      )
+    end
+    # rubocop:enable Metrics
+  end
+end

lib/submissions/generate_result_attachments.rb

@@ -92,19 +92,13 @@ module Submissions
     end
 
     def generate_pdfs(submitter)
-      cell_layouter = HexaPDF::Layout::TextLayouter.new(text_valign: :center, text_align: :center)
+      configs = submitter.account.account_configs.where(key: [AccountConfig::FLATTEN_RESULT_PDF_KEY,
+                                                              AccountConfig::WITH_SIGNATURE_ID])
 
-      with_signature_id = submitter.account.account_configs
-                                   .exists?(key: AccountConfig::WITH_SIGNATURE_ID, value: true)
+      with_signature_id = configs.find { |c| c.key == AccountConfig::WITH_SIGNATURE_ID }&.value == true
+      is_flatten = configs.find { |c| c.key == AccountConfig::FLATTEN_RESULT_PDF_KEY }&.value != false
 
-      is_flatten =
-        submitter.account.account_configs
-                 .find_or_initialize_by(key: AccountConfig::FLATTEN_RESULT_PDF_KEY).value != false
-
-      account = submitter.account
-      attachments_data_cache = {}
-
-      pdfs_index = build_pdfs_index(submitter, flatten: is_flatten)
+      pdfs_index = build_pdfs_index(submitter.submission, submitter:, flatten: is_flatten)
 
       if with_signature_id || submitter.account.testing?
         pdfs_index.each_value do |pdf|
@@ -145,6 +139,16 @@ module Submissions
         end
       end
 
+      fill_submitter_fields(submitter, submitter.account, pdfs_index, with_signature_id:, is_flatten:)
+
+      pdfs_index
+    end
+
+    def fill_submitter_fields(submitter, account, pdfs_index, with_signature_id:, is_flatten:)
+      cell_layouter = HexaPDF::Layout::TextLayouter.new(text_valign: :center, text_align: :center)
+
+      attachments_data_cache = {}
+
       submitter.submission.template_fields.each do |field|
         next if field['submitter_uuid'] != submitter.uuid
 
@@ -442,8 +446,6 @@ module Submissions
           end
         end
       end
-
-      pdfs_index
     end
 
     def build_pdf_attachment(pdf:, submitter:, pkcs:, tsa_url:, uuid:, name:)
@@ -514,13 +516,13 @@ module Submissions
       Digest::UUID.uuid_v5(Digest::UUID::OID_NAMESPACE, attachments.map(&:uuid).sort.join(':'))
     end
 
-    def build_pdfs_index(submitter, flatten: true)
-      latest_submitter = find_last_submitter(submitter)
+    def build_pdfs_index(submission, submitter: nil, flatten: true)
+      latest_submitter = find_last_submitter(submission, submitter:)
 
       Submissions::EnsureResultGenerated.call(latest_submitter) if latest_submitter
 
       documents   = latest_submitter&.documents&.preload(:blob).to_a.presence
-      documents ||= submitter.submission.template_schema_documents.preload(:blob)
+      documents ||= submission.template_schema_documents.preload(:blob)
 
       documents.to_h do |attachment|
         pdf =
@@ -582,11 +584,11 @@ module Submissions
       font_wrapper.custom_glyph(replace_with, character)
     end
 
-    def find_last_submitter(submitter)
-      submitter.submission.submitters
-               .select(&:completed_at?)
-               .select { |e| e.id != submitter.id && e.completed_at <= submitter.completed_at }
-               .max_by(&:completed_at)
+    def find_last_submitter(submission, submitter: nil)
+      submission.submitters
+                .select(&:completed_at?)
+                .select { |e| submitter.nil? ? true : e.id != submitter.id && e.completed_at <= submitter.completed_at }
+                .max_by(&:completed_at)
     end
 
     def build_pdf_from_image(attachment)