From cc1d141127e1f3fa4f3e454460df3238cd062417 Mon Sep 17 00:00:00 2001
From: Andreas Brandl <abrandl@gitlab.com>
Date: Wed, 25 Apr 2018 15:19:55 +0200
Subject: [PATCH] Refactor and extract DefaultPaginationStrategy.

---
 lib/api/helpers/pagination.rb       | 117 +++++++++++++++-------------
 lib/gitlab/serializer/pagination.rb |   2 -
 2 files changed, 65 insertions(+), 54 deletions(-)

diff --git a/lib/api/helpers/pagination.rb b/lib/api/helpers/pagination.rb
index 09805049169..cf9501c31fe 100644
--- a/lib/api/helpers/pagination.rb
+++ b/lib/api/helpers/pagination.rb
@@ -2,67 +2,80 @@ module API
   module Helpers
     module Pagination
       def paginate(relation)
-        relation = add_default_order(relation)
-
-        relation.page(params[:page]).per(params[:per_page]).tap do |data|
-          add_pagination_headers(data)
-        end
+        DefaultPaginationStrategy.new(self).paginate(relation)
       end
 
-      private
+      class DefaultPaginationStrategy
+        attr_reader :ctx
+        delegate :params, :header, :request, to: :ctx
 
-      def add_pagination_headers(paginated_data)
-        header 'X-Per-Page',    paginated_data.limit_value.to_s
-        header 'X-Page',        paginated_data.current_page.to_s
-        header 'X-Next-Page',   paginated_data.next_page.to_s
-        header 'X-Prev-Page',   paginated_data.prev_page.to_s
-        header 'Link',          pagination_links(paginated_data)
-
-        return if data_without_counts?(paginated_data)
-
-        header 'X-Total',       paginated_data.total_count.to_s
-        header 'X-Total-Pages', total_pages(paginated_data).to_s
-      end
-
-      def pagination_links(paginated_data)
-        request_url = request.url.split('?').first
-        request_params = params.clone
-        request_params[:per_page] = paginated_data.limit_value
-
-        links = []
-
-        request_params[:page] = paginated_data.prev_page
-        links << %(<#{request_url}?#{request_params.to_query}>; rel="prev") if request_params[:page]
-
-        request_params[:page] = paginated_data.next_page
-        links << %(<#{request_url}?#{request_params.to_query}>; rel="next") if request_params[:page]
-
-        request_params[:page] = 1
-        links << %(<#{request_url}?#{request_params.to_query}>; rel="first")
-
-        unless data_without_counts?(paginated_data)
-          request_params[:page] = total_pages(paginated_data)
-          links << %(<#{request_url}?#{request_params.to_query}>; rel="last")
+        def initialize(ctx)
+          @ctx = ctx
         end
 
-        links.join(', ')
-      end
+        def paginate(relation)
+          relation = add_default_order(relation)
 
-      def total_pages(paginated_data)
-        # Ensure there is in total at least 1 page
-        [paginated_data.total_pages, 1].max
-      end
-
-      def add_default_order(relation)
-        if relation.is_a?(ActiveRecord::Relation) && relation.order_values.empty?
-          relation = relation.order(:id)
+          relation.page(params[:page]).per(params[:per_page]).tap do |data|
+            add_pagination_headers(data)
+          end
         end
 
-        relation
-      end
+        private
 
-      def data_without_counts?(paginated_data)
-        paginated_data.is_a?(Kaminari::PaginatableWithoutCount)
+        def add_default_order(relation)
+          if relation.is_a?(ActiveRecord::Relation) && relation.order_values.empty?
+            relation = relation.order(:id)
+          end
+
+          relation
+        end
+
+        def add_pagination_headers(paginated_data)
+          header 'X-Per-Page',    paginated_data.limit_value.to_s
+          header 'X-Page',        paginated_data.current_page.to_s
+          header 'X-Next-Page',   paginated_data.next_page.to_s
+          header 'X-Prev-Page',   paginated_data.prev_page.to_s
+          header 'Link',          pagination_links(paginated_data)
+
+          return if data_without_counts?(paginated_data)
+
+          header 'X-Total',       paginated_data.total_count.to_s
+          header 'X-Total-Pages', total_pages(paginated_data).to_s
+        end
+
+        def pagination_links(paginated_data)
+          request_url = request.url.split('?').first
+          request_params = params.clone
+          request_params[:per_page] = paginated_data.limit_value
+
+          links = []
+
+          request_params[:page] = paginated_data.prev_page
+          links << %(<#{request_url}?#{request_params.to_query}>; rel="prev") if request_params[:page]
+
+          request_params[:page] = paginated_data.next_page
+          links << %(<#{request_url}?#{request_params.to_query}>; rel="next") if request_params[:page]
+
+          request_params[:page] = 1
+          links << %(<#{request_url}?#{request_params.to_query}>; rel="first")
+
+          unless data_without_counts?(paginated_data)
+            request_params[:page] = total_pages(paginated_data)
+            links << %(<#{request_url}?#{request_params.to_query}>; rel="last")
+          end
+
+          links.join(', ')
+        end
+
+        def total_pages(paginated_data)
+          # Ensure there is in total at least 1 page
+          [paginated_data.total_pages, 1].max
+        end
+
+        def data_without_counts?(paginated_data)
+          paginated_data.is_a?(Kaminari::PaginatableWithoutCount)
+        end
       end
     end
   end
diff --git a/lib/gitlab/serializer/pagination.rb b/lib/gitlab/serializer/pagination.rb
index 9c92b83dddc..6bb00d8ae21 100644
--- a/lib/gitlab/serializer/pagination.rb
+++ b/lib/gitlab/serializer/pagination.rb
@@ -17,8 +17,6 @@ module Gitlab
         end
       end
 
-      private
-
       # Methods needed by `API::Helpers::Pagination`
       #