Style the publications page pagination controls

Copy the way Whitehall Publisher overrides Kaminari's partials to style
 its pagination components. It would be good for the
 govuk_publishing_components gem to have a pagination control which both
 apps could use, but implementing that would take some time so we will
 create a new ticket for this.

app/assets/stylesheets/application.scss

@@ -20,6 +20,7 @@ $govuk-page-width: 1140px;
 @import 'govuk_publishing_components/components/layout-header';
 @import 'govuk_publishing_components/components/lead-paragraph';
 @import 'govuk_publishing_components/components/notice';
+@import 'govuk_publishing_components/components/previous-and-next-navigation';
 @import 'govuk_publishing_components/components/search';
 @import 'govuk_publishing_components/components/skip-link';
 @import 'govuk_publishing_components/components/success-alert';

app/helpers/pagination_helper.rb

@@ -0,0 +1,158 @@
+module PaginationHelper
+  class << self
+    LARGE_NUMBER_OF_PAGES = 6
+
+    def pagination_hash(current_page:, total_pages:, path:)
+      return if total_pages == 1
+
+      self.current_page = current_page
+      self.total_pages = total_pages
+      self.path = normalise_path(path, current_page)
+
+      previous_page = current_page - 1 if current_page >= 2
+      next_page = current_page + 1 if current_page < total_pages
+
+      previous_page_href = build_path_for(current_page - 1)
+      self.previous_href = previous_page.present? ? previous_page_href : nil
+
+      next_page_href = build_path_for(current_page + 1) if next_page.present?
+      self.next_href = next_page_href.presence
+
+      if total_pages >= LARGE_NUMBER_OF_PAGES
+        large_page_number_hash
+      else
+        small_page_number_hash
+      end
+    end
+
+  private
+
+    attr_accessor :path, :previous_href, :next_href, :current_page, :total_pages
+
+    def normalise_path(path, current_page)
+      if url_has_page_param?(path)
+        path
+      elsif url_has_a_query_string?(path) && !url_has_an_anchor?(path)
+        path + "&page=#{current_page}"
+      elsif url_has_a_query_string?(path) && url_has_an_anchor?(path)
+        path.gsub("#", "&page=#{current_page}#")
+      elsif url_has_an_anchor?(path)
+        path.gsub("#", "?page=#{current_page}#")
+      else
+        path + "?page=#{current_page}"
+      end
+    end
+
+    def url_has_page_param?(path)
+      path.include?("page=#{current_page}")
+    end
+
+    def url_has_a_query_string?(path)
+      path.include?("?")
+    end
+
+    def url_has_an_anchor?(path)
+      path.include?("#")
+    end
+
+    def build_path_for(page)
+      path.gsub("page=#{current_page}", "page=#{page}")
+    end
+
+    def small_page_number_hash
+      items = []
+
+      [*1..total_pages].map do |page|
+        items << {
+          href: build_path_for(page),
+          current: page == current_page,
+        }
+      end
+
+      {
+        previous_href:,
+        next_href:,
+        items:,
+      }
+    end
+
+    def large_page_number_hash
+      items = [
+        first_page_hash,
+        first_elipsis_hash,
+        middle_pages_array,
+        second_elipsis_hash,
+        last_page_hash,
+      ]
+      .flatten
+      .compact
+
+      {
+        previous_href:,
+        next_href:,
+        items:,
+      }
+    end
+
+    def first_page_hash
+      {
+        href: build_path_for(1),
+        label: "1",
+        current: current_page == 1,
+        aria_label: "Page 1",
+      }
+    end
+
+    def first_elipsis_hash
+      return unless current_page >= 4
+
+      { ellipses: true }
+    end
+
+    def middle_pages_array
+      get_page_numbers.map do |page|
+        {
+          href: build_path_for(page),
+          label: page.to_s,
+          current: current_page == page,
+          aria_label: "Page #{page}",
+        }
+      end
+    end
+
+    def get_page_numbers
+      first_page = 1
+      second_page = 2
+      penultimate_page = total_pages - 1
+      last_page = total_pages
+
+      case current_page
+      when first_page
+        [first_page + 1, first_page + 2, first_page + 3]
+      when second_page
+        [second_page, second_page + 1, second_page + 2]
+      when last_page
+        [last_page - 3, last_page - 2, last_page - 1]
+      when penultimate_page
+        [penultimate_page - 2, penultimate_page - 1, penultimate_page]
+      else
+        [current_page - 1, current_page, current_page + 1]
+      end
+    end
+
+    def second_elipsis_hash
+      return unless total_pages - current_page >= 3
+
+      { ellipses: true }
+    end
+
+    def last_page_hash
+      {
+        href: build_path_for(total_pages),
+        label: total_pages.to_s,
+        current: current_page == total_pages,
+        aria_label: "Page #{total_pages}",
+      }
+    end
+  end
+end

app/views/components/_pagination.html.erb

@@ -0,0 +1,60 @@
+<%
+  id ||= "pagination-#{SecureRandom.hex(4)}"
+  aria_label ||= "Pagination"
+  items ||= []
+  previous_href ||= false
+  next_href ||= false
+%>
+
+<nav id="<% id %>" class="app-c-pagination govuk-pagination" role="navigation" aria-label="<%= aria_label %>">
+  <% if previous_href %>
+    <div class="govuk-pagination__prev">
+      <a class="govuk-link govuk-pagination__link" href="<%= previous_href %>" rel="prev">
+        <svg class="govuk-pagination__icon govuk-pagination__icon--prev" xmlns="http://www.w3.org/2000/svg" height="13" width="15" aria-hidden="true" focusable="false" viewBox="0 0 15 13">
+          <path d="m6.5938-0.0078125-6.7266 6.7266 6.7441 6.4062 1.377-1.449-4.1856-3.9768h12.896v-2h-12.984l4.2931-4.293-1.414-1.414z"></path>
+        </svg>
+        <span class="govuk-pagination__link-title">Previous<span class="govuk-visually-hidden"> page</span></span>
+      </a>
+    </div>
+  <% end %>
+
+  <ul class="govuk-pagination__list">
+    <% items.each_with_index do | item, index | %>
+      <%
+        item_label = item[:label] ? item[:label] : index + 1
+        item_aria_label = item[:label] ? item[:label] : "Page #{item_label}"
+        item_aria_label = (item[:aria_label].presence || item_aria_label)
+        list_item_classes = %w[govuk-pagination__item]
+        list_item_classes << "govuk-pagination__item--current" if item[:current]
+        list_item_classes << "govuk-pagination__item--ellipses" if item[:ellipses]
+      %>
+
+      <%= tag.li class: list_item_classes do %>
+        <% if item[:ellipses] %>
+          &ctdot;
+        <% else %>
+          <%= tag.a(
+            item_label,
+            class: "govuk-link govuk-pagination__link",
+            href: item[:href],
+            aria: {
+              label: item_aria_label,
+              current: item[:current] ? "page" : nil,
+            },
+          ) %>
+        <% end %>
+      <% end %>
+    <% end %>
+  </ul>
+
+  <% if next_href %>
+    <div class="govuk-pagination__next">
+      <a class="govuk-link govuk-pagination__link" href="<%= next_href %>" rel="next">
+        <span class="govuk-pagination__link-title">Next<span class="govuk-visually-hidden"> page</span></span>
+        <svg class="govuk-pagination__icon govuk-pagination__icon--next" xmlns="http://www.w3.org/2000/svg" height="13" width="15" aria-hidden="true" focusable="false" viewBox="0 0 15 13">
+          <path d="m8.107-0.0078125-1.4136 1.414 4.2926 4.293h-12.986v2h12.896l-4.1855 3.9766 1.377 1.4492 6.7441-6.4062-6.7246-6.7266z"></path>
+        </svg>
+      </a>
+    </div>
+  <% end %>
+</nav>

app/views/kaminari/_paginator.html.erb

@@ -0,0 +1,11 @@
+<% anchor = anchor.presence || "" %>
+
+<% if total_pages > 1 %>
+  <% PaginationHelper.pagination_hash(current_page: current_page.to_i, total_pages:, path: request.url + anchor).tap do |hash| %>
+    <%= render "components/pagination", {
+      previous_href: hash[:previous_href],
+      next_href: hash[:next_href],
+      items: hash[:items],
+    } %>
+  <% end %>
+<% end %>

test/integration/edition_scheduled_publishing_test.rb

@@ -7,6 +7,9 @@ class EditionScheduledPublishingTest < LegacyJavascriptIntegrationTest
     stub_holidays_used_by_fact_check
     # queue up the edition, don't perform inline
     Sidekiq::Testing.fake!
+
+    test_strategy = Flipflop::FeatureSet.current.test!
+    test_strategy.switch!(:design_system_publications_filter, false)
   end
 
   teardown do