paginator: fix showing page 5000 when page count is unknown

Fix a bug where if you did a slow search that took too long to calculate
the page count, and you had 200 posts per page, then we would show page
5000 as the last page of the search.

This was because we were artificially returning 1,000,000 as the post
count to signal that the count timed out, but at 200 posts per page this
would show 5000 as the last page of the search.

app/components/paginator_component.rb

@@ -27,7 +27,7 @@ class PaginatorComponent < ApplicationComponent
       ("..." unless left == 2),
       (left..right).to_a,
       ("..." unless right == last_page - 1),
-      (last_page unless last_page == 1),
+      (last_page unless last_page == 1 || last_page.infinite?),
     ].flatten.compact
   end
 

app/logical/pagination_extension.rb

@@ -39,7 +39,7 @@ module PaginationExtension
     if count.present?
       @paginator_count = count
     elsif !search_count.nil? && search_count.blank?
-      @paginator_count = 1_000_000
+      @paginator_count = Float::INFINITY
     end
 
     if page.to_s =~ /\Ab(\d+)\z/i
@@ -138,15 +138,17 @@ module PaginationExtension
     end
   end
 
+  # Return the number of pages of results, or infinity if it takes too long to count.
   def total_pages
+    return Float::INFINITY if total_count.infinite?
     (total_count.to_f / records_per_page).ceil
   end
 
-  # taken from kaminari (https://github.com/amatsuda/kaminari)
+  # Return the number of results, or infinity if it takes too long to count.
   def total_count
     @paginator_count ||= unscoped.from(except(:offset, :limit, :order).reorder(nil)).count
   rescue ActiveRecord::StatementInvalid => e
     raise unless e.to_s =~ /statement timeout/
-    @paginator_count ||= 1_000_000
+    @paginator_count ||= Float::INFINITY
   end
 end

test/components/paginator_component_test.rb

@@ -76,6 +76,19 @@ class PaginatorComponentTest < ViewComponent::TestCase
           assert_css("span", count: 3)
         end
       end
+
+      context "for a search with an unknown number of pages" do
+        should "show the unlimited paginator" do
+          @tags = Tag.all
+          @tags.stubs(:total_count).returns(Float::INFINITY)
+          html = render_paginator(:numbered, @tags, page: 1, limit: 200)
+
+          assert_css("span.paginator-current", text: "1")
+          assert_css("span.paginator-prev")
+          assert_css("a.paginator-next")
+          assert_css(".paginator a.paginator-page", count: 4, visible: :all)
+        end
+      end
     end
   end
 end