[Posts] Add an approximate result counter (#903)

app/helpers/pagination_helper.rb

@@ -1,6 +1,29 @@
 # frozen_string_literal: true
 
 module PaginationHelper
+  def approximate_count(records)
+    return "" if records.pagination_mode != :numbered
+
+    if records.total_pages > records.max_numbered_pages
+      pages = records.max_numbered_pages
+      schar = "over "
+      count = pages * records.records_per_page
+      title = "Over #{count} results found.\nActual result count may be much larger."
+    else
+      pages = records.total_pages
+      schar = "~"
+      count = pages * records.records_per_page
+      title = "Approximately #{count} results found.\nActual result count may differ."
+    end
+
+    tag.span(class: "approximate-count", title: title, data: { count: count, pages: pages, per: records.max_numbered_pages }) do
+      concat schar
+      concat number_to_human(count, precision: 2, format: "%n%u", units: { thousand: "k" })
+      concat " "
+      concat "result".pluralize(count)
+    end
+  end
+
   def sequential_paginator(records)
     tag.nav(class: "pagination sequential", aria: { label: "Pagination" }) do
       return "" if records.try(:none?)

app/javascript/src/styles/views/posts/_posts.scss

@@ -7,6 +7,7 @@
 // Features
 @import "index/partials/mode_menu";
 @import "index/partials/wiki_excerpt";
+@import "index/partials/stats";
 
 @include window-larger-than(50rem) {
   @include with-setting("fullscreen", "true") {

app/javascript/src/styles/views/posts/index/partials/_stats.scss

@@ -0,0 +1,13 @@
+.posts-index-stats {
+  display: flex;
+  justify-content: end;
+
+  margin: -0.5rem 0rem 0.25rem;
+
+  font-size: 0.75rem;
+  line-height: 0.75rem;
+  color: #fffa;
+  font-family: monospace;
+
+  & > span { cursor: help; }
+}

app/views/posts/index.html.erb

@@ -24,6 +24,7 @@
     <div class="content">
       <%= render "ads/leaderboard", tag_string: @post_set.ad_tag_string %>
       <%= render "posts/partials/index/edit" %>
+      <%= render "posts/partials/index/stats", :post_set => @post_set %>
       <%= render "posts/partials/index/posts", :post_set => @post_set %>
     </div>
 

app/views/posts/partials/index/_stats.html.erb

@@ -0,0 +1,3 @@
+<div class="posts-index-stats">
+  <%= approximate_count(post_set.posts) %>
+</div>