Add recent resource sitemap endpoint for posts (#14857)

* Add generic recent resource sitemap endpoint

* Update spec/requests/sitemaps_spec.rb

Co-authored-by: Julianna Tetreault <32834804+juliannatetreault@users.noreply.github.com>

* Update spec/requests/sitemaps_spec.rb

Co-authored-by: Julianna Tetreault <32834804+juliannatetreault@users.noreply.github.com>

* Update spec/requests/sitemaps_spec.rb

Co-authored-by: Julianna Tetreault <32834804+juliannatetreault@users.noreply.github.com>

* Update spec/requests/sitemaps_spec.rb

Co-authored-by: Julianna Tetreault <32834804+juliannatetreault@users.noreply.github.com>

Co-authored-by: Julianna Tetreault <32834804+juliannatetreault@users.noreply.github.com>

app/controllers/sitemaps_controller.rb

@@ -2,8 +2,28 @@ class SitemapsController < ApplicationController
   before_action :set_cache_control_headers, only: %i[show]
 
   SITEMAP_REGEX = /\Asitemap-(?<date_string>[A-Z][a-z][a-z]-\d{4})\.xml\z/
+  RESULTS_LIMIT = Rails.env.production? ? 10_000 : 5
 
   def show
+    if params[:sitemap].start_with? "sitemap-posts"
+      posts_sitemap
+    else
+      monthly_sitemap
+    end
+    set_cache_control_headers(@max_age,
+                              stale_while_revalidate: @stale_while_revalidate,
+                              stale_if_error: @stale_if_error)
+    render layout: false
+  end
+
+  private
+
+  def posts_sitemap
+    @articles = Article.published.order("published_at DESC").limit(RESULTS_LIMIT).offset(offset).pluck(:path, :last_comment_at)
+    set_surrogate_controls(Time.now)
+  end
+
+  def monthly_sitemap
     match = params[:sitemap].match(SITEMAP_REGEX)
     not_found unless match && match[:date_string]
     begin
@@ -18,14 +38,8 @@ class SitemapsController < ApplicationController
       .pluck(:path, :last_comment_at)
 
     set_surrogate_controls(date)
-    set_cache_control_headers(@max_age,
-                              stale_while_revalidate: @stale_while_revalidate,
-                              stale_if_error: @stale_if_error)
-    render layout: false
   end
 
-  private
-
   def set_surrogate_controls(date)
     @stale_if_error = "86400"
     if date > 1.month.ago
@@ -36,4 +50,8 @@ class SitemapsController < ApplicationController
       @stale_while_revalidate = "432000" # five days
     end
   end
+
+  def offset
+    params[:sitemap].split("-")[2].to_i * RESULTS_LIMIT # elvaluates to 0 if not present or not a number
+  end
 end

spec/requests/sitemaps_spec.rb

@@ -40,5 +40,39 @@ RSpec.describe "Sitemaps", type: :request do
       expect(response.body).not_to include(articles.last.path)
       expect(response.media_type).to eq("application/xml")
     end
+
+    it "renders most recent posts if /sitemap-posts", :aggregate_failures do
+      create_list(:article, 8)
+      get "/sitemap-posts.xml"
+      expect(response.body).to include(Article.order("published_at DESC").first.path)
+      expect(response.body).not_to include(Article.order("published_at DESC").last.path)
+    end
+
+    it "renders second page if /sitemap-posts-1", :aggregate_failures do
+      create_list(:article, 8)
+      get "/sitemap-posts-1.xml"
+      expect(response.body).not_to include(Article.order("published_at DESC").first.path)
+      expect(response.body).to include(Article.order("published_at DESC").last.path)
+    end
+
+    it "renders first page if /sitemap-posts-randomn0tnumber", :aggregate_failures do
+      create_list(:article, 8)
+      get "/sitemap-posts-randomn0tnumber.xml"
+      expect(response.body).to include(Article.order("published_at DESC").first.path)
+      expect(response.body).not_to include(Article.order("published_at DESC").last.path)
+    end
+
+    it "renders empty if /sitemap-posts-2", :aggregate_failures do
+      # no posts this far down.
+      create_list(:article, 8)
+      get "/sitemap-posts-2.xml"
+      expect(response.body).not_to include(Article.order("published_at DESC").first.path)
+      expect(response.body).not_to include(Article.order("published_at DESC").last.path)
+    end
+
+    it "renders 'recent' version of surrogate control" do
+      get "/sitemap-posts-2.xml"
+      expect(response.header["Surrogate-Control"]).to include("8640")
+    end
   end
 end