capotej · capotej · Sep 14, 2025
diff --git a/app/controllers/links_controller.rb b/app/controllers/links_controller.rb
@@ -15,7 +15,12 @@ def index
   end
 
   def feed
-    @links = Link.order(created_at: :desc).limit(20)
+    # Get both links and papers, ordered by creation date
+    links = Link.order(created_at: :desc).limit(20)
+    papers = Paper.order(created_at: :desc).limit(20)
+
+    # Combine and sort by created_at, then take the first 20
+    @items = (links + papers).sort_by(&:created_at).reverse.first(20)
     respond_to do |format|
       format.atom
     end

diff --git a/app/views/links/feed.atom.builder b/app/views/links/feed.atom.builder
@@ -1,13 +1,25 @@
 atom_feed do |feed|
   feed.title "#{Rails.application.config.site_name} - Interesting Links Feed"
-  feed.updated(@links.first.updated_at)
+  feed.updated(@items.first&.updated_at || Time.current)
 
-  @links.each do |link|
-    feed.entry(link, id: link.uuid, url: link.url) do |entry|
-      entry.title(link.title)
-      entry.content(link.description, type: "text")
-      entry.author do |author|
-        author.name "N/A"
+  @items.each do |item|
+    if item.is_a?(Link)
+      feed.entry(item, id: item.uuid, url: item.url) do |entry|
+        entry.title(item.title)
+        entry.content(item.description, type: "text")
+        entry.author do |author|
+          author.name "N/A"
+        end
+      end
+    elsif item.is_a?(Paper)
+      # Use display_url for arXiv papers, otherwise use the paper's url
+      entry_url = item.arxiv? ? item.display_url : item.url
+      feed.entry(item, id: "paper-#{item.id}", url: entry_url) do |entry|
+        entry.title(item.title)
+        entry.content(item.description, type: "text")
+        entry.author do |author|
+          author.name "N/A"
+        end
       end
     end
   end

diff --git a/test/controllers/links_controller_test.rb b/test/controllers/links_controller_test.rb
@@ -1,4 +1,5 @@
 require "test_helper"
+require "nokogiri"
 
 class LinksControllerTest < ActionDispatch::IntegrationTest
   def setup
@@ -32,6 +33,106 @@ def setup
     assert_redirected_to links_path
   end
 
+  test "feed should include both links and papers" do
+    # Stub HTTP requests for link creation
+    stub_request(:get, "http://example.com/test-link1")
+      .to_return(status: 200, body: "<html><head><title>Link 1</title><meta name='description' content='Description 1'></head></html>", headers: { "Content-Type" => "text/html" })
+    stub_request(:get, "http://example.com/test-link2")
+      .to_return(status: 200, body: "<html><head><title>Link 2</title><meta name='description' content='Description 2'></head></html>", headers: { "Content-Type" => "text/html" })
+
+    # Create some links
+    link1 = Link.create!(url: "http://example.com/test-link1")
+    link2 = Link.create!(url: "http://example.com/test-link2")
+
+    # Create some papers
+    paper1 = Paper.create!(url: "http://example.com/test-paper1.pdf", title: "Paper 1", description: "Description 1")
+    paper2 = Paper.create!(url: "http://example.com/test-paper2.pdf", title: "Paper 2", description: "Description 2")
+
+    # Make sure the papers have different created_at times
+    paper1.update(created_at: 2.days.ago)
+    paper2.update(created_at: 1.day.ago)
+
+    get links_feed_url, params: { format: "atom" }
+
+    assert_response :success
+    assert response.content_type.start_with?("application/atom+xml")
+
+    # Check that both links and papers are in the feed
+    # Note: We might have more than 4 entries if there are existing fixtures
+    assert_select "entry title", text: "Link 1"
+    assert_select "entry title", text: "Link 2"
+    assert_select "entry title", text: "Paper 1"
+    assert_select "entry title", text: "Paper 2"
+  end
+
+  test "feed should use proper URLs for arXiv papers" do
+    # Stub HTTP requests for link creation
+    stub_request(:get, "http://example.com/test-link")
+      .to_return(status: 200, body: "<html><head><title>Regular Link</title><meta name='description' content='Description'></head></html>", headers: { "Content-Type" => "text/html" })
+
+    # Create a regular link
+    link = Link.create!(url: "http://example.com/test-link")
+
+    # Create a regular paper
+    regular_paper = Paper.create!(url: "http://example.com/test-paper.pdf", title: "Regular Paper", description: "Description")
+
+    # Create an arXiv paper
+    arxiv_paper = Paper.create!(url: "https://arxiv.org/abs/1234.56789", title: "ArXiv Paper", description: "Description")
+
+    get links_feed_url, params: { format: "atom" }
+
+    assert_response :success
+
+    # Check that the regular paper uses its own URL
+    assert_select "entry link[href='#{regular_paper.url}']", count: 1
+
+    # Check that the arXiv paper uses the PDF URL
+    assert_select "entry link[href='#{arxiv_paper.display_url}']", count: 1
+  end
+
+  test "feed should be ordered by creation date" do
+    # Stub HTTP requests for link creation
+    stub_request(:get, "http://example.com/test-oldest")
+      .to_return(status: 200, body: "<html><head><title>Oldest Link</title><meta name='description' content='Description'></head></html>", headers: { "Content-Type" => "text/html" })
+    stub_request(:get, "http://example.com/test-newest")
+      .to_return(status: 200, body: "<html><head><title>Newest Link</title><meta name='description' content='Description'></head></html>", headers: { "Content-Type" => "text/html" })
+
+    # Create items at different times
+    oldest_link = Link.create!(url: "http://example.com/test-oldest")
+    oldest_link.update(created_at: 3.days.ago)
+
+    middle_paper = Paper.create!(url: "http://example.com/test-middle.pdf", title: "Middle Paper", description: "Description")
+    middle_paper.update(created_at: 2.days.ago)
+
+    newest_link = Link.create!(url: "http://example.com/test-newest")
+    newest_link.update(created_at: 1.day.ago)
+
+    get links_feed_url, params: { format: "atom" }
+
+    assert_response :success
+
+    # Parse the XML to check ordering
+    xml = Nokogiri::XML(response.body)
+    entries = xml.xpath("//xmlns:entry")
+
+    # Find our specific entries among possibly others
+    entry_titles = entries.map { |entry| entry.at_xpath(".//xmlns:title").text }
+
+    # Find positions of our test entries
+    oldest_pos = entry_titles.index("Oldest Link")
+    middle_pos = entry_titles.index("Middle Paper")
+    newest_pos = entry_titles.index("Newest Link")
+
+    # Verify that they exist
+    refute_nil oldest_pos, "Oldest Link should be in the feed"
+    refute_nil middle_pos, "Middle Paper should be in the feed"
+    refute_nil newest_pos, "Newest Link should be in the feed"
+
+    # Verify ordering: newest should come before middle, which should come before oldest
+    assert newest_pos < middle_pos, "Newest Link should come before Middle Paper"
+    assert middle_pos < oldest_pos, "Middle Paper should come before Oldest Link"
+  end
+
   private
 
   def sign_in(user)