refactor: extract feed and sitemap helpers into FeedHelpers module

Move feed_xml, feed_item, feed_json, json_feed_item, rfc822_date,
iso_date, and sitemap_xml out of Server into a dedicated FeedHelpers
module included via helpers. Reduces Server from ~500 to ~400 lines
and separates feed generation concerns from routing.

lib/volumen/feed_helpers.rb

@@ -0,0 +1,104 @@
+# frozen_string_literal: true
+
+module Volumen
+  # RSS, JSON Feed, and sitemap helpers extracted from Server to keep the
+  # main class focused on configuration and routing.
+  module FeedHelpers
+    private
+
+    def feed_xml
+      site = config.site
+      items = published_posts.first(20).map { |post| feed_item(post) }.join("\n")
+      <<~XML
+        <?xml version="1.0" encoding="UTF-8"?>
+        <rss version="2.0" xmlns:dc="http://purl.org/dc/elements/1.1/">
+          <channel>
+            <title>#{escape(site["title"])}</title>
+            <link>#{escape(base_url)}</link>
+            <description>#{escape(site["description"])}</description>
+            <language>#{escape(site["language"])}</language>
+        #{items}
+          </channel>
+        </rss>
+      XML
+    end
+
+    def feed_item(post)
+      link = "#{base_url}/#{post.slug}"
+      pub = if post.metadata["date"]
+              "\n      <pubDate>#{escape(rfc822_date(post))}</pubDate>"
+            else
+              ""
+            end
+      creator = post.fediverse_creator
+      creator_tag = creator ? "\n      <dc:creator>#{escape(creator)}</dc:creator>" : ""
+      <<~XML.chomp
+        <item>
+          <title>#{escape(post.title)}</title>
+          <link>#{escape(link)}</link>
+          <guid>#{escape(link)}</guid>
+          <description>#{escape(post.excerpt)}</description>#{pub}#{creator_tag}
+        </item>
+      XML
+    end
+
+    def rfc822_date(post)
+      value = post.metadata["date"]
+      case value
+      when Date then value.to_time.rfc822
+      when Time then value.rfc822
+      end
+    end
+
+    def feed_json
+      site = config.site
+      feed_url = "#{base_url}/api/volumen/feed.json"
+      {
+        "version" => "https://jsonfeed.org/version/1.1",
+        "title" => site["title"],
+        "home_page_url" => base_url,
+        "feed_url" => feed_url,
+        "description" => site["description"],
+        "language" => site["language"],
+        "items" => published_posts.first(20).map { |post| json_feed_item(post) }
+      }
+    end
+
+    def json_feed_item(post)
+      link = "#{base_url}/#{post.slug}"
+      item = {
+        "id" => link,
+        "url" => link,
+        "title" => post.title,
+        "content_html" => post.html,
+        "summary" => post.excerpt,
+        "date_published" => iso_date(post.metadata["date"]),
+        "tags" => post.tags
+      }
+      author = post.fediverse_creator || site_fediverse_creator
+      item["authors"] = [{ "name" => author }] if author
+      item.reject { |_k, v| v.nil? || v == "" || v == [] }
+    end
+
+    def iso_date(value)
+      case value
+      when Date then value.iso8601
+      when Time then value.to_date.iso8601
+      end
+    end
+
+    def sitemap_xml
+      urls = published_posts.map do |post|
+        url = "  <url><loc>#{escape("#{base_url}/#{post.slug}")}</loc>"
+        url << "<lastmod>#{escape(post.date_string)}</lastmod>" if post.date_string
+        url << "</url>"
+      end.join("\n")
+      <<~XML
+        <?xml version="1.0" encoding="UTF-8"?>
+        <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
+        #{urls}
+        </urlset>
+      XML
+    end
+  end
+end

lib/volumen/server.rb

@@ -10,6 +10,7 @@ require_relative "markdown"
 require_relative "password"
 require_relative "api_routes"
 require_relative "admin_routes"
+require_relative "feed_helpers"
 
 module Volumen
   # Sinatra application: the public JSON API at /api/volumen and the
@@ -25,6 +26,7 @@ module Volumen
 
     register ApiRoutes
     register AdminRoutes
+    helpers FeedHelpers
 
     configure do
       set :show_exceptions, false
@@ -167,101 +169,6 @@ module Volumen
       config.site["base_url"].to_s.chomp("/")
     end
 
-    def feed_xml
-      site = config.site
-      items = published_posts.first(20).map { |post| feed_item(post) }.join("\n")
-      <<~XML
-        <?xml version="1.0" encoding="UTF-8"?>
-        <rss version="2.0" xmlns:dc="http://purl.org/dc/elements/1.1/">
-          <channel>
-            <title>#{escape(site["title"])}</title>
-            <link>#{escape(base_url)}</link>
-            <description>#{escape(site["description"])}</description>
-            <language>#{escape(site["language"])}</language>
-        #{items}
-          </channel>
-        </rss>
-      XML
-    end
-
-    def feed_item(post)
-      link = "#{base_url}/#{post.slug}"
-      pub = if post.metadata["date"]
-              "\n      <pubDate>#{escape(rfc822_date(post))}</pubDate>"
-            else
-              ""
-            end
-      creator = post.fediverse_creator
-      creator_tag = creator ? "\n      <dc:creator>#{escape(creator)}</dc:creator>" : ""
-      <<~XML.chomp
-        <item>
-          <title>#{escape(post.title)}</title>
-          <link>#{escape(link)}</link>
-          <guid>#{escape(link)}</guid>
-          <description>#{escape(post.excerpt)}</description>#{pub}#{creator_tag}
-        </item>
-      XML
-    end
-
-    def rfc822_date(post)
-      value = post.metadata["date"]
-      case value
-      when Date then value.to_time.rfc822
-      when Time then value.rfc822
-      end
-    end
-
-    def feed_json
-      site = config.site
-      feed_url = "#{base_url}/api/volumen/feed.json"
-      {
-        "version" => "https://jsonfeed.org/version/1.1",
-        "title" => site["title"],
-        "home_page_url" => base_url,
-        "feed_url" => feed_url,
-        "description" => site["description"],
-        "language" => site["language"],
-        "items" => published_posts.first(20).map { |post| json_feed_item(post) }
-      }
-    end
-
-    def json_feed_item(post)
-      link = "#{base_url}/#{post.slug}"
-      item = {
-        "id" => link,
-        "url" => link,
-        "title" => post.title,
-        "content_html" => post.html,
-        "summary" => post.excerpt,
-        "date_published" => iso_date(post.metadata["date"]),
-        "tags" => post.tags
-      }
-      author = post.fediverse_creator || site_fediverse_creator
-      item["authors"] = [{ "name" => author }] if author
-      item.reject { |_k, v| v.nil? || v == "" || v == [] }
-    end
-
-    def iso_date(value)
-      case value
-      when Date then value.iso8601
-      when Time then value.to_date.iso8601
-      end
-    end
-
-    def sitemap_xml
-      urls = published_posts.map do |post|
-        url = "  <url><loc>#{escape("#{base_url}/#{post.slug}")}</loc>"
-        url << "<lastmod>#{escape(post.date_string)}</lastmod>" if post.date_string
-        url << "</url>"
-      end.join("\n")
-      <<~XML
-        <?xml version="1.0" encoding="UTF-8"?>
-        <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
-        #{urls}
-        </urlset>
-      XML
-    end
-
     def escape(text)
       Rack::Utils.escape_html(text.to_s)
     end