Option to split feeds

lib/perron/feeds.rb

@@ -1,8 +1,11 @@
 # frozen_string_literal: true
 
+require "perron/feeds/split"
+
 module Perron
   class Feeds
     include ActionView::Helpers::TagHelper
+    include Perron::Feeds::Split
 
     def render(options = {})
       html_tags = []
@@ -22,6 +25,16 @@ def render(options = {})
             title = "#{collection.name.humanize} #{type.to_s.humanize} Feed"
 
             html_tags << tag(:link, rel: "alternate", type: MIME_TYPES[type], title: title, href: absolute_url)
+
+            next unless feed[:split_by]
+
+            split_values(collection.resources, feed[:split_by][:extractor]).each do |value|
+              split_path = split_path_for(feed, value)
+              split_url = URI.join(url.root_url, split_path).to_s
+              split_title = "#{collection.name.humanize}: #{value.to_s.humanize} #{type.to_s.humanize} Feed"
+
+              html_tags << tag(:link, rel: "alternate", type: MIME_TYPES[type], title: split_title, href: split_url)
+            end
           end
         end
       end

lib/perron/feeds/split.rb

@@ -0,0 +1,46 @@
+# frozen_string_literal: true
+
+module Perron
+  class Feeds
+    module Split
+      module_function
+
+      def grouped_resources(resources, extractor)
+        resources
+          .flat_map { |resource| extract(resource, extractor).map { [it, resource] } }
+          .group_by(&:first)
+          .transform_values { it.map(&:last) }
+      end
+
+      def split_values(resources, extractor)
+        resources
+          .flat_map { extract(it, extractor) }
+          .uniq
+      end
+
+      def extract(resource, extractor)
+        value = case extractor
+        when Symbol then resource.public_send(extractor)
+        when Proc then extractor.call(resource)
+        end
+
+        Array(value)
+      end
+
+      def split_path_for(type_config, value)
+        split_by = type_config[:split_by]
+
+        if split_by[:path]
+          split_by[:path].gsub(":value", value.to_s.parameterize)
+        else
+          extension = File.extname(type_config.path)
+          base_path = type_config.path.delete_suffix(extension)
+          field = split_by[:extractor]
+          field_name = field.is_a?(Symbol) ? field.to_s : "custom"
+
+          "#{base_path}/#{field_name}/#{value.to_s.parameterize}#{extension}"
+        end
+      end
+    end
+  end
+end

lib/perron/resource/configuration.rb

@@ -12,17 +12,17 @@ def configuration
 
             config.feeds = Options.new
 
-            config.feeds.atom = ActiveSupport::OrderedOptions.new
+            config.feeds.atom = FeedTypeConfig.new
             config.feeds.atom.enabled = false
             config.feeds.atom.path = "feeds/#{collection.name.demodulize.parameterize}.atom"
             config.feeds.atom.max_items = 20
 
-            config.feeds.json = ActiveSupport::OrderedOptions.new
+            config.feeds.json = FeedTypeConfig.new
             config.feeds.json.enabled = false
             config.feeds.json.path = "feeds/#{collection.name.demodulize.parameterize}.json"
             config.feeds.json.max_items = 20
 
-            config.feeds.rss = ActiveSupport::OrderedOptions.new
+            config.feeds.rss = FeedTypeConfig.new
             config.feeds.rss.enabled = false
             config.feeds.rss.path = "feeds/#{collection.name.demodulize.parameterize}.xml"
             config.feeds.rss.max_items = 20
@@ -58,6 +58,15 @@ def respond_to_missing?(name, include_private = false)
         end
       end
       private_constant :Options
+
+      class FeedTypeConfig < ActiveSupport::OrderedOptions
+        def split_by(method_or_lambda = nil, path: nil, &block)
+          extractor = method_or_lambda || block
+
+          self[:split_by] = {extractor: extractor}
+          self[:split_by][:path] = path if path
+        end
+      end
     end
   end
 end

lib/perron/site/builder/feeds.rb

@@ -4,10 +4,14 @@
 require "perron/site/builder/feeds/json"
 require "perron/site/builder/feeds/rss"
 
+require "perron/feeds/split"
+
 module Perron
   module Site
     class Builder
       class Feeds
+        include Perron::Feeds::Split
+
         def initialize(output_path)
           @output_path = output_path
         end
@@ -18,21 +22,39 @@ def generate
 
             config = collection.configuration.feeds
 
-            if config.atom.enabled
-              create_file at: config.atom.path, with: Atom.new(collection: collection).generate
-            end
+            generate_feed(collection: collection, type_config: config.atom, generator_class: Atom) if config.atom.enabled
+            generate_feed(collection: collection, type_config: config.json, generator_class: Json) if config.json.enabled
+            generate_feed(collection: collection, type_config: config.rss, generator_class: Rss) if config.rss.enabled
+          end
+        end
+
+        private
+
+        def generate_feed(collection:, type_config:, generator_class:)
+          generator = generator_class.new(collection: collection)
+          content = generator.generate
 
-            if config.json.enabled
-              create_file at: config.json.path, with: Json.new(collection: collection).generate
-            end
+          create_file(at: type_config.path, with: content) if content.present?
 
-            if config.rss.enabled
-              create_file at: config.rss.path, with: Rss.new(collection: collection).generate
-            end
+          return unless type_config[:split_by]
+
+          grouped_resources(collection.resources, type_config[:split_by][:extractor]).each do |value, group|
+            path = split_path_for(type_config, value)
+            config = split_config(type_config, value, path)
+            content = generator_class.new(collection: collection, resources: group, feed_config: config).generate
+
+            create_file(at: path, with: content) if content.present?
           end
         end
 
-        private
+        def split_config(type_config, value, split_path)
+          ActiveSupport::OrderedOptions.new.tap do |config|
+            type_config.each { |key, value| config[key] = value unless key == :split_by }
+
+            config.path = split_path
+            config.title = "#{type_config.title.presence || Perron.configuration.site_name}: #{value.to_s.humanize}"
+          end
+        end
 
         def create_file(at:, with:)
           return if with.blank?

lib/perron/site/builder/feeds/atom.rb

@@ -11,8 +11,10 @@ class Atom
           include Feeds::Author
           include Feeds::Template
 
-          def initialize(collection:)
+          def initialize(collection:, resources: nil, feed_config: nil)
             @collection = collection
+            @resources = resources
+            @feed_config = feed_config
             @configuration = Perron.configuration
           end
 
@@ -28,12 +30,16 @@ def generate
           private
 
           def resources
-            @resource ||= @collection.resources
+            (@resources || @collection.resources)
               .reject { it.metadata.feed == false }
               .sort_by { it.metadata.published_at || it.metadata.updated_at || Time.current }
               .reverse
               .take(feed_configuration.max_items)
           end
+
+          def feed_configuration
+            @feed_config || super
+          end
         end
       end
     end

lib/perron/site/builder/feeds/json.rb

@@ -11,8 +11,10 @@ class Json
           include Feeds::Author
           include Feeds::Template
 
-          def initialize(collection:)
+          def initialize(collection:, resources: nil, feed_config: nil)
             @collection = collection
+            @resources = resources
+            @feed_config = feed_config
             @configuration = Perron.configuration
           end
 
@@ -28,12 +30,16 @@ def generate
           private
 
           def resources
-            @resource ||= @collection.resources
+            (@resources || @collection.resources)
               .reject { it.metadata.feed == false }
               .sort_by { it.metadata.published_at || it.metadata.updated_at || Time.current }
               .reverse
               .take(feed_configuration.max_items)
           end
+
+          def feed_configuration
+            @feed_config || super
+          end
         end
       end
     end

lib/perron/site/builder/feeds/rss.rb

@@ -11,8 +11,10 @@ class Rss
           include Feeds::Author
           include Feeds::Template
 
-          def initialize(collection:)
+          def initialize(collection:, resources: nil, feed_config: nil)
             @collection = collection
+            @resources = resources
+            @feed_config = feed_config
             @configuration = Perron.configuration
           end
 
@@ -28,12 +30,16 @@ def generate
           private
 
           def resources
-            @resource ||= @collection.resources
+            (@resources || @collection.resources)
               .reject { it.metadata.feed == false }
               .sort_by { it.metadata.published_at || it.metadata.updated_at || Time.current }
               .reverse
               .take(feed_configuration.max_items)
           end
+
+          def feed_configuration
+            @feed_config || super
+          end
         end
       end
     end

test/perron/feeds_test.rb

@@ -8,9 +8,14 @@ class Perron::FeedsTest < ActionDispatch::IntegrationTest
   end
 
   teardown do
-    Content::Post.configure { it.feeds.rss.enabled = false }
-    Content::Post.configure { it.feeds.atom.enabled = false }
-    Content::Post.configure { it.feeds.json.enabled = false }
+    Content::Post.configure do |config|
+      config.feeds.rss.enabled = false
+      config.feeds.atom.enabled = false
+      config.feeds.json.enabled = false
+
+      config.feeds.atom[:split_by] = nil
+    end
+
     Content::Page.configure { it.feeds.rss.enabled = false }
   end
 
@@ -39,6 +44,32 @@ class Perron::FeedsTest < ActionDispatch::IntegrationTest
     assert_select document, 'link[href*="feeds/posts.xml"]', count: 0, message: "Posts feed should be excluded"
   end
 
+  test "renders split feed link tags when split_by is configured" do
+    Content::Post.configure { it.feeds.atom.split_by :category }
+
+    document = rendered_document
+
+    assert_select document, 'link[rel="alternate"][type="application/atom+xml"][href*="feeds/posts.atom"]', count: 1
+    assert_select document, 'link[rel="alternate"][type="application/atom+xml"][href*="feeds/posts/category/news.atom"][title*="News"]', count: 1
+    assert_select document, 'link[rel="alternate"][type="application/atom+xml"][href*="feeds/posts/category/tutorial.atom"][title*="Tutorial"]', count: 1
+  end
+
+  test "does not render split feed links when split_by is not configured" do
+    document = rendered_document
+
+    assert_select document, 'link[href*="category/"]', count: 0
+  end
+
+  test "renders split feed link tags respect :only and :except options" do
+    Content::Post.configure { it.feeds.atom.split_by :category }
+
+    document = rendered_document(only: [:posts])
+    assert_select document, 'link[href*="feeds/posts/category/"]', count: 2
+
+    document = rendered_document(only: [:pages])
+    assert_select document, 'link[href*="feeds/posts/category/"]', count: 0
+  end
+
   test "returns an empty document if no matching feeds are found" do
     document = rendered_document(only: [:nonexistent_collection])