Add basic validation of internal anchors

1 files changed, 122 insertions, 0 deletions

diff --git a/lib/checks/anchors.rb b/lib/checks/anchors.rb
new file mode 100644
index 00000000..77221031
--- /dev/null
+++ b/lib/checks/anchors.rb
@@ -0,0 +1,122 @@
+module Gitlab
+  module Nanoc
+    def self.config
+      @config ||= YAML.load(File.read('nanoc.yaml'))
+    end
+
+    def self.output_dir
+      config.fetch('output_dir')
+    end
+  end
+
+  class Page
+    attr_reader :file
+
+    def initialize(file)
+      @file = file
+    end
+
+    def exists?
+      File.exists?(@file)
+    end
+
+    def path
+      File.dirname(@file)
+    end
+
+    def document
+      raise ArgumentError unless exists?
+
+      @doc ||= Nokogiri::HTML(File.read(@file))
+    end
+
+    def links
+      @links ||= document.css(:a).map do |link|
+        Gitlab::Link.new(link, self)
+      end
+    end
+
+    def has_anchor?(name)
+      document.at_css(%Q{[id="#{name}"]})
+    end
+  end
+
+  class Link
+    attr_reader :link, :href, :page
+
+    def initialize(link, page)
+      @link = link
+      @href = link[:href]
+      @page = page
+    end
+
+    def path
+      @href.to_s.partition('#').first
+    end
+
+    def to_anchor?
+      @href.to_s.include?('#')
+    end
+
+    def anchor_name
+      raise ArguentError unless to_anchor?
+
+      @href.to_s.partition('#').last
+    end
+
+    def internal_anchor?
+      raise ArguentError unless to_anchor?
+
+      @href.to_s.partition('#').first.empty?
+    end
+
+    def internal?
+      @href.to_s.length > 0 && !@href.include?(':')
+    end
+
+    def destination_path
+      raise unless internal?
+
+      if @href.start_with?('/')
+        Gitlab::Nanoc.output_dir + path
+      else
+        ::File.expand_path(path, @page.path)
+      end
+    end
+
+    def destination_file
+      if destination_path.end_with?('.html')
+        destination_path
+      else
+        File.join(destination_path, 'index.html')
+      end
+    end
+
+    def destination_page
+      if internal_anchor?
+        @page
+      else
+        Gitlab::Page.new(destination_file)
+      end
+    end
+  end
+end
+
+Nanoc::Check.define(:internal_anchors) do
+  @output_filenames.each do |file|
+    Gitlab::Page.new(file).links.each do |link|
+      next unless link.internal?
+      next unless link.to_anchor?
+
+      link.destination_page.yield_self do |page|
+        next if link.anchor_name == 'markdown-toc'
+
+        if !page.exists?
+          add_issue("Page `#{page.file}` linked from `#{link.page.file}` not found!")
+        elsif !page.has_anchor?(link.anchor_name)
+          add_issue("Broken anchor `##{link.anchor_name}` found in `#{link.page.file}` to `#{link.destination_file}`")
+        end
+      end
+    end
+  end
+end