Create directly_addressed Todos when mentioned in beginning of a line

4 files changed, 67 insertions, 7 deletions

diff --git a/lib/banzai/querying.rb b/lib/banzai/querying.rb
index 1e1b51e683e..fb2faae02bc 100644
--- a/lib/banzai/querying.rb
+++ b/lib/banzai/querying.rb
@@ -1,18 +1,64 @@
 module Banzai
   module Querying
+    module_function
+
     # Searches a Nokogiri document using a CSS query, optionally optimizing it
     # whenever possible.
     #
-    # document - A document/element to search.
-    # query    - The CSS query to use.
+    # document          - A document/element to search.
+    # query             - The CSS query to use.
+    # reference_options - A hash with nodes filter options
     #
-    # Returns a Nokogiri::XML::NodeSet.
-    def self.css(document, query)
+    # Returns an array of Nokogiri::XML::Element objects if location is specified
+    # in reference_options. Otherwise it would a Nokogiri::XML::NodeSet.
+    def css(document, query, reference_options = {})
       # When using "a.foo" Nokogiri compiles this to "//a[...]" but
       # "descendant::a[...]" is quite a bit faster and achieves the same result.
       xpath = Nokogiri::CSS.xpath_for(query)[0].gsub(%r{^//}, 'descendant::')
+      xpath = restrict_to_p_nodes_at_root(xpath) if filter_nodes_at_beginning?(reference_options)
+      nodes = document.xpath(xpath)
+
+      filter_nodes(nodes, reference_options)
+    end
+
+    def restrict_to_p_nodes_at_root(xpath)
+      xpath.gsub('descendant::', './p/')
+    end
+
+    def filter_nodes(nodes, reference_options)
+      if filter_nodes_at_beginning?(reference_options)
+        filter_nodes_at_beginning(nodes)
+      else
+        nodes
+      end
+    end
+
+    def filter_nodes_at_beginning?(reference_options)
+      reference_options && reference_options[:location] == :beginning
+    end
+
+    # Selects child nodes if they are present in the beginning among other siblings.
+    #
+    # nodes - A Nokogiri::XML::NodeSet.
+    #
+    # Returns an array of Nokogiri::XML::Element objects.
+    def filter_nodes_at_beginning(nodes)
+      parents_and_nodes = nodes.group_by(&:parent)
+      filtered_nodes = []
+
+      parents_and_nodes.each do |parent, nodes|
+        children = parent.children
+        nodes    = nodes.to_a
+
+        children.each do |child|
+          next if child.text.blank?
+          node = nodes.shift
+          break unless node == child
+          filtered_nodes << node
+        end
+      end
 
-      document.xpath(xpath)
+      filtered_nodes
     end
   end
 end
diff --git a/lib/banzai/reference_extractor.rb b/lib/banzai/reference_extractor.rb
index b26a41a1f3b..8e3b0c4db79 100644
--- a/lib/banzai/reference_extractor.rb
+++ b/lib/banzai/reference_extractor.rb
@@ -16,6 +16,11 @@ module Banzai
       processor.process(html_documents)
     end
 
+    def reset_memoized_values
+      @html_documents     = nil
+      @texts_and_contexts = []
+    end
+
     private
 
     def html_documents
diff --git a/lib/banzai/reference_parser/base_parser.rb b/lib/banzai/reference_parser/base_parser.rb
index d8a855ec1fe..2058a58d0ae 100644
--- a/lib/banzai/reference_parser/base_parser.rb
+++ b/lib/banzai/reference_parser/base_parser.rb
@@ -33,7 +33,7 @@ module Banzai
     # they have access to.
     class BaseParser
       class << self
-        attr_accessor :reference_type
+        attr_accessor :reference_type, :reference_options
       end
 
       # Returns the attribute name containing the value for every object to be
@@ -182,9 +182,10 @@ module Banzai
       # the references.
       def process(documents)
         type = self.class.reference_type
+        reference_options = self.class.reference_options
 
         nodes = documents.flat_map do |document|
-          Querying.css(document, "a[data-reference-type='#{type}'].gfm").to_a
+          Querying.css(document, "a[data-reference-type='#{type}'].gfm", reference_options).to_a
         end
 
         gather_references(nodes)
diff --git a/lib/banzai/reference_parser/directly_addressed_user_parser.rb b/lib/banzai/reference_parser/directly_addressed_user_parser.rb
new file mode 100644
index 00000000000..77df9bbd024
--- /dev/null
+++ b/lib/banzai/reference_parser/directly_addressed_user_parser.rb
@@ -0,0 +1,8 @@
+module Banzai
+  module ReferenceParser
+    class DirectlyAddressedUserParser < UserParser
+      self.reference_type = :user
+      self.reference_options = { location: :beginning }
+    end
+  end
+end