# frozen_string_literal: true

module Banzai
  module Filter
    module References
      # HTML filter that replaces project references with links.
      class ProjectReferenceFilter < ReferenceFilter
        self.reference_type = :project

        # Public: Find `namespace/project>` project references in text
        #
        #   ProjectReferenceFilter.references_in(text) do |match, project|
        #     "<a href=...>#{project}></a>"
        #   end
        #
        # text - String text to search.
        #
        # Yields the String match, and the String project name.
        #
        # Returns a String replaced with the return of the block.
        def self.references_in(text)
          text.gsub(Project.markdown_reference_pattern) do |match|
            yield match, "#{$~[:namespace]}/#{$~[:project]}"
          end
        end

        def call
          ref_pattern = Project.markdown_reference_pattern
          ref_pattern_start = /\A#{ref_pattern}\z/

          nodes.each_with_index do |node, index|
            if text_node?(node)
              replace_text_when_pattern_matches(node, index, ref_pattern) do |content|
                project_link_filter(content)
              end
            elsif element_node?(node)
              yield_valid_link(node) do |link, inner_html|
                if link =~ ref_pattern_start
                  replace_link_node_with_href(node, index, link) do
                    project_link_filter(link, link_content: inner_html)
                  end
                end
              end
            end
          end

          doc
        end

        # Replace `namespace/project>` project references in text with links to the referenced
        # project page.
        #
        # text - String text to replace references in.
        # link_content - Original content of the link being replaced.
        #
        # Returns a String with `namespace/project>` references replaced with links. All links
        # have `gfm` and `gfm-project` class names attached for styling.
        def project_link_filter(text, link_content: nil)
          self.class.references_in(text) do |match, project_path|
            cached_call(:banzai_url_for_object, match, path: [Project, project_path.downcase]) do
              if project = projects_hash[project_path.downcase]
                link_to_project(project, link_content: link_content) || match
              else
                match
              end
            end
          end
        end

        # Returns a Hash containing all Project objects for the project
        # references in the current document.
        #
        # The keys of this Hash are the project paths, the values the
        # corresponding Project objects.
        def projects_hash
          @projects ||= Project.eager_load(:route, namespace: [:route])
                               .where_full_path_in(projects)
                               .index_by(&:full_path)
                               .transform_keys(&:downcase)
        end

        # Returns all projects referenced in the current document.
        def projects
          refs = Set.new

          nodes.each do |node|
            node.to_html.scan(Project.markdown_reference_pattern) do
              refs << "#{$~[:namespace]}/#{$~[:project]}"
            end
          end

          refs.to_a
        end

        private

        def urls
          Gitlab::Routing.url_helpers
        end

        def link_class
          reference_class(:project)
        end

        def link_to_project(project, link_content: nil)
          url = urls.project_url(project, only_path: context[:only_path])
          data = data_attribute(project: project.id)
          content = link_content || project.to_reference

          link_tag(url, data, content, project.name)
        end

        def link_tag(url, data, link_content, title)
          %(<a href="#{url}" #{data} class="#{link_class}" title="#{escape_once(title)}">#{link_content}</a>)
        end
      end
    end
  end
end