require 'jsduck/logger'

module JsDuck
  module Format

    # Tracks opening and closing of HTML tags, with the purpose of
    # closing down the unfinished tags.
    #
    # See Format::Doc#replace for the use of this class.
    class HtmlStack

      # Initializes the stack with two optional parameters:
      #
      # @param ignore_html A hash of additional HTML tags that don't need closing.
      # @param doc_context Filename and linenr of the current doc-comment.
      def initialize(ignore_html={}, doc_context={})
        @ignore_html = ignore_html
        @doc_context = doc_context
        @open_tags = []
      end

      # Scans an opening tag in HTML using the passed in StringScanner.
      def open(s)
        s.scan(/</) + push_tag(s.scan(/\w+/)) + s.scan_until(/>|\Z/)
      end

      # Scans a closing tag in HTML using the passed in StringScanner.
      def close(s)
        s.scan(/<\//)
        tag = s.scan(/\w+/)
        s.scan(/>/)

        pop_tags(tag).map {|t| "</#{t}>" }.join
      end

      # Registers opening of a tag.  Returns the tag.
      def push_tag(tag)
        @open_tags.push(tag) unless void?(tag)
        tag
      end

      # True when the tag is currently open.
      def open?(tag)
        @open_tags.include?(tag)
      end

      private

      # Registers closing of a tag.  Returns all the tags that need to
      # be closed at that point.
      def pop_tags(tag)
        if !@open_tags.include?(tag)
          if @ignore_html[tag]
            return [tag]
          else
            warn_unopened(tag)
            return []
          end
        end

        popped = []
        begin
          popped << t = @open_tags.pop
          if t != tag
            warn_unclosed(t)
          end
        end until t == tag

        popped
      end

      def warn_unopened(*tags)
        warn("Unopened HTML tag", tags)
      end

      def warn_unclosed(*tags)
        warn("Unclosed HTML tag", tags)
      end

      def warn(msg, tags)
        tag_list = tags.map {|tag| "<#{tag}>" }.join(", ")
        Logger.warn(:html, "#{msg}: #{tag_list}", @doc_context)
      end

      def void?(tag)
        VOID_TAGS[tag] || @ignore_html[tag]
      end

      # Tags that don't require closing
      VOID_TAGS = {
        "base" => true,
        "link" => true,
        "meta" => true,
        "hr" => true,
        "br" => true,
        "wbr" => true,
        "area" => true,
        "img" => true,
        "param" => true,
        "input" => true,
        "isindex" => true,
        "option" => true,
      }

    end

  end
end