module Starscope
  module Lang
    module ERB
      VERSION = 1

      ERB_START = /<%(?:-|={1,4})?/.freeze
      ERB_END = /[-=]?%>/.freeze

      def self.match_file(name)
        name.end_with?('.erb')
      end

      def self.extract(_path, contents)
        multiline = false # true when parsing a multiline <% ... %> block

        contents.lines.each_with_index do |line, line_no|
          line_no += 1 # zero-index to one-index

          if multiline
            term = line.index(ERB_END)
            if term
              yield Starscope::DB::FRAGMENT, :Ruby, frag: line[0...term], line_no: line_no
              line = line[term + 1..]
              multiline = false
            else
              yield Starscope::DB::FRAGMENT, :Ruby, frag: line, line_no: line_no
            end
          end

          next if multiline

          line.scan(/#{ERB_START}(.*?)#{ERB_END}/) do |match|
            yield Starscope::DB::FRAGMENT, :Ruby, frag: match[0], line_no: line_no
          end

          line.gsub!(/<%.*?%>/, '')

          match = /#{ERB_START}(.*)$/.match(line)
          next unless match

          yield Starscope::DB::FRAGMENT, :Ruby, frag: match[1], line_no: line_no
          multiline = true
        end
      end
    end
  end
end