# encoding: utf-8

module Watir
  module HTML
    class Generator

      IGNORED_ATTRIBUTES = %w(cells elements hash rows span text)

      def generate(spec_url, io = StringIO.new)
        @spec_url, @io = spec_url, io

        extract_spec
        cleanup_spec

        write_header
        write_class_defs
        write_container_methods
        write_footer

        io
      end

      private

      def generator
        @generator ||= WebIDL::Generator.new(visitor)
      end

      def visitor
        @visitor ||= Visitor.new
      end

      def extractor
        @extractor ||= SpecExtractor.new(@spec_url)
      end

      def extract_spec
        @tag2interfaces    = extractor.process
        @sorted_interfaces = extractor.sorted_interfaces

        if extractor.errors.any?
          raise "error extracting spec: #{extractor.errors.join("\n")}"
        end
      end

      def cleanup_spec
        # ignore the link element for now
        @tag2interfaces.delete("link")
        @sorted_interfaces.reject! { |intf| intf.name == "HTMLLinkElement" }
        # frame is implemented manually, see https://github.com/watir/watir-webdriver/issues/204
        @sorted_interfaces.reject! { |intf| intf.name == "HTMLFrameElement"  }

        # cleanup attributes
        @sorted_interfaces.each do |intf|
          intf.members.delete_if { |member| IGNORED_ATTRIBUTES.include?(member.name) }
        end
      end

      def write_header
        @io.puts "# Autogenerated from the HTML5 specification. Edits may be lost."
        @io.puts "module Watir"
      end

      def write_class_defs
        @sorted_interfaces.each do |interface|
          interface = generator.generate(interface)
          unless interface.empty?
            interface.gsub!(/^\s+\n/, '') # remove empty lines
            @io.puts indent(interface)
          end
        end
      end

      def write_container_methods
        @io.puts "\n\n"
        @io.puts indent("module Container")

        @tag2interfaces.sort.each do |tag, interfaces|
          raise "multiple interfaces for tag #{tag.inspect}" unless interfaces.map { |e| e.name }.uniq.size == 1

          tag_string       = tag.inspect
          singular         = Util.paramify(tag)
          plural           = singular.pluralize
          element_class    = Util.classify(interfaces.first.name)
          collection_class = "#{element_class}Collection"

          # visitor.visit_tag(tag, interfaces.first.name) !?
          @io.puts indent(<<-CODE, 3)

#
# @return [#{element_class}]
#

def #{singular}(*args)
  #{element_class}.new(self, extract_selector(args).merge(:tag_name => #{tag_string}))
end

#
# @return [#{collection_class}]
#

def #{plural}(*args)
  #{collection_class}.new(self, extract_selector(args).merge(:tag_name => #{tag_string}))
end

Watir.tag_to_class[#{tag.to_sym.inspect}] = #{element_class}

CODE
        end

        @io.puts indent("end # Container")
      end

      def write_footer
        @io.puts "end # Watir"
      end

      def indent(code, indent = 1)
        indent_string = "  " * indent
        code.split("\n").map { |line| line.empty? ? line : indent_string + line }.join("\n")
      end

    end # Generator
  end # HTML5
end # Watir