# frozen_string_literal: true

module RubyWasmVdom
  module DomParser
    module_function

    def parse(doc)
      parser = JS.eval('return new DOMParser()')
      document = parser.call(:parseFromString, JS.try_convert(doc), 'text/html')
      elements = document.getElementsByTagName('body')[0][:childNodes]

      build_vdom(elements)
    end

    def build_vdom(elements)
      vdom = []
      elements.forEach do |element|
        if element[:nodeType] == JS.global[:Node][:TEXT_NODE]
          value = element[:nodeValue].to_s.chomp.strip

          next if value.empty?

          vdom << if embed_script?(value)
                    get_embed_script(value)
                  else
                    "'#{value}'"
                  end

          next
        end

        attributes_str = []
        attributes = element[:attributes]
        length = attributes[:length].to_i
        length.times do |i|
          attribute = attributes[i]
          key = attribute[:name].to_s
          value = attribute[:value].to_s

          result = if embed_script?(value)
                     script = get_embed_script(value)
                     ":#{key} => #{script}"
                   else
                     ":#{key} => '#{value}'"
                   end
          attributes_str << result
        end

        vdom << "h(:#{element[:tagName].to_s.downcase}, {#{attributes_str.join(', ')}}, [#{build_vdom(element[:childNodes])}])"
      end
      vdom.join(',')
    end

    def embed_script?(doc)
      doc.match?(/\{.+\}/)
    end

    def get_embed_script(script)
      script.gsub(/\{(.+)\}/) { ::Regexp.last_match(1) }
    end
  end
end