# frozen_string_literal: true

require 'css_parser'
require 'singleton'

module Cucumber
  module UnusedCss
    class Checker
      include Singleton

      def self.prepare(output_directory:)
        @output_directory = output_directory
        @used_selectors = []
        @unused_selectors = []
        @css_files = []
        @ignored_selectors = []
        @ignores = [
          /^@(font-face|(-moz-|-webkit-)?keyframes)/,
          /^\*$/,
          /:active/,
          /:hover/,
          /::(before|after)/,
        ]
      end

      def self.ignore(list = [])
        @ignores += list
      end

      def self.load_css_in_page(html_string, current_url)
        html_page = Nokogiri::HTML(html_string)

        html_page.css('link[rel="stylesheet"]').each do |file_tag|
          if file_tag['href'].match?(/^https?:/)
            css_file_url = file_tag['href']
          else
            uri          = URI.parse(current_url)
            css_file_url = "#{uri.scheme}://#{uri.host}:#{uri.port}#{file_tag['href']}"
          end

          load_selectors css_file_url
        end
      end

      def self.check_selectors(page)
        new_used_selectors = []
        @unused_selectors.each do |selector|
          new_used_selectors.push selector if page.has_css?(selector, wait: 0)
        end

        # Add newly used selectors
        @used_selectors += new_used_selectors

        # Remove from unused list
        @unused_selectors -= new_used_selectors
      end

      def self.save_and_summarize
        @unused_selectors.sort!
        @used_selectors.sort!
        @ignored_selectors.sort!

        write_files
        summarize
      end

      class << self
        attr_reader :unused_selectors, :used_selectors, :ignored_selectors

        private

        def load_selectors(url)
          return if @css_files.include? url

          parser = CssParser::Parser.new
          parser.load_uri! url
          parser.each_selector do |selector|
            # Ignore some CSS directive that are not selectors
            if ignore? selector
              @ignored_selectors.push selector
              next
            end

            @unused_selectors.push(selector) unless @used_selectors.include?(selector) || @unused_selectors.include?(selector)
          end

          @css_files.push url
        end

        def ignore?(selector)
          @ignores.each do |regexp|
            return true if selector.match? regexp
          end

          false
        end

        def write_files
          File.write @output_directory.join('css_unused_selectors.yml'), @unused_selectors.to_yaml
          File.write @output_directory.join('css_used_selectors.yml'), @used_selectors.to_yaml
          File.write @output_directory.join('css_ignored_selectors.yml'), @ignored_selectors.to_yaml
        end

        def summarize
          puts "\nCSS selectors summary"
          puts '---------------------'
          puts " > Ignored selectors: #{@ignored_selectors.count}"
          puts " > Used selectors: #{@used_selectors.count}"
          puts " > Unused selectors: #{@unused_selectors.count}"
          puts " > Total selectors: #{@used_selectors.count + @unused_selectors.count + @ignored_selectors.count}"
          puts "\nLists saved in tmp as css_*.yml"
        end
      end
    end
  end
end