# frozen_string_literal: true

require 'css_parser'

module Epuber
  class Compiler
    module FileTypes
      require_relative 'source_file'

      class CSSFile < SourceFile
        DECLARATION_TO_FILE_GROUP_MAP = {
          'background' => :image,
          'background-image' => :image,
          'list-style' => :image,
          'list-style-image' => :image,
          'content' => :image,
          'cursor' => :image,
          'border-image' => :image,
          'border-image-source' => :image,
          'mask-image' => :image,
          'mask-box-image' => :image,
          'src' => :font,
        }.freeze

        URL_REGEXP = /url\((.+?)\)/.freeze

        # @param [Compiler::CompilationContext] compilation_context
        #
        def process(compilation_context)
          if destination_file_up_to_date?
            # HACK: for now, we need to process the file again, because we need to find linked files
            process_css(File.read(final_destination_path), compilation_context)
          else
            write_processed(process_css(File.read(abs_source_path), compilation_context))
          end
        end

        # Processes CSS file, resolves all linked files and adds them to file resolver
        #
        # @param [String] content
        # @param [Compiler::CompilationContext] compilation_context
        #
        # @return [String]
        #
        def process_css(content, compilation_context)
          parser = UI.print_step_processing_time('css parsing') do
            parser = CssParser::Parser.new
            parser.load_string!(content)
            parser
          end

          # resolve links to files, add other linked resources and compute correct path
          UI.print_step_processing_time('resolving url()') do
            parser.each_rule_set do |rule_set, _media_types|
              # @type [CssParser::RuleSet::Declarations]
              declarations = rule_set.instance_eval { @declarations }
              declarations.each do |property, decl_value|
                decl_value.to_s.scan(URL_REGEXP) do
                  url_function = Regexp.last_match(0)
                  path = Regexp.last_match(1)
                  if path.start_with?('"') && path.end_with?('"')
                    path = path[1..-2]
                    quote = '"'
                  end
                  if path.start_with?("'") && path.end_with?("'")
                    path = path[1..-2]
                    quote = "'"
                  end

                  next if path.start_with?('data:') || path.start_with?('http://') || path.start_with?('https://')

                  resource_group = DECLARATION_TO_FILE_GROUP_MAP[property]
                  new_url = SourceFile.resolve_relative_file(destination_path,
                                                             path,
                                                             compilation_context.file_resolver,
                                                             group: resource_group,
                                                             location: self)

                  content = content.gsub(url_function, "url(#{quote}#{new_url}#{quote})") if new_url
                end
              end
            end
          end

          content
        end
      end
    end
  end
end