module SassC
  module Script
    class String
      # The Ruby value of the string.
      #
      # @return [String]
      attr_reader :value

      # Whether this is a CSS string or a CSS identifier.
      # The difference is that strings are written with double-quotes,
      # while identifiers aren't.
      #
      # @return [Symbol] `:string` or `:identifier`
      attr_reader :type

      def self.value(contents)
        contents.gsub("\\\n", "").gsub(/\\(?:([0-9a-fA-F]{1,6})\s?|(.))/) do
          next $2 if $2
          # Handle unicode escapes as per CSS Syntax Level 3 section 4.3.8.
          code_point = $1.to_i(16)
          if code_point == 0 || code_point > 0x10FFFF ||
              (code_point >= 0xD800 && code_point <= 0xDFFF)
            '�'
          else
            [code_point].pack("U")
          end
        end
      end

      def self.quote(contents, quote = nil)
        # Short-circuit if there are no characters that need quoting.
        unless contents =~ /[\n\\"']/
          quote ||= '"'
          return "#{quote}#{contents}#{quote}"
        end

        if quote.nil?
          if contents.include?('"')
            if contents.include?("'")
              quote = '"'
            else
              quote = "'"
            end
          else
            quote = '"'
          end
        end

        # Replace single backslashes with multiples.
        contents = contents.gsub("\\", "\\\\\\\\")

        if quote == '"'
          contents = contents.gsub('"', "\\\"")
        else
          contents = contents.gsub("'", "\\'")
        end

        contents = contents.gsub(/\n(?![a-fA-F0-9\s])/, "\\a").gsub("\n", "\\a ")
        "#{quote}#{contents}#{quote}"
      end

      def self.type(contents)
        unquote(contents) == contents ? :identifier : :string
      end

      def self.unquote(contents)
        s = contents.dup

        case contents[0, 1]
        when "'", '"', '`'
          s[0] = ''
        end

        case contents[-1, 1]
        when "'", '"', '`'
          s[-1] = ''
        end

        return s
      end

      # Creates a new string.
      #
      # @param value [String] See \{#value}
      # @param type [Symbol] See \{#type}
      def initialize(value, type = :identifier)
        value.freeze unless value.nil? || value == true || value == false
        @value = value
        @type = type
      end

      def to_native
        Native::make_string(to_s)
      end

      # @see Value#to_s
      def to_s(opts = {})
        return @value.gsub(/\n\s*/, ' ') if opts[:quote] == :none || @type == :identifier
        SassC::Script::String.quote(value, opts[:quote])
      end
    end
  end
end