module Rainbow
  class Color

    attr_reader :ground

    def self.build(ground, values)
      raise ArgumentError.new(
        "Wrong number of arguments for color definition, should be 1 or 3"
      ) unless [1, 3].include?(values.size)

      color = values.size == 1 ? values.first : values

      case color
        when ::Fixnum then Indexed.new(ground, color)
        when ::Symbol then Named.new(ground, color)
        when ::Array  then RGB.new(ground, *color)
        when ::String then RGB.new(ground, *parse_hex_color(color))
      end
    end

    def self.parse_hex_color(hex)
      hex = hex.gsub('#', '')
      r   = hex[0..1].to_i(16)
      g   = hex[2..3].to_i(16)
      b   = hex[4..5].to_i(16)

      [r, g, b]
    end

    class Indexed < Color

      attr_reader :num

      def initialize(ground, num)
        @ground = ground
        @num = num
      end

      def codes
        code = num + (ground == :foreground ? 30 : 40)

        [code]
      end

    end

    class Named < Indexed

      NAMES = {
        :black   => 0,
        :red     => 1,
        :green   => 2,
        :yellow  => 3,
        :blue    => 4,
        :magenta => 5,
        :cyan    => 6,
        :white   => 7,
        :default => 9,
      }

      def initialize(ground, name)
        raise ArgumentError.new(
          "Unknown color name, valid names: #{color_names.join(', ')}"
        ) unless color_names.include?(name)

        super(ground, NAMES[name])
      end

      private

      def color_names
        NAMES.keys
      end

    end

    class RGB < Indexed

      attr_reader :r, :g, :b

      def self.to_ansi_domain(value)
        (6 * (value / 256.0)).to_i
      end

      def initialize(ground, *values)
        raise ArgumentError.new(
          "RGB value outside 0-255 range"
        ) if values.min < 0 or values.max > 255

        super(ground, 8)
        @r, @g, @b = values
      end

      def codes
        super + [5, code_from_rgb]
      end

      private

      def code_from_rgb
        16 + self.class.to_ansi_domain(r) * 36 +
             self.class.to_ansi_domain(g) * 6  +
             self.class.to_ansi_domain(b)
      end

    end

  end
end