class Term::ANSIColor::Attribute

def self.[](name)
  case
  when self === name                              then name
  when Array === name                             then nearest_rgb_color name
  when name.to_s =~ /\A(on_)?(\d+)\z/             then get "#$1color#$2"
  when name.to_s =~ /\A#([0-9a-f]{3}){1,2}\z/i    then nearest_rgb_color name
  when name.to_s =~ /\Aon_#([0-9a-f]{3}){1,2}\z/i then nearest_rgb_on_color name
  else                                            get name
  end
end

def self.attributes(&block)
  @__order__.map { |name| @__store__[name] }
end

def self.attributes(&block)
  @__store__.each_value(&block)
end

def self.get(name)
  @__store__[name.to_sym]
end

def self.named_attributes(&block)
  @named_attributes ||= attributes.reject(&:rgb_color?).each(&block)
end

def self.nearest_rgb_color(color, options = {})
  rgb = RGBTriple[color]
  colors = rgb_colors
  if options.key?(:gray) && !options[:gray]
    colors = colors.reject(&:gray?)
  end
  colors.reject(&:background?).min_by { |c| c.distance_to(rgb, options) }
end

def self.nearest_rgb_on_color(color, options = {})
  rgb = RGBTriple[color]
  colors = rgb_colors
  if options.key?(:gray) && !options[:gray]
    colors = colors.reject(&:gray?)
  end
  colors.select(&:background?).min_by { |c| c.distance_to(rgb, options) }
end

def self.rgb_colors(&block)
  @rgb_colors ||= attributes.select(&:rgb_color?).each(&block)
end

def self.set(name, code, options = {})
  name = name.to_sym
  result = @__store__[name] = new(name, code, options)
  @__order__ << name
  @rgb_colors = nil
  result
end

def self.set(name, code, options = {})
  name = name.to_sym
  result = @__store__[name] = new(name, code, options)
  @rgb_colors = nil
  result
end

def apply(string = nil, &block)
  ::Term::ANSIColor.color(self, string, &block)
end

def background?
  @name.to_s.start_with?('on_')
end

def code
  if rgb_color?
    background? ? "48;5;#{@code}" : "38;5;#{@code}"
  else
    @code
  end
end

def distance_to(other, options = {})
  if our_rgb = to_rgb_triple and
    other.respond_to?(:to_rgb_triple) and
    other_rgb = other.to_rgb_triple
  then
    our_rgb.distance_to(other_rgb, options)
  else
    1 / 0.0
  end
end

def gradient_to(other, options = {})
  if our_rgb = to_rgb_triple and
    other.respond_to?(:to_rgb_triple) and
    other_rgb = other.to_rgb_triple
  then
    our_rgb.gradient_to(other_rgb, options).map do |rgb_triple|
      self.class.nearest_rgb_color(rgb_triple, options)
    end
  else
    []
  end
end

def gray?
  rgb_color? && to_rgb_triple.gray?
end

def initialize(name, code, options = {})
  @name = name.to_sym
  @code = code.to_s
  if html = options[:html]
    @rgb = RGBTriple.from_html(html)
  elsif !options.empty?
    @rgb = RGBTriple.from_hash(options)
  else
    @rgb = nil # prevent instance variable not initialized warnings
  end
end

def rgb_color?
  !!@rgb
end

def to_rgb_triple
  @rgb
end