# TODO: Move class method implementations to Timer::Timer
module Timer
  def self.on!() @on = true end
  def self.off!() @on = false end
  def self.on?() @on end
  def self.off?() !@on end

  # Output file used by #emit. Default is STDERR (this is set at load-time)
  def self.file() @file end
  def self.file=(file) @file = file end

  # Currently only :s, or :ms. Default is :ms
  def self.unit() @unit end
  def self.unit=(unit) @unit = unit end

  # Number of digits after the decimal point. Default 0
  def self.scale() @scale end
  def self.scale=(scale) @scale = scale end

  def self.time(label, &block)
    if on?
      timer = Timer.new(label)
      r = yield
      timer.emit
      r
    else
      yield
    end
  end

  def time(label, &block) ::Timer.time(label, &block) end

  def self.new(*args)
    object = Timer.allocate
    object.send(:initialize, *args)
    object
  end

  class Timer
    attr_reader :title

    def file() ::Timer.file end

    def self.on!() ::Timer.on! end
    def self.on?() ::Time.on? end

    def unit() ::Timer.unit end
    def unit=(unit) ::Timer.unit = unit end

    def scale() ::Timer.scale end
    def scale=(scale) ::Timer.scale scale end

    def initialize(title = nil)
      @title = title
      start
    end

    def start(title = self.title) @t0 = Time.now; @title = title end
    def stop() @t1 ||= Time.now end
    def time() @t1 - @t0 end

    def to_s(title = self.title) "#{title}: #{Timer.format(time)}" end

    def emit(title = self.title)
      stop
      ::Timer.file.puts to_s(title) if ::Timer.on?
    end

    def self.factor() { s: 1, ms: 1000 }[::Timer.unit] end

    def self.format(time)
      time ? sprintf("%.#{::Timer.scale}f#{::Timer.unit}", Timer.factor * time) : time.inspect
    end
  end

private
  @on = false
  @file = STDERR
  @unit = :ms
  @scale = 0
end







#def time(title, &block)
# t0 = Time.now
# result = yield
# t1 = Time.now
# dt = (1000 * (t1 - t0)).round(0)
# puts "#{title}: #{dt}ms" if defined?(TIME) ? TIME : true
# result
#end