class Console::Progress

def self.now
	Process.clock_gettime(Process::CLOCK_MONOTONIC)
end

def average_duration
	if @current > 0
		duration / @current
	end
end

def duration
	Progress.now - @start_time
end

def duration_since_last_output
	if @last_output_time
		Progress.now - @last_output_time
	end
end

def estimated_remaining_time
	if average_duration = self.average_duration
		average_duration * remaining
	end
end

def increment(amount = 1)
	@current += amount
	
	if output?
		@output.info(@subject, self) {Event::Progress.new(@current, @total)}
		@last_output_time = Progress.now
	end
	
	return self
end

def initialize(output, subject, total = 0, minimum_output_duration: 0.1)
	@output = output
	@subject = subject
	
	@start_time = Progress.now
	
	@last_output_time = nil
	@minimum_output_duration = minimum_output_duration
	
	@current = 0
	@total = total
end

def mark(...)
	@output.info(@subject, ...)
end

def output?
	if remaining.zero?
		return true
	elsif duration = duration_since_last_output
		return duration > @minimum_output_duration
	else
		return true
	end
end

def ratio
	Rational(@current.to_f, @total.to_f)
end

def remaining
	@total - @current
end

def resize(total)
	@total = total
	
	@output.info(@subject, self) {Event::Progress.new(@current, @total)}
	@last_output_time = Progress.now
	
	return self
end

def to_s
	if estimated_remaining_time = self.estimated_remaining_time
		"#{@current}/#{@total} completed in #{Clock.formatted_duration(self.duration)}, #{Clock.formatted_duration(estimated_remaining_time)} remaining."
	else
		"#{@current}/#{@total} completed, waiting for estimate..."
	end
end