require 'thread'
require 'timers'

class RestCore::Timer
  @mutex = Mutex.new
  @interval = 1

  singleton_class.module_eval do
    attr_accessor :interval

    def group
      @group ||= @mutex.synchronize{ @group || group_new }
    end

    private
    def group_new
      g = Timers::Group.new
      g.every(interval){}
      @thread = Thread.new do
        begin
          g.wait
        rescue => e
          warn "RestCore::Timer: ERROR: #{e}\n  from #{e.backtrace.inspect}"
        end while g.count > 1
        @group = nil
      end
      g
    end
  end

  attr_accessor :timeout, :error
  def initialize timeout, error, &block
    self.timeout = timeout
    self.error   = error
    self.block   = block
    start
  end

  def on_timeout &block
    self.block = block
  end

  def cancel
    timer.cancel
    self.block = nil
  end

  def start
    return if timeout.nil? || timeout.zero?
    self.timer = self.class.group.after(timeout){ block.call if block }
  end

  protected
  attr_accessor :block, :timer
end