require 'thread'

module Outlander

  class ThreadsPool

    def initialize(num_threads = 3)
      @num_threads = num_threads
      @queue = Queue.new
    end

    def enqueue(&task)
      @queue << task
    end

    def start
      raise "Could not start with empty queue" if @queue.empty?
      run_threads(@num_threads)
      sleep 1 until @queue.empty? && @queue.num_waiting == @num_threads
    end

    private

    def run_threads(num_threads = 1)
      1.upto(num_threads) do
        Thread.new do
          while task = @queue.pop
            task.call
          end
        end
      end
    end
  end
end