# encoding: UTF-8
module Benchmark
  module Avg
    class Job
      PRECISION = 2

      def initialize(label, block)
        @label          = label
        @block          = block
        @warmup_samples = []
        @run_samples    = []
        @warming_up     = true
      end

      def run(warmup_time, run_time)
        warmup_finish = Time.now + warmup_time
        measure_until(@warmup_samples, warmup_finish)
        finish_warmup

        suite_finish = Time.now + run_time
        measure_until(@run_samples, suite_finish)
        finish_measure
      end


      def warmup_report
        report @warmup_samples
      end

      def runtime_report
        report @run_samples
      end

      private
      def measure_until(samples, finish_time)
        while Time.now < finish_time do
          measure_block(samples)
        end
      end

      def measure_block(samples)
        start = Time.now
        @block.call
        finish = Time.now
        samples << (finish - start)
      end

      def finish_warmup
        @warming_up = false
        puts "Finished warm up for #{@label}, running the real bechmarks now"
      end

      def finish_measure
        puts "Finished measuring the run time for #{@label}"
      end

      def report(samples)
        times   = extract_times(samples)
        label   = @label.ljust(LABEL_WIDTH - PADDING) + padding_space
        metrics = "#{round(times[:ipm])} i/min" << padding_space
        metrics << "#{round(times[:avg])} s (avg)" << padding_space
        metrics << "(± #{round(times[:standard_deviation_percent])}%)"
        label + metrics
      end

      def round(number)
        # not Float#round to also get numbers like 3.20 (static number after ,)
        sprintf("%.#{PRECISION}f", number)
      end

      def padding_space
        ' ' * PADDING
      end

      def extract_times(samples)
        times         = {}
        times[:total] = samples.inject(:+)
        iterations    = samples.size
        times[:avg]   = times[:total] / iterations
        times[:ipm]   = iterations / (times[:total] / 60)
        total_variane = samples.inject(0) do |total, time|
          total + ((time - times[:avg]) ** 2)
        end
        times[:variance] = total_variane / iterations
        times[:standard_deviation] = Math.sqrt times[:variance]
        times[:standard_deviation_percent] =
          100.0 * (times[:standard_deviation] / times[:avg])
        times
      end
    end
  end
end