require 'yaml'
require 'benchmark'

module Jeka

  class Implementation < JekaHelper
    
    jeka_reader :language
    jeka_reader :source
    jeka_reader :comment
    
    attr_accessor :algorithm
    
    def initialize(folder)
      super(File.join(folder, "_implementation.yaml"))
    end
    
    def source_code
      f = File.open(File.join(@folder, source), "r")
      return f.readlines.join()
    end
    
    def build
      if @jeka["build"]
        command = @jeka["build"]["command"].gsub("$", @folder)
        system(command)
      end
    end
    
    def run(input, verbose)
      command = "#{@jeka["run"]["command"].gsub("$", @folder)} #{"< #{input}" if input}"
      if verbose
        system(command)
      else
        out = ""
        IO.popen(command) do |io|
          out = io.readlines
        end
        return out.join("")
      end
    end
    
    def benchmark(input, n)
      b = Benchmark.measure {run(input, false)}.to_a
      bench = Hash.new
      bench[:user_cpu_time] = b[1]
      bench[:system_cpu_time] = b[2]
      bench[:childrens_use_cpu_time] = b[3]
      bench[:childrens_system_cpu_time] = b[4]
      bench[:elapsed_real_time] = b[5]
      (n-1).times do
        b = Benchmark.measure {run(input, false)}.to_a
        bench[:user_cpu_time] += b[1]
        bench[:system_cpu_time] += b[2]
        bench[:childrens_use_cpu_time] += b[3]
        bench[:childrens_system_cpu_time] += b[4]
        bench[:elapsed_real_time] += b[5]
      end
      bench[:user_cpu_time] /= n
      bench[:system_cpu_time] /= n
      bench[:childrens_use_cpu_time] /= n
      bench[:childrens_system_cpu_time] /= n
      bench[:elapsed_real_time] /= n
      
      filename = File.join(@folder, File.basename(input).gsub(/\..*/, ".benchmark"))
      f = File.open(filename, "w")
      f.write(bench)
      f.close
      
      return bench
    end
    
    def benchmark_results
      benchmarks = []
      n = 0
      dir = Dir.new(@folder)
      dir.each do |d|
        if d.index(/^test_.*\.benchmark$/)
          f = File.open(File.join(@folder, d), "r")
          benchmarks << eval(f.readlines.join(""))
          n += 1
        end
      end
      
      bench = Hash.new
      bench[:language] = language
      bench[:comment] = comment
      bench[:user_cpu_time] = 0
      bench[:system_cpu_time] = 0
      bench[:childrens_use_cpu_time] = 0
      bench[:childrens_system_cpu_time] = 0
      bench[:elapsed_real_time] = 0
      benchmarks.each do |b|
        bench[:user_cpu_time] += b[:user_cpu_time]
        bench[:system_cpu_time] += b[:system_cpu_time]
        bench[:childrens_use_cpu_time] += b[:childrens_use_cpu_time]
        bench[:childrens_system_cpu_time] += b[:childrens_system_cpu_time]
        bench[:elapsed_real_time] += b[:elapsed_real_time]
      end
      bench[:user_cpu_time] /= n
      bench[:system_cpu_time] /= n
      bench[:childrens_use_cpu_time] /= n
      bench[:childrens_system_cpu_time] /= n
      bench[:elapsed_real_time] /= n
      
      return bench
    end
    
  end
  
end