class Numeric

  def add(n)
    self + n
  end

  def divide(n)
    self / n
  end

  def multiply(n)
    self * n
  end

  unless method_defined?(:multiple_of?)
    def multiple_of?(number)
      number != 0 ? modulo(number).zero? : zero?
    end
  end

  def negative?
    self < 0
  end

  def positive?
    self > 0
  end

  def power(n)
    self ** n
  end

  def subtract(n)
    self - n
  end

  def to_byte(from=:b, to=:kb)
    scalers = { b: 1, kb: 1024 ** 1, mb: 1024 ** 2, gb: 1024 ** 3, tb: 1024 ** 4, pb: 1024 ** 5, eb: 1024 ** 6 }

    to_f * scalers[from] / scalers[to]
  end

  def to_length(from=:mm, to=:in)
    imperical_scalers = {
      mm: 25.4, cm: 2.54, m: 0.0254, km: 0.0000254,
      in: 1, ft: 12, yd: 36, mi: 63360, nm: 72913.4
    }
    metric_scalers    = {
      mm: 1, cm: 10, m: 1000, km: 1000000,
      in: 0.039370078740157, ft: 0.0032808398950131, yd: 0.0010936132983377, mi: 0.00000062137119223733, nm: 0.00000053995680345572
    }

    case to
    when from
      self
    when :mm, :cm, :m, :km
      if [:in, :ft, :yd, :mi, :nm].include?(from)
        to_f * imperical_scalers[from] * imperical_scalers[to]
      else
        to_f * metric_scalers[from] / metric_scalers[to]
      end
    when :in, :ft, :yd, :mi, :nm
      if [:mm, :cm, :m, :km].include?(from)
        to_f * metric_scalers[from] * metric_scalers[to]
      else
        to_f * imperical_scalers[from] / imperical_scalers[to]
      end
    end
  end

  def to_temperature(from=:c, to=:f)
    case to
    when from
      self
    when :c, :celsius
      (to_f - 32) * 5 / 9
    when :f, :fahrenheit
      (to_f * 9 / 5) + 32
    when :k, :kelvin
      if [:c, :celsius].include?(from)
        to_f + 273.15
      else
        ((to_f - 32) * 5 / 9) + 273.15
      end
    end
  end

  def to_time_unit(from=:sec, to=:min)
    scalers = { sec: 1, min: 60 ** 1, hr: 60 ** 2, day: (60 ** 2) * 24, yr: (60 ** 2) * 24 * 365 }

    to_f * scalers[from] / scalers[to]
  end

  def to_weight(from=:g, to=:oz)
    imperical_scalers = {
      mg: 28349.523125, cg: 2834.9523125, g: 28.349523125, kg: 0.028349523125, mt: 0.000028349523125,
      oz: 1, lb: 16, tn: 32000
    }
    metric_scalers    = {
      mg: 1, cg: 10, g: 1000, kg: 1000000, mt: 1000000000,
      oz: 0.00003527396194958, lb: 0.0000022046226218488, tn: 0.0000000011023113109244
    }

    case to
    when from
      self
    when :mg, :cg, :g, :kg, :mt
      if [:oz, :lb, :tn].include?(from)
        to_f * imperical_scalers[from] * imperical_scalers[to]
      else
        to_f * metric_scalers[from] / metric_scalers[to]
      end
    when :oz, :lb, :tn
      if [:mg, :cg, :g, :kg, :mt].include?(from)
        to_f * metric_scalers[from] * metric_scalers[to]
      else
        to_f * imperical_scalers[from] / imperical_scalers[to]
      end
    end
  end

end