#! /usr/bin/env python

"""time format converter

converts between time in seconds as floating point value and time as
human-readable string in hours, minutes and seconds

<time string> = ((<hours>:)?<minutes>:)?<seconds>
<hours> = [0-9]+
<minutes> = [0-9]+
<seconds> = [0-9]+(.[0-9]+)"""

def sec2str(sec):
  """convert time in seconds to human-readable time string"""
  sign = ""
  sec100 = round(sec * 100)
  if sec100 < 0:
    sign = "-";
    sec100 = -sec100;
  sec1 = sec100 // 100
  sec100 = sec100 % 100
  minu = sec1 // 60
  sec1 = sec1 % 60
  hour = minu // 60
  minu = minu % 60
  return "%s%u:%02u:%02u.%02u" % (sign, hour, minu, sec1, sec100)

def str2sec(str):
  """convert a human readable time string into time in seconds"""
  total = 0
  section = 0
  sign = 1
  decimal = 1
  for c in str:
    if c == ":":
      total = (total + sign * section) * 60
      section = 0
      sign = 1
      decimal = 1
    elif c == "-":
      sign = -sign
    elif c == ".":
      decimal = 0.1
    elif c >= "0" and c <= "9":
      if decimal < 1:
        section = section + int(c) * decimal
        decimal = decimal * 0.1
      else:
        section = section * 10 + int(c)
  total = total + sign * section
  return total