#!/usr/bin/env python3

""" give a nice string representation for a duration

Christian Herdtweck, Intra2net, November 2014
Licensed under GPL
"""

from datetime import timedelta

# Version History
# 24/11/14 Christian Herdtweck: started creation by copying strftimedelta


def strftimedelta(delta, max_parts=2, only_up_to_hours=False):
    """ nice and length-adjustable text representation of a timespan 

    will output the most significant non-zero time units, e.g.
    '2h23m50s' or '3d50s12ms' (skipping 0 minutes), or '3y63d12h'
    or for max_parts=2: '2h23m' / '3d50s' / '3y63d'

    Assumes that each year has 365 days, every day 24h, every hour 60 mins, ...
      not accounting for leap years / leap days, changes of timezones, etc
    
    @delta:timedelta or anything that can be converted to float;
       if numeric, this is interpreted as number of seconds
    @param max_parts: precision (i.e., length) of output (default: 2)
       set to None if always want precision down to microseconds
    @param only_up_to_hours: set to True to never give number of days/years
      (e.g. to get '40h' instead of '1d16h')
      default: False

    returns a string
    """

    units = '\u00B5s', 'ms', 's', 'm', 'h', 'd', 'y'

    if (max_parts is None) or (max_parts < 1):
        max_parts = 100

    # get number of seconds and sign
    if isinstance(delta, timedelta):
        seconds = delta.total_seconds()
    else:
        seconds = float(delta)
    negative = False
    if seconds < 0:
        negative = True
        seconds = abs(seconds)

    # split sub-second part
    seconds, second_part = divmod(seconds, 1)
    milliseconds, milli_part = divmod(second_part*1000, 1)
    microseconds = int(round(milli_part*1000))
    seconds = int(seconds)   # convert to int here --> all other variables will be int
    vals = [microseconds, int(milliseconds), ]

    # split longer units
    minutes = hours = days = years = 0
    if seconds > 0:
        minutes, seconds = divmod(seconds, 60)
    if minutes > 0:
        hours, minutes = divmod(minutes, 60)
    if hours > 0 and not only_up_to_hours:
        days, hours = divmod(hours, 24)
    if days > 0:
        years, days = divmod(days, 365)
    vals.append(seconds)
    vals.append(minutes)
    vals.append(hours)
    vals.append(days)
    vals.append(years)

    # build string
    str_parts = []
    if negative:
        str_parts.append('-')

    n_used = 0
    for val,unit in zip( reversed(vals), reversed(units) ):
        if val == 0:
            continue
        str_parts.append(str(val))
        str_parts.append(unit)
        n_used += 1
        if n_used >= max_parts:
            break
    return ''.join(str_parts)

#end: strftimedelta



def main():
    """ Main function, called when running file as script; currently raises a NotImplementedError 
    """
    raise NotImplementedError('nothing to run here -- only a lib!')
#end: function main


if __name__ == '__main__':
    main()

# (created using vim -- the world's best text editor)