# -*- coding: utf-8 -*-
from django.utils import timezone
from django.utils.translation import ngettext


def duration_string(duration, precision="s"):
    """Format hours, minutes and seconds as a human-friendly string (e.g. "2
    hours, 25 minutes, 31 seconds") with precision to h = hours, m = minutes or
    s = seconds.
    """
    h, m, s = duration_parts(duration)

    duration = ""
    if h > 0:
        duration = ngettext("%(hours)s hour", "%(hours)s hours", h) % {"hours": h}
    if m > 0 and precision != "h":
        if duration != "":
            duration += ", "
        duration += ngettext("%(minutes)s minute", "%(minutes)s minutes", m) % {
            "minutes": m
        }
    if s > 0 and precision != "h" and precision != "m":
        if duration != "":
            duration += ", "
        duration += ngettext("%(seconds)s second", "%(seconds)s seconds", s) % {
            "seconds": s
        }

    return duration


def duration_parts(duration):
    """Get hours, minutes and seconds from a timedelta."""
    if not isinstance(duration, timezone.timedelta):
        raise TypeError("Duration provided must be a timedetla")
    h, remainder = divmod(duration.seconds, 3600)
    h += duration.days * 24
    m, s = divmod(remainder, 60)
    return h, m, s