"""Utility functions."""
from datetime import datetime


def date_to_relative(d):
    """Converts the given datetime object to relative string representation, such as "2 days ago", etc.

    :param d: The datetime object to convert.
    :return: A string representing the given date relative to current time.
    """
    diff = datetime.utcnow() - d
    s = diff.seconds
    if diff.days > 7 or diff.days < 0:
        return d.strftime('%d %b %y')
    elif diff.days == 1:
        return '1 day ago'
    elif diff.days > 1:
        return '{} days ago'.format(diff.days)
    elif s <= 1:
        return 'just now'
    elif s < 60:
        return '{} seconds ago'.format(s)
    elif s < 120:
        return '1 minute ago'
    elif s < 3600:
        return '{} minutes ago'.format(s//60)
    elif s < 7200:
        return '1 hour ago'
    else:
        return '{} hours ago'.format(s//3600)