#    Copyright (C) 2017  Alban Gruin
#
#    celcatsanitizer is free software; you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation; either version 2 of the License, or
#    (at your option) any later version.
#
#    celcatsanitizer is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License along
#    with celcatsanitizer; if not, write to the Free Software Foundation, Inc.,
#    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

from django.utils import timezone

import datetime
import re

def get_current_week():
    return timezone.now().isocalendar()[:2]

def get_current_or_next_week():
    year, week, day = timezone.now().isocalendar()
    if day >= 6:
        year, week, _ = (timezone.now() + datetime.timedelta(weeks=1)).isocalendar()

    return year, week

def get_week(year, week):
    start = timezone.make_aware(datetime.datetime.strptime(
        "{0}-W{1:02d}-1".format(year, week), "%Y-W%W-%w"))
    end = start + datetime.timedelta(weeks=1)

    return start, end

def group_courses(courses):
    grouped_courses = []
    for i, course in enumerate(courses):
        if i == 0 or courses[i - 1].begin.day != course.begin.day:
            grouped_courses.append([course])
        else:
            grouped_courses[-1].append(course)

    return grouped_courses

def parse_group(name):
    # Explication de la regex
    #
    # ^([\w ]+?)(\s*(((CM)(\w))|((TD)(\w)(\d))|((TP)(\w)(\d)(\d))))?$
    # ^                                                               début de la ligne
    #  ([\w ]+?)                                                      correspond à au moins un caractère
    #           (\s*                                                  zéro, un ou plusieurs espaces
    #               (((CM)(\w))|                                      correspond à CM suivi d'une lettre ou...
    #                           ((TD)(\w)(\d))|                       ... à TD suivi d’une lettre et d'un chiffre ou...
    #                                          ((TP)(\w)(\d)(\d)))    ... à TP suivi d’une lettre et de deux chiffres
    #                                                             )?  groupe optionel
    #                                                               $ fin de la ligne
    group_regex = re.compile("^([\w ]+?)(\s*(((CM)(\w))|((TD)(\w)(\d))|((TP)(\w)(\d)(\d))))?$")
    search = group_regex.search(name)
    if search is None:
        return name, None, None, None

    parts = search.groups(0)
    if parts[1] == 0:
        return parts[0], None, None, None
    elif parts[4] == "CM":
        return parts[0], parts[5], None, None
    elif parts[7] == "TD":
        return parts[0], parts[8], parts[9], None
    elif parts[11] == "TP":
        return parts[0], parts[12], parts[13], parts[14]