root/trunk/datetimeutils/__init__.py

#!/usr/bin/python
# -*- encoding: utf-8 -*-

##
## datetimeutils.py
## Created on Wed Feb  8 22:21:13 2006
## by Antti Kaihola <akaihola@ambitone.com>
## 
## Copyright (C) 2006 Antti Kaihola
## This program 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.
## 
## This program 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 this program; if not, write to the Free Software
## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
##

from datetime import datetime, timedelta
from django.http import HttpResponseNotFound
import re

re_datespan = ''.join(x for x in
                      r'''(?P<startyear>\d{4})
                          ((?P<startmonth>\d\d)
                           ((?P<startday>\d\d)
                            (-
                             ((?P<endyear>\d{4})?
                              (?P<endmonth>\d\d)
                             )?
                             (?P<endday>\d\d)
                            )?
                           )?
                          )?'''
                      if x not in ' \n')


def normalize_datespan(startyear=None, startmonth=None, startday=None,
                       endyear  =None,   endmonth=None,   endday=None):
    startdate = datetime(int(startyear  or datetime.now().year),
                         int(startmonth or 1                  ),
                         int(startday   or 1                  ),
                         4)
    enddate   = datetime(int(endyear    or (startmonth and startdate.year
                                            or startdate.year+1+(startdate.month==12))),
                         int(endmonth   or ((startmonth is not None and startday is None)
                                            and startdate.month%12+1
                                            or  startdate.month)),
                         int(endday     or startdate.day  ),
                         4)
    if startday is not None:
        enddate += timedelta(days=1)
    return startdate, enddate

    
def datespan(view):
    def datespan_wrapper(*args, **kw):
        kp = {}
        for key in ('startyear', 'startmonth', 'startday',
                    'endyear'  , 'endmonth'  , 'endday'):
            kp[key] = kw.pop(key, None)

        try:
            kw['startdate'], kw['enddate'] = normalize_datespan(**kp)
        except ValueError:
            start = (kp['startyear' ] or '') + \
                    (kp['startmonth'] or '') + \
                    (kp['startday'  ] or '')
            end   = (kp['endyear'   ] or '') + \
                    (kp['endmonth'  ] or '') + \
                    (kp['endday'    ] or '')
            daterange = '-'.join(filter(None, (start, end)))
            
            return HttpResponseNotFound('''\
<h1>Unrecognized date "%s"</h1>
<p>
  Please make sure that you specify the date range in the YYYYMMDD format,
  e.g. June 20, 2006 should be expressed as 20060620.
</p>
<p>
  Here are some examples of accepted dates and date ranges:
</p>
<ul>
  <li>20060714 (July 14, 2006)</li>
  <li>20060714-15 (July 14-15, 2006)</li>
  <li>20060714-0801 (July 14 - Aug 1, 2006)</li>
  <li>20060714-20070713 (July 14, 2006 - July 13, 2007)
</ul>''' % daterange)
        return view(*args, **kw)
    return datespan_wrapper


def datespanstr_from_GET(getdict):
    return getdict.get('dates', '')


def datespan_from_GET(getdict):
    m = re.match(re_datespan, datespanstr_from_GET(getdict))
    return normalize_datespan(**m.groupdict())

    
def datespan_from_GET_decorator(view):
    def wrapper(*args, **kw):
        request = kw.get('request', None)
        if request:
            kw['startdate'], kw['enddate'] = datespan_from_GET(request.GET)
        view(*args, **kw)
    return wrapper    
            

if __name__ == "__main__":
    import doctest
    doctest.testmod()