Fonctionnalité pour générer un datetime timezone aware

* Prend un truc de la forme %Y%m%d%H%M%S, et une tz de la forme [+-]XXXX
 * On peut ne pas fournir le premier argument, auquel cas on prend la
 date actuele
 * On peut ne pas fournir la timezone, auquel cas elle sera fixée à
 celle du système si dateutil est installé, ou à UTC à défaut.
 * Si pas de pytz et que pas de tz fournie, dateutil est utilisé.
 * Si pas de pytz et pas de dateutil, le datetime ne sera pas timezone
 aware

crans_utils.py

@@ -55,6 +55,11 @@ try:
 except:
     pytz = None
 
+try:
+    import dateutil.tz
+except:
+    dateutil = None
+
 DEVNULL = open(os.devnull, 'w')
 
 def find_rid_plage(rid):
@@ -340,21 +345,50 @@ def from_generalized_time_format(gtf):
     """
     return time.mktime(time.strptime(gtf.split("-", 1)[0].split("+", 1)[0].split('Z', 1)[0], "%Y%m%d%H%M%S"))
 
-def datetime_from_generalized_time_format(gtf):
-    """Returns a datetime from generalized time format
+def localized_datetime(date=None, tz=None):
+    """Builds a datetime object based on a date string formatted as
+    %Y%m%d%H%M%S, and a tz timezone looking like +0200"""
 
-    """
+    _notz = (tz is None)
+
+    # Shit may happen
+    if tz == "Z":
+        tz = "+0000"
+
+    if date is not None:
+        the_date = datetime.datetime.strptime(date, "%Y%m%d%H%M%S")
+    else:
+        the_date = datetime.datetime.now()
+
+    # No timezone means we try to get from the system
+    # if we have dateutil, else, UTC.
+    if tz is None:
+        if dateutil is not None:
+            tz = datetime.datetime.now(dateutil.tz.tzlocal()).strftime("%z")
+        else:
+            tz = "+0000"
+
+    # No pytz means no timezoned datetime
+    if pytz is not None:
+        the_timezone = pytz.FixedOffset(int(tz[0:-2])*60 + int(tz[-2:]))
+        the_date = the_timezone.localize(the_date)
+        the_date = the_timezone.normalize(the_date)
+    else:
+        # Maybe we can do something
+        if dateutil is not None:
+            if _notz:
+                the_date.replace(tzinfo=dateutil.tz.tzlocal())
+
+    return the_date
+
+def datetime_from_generalized_time_format(gtf):
+    """Returns a datetime from generalized time format"""
     if '-' in gtf or '+' in gtf:
         date, tz = gtf[0:14], gtf[14:]
     else:
         date = gtf.replace("Z", '')
         tz = '+0000'
-    the_date = datetime.datetime.strptime(date, "%Y%m%d%H%M%S")
-    if pytz is not None:
-        the_timezone = pytz.FixedOffset(int(tz[0:-2])*60 + int(tz[-2:]))
-        the_date = the_timezone.localize(the_date)
-        the_date = the_timezone.normalize(the_date)
-    return the_date
+    return localized_datetime(date, tz)
 
 def datetime_to_generalized_time_format(datetime_obj):
     """Transforms a datetime to a GTF"""