[Predator] Move time_util from common/ to lib/, split code review related part to code_review_util

appengine/findit/lib/time_util.py

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import calendar
 from datetime import datetime
 from datetime import time
 from datetime import timedelta
 
 import pytz
@@ skipping 48 matching lines @@
 
   Args:
     timezone_name (str): The name of any timezone supported by pytz.
     date_time (datetime.datetime): The optional datetime to be converted into
         the new timezone.
 
   Returns:
     A datetime.datetime of the given one in the specified timezone.
   """
   return date_time.astimezone(pytz.timezone(timezone_name))
+
+
+class TimeZoneInfo(object):
+  """Gets time zone info from string like: +0800.
+
+  The string is HHMM offset relative to UTC timezone."""
+
+  def __init__(self, offset_str):
+    self._utcoffset = self.GetOffsetFromStr(offset_str)
+
+  def GetOffsetFromStr(self, offset_str):
+    offset = int(offset_str[-4:-2]) * 60 + int(offset_str[-2:])
+    if offset_str[0] == '-':
+      offset = -offset
+    return timedelta(minutes=offset)
+
+  def LocalToUTC(self, naive_time):
+    """Localizes naive datetime and converts it to utc naive datetime.
+
+    Args:
+      naive_time(datetime): naive time in local time zone, for example '+0800'.
+
+    Return:
+      A naive datetime object in utc time zone.
+      For example:
+      For TimeZoneInfo('+0800'), and naive local time is
+      datetime(2016, 9, 1, 10, 0, 0), the returned result should be
+      datetime(2016, 9, 1, 2, 0, 0) in utc time.
+    """
+    return naive_time - self._utcoffset