#!/usr/bin/env python

import time
import pytz 
import datetime
from tzlocal import get_localzone 
from dm.common.exceptions.invalidArgument import InvalidArgument

class TimeUtility:

    UTC_MINUS_LOCAL_TIME = None

    @classmethod
    def getCurrentGMTimestamp(cls):
        """ Formats GMT timestamp. """
        return time.strftime('%Y-%m-%d %H:%M:%S', time.gmtime(time.time()))

    @classmethod
    def formatGMTimestamp(cls, t):
        """ Format GMT timestamp. """
        return time.strftime('%Y-%m-%d %H:%M:%S', time.gmtime(t))

    @classmethod
    def getCurrentLocalTimestamp(cls):
        """ Formats local timestamp. """
        return time.strftime('%Y/%m/%d %H:%M:%S %Z', time.localtime(time.time()))

    @classmethod
    def formatLocalTimestamp(cls, t):
        """ Formats local timestamp. """
        return time.strftime('%Y/%m/%d %H:%M:%S %Z', time.localtime(t))

    @classmethod
    def toDateTime(cls, t, format):
        if not t:
            return None
        tz = get_localzone()
        try:
            dt = datetime.datetime.strptime(t, format)
        except Exception, ex:
            raise InvalidArgument('Cannot parse input: %s' % ex)
        return tz.localize(dt, is_dst=None)

    @classmethod
    def utcToLocalTime(cls, utc):
        if cls.UTC_MINUS_LOCAL_TIME is None:
            cls.UTC_MINUS_LOCAL_TIME = (datetime.datetime.utcnow()-datetime.datetime.now()).total_seconds()
            if cls.UTC_MINUS_LOCAL_TIME > 0:
                cls.UTC_MINUS_LOCAL_TIME = int(cls.UTC_MINUS_LOCAL_TIME+0.5)
            else:
                cls.UTC_MINUS_LOCAL_TIME = int(cls.UTC_MINUS_LOCAL_TIME-0.5)
        localTime = utc - cls.UTC_MINUS_LOCAL_TIME 
        return localTime

#######################################################################
# Testing.
if __name__ == '__main__':
    print TimeUtility.toDateTime('2015-01-03', '%Y-%m-%d')
    dt0 = datetime.datetime.utcnow()
    dt1 = datetime.datetime.now()
    ts0 = time.mktime(dt0.timetuple())
    ts1 = time.mktime(dt1.timetuple())
    t0 = time.strftime("%Y/%m/%d %H:%M:%S", dt0.timetuple())
    print 'UTC:   ', t0, ts0
    t1 = time.strftime("%Y/%m/%d %H:%M:%S", dt1.timetuple())
    print 'LOCAL: ', t1, ts1
    print 'UTC TO LOCAL: ', TimeUtility.utcToLocalTime(ts0)