# -*- coding: latin-1 -*-

""" Timezone information.

    XXX This module still has prototype status and is undocumented.

    XXX Double check the offsets given in the zonetable below.

    XXX Add TZ environment variable parsing functions. The REs are already

        there.

    Copyright (c) 1998-2000, Marc-Andre Lemburg; mailto:mal@lemburg.com

    Copyright (c) 2000-2007, eGenix.com Software GmbH; mailto:info@egenix.com

    See the documentation for further information on copyrights,

    or contact the author. All Rights Reserved.

"""

import DateTime

import re,string

### REs

# time zone parsing

isozone = ('(?P<zone>[+-]\d\d:?(?:\d\d)?|Z)')

zone = ('(?P<zone>[A-Z]+|[+-]\d\d?:?(?:\d\d)?)')

zoneoffset = ('(?:'

              '(?P<zonesign>[+-])?'

              '(?P<hours>\d\d?)'

              ':?'

              '(?P<minutes>\d\d)?'

              '(?P<extra>\d+)?'

              ')'

              )

# TZ environment variable parsing

dstswitchtime = ('(?P<hour>\d\d?):?'

                 '(?P<minute>\d\d)?:?'

                 '(?P<second>\d\d)?')

dstswitch = ('(?:'

              '(?P<doy>\d+)|'

              '(?:J(?P<jdoy>\d+))|'

              '(?:M(?P<month>\d+).(?P<week>\d+).(?P<day>\d+))'

             ')'

             '(?:/' + dstswitchtime + ')?'

             )

# XXX Doesn't work since re doesn't like multiple occurrences of

#     group names.

#tz = ('(?::(?P<filename>.+))|'

#      '(?P<std>[A-Z]+)' + zoneoffset + 

#      '(?:'

#       '(?P<dst>[A-Z]+)' + zoneoffset + '?'+

#       '(?:[;,]' + dstswitch + '[;,]' + dstswitch + ')'

#      ')?'

#      )

# Compiled RE objects

isozoneRE = re.compile(zone)

zoneRE = re.compile(zone)

zoneoffsetRE = re.compile(zoneoffset)

#tzRE= re.compile(tz)

### Time zone offset table

#

# The offset given here represent the difference between UTC and the

# given time zone.

#

# Additions and corrections are always welcome :-)

#

# Note that some zone names are ambiguous, e.g. IST can refer to Irish

# Summer Time, Indian Standard Time, Israel Standard Time. We've

# usualy chosen meaning with the most wide-spread use.

#

zonetable = {

              # Timezone abbreviations

              # Std     Summer

              # Standards

              'UT':0,

              'UTC':0,

              'GMT':0,

              # A few common timezone abbreviations

              'CET':1,  'CEST':2, 'CETDST':2, # Central European

              'MET':1,  'MEST':2, 'METDST':2, # Mean European

              'MEZ':1,  'MESZ':2,             # Mitteleurop�ische Zeit

              'EET':2,  'EEST':3, 'EETDST':3, # Eastern Europe

              'WET':0,  'WEST':1, 'WETDST':1, # Western Europe

              'MSK':3,  'MSD':4,  # Moscow

              'IST':5.5,          # India

              'JST':9,            # Japan

              'KST':9,            # Korea

              'HKT':8,            # Hong Kong

              # US time zones

              'AST':-4, 'ADT':-3, # Atlantic

              'EST':-5, 'EDT':-4, # Eastern

              'CST':-6, 'CDT':-5, # Central

              'MST':-7, 'MDT':-6, # Midwestern

              'PST':-8, 'PDT':-7, # Pacific

              # Australian time zones

              'CAST':9.5, 'CADT':10.5, # Central

              'EAST':10,  'EADT':11,   # Eastern

              'WAST':8,   'WADT':9,    # Western

              'SAST':9.5, 'SADT':10.5, # Southern

              # US military time zones

              'Z': 0,

              'A': 1,

              'B': 2,

              'C': 3,

              'D': 4,

              'E': 5,

              'F': 6,

              'G': 7,

              'H': 8,

              'I': 9,

              'K': 10,

              'L': 11,

              'M': 12,

              'N':-1,

              'O':-2,

              'P':-3,

              'Q':-4,

              'R':-5,

              'S':-6,

              'T':-7,

              'U':-8,

              'V':-9,

              'W':-10,

              'X':-11,

              'Y':-12

              }    

def utc_offset(zone,

               atoi=string.atoi,zoneoffset=zoneoffsetRE,

               zonetable=zonetable,zerooffset=DateTime.DateTimeDelta(0),

               oneMinute=DateTime.oneMinute,upper=string.upper):

    """ utc_offset(zonestring)

        Return the UTC time zone offset as DateTimeDelta instance.

        zone must be string and can either be given as +-HH:MM,

        +-HHMM, +-HH numeric offset or as time zone

        abbreviation. Daylight saving time must be encoded into the

        zone offset.

        Timezone abbreviations are treated case-insensitive.

    """

    if not zone:

        return zerooffset

    uzone = upper(zone)

    if zonetable.has_key(uzone):

        return zonetable[uzone]*DateTime.oneHour

    offset = zoneoffset.match(zone)

    if not offset:

        raise ValueError,'wrong format or unknown time zone: "%s"' % zone

    zonesign,hours,minutes,extra = offset.groups()

    if extra:

        raise ValueError,'illegal time zone offset: "%s"' % zone

    offset = int(hours or 0) * 60 + int(minutes or 0)

    if zonesign == '-':

        offset = -offset

    return offset*oneMinute