""" This module provides a set of constructors and routines to convert

    between DateTime[Delta] instances and ARPA representations of date

    and time. The format is specified by RFC822 + RFC1123.

    Note: Timezones are only interpreted by ParseDateTimeGMT(). All

    other constructors silently ignore the time zone information.

    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,Timezone

import re,string

# Grammar: RFC822 + RFC1123 + depreciated RFC850

_litday = '(?P<litday>Mon|Tue|Wed|Thu|Fri|Sat|Sun)[a-z]*'

_litmonth = '(?P<litmonth>Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)'\

            '[a-z]*'

_date = ('(?:(?P<day>\d?\d)(?: +' + _litmonth + 

         ' +|-(?P<month>\d?\d)-)(?P<year>(?:\d\d)?\d\d))')

_zone = Timezone.zone

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

         '(?::(?P<second>\d\d))?(?: +'+_zone+')?)')

#       Timezone information is made optional because some mail apps

#       forget to add it (most of these seem to be spamming engines, btw).

#       It defaults to UTC.

_arpadate = '(?:'+ _litday + ',? )? *' + _date

_arpadatetime = '(?:'+ _litday + ',? )? *' + _date + ' +' + _time

#       We are not strict about the extra characters: some applications

#       add extra information to the date header field. Additional spaces

#       between the fields and extra characters in the literal day

#       and month fields are also silently ignored.

arpadateRE = re.compile(_arpadate)

arpadatetimeRE = re.compile(_arpadatetime)

# Translation tables

litdaytable = {'mon':0, 'tue':1, 'wed':2, 'thu':3, 'fri':4, 'sat':5, 'sun':6 }

litmonthtable = {'jan':1, 'feb':2, 'mar':3, 'apr':4, 'may':5, 'jun':6,

                 'jul':7, 'aug':8, 'sep':9, 'oct':10, 'nov':11, 'dec':12 }

_days = ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun']

_months = [None, 'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun',

                 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec' ]

def ParseDate(arpastring,parse_arpadate=arpadateRE.match,

              strip=string.strip,atoi=string.atoi,atof=string.atof,

              lower=string.lower):

    """ParseDate(arpastring)

       Returns a DateTime instance reflecting the given ARPA

       date. Only the date part is parsed, any time part will be

       ignored. The instance's time is set to 0:00:00.

    """

    s = strip(arpastring)

    date = parse_arpadate(s)

    if not date:

        raise ValueError,'wrong format'

    litday,day,litmonth,month,year = date.groups()

    if len(year) == 2:

        year = DateTime.add_century(atoi(year))

    else:

        year = atoi(year)

    if litmonth:

        litmonth = lower(litmonth)

        try:

            month = litmonthtable[litmonth]

        except KeyError:

            raise ValueError,'wrong month format'

    else:

        month = atoi(month)

    day = atoi(day)

    # litday and timezone are ignored

    return DateTime.DateTime(year,month,day)

def ParseDateTime(arpastring,parse_arpadatetime=arpadatetimeRE.match,

                  strip=string.strip,atoi=string.atoi,atof=string.atof,

                  lower=string.lower):

    """ParseDateTime(arpastring)

       Returns a DateTime instance reflecting the given ARPA date assuming

       it is local time (timezones are silently ignored).

    """

    s = strip(arpastring)

    date = parse_arpadatetime(s)

    if not date:

        raise ValueError,'wrong format or unknown time zone'

    litday,day,litmonth,month,year,hour,minute,second,zone = date.groups()

    if len(year) == 2:

        year = DateTime.add_century(atoi(year))

    else:

        year = atoi(year)

    if litmonth:

        litmonth = lower(litmonth)

        try:

            month = litmonthtable[litmonth]

        except KeyError:

            raise ValueError,'wrong month format'

    else:

        month = atoi(month)

    day = atoi(day)

    hour = atoi(hour)

    minute = atoi(minute)

    if second is None:

        second = 0.0

    else:

        second = atof(second)

    # litday and timezone are ignored

    return DateTime.DateTime(year,month,day,hour,minute,second)

def ParseDateTimeGMT(arpastring,parse_arpadatetime=arpadatetimeRE.match,

                     strip=string.strip,atoi=string.atoi,atof=string.atof,

                     lower=string.lower):

    """ParseDateTimeGMT(arpastring)

       Returns a DateTime instance reflecting the given ARPA date converting

       it to UTC (timezones are honored).

    """

    s = strip(arpastring)

    date = parse_arpadatetime(s)

    if not date:

        raise ValueError,'wrong format or unknown time zone'

    litday,day,litmonth,month,year,hour,minute,second,zone = date.groups()

    if len(year) == 2:

        year = DateTime.add_century(atoi(year))

    else:

        year = atoi(year)

    if litmonth:

        litmonth = lower(litmonth)

        try:

            month = litmonthtable[litmonth]

        except KeyError:

            raise ValueError,'wrong month format'

    else:

        month = atoi(month)

    day = atoi(day)

    hour = atoi(hour)

    minute = atoi(minute)

    if second is None:

        second = 0.0

    else:

        second = atof(second)

    offset = Timezone.utc_offset(zone)

    # litday is ignored

    return DateTime.DateTime(year,month,day,hour,minute,second) - offset

# Alias

ParseDateTimeUTC = ParseDateTimeGMT

def str(datetime,tz=None):

    """str(datetime,tz=DateTime.tz_offset(datetime))

    Returns the datetime instance as ARPA date string. tz can be given

    as DateTimeDelta instance providing the time zone difference from

    datetime's zone to UTC. It defaults to

    DateTime.tz_offset(datetime) which assumes local time. """

    if tz is None:

        tz = datetime.gmtoffset()

    return '%s, %02i %s %04i %02i:%02i:%02i %+03i%02i' % (

        _days[datetime.day_of_week], datetime.day, 

        _months[datetime.month], datetime.year,

        datetime.hour, datetime.minute, datetime.second,

        tz.hour,tz.minute)

def strGMT(datetime):

    """ strGMT(datetime)

    Returns the datetime instance as ARPA date string assuming it

    is given in GMT. """

    return '%s, %02i %s %04i %02i:%02i:%02i GMT' % (

        _days[datetime.day_of_week], datetime.day, 

        _months[datetime.month], datetime.year,

        datetime.hour, datetime.minute, datetime.second)

def strUTC(datetime):

    """ strUTC(datetime)

    Returns the datetime instance as ARPA date string assuming it

    is given in UTC. """

    return '%s, %02i %s %04i %02i:%02i:%02i UTC' % (

        _days[datetime.day_of_week], datetime.day, 

        _months[datetime.month], datetime.year,

        datetime.hour, datetime.minute, datetime.second)

def _test():

    import sys, os, rfc822

    file = os.path.join(os.environ['HOME'], 'nsmail/Inbox')

    f = open(file, 'r')

    while 1:

        m = rfc822.Message(f)

        if not m:

            break

        print 'From:', m.getaddr('from')

        print 'To:', m.getaddrlist('to')

        print 'Subject:', m.getheader('subject')

        raw = m.getheader('date')

        try:

            date = ParseDateTimeUTC(raw)

            print 'Date:',strUTC(date)

        except ValueError,why:

            print 'PROBLEMS:',repr(raw),'-->',why

            raw_input('...hit return to continue')

        print

        # Netscape mail file

        while 1:

            line = f.readline()

            if line[:6] == 'From -':

                break

if __name__ == '__main__':

    _test()