# imei.py - functions for handling International Mobile Equipment Identity
#           (IMEI) numbers
#
# Copyright (C) 2010, 2011, 2012, 2013 Arthur de Jong
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301 USA

"""IMEI (International Mobile Equipment Identity).

The  IMEI is used to identify mobile phones. The IMEI may optionally
include a check digit which is validated using the Luhn algorithm.

>>> validate('35686800-004141-20')
'3568680000414120'
>>> validate('35-417803-685978-1')
Traceback (most recent call last):
    ...
InvalidChecksum: ...
>>> compact('35686800-004141-20')
'3568680000414120'
>>> format('354178036859789')
'35-417803-685978-9'
>>> format('35686800-004141', add_check_digit=True)
'35-686800-004141-8'
>>> imei_type('35686800-004141-20')
'IMEISV'
>>> split('35686800-004141')
('35686800', '004141', '')
"""

from stdnum import luhn
from stdnum.exceptions import *
from stdnum.util import clean


def compact(number):
    """Convert the IMEI number to the minimal representation. This strips the
    number of any valid separators and removes surrounding whitespace."""
    return clean(number, ' -').strip().upper()


def validate(number):
    """Checks to see if the number provided is a valid IMEI (or IMEISV)
    number."""
    number = compact(number)
    if not number.isdigit():
        raise InvalidFormat()
    if len(number) == 15:
        # only 15 digit IMEI has check digit
        luhn.validate(number)
    elif len(number) not in (14, 16):
        # neither IMEI without check digit or IMEISV (which doesn't have one)
        raise InvalidLength()
    return number


def imei_type(number):
    """Check the passed number and returns 'IMEI', 'IMEISV' or None (for
    invalid) for checking the type of number passed."""
    try:
        number = validate(number)
    except ValidationError:
        return None
    if len(number) in (14, 15):
        return 'IMEI'
    else:  # len(number) == 16:
        return 'IMEISV'


def is_valid(number):
    """Checks to see if the number provided is a valid IMEI (or IMEISV)
    number."""
    try:
        return bool(validate(number))
    except ValidationError:
        return False


def split(number):
    """Split the number into a Type Allocation Code (TAC), serial number
    and either the checksum (for IMEI) or the software version number (for
    IMEISV)."""
    number = compact(number)
    return (number[:8], number[8:14], number[14:])


def format(number, separator='-', add_check_digit=False):
    """Reformat the passed number to the standard format."""
    number = compact(number)
    if len(number) == 14 and add_check_digit:
        number += luhn.calc_check_digit(number)
    number = (number[:2], number[2:8], number[8:14], number[14:])
    return separator.join(x for x in number if x)