#!/usr/bin/env python
# -*- coding: utf-8 -*-

""" pySim: various utilities
"""

#
# Copyright (C) 2009-2010  Sylvain Munaut <tnt@246tNt.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 2 of the License, or
# (at your option) any later version.
#
# This program 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#


def h2b(s):
	return ''.join([chr((int(x,16)<<4)+int(y,16)) for x,y in zip(s[0::2], s[1::2])])

def b2h(s):
	return ''.join(['%02x'%ord(x) for x in s])

def h2i(s):
	return [(int(x,16)<<4)+int(y,16) for x,y in zip(s[0::2], s[1::2])]

def i2h(s):
	return ''.join(['%02x'%(x) for x in s])

def swap_nibbles(s):
	return ''.join([x+y for x,y in zip(s[1::2], s[0::2])])

def rpad(s, l, c='f'):
	return s + c * (l - len(s))

def lpad(s, l, c='f'):
	return c * (l - len(s)) + s

def enc_imsi(imsi):
	"""Converts a string imsi into the value of the EF"""
	l = (len(imsi) + 1) // 2	# Required bytes
	oe = len(imsi) & 1			# Odd (1) / Even (0)
	ei = '%02x' % l + swap_nibbles(lpad('%01x%s' % ((oe<<3)|1, imsi), 16))
	return ei

def dec_imsi(ef):
	"""Converts an EF value to the imsi string representation"""
	if len(ef) < 4:
		return None
	l = int(ef[0:2]) * 2			# Length of the IMSI string
	swapped = swap_nibbles(ef[2:])
	oe = (int(swapped[0])>>3) & 1	# Odd (1) / Even (0)
	if oe:
		l = l-1
	if l+1 > len(swapped):
		return None
	imsi = swapped[1:l+2]
	return imsi

def dec_iccid(ef):
	return swap_nibbles(ef).strip('f')

def enc_iccid(iccid):
	return swap_nibbles(rpad(iccid, 20))

def enc_plmn(mcc, mnc):
	"""Converts integer MCC/MNC into 6 bytes for EF"""
	return swap_nibbles(lpad('%d' % mcc, 3) + lpad('%d' % mnc, 3))