#!/usr/bin/env python2
# -*- coding: utf-8 -*-

from itertools import izip_longest
import string
from binascii import hexlify
from math import log
from random import randint
import io

# global variables

# TODO: create dirty hack to work with 3 capacity during specification
capacity    = 4
cap         = capacity/2
maxInt      = 2**(cap*8) - 1
rewriteBin  = True
bin         = "bin"

# amount of address cells
N           = 4
# amount of data cells
D_count     = 8


# end global variables

def convert(numb):
    # getting HEX represent, in string, to use it when writing into binary file
    hexNumb = '{0:x}'.format(numb)
    out = ""

    # analyze input number, and compute
    if not capacity == 0:
        # checking power of two
        if log(capacity, 2) % 1 == 0.0:
            # we have valid capacity of our integer.
            # now check the max number to given capacity, else raise an Exception
            if numb >= (2**(capacity*8)):
                raise ValueError("Integer %s not filling in %s bytes capacity, Max INT: %s" %
                                                            (numb, capacity, maxInt))

            # starting pushing to output
            for i in _grouper(cap, hexNumb.zfill(capacity), '0'):
                # performing modification of izip_longest to string
                i = string.join(i, "")
#                print i
                out += chr(int(i, 16))
                # using statement below when i want a generator
                # yield chr(int(i, 16))
    return out

# return normalized data from convert function
def unconvert(numb):
    # using thih hack to avoid bug with zero
    h = hexlify(numb)
    print h
    if not "0"*cap == h:
        h = h.lstrip("0")

    return int(h, 16)

# grabbed from python recipes
def _grouper(n, iterable, fillvalue=None):
    "grouper(3, 'ABCDEFG', 'x') --> ABC DEF Gxx"
    args = [iter(iterable)] * n
    return izip_longest(fillvalue=fillvalue, *args)

# Code to provide working lab =)

def _writeDefaultData2Bin():
    fd = open(bin, "wb")
    # using it for code less
    cv = convert

    fd.write(cv(N))
    for i in xrange(1, N+1):
        fd.write(cv(i))

    for i in xrange(0, D_count):
        rnd = randint(0, maxInt)
#        print rnd
        fd.write(cv(rnd))

    fd.close()


def showBinContent():
    fd = open(bin, "rb")

    # use it for less code
    uc = unconvert
    # getting amount of addresses
    binN = fd.read(cap)
    binN = unconvert(binN)

    # list for storing already read data
    addresses = []
    data = []


    for i in xrange(0,N):
        addresses.append(uc(fd.read(cap)))


    for i in xrange(0, D_count):
        data.append(uc(fd.read(cap)))

    print addresses
    print data

    fd.close()


def InteractWithUser():
    _writeDefaultData2Bin()
    showBinContent()
#    _movingLoader()
    showBinContent()

def _movingLoader():
    fd = io.open(bin, "r+b")
    uc = unconvert

    fd.seek(cap+cap*N+cap*(1-1))

    data = uc(fd.read(cap))
    print "Updating Data: %s" % data
    data += 10
    print "New Data: %s" % data

    # moving back
    fd.seek(-cap, 1)

    fd.write(convert(data))

    fd.close()




if __name__ == "__main__":
    InteractWithUser()
#    print unconvert(convert(0))