#!/usr/bin/env python3
"""
Binary image data utilities for XMOS devices.
- MSB-to-LSB transformation of binary image file.
  If done twice, will return the original image file.
- Generate header file from image file
"""
import argparse
import os


test_xxd = ' '.join(['xxd', '-v'])  # Cant find xxd for raspberry
if os.system(test_xxd) == 0:
    XXD_EXISTS = True
else:
    print('xxd seems not to exists on this machine. Will not be able to run option --header')
    XXD_EXISTS = False


# ref: https://www.raspberrypi.org/forums/viewtopic.php?t=36288
# Reverse table is used because we don't know how to change bit-order on SPI settings
BitReverseTable256 = [0x00, 0x80, 0x40, 0xC0, 0x20, 0xA0, 0x60, 0xE0, 0x10, 0x90, 0x50, 0xD0, 0x30, 0xB0, 0x70, 0xF0,
                      0x08, 0x88, 0x48, 0xC8, 0x28, 0xA8, 0x68, 0xE8, 0x18, 0x98, 0x58, 0xD8, 0x38, 0xB8, 0x78, 0xF8,
                      0x04, 0x84, 0x44, 0xC4, 0x24, 0xA4, 0x64, 0xE4, 0x14, 0x94, 0x54, 0xD4, 0x34, 0xB4, 0x74, 0xF4,
                      0x0C, 0x8C, 0x4C, 0xCC, 0x2C, 0xAC, 0x6C, 0xEC, 0x1C, 0x9C, 0x5C, 0xDC, 0x3C, 0xBC, 0x7C, 0xFC,
                      0x02, 0x82, 0x42, 0xC2, 0x22, 0xA2, 0x62, 0xE2, 0x12, 0x92, 0x52, 0xD2, 0x32, 0xB2, 0x72, 0xF2,
                      0x0A, 0x8A, 0x4A, 0xCA, 0x2A, 0xAA, 0x6A, 0xEA, 0x1A, 0x9A, 0x5A, 0xDA, 0x3A, 0xBA, 0x7A, 0xFA,
                      0x06, 0x86, 0x46, 0xC6, 0x26, 0xA6, 0x66, 0xE6, 0x16, 0x96, 0x56, 0xD6, 0x36, 0xB6, 0x76, 0xF6,
                      0x0E, 0x8E, 0x4E, 0xCE, 0x2E, 0xAE, 0x6E, 0xEE, 0x1E, 0x9E, 0x5E, 0xDE, 0x3E, 0xBE, 0x7E, 0xFE,
                      0x01, 0x81, 0x41, 0xC1, 0x21, 0xA1, 0x61, 0xE1, 0x11, 0x91, 0x51, 0xD1, 0x31, 0xB1, 0x71, 0xF1,
                      0x09, 0x89, 0x49, 0xC9, 0x29, 0xA9, 0x69, 0xE9, 0x19, 0x99, 0x59, 0xD9, 0x39, 0xB9, 0x79, 0xF9,
                      0x05, 0x85, 0x45, 0xC5, 0x25, 0xA5, 0x65, 0xE5, 0x15, 0x95, 0x55, 0xD5, 0x35, 0xB5, 0x75, 0xF5,
                      0x0D, 0x8D, 0x4D, 0xCD, 0x2D, 0xAD, 0x6D, 0xED, 0x1D, 0x9D, 0x5D, 0xDD, 0x3D, 0xBD, 0x7D, 0xFD,
                      0x03, 0x83, 0x43, 0xC3, 0x23, 0xA3, 0x63, 0xE3, 0x13, 0x93, 0x53, 0xD3, 0x33, 0xB3, 0x73, 0xF3,
                      0x0B, 0x8B, 0x4B, 0xCB, 0x2B, 0xAB, 0x6B, 0xEB, 0x1B, 0x9B, 0x5B, 0xDB, 0x3B, 0xBB, 0x7B, 0xFB,
                      0x07, 0x87, 0x47, 0xC7, 0x27, 0xA7, 0x67, 0xE7, 0x17, 0x97, 0x57, 0xD7, 0x37, 0xB7, 0x77, 0xF7,
                      0x0F, 0x8F, 0x4F, 0xCF, 0x2F, 0xAF, 0x6F, 0xEF, 0x1F, 0x9F, 0x5F, 0xDF, 0x3F, 0xBF, 0x7F, 0xFF]


# I/O and dependencies
def read_bin_file(fname):
    with open(fname, 'rb') as fd:
        contents = fd.read()
    return contents


def write_bin_file(data, fname):
    with open(fname, 'wb') as fd:
        fd.write(data)


def read_file(fname):
    contents = ''
    with open(fname, 'r') as fd:
        for line in fd.readlines():
            contents += line
    return contents


def generate_header_file(src, dst):
    if not XXD_EXISTS:
        print('ERROR. CAnt generate header file - xxd is missing.')
        return
    cmd = ' '.join(['xxd', '-i', '<', src, '>', dst])
    os.system(cmd)
# END I/O


# Functional core
# rbo - Reverse Bit Order.  Because SPI is working in reverse bit order.
def rbo(original):
    """ print('Org is 0x{:02x}'.format(i))
    r = rbo(i)
    print("Rev is 0x{:02x}".format(r))

    :param original: 
    :return:    """
    reversed_ = BitReverseTable256[original & 0xff]
    return reversed_


def msb_to_lsb(bytearr):
    ba_lsb = bytearray(b'')
    for b in bytearr:
        ba_lsb.append(rbo(b))
    return ba_lsb

"""
def to_list(contents, sep='\n'):
    return contents.split(sep)


def to_bytearr(s):
    i = int(s.strip(), 0)
    if i >= 0 and i < 256:
        b = i.to_bytes(1, sys.byteorder, signed=False)
    else:
        raise ValueError
    return b


def to_nums(l):
    new_l = []
    for i in l:
        sub_l = []
        _i = i.split(',')
        for __i in _i:
            if __i != '':
                sub_l.append(to_bytearr(__i))
        if sub_l:
            new_l.append(sub_l)
    return new_l
"""


if __name__ == '__main__':
    parser = argparse.ArgumentParser(description='Binary image data to LSB format.')
    parser.add_argument('src', help='source binary image file')
    parser.add_argument('dst', help='destination binary image file')
    parser.add_argument('--header', help='generate header file with xxd: xxd -i < dst > HEADER ')
    args = parser.parse_args()

    img = msb_to_lsb(read_bin_file(args.src))
    write_bin_file(fname=args.dst, data=img)
    if args.header:
        generate_header_file(src=args.dst, dst=args.header)
