#!/usr/bin/env python3

from sys import argv
from itertools import cycle, islice
from subprocess import run


run(['sh', '-c', 'rm -f dcm*'])


def roundrobin(*iterables):
    "roundrobin('ABC', 'D', 'EF') --> A D E B F C"
    # Recipe credited to George Sakkis
    num_active = len(iterables)
    nexts = cycle(iter(it).__next__ for it in iterables)
    while num_active:
        try:
            for next in nexts:
                yield next()
        except StopIteration:
            # Remove the iterator we just exhausted from the cycle.
            num_active -= 1
            nexts = cycle(islice(nexts, num_active))


filenames = argv[1:]


roms = [None] * len(filenames)
for i, f in enumerate(filenames):
    with open(f, 'rb') as fd:
        roms[i] = fd.read()


path_offset_stop_tuples = []

with open(filenames[0] + '-info.txt') as f:
    for l in f:
        if '\t' not in l: continue
        label, directive, *misc = l.split()
        if directive.lower() != 'file': continue

        file_offset = int(label, 16)
        file_path, _, _ = misc[0].partition(',')

        for l in f:
            if '\t' not in l: continue
            label, directive, *_ = l.split()
            if directive.lower() != 'endf': continue

            file_len = int(label, 16)

            path_offset_stop_tuples.append((file_path, file_offset, file_len))
            break

# for p, o, l in path_offset_stop_tuples:
#     print(p, hex(o), hex(l))


path_offset_bin_tuples = []

for p, o, s in path_offset_stop_tuples:
    b = roms[0][o:s]
    path_offset_bin_tuples.append((p,o,b))

skippery = 128


single_letters = iter('bcdefg')


for n, r in zip(filenames[1:], roms[1:]):
    print('Comparing %s against original %s' % (n, filenames[0]))

    sl = next(single_letters)

    for objpath, objoffset, objbin in path_offset_bin_tuples:
        _, _, objname = objpath.rpartition('/')

        earlier = reversed(range(0, objoffset, 16))
        later = range(objoffset, len(r)-len(objbin)+16, 16)
        bothways = roundrobin(later, earlier)

        for tryoffset in bothways:
            # print(hex(tryoffset), end='=', flush=True)
            objbincmp = r[tryoffset:tryoffset+len(objbin)]

            a = objbin[0:len(objbin):skippery]
            b = objbincmp[0:len(objbin):skippery]

            maxmatches = len(a)
            matches = sum(ax == bx for (ax, bx) in zip(a, b))
            # print(str(int(matches*100/len(objbin))) + '%', end= ' ', flush=True)
            if matches * 3 >= maxmatches:
                print('Found %s at %X (moved from %X)' % (objname, tryoffset, objoffset))
 
                with open('dcm-a-%05X-%s' % (objoffset, objname), 'wb') as f:
                    f.write(objbin)
                with open('dcm-%s-%05X-%s-%05X' % (sl, objoffset, objname, tryoffset), 'wb') as f:
                    f.write(objbincmp)

                print('\tvbindiff dcm*%s*' % objname)

                break

        else:
            print('Did not find %s' % objname)