from argparse import ArgumentParser
from itertools import zip_longest
from pathlib import Path

CHUNK_SIZE = 16


def hl(b: str):
    return f"\033[31;47;1m{b}\033[0m"


if __name__ == "__main__":
    parser = ArgumentParser()
    parser.add_argument("file1", type=Path, help="First file.")
    parser.add_argument("file2", type=Path, help="Second file.")
    args = parser.parse_args()

    # Read files
    with open(args.file1, "rb") as fd1, open(args.file2, "rb") as fd2:
        file1 = fd1.read()
        file2 = fd2.read()

    # Find differences
    diff = [b1 == b2 for b1, b2 in zip_longest(file1, file2, fillvalue=-1)]

    n1 = len(file1)
    n2 = len(file2)
    values1 = [f"{b:02X}" for b in file1]
    values2 = [f"{b:02X}" for b in file2]

    # Highlight different values
    values1 = [b if diff[i] else hl(b) for i, b in enumerate(values1)]
    values2 = [b if diff[i] else hl(b) for i, b in enumerate(values2)]

    # Pad to same length
    values1 = values1 + ["  "] * (max(n1, n2) - n1)
    values2 = values2 + ["  "] * (max(n1, n2) - n2)

    # Print bytes in chunks
    print()
    print(args.file1.name, " " * ((3 * CHUNK_SIZE - 1) + 2 - len(args.file1.name)), args.file2.name)
    print("-" * (3 * CHUNK_SIZE - 1), "  ", "-" * (3 * CHUNK_SIZE - 1))
    for chunk in [slice(i, i + CHUNK_SIZE) for i in range(0, max(n1, n2), CHUNK_SIZE)]:
        print(" ".join(values1[chunk]), "  ", " ".join(values2[chunk]))

    print()
    print(f"Files differ at {diff.count(False)} places.")