def verify_checksum()

in main.py [0:0]

• 32 lines of code
• 15 McCabe index (conditional complexity)

def verify_checksum(filepath: str, method: str) -> list:
    """Verifies a filepath against its checksum file, given a checksum method. Returns a list of errors if any found"""
    filename = os.path.basename(filepath)
    checksum_filepath = filepath + "." + method  # foo.sha256
    if not os.path.exists(checksum_filepath):
        checksum_filepath = filepath + "." + method.upper()  # foo.SHA256 fallback
    checksum_filename = os.path.basename(checksum_filepath)
    errors = []
    try:
        try:
            checksum_value = open(checksum_filepath, "r", encoding="utf-8").read()
        except UnicodeDecodeError:  # UTF-16??
            checksum_value = open(checksum_filepath, "r", encoding="utf-16").read()
    except UnicodeError as e:
        errors.append(f"[CHK06] Checksum file {checksum_filename} contains garbage characters: {e}")
        return errors
    checksum_value_trimmed = ""
    # Strip away comment lines first
    for line in checksum_value.split("\n"):
        if not line.startswith("//") and not line.startswith("#"):
            checksum_value_trimmed += line.strip() + " "
    checksum_options = checksum_value_trimmed.split(" ")
    checksum_on_disk = "".join(x.strip() for x in checksum_options if all(c in string.hexdigits for c in x.strip())).lower()
    checksum_calculated = digest(filepath, method)
    if checksum_on_disk != checksum_calculated:
        errors.append(f"[CHK06] Checksum does not match checksum file {checksum_filename}!")
        errors.append(f"[CHK06] Calculated {method} checksum of {filename} was: {checksum_calculated}")
        errors.append(f"[CHK06] Checksum file {checksum_filename} said it should have been: {checksum_on_disk}")
        # Simple check for whether this file is just typoed.
        if len(checksum_on_disk) != CHECKSUM_LENGTHS[method]/4:  # Wrong filetype??
            for m, l in CHECKSUM_LENGTHS.items():
                if len(checksum_on_disk) == l/4:
                    errors.append(f"[CHK06] {checksum_filename} looks like it could be a {m} checksum, but has a {method} extension!")
                    break
    return errors