from string import ascii_lowercase, ascii_uppercase


def encodeSubstitutionCipher(msg: str, key: str) -> str:
    """Encode a message using a substitution cipher."""
    unique = set(msg)
    for c in unique:
        if c.isalpha():
            if c.isupper():
                encoded = key[ord(c) - ord("A")]
            else:
                encoded = key[ord(c) - ord("a")]
                encoded = encoded.lower()
            msg = msg.replace(c, encoded)
    return msg


def decodeSubstitutionCipher(encodedMsg: str, key: str) -> str:
    """Decode a message using a substitution cipher."""
    unique = set(encodedMsg)
    for c in unique:
        if c.isalpha():
            if c.isupper():
                decoded = ascii_uppercase[key.index(c.upper())]
            else:
                decoded = ascii_lowercase[key.index(c.upper())]
            encodedMsg = encodedMsg.replace(c, decoded)
    return encodedMsg


print("Testing encodeSubstitutionCipher()...", end="")
assert encodeSubstitutionCipher("CAB", "SQGYFEZXLANKJIMPURDCWTHVOB") == "GSQ"
assert encodeSubstitutionCipher("Cab Z?", "SQGYFEZXLANKJIMPURDCWTHVOB") == "Gsq B?"
assert (
    encodeSubstitutionCipher("Hello, World!", "ABCDEFGHIJKLMNOPQRSTUVWXYZ")
    == "Hello, World!"
)
assert (
    encodeSubstitutionCipher("42 - 0 = 42", "XHNSBMTOPQWGZDCEAVLKJYIURF")
    == "42 - 0 = 42"
)
assert encodeSubstitutionCipher("", "XHNSBMTOPQWGZDCEAVLKJYIURF") == ""


print("Testing decodeSubstitutionCipher()...", end="")
assert decodeSubstitutionCipher("GSQ", "SQGYFEZXLANKJIMPURDCWTHVOB") == "CAB"
assert decodeSubstitutionCipher("Gsq B?", "SQGYFEZXLANKJIMPURDCWTHVOB") == "Cab Z?"
assert (
    decodeSubstitutionCipher("Hello, World!", "ABCDEFGHIJKLMNOPQRSTUVWXYZ")
    == "Hello, World!"
)
assert (
    decodeSubstitutionCipher("42 - 0 = 42", "XHNSBMTOPQWGZDCEAVLKJYIURF")
    == "42 - 0 = 42"
)
assert decodeSubstitutionCipher("", "XHNSBMTOPQWGZDCEAVLKJYIURF") == ""
print("Passed!")