from math import ceil
from string import ascii_lowercase


def getIndex(row: int, col: int, rows: int) -> int:
    return col * rows + row


def getRowAndCol(x: int, rows: int) -> tuple[int, int]:
    return x // rows, x % rows


def encodeRouteCipher(message: str, rows: int) -> str:
    row_len = ceil(len(message) / rows)
    missing_chars = row_len * rows - len(message)
    message += "".join(reversed(ascii_lowercase))[:missing_chars]
    encoded_string = ""
    for i in range(len(message)):
        row, col = getRowAndCol(i, row_len)
        encoded_string += message[getIndex(row, col, rows)]
    encoded_message = f"{rows}"
    for i in range(0, rows):
        if i % 2 == 0:
            encoded_message += encoded_string[i * row_len : (i + 1) * row_len]
        else:
            encoded_message += encoded_string[i * row_len : (i + 1) * row_len][::-1]
    return encoded_message


def decodeRouteCipher(encodedMessage: str) -> str:
    decoded_message = ""
    rows = int(encodedMessage[0])
    encoded_string = encodedMessage[1:]
    row_len = ceil(len(encoded_string) / rows)
    decoded_string = ""
    for i in range(rows):
        if i % 2 == 0:
            decoded_string += encoded_string[i * row_len : (i + 1) * row_len]
        else:
            decoded_string += encoded_string[i * row_len : (i + 1) * row_len][::-1]
    for i in range(len(decoded_string)):
        row, col = getRowAndCol(i, rows)
        decoded_message += decoded_string[getIndex(row, col, row_len)]
    return decoded_message.rstrip(ascii_lowercase)


print("Testing encodeRouteCipher()...", end="")
assert encodeRouteCipher("ASECRETMESSAGE", 4) == "4AREGESESETSzyAMC"
assert encodeRouteCipher("ASECRETMESSAGE", 3) == "3ACTSGESMRSEEEAz"
assert encodeRouteCipher("ASECRETMESSAGE", 5) == "5AESATSEMGEECRSz"
assert encodeRouteCipher("ANOTHERSECRET", 4) == "4AHETzCENORRyxEST"


print("Testing decodeRouteCipher()...", end="")
assert decodeRouteCipher("4AREGESESETSzyAMC") == "ASECRETMESSAGE"
assert decodeRouteCipher("3ACTSGESMRSEEEAz") == "ASECRETMESSAGE"
assert decodeRouteCipher("5AESATSEMGEECRSz") == "ASECRETMESSAGE"
assert decodeRouteCipher("4AHETzCENORRyxEST") == "ANOTHERSECRET"
message = "SECRETSTUFFGOESHERE"
encodedMessage = encodeRouteCipher(message, 6)
plaintext = decodeRouteCipher(encodedMessage)
assert plaintext == message
print("Passed!")