"""
Base85 (Ascii85) encoding and decoding

https://en.wikipedia.org/wiki/Ascii85
"""


def _base10_to_85(d: int) -> str:
 return "".join(chr(d % 85 + 33)) + _base10_to_85(d // 85) if d > 0 else ""


def _base85_to_10(digits: list) -> int:
 return sum(char * 85**i for i, char in enumerate(reversed(digits)))


def ascii85_encode(data: bytes) -> bytes:
 """
 >>> ascii85_encode(b"")
 b''
 >>> ascii85_encode(b"12345")
 b'0etOA2#'
 >>> ascii85_encode(b"base 85")
 b'@UX=h+?24'
 """
 binary_data = "".join(bin(ord(d))[2:].zfill(8) for d in data.decode("utf-8"))
 null_values = (32 * ((len(binary_data) // 32) + 1) - len(binary_data)) // 8
 binary_data = binary_data.ljust(32 * ((len(binary_data) // 32) + 1), "0")
 b85_chunks = [int(_s, 2) for _s in map("".join, zip(*[iter(binary_data)] * 32))]
 result = "".join(_base10_to_85(chunk)[::-1] for chunk in b85_chunks)
 return bytes(result[:-null_values] if null_values % 4 != 0 else result, "utf-8")


def ascii85_decode(data: bytes) -> bytes:
 """
 >>> ascii85_decode(b"")
 b''
 >>> ascii85_decode(b"0etOA2#")
 b'12345'
 >>> ascii85_decode(b"@UX=h+?24")
 b'base 85'
 """
 null_values = 5 * ((len(data) // 5) + 1) - len(data)
 binary_data = data.decode("utf-8") + "u" * null_values
 b85_chunks = map("".join, zip(*[iter(binary_data)] * 5))
 b85_segments = [[ord(_s) - 33 for _s in chunk] for chunk in b85_chunks]
 results = [bin(_base85_to_10(chunk))[2::].zfill(32) for chunk in b85_segments]
 char_chunks = [
 [chr(int(_s, 2)) for _s in map("".join, zip(*[iter(r)] * 8))] for r in results
 ]
 result = "".join("".join(char) for char in char_chunks)
 offset = int(null_values % 5 == 0)
 return bytes(result[: offset - null_values], "utf-8")


if __name__ == "__main__":
 import doctest

 doctest.testmod()