import base64
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import string
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import struct
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import typing as _t
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from .exc import BadData
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_t_str_bytes = _t.Union[str, bytes]
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def want_bytes(
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s: _t_str_bytes, encoding: str = "utf-8", errors: str = "strict"
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) -> bytes:
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if isinstance(s, str):
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s = s.encode(encoding, errors)
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return s
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def base64_encode(string: _t_str_bytes) -> bytes:
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"""Base64 encode a string of bytes or text. The resulting bytes are
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safe to use in URLs.
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"""
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string = want_bytes(string)
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return base64.urlsafe_b64encode(string).rstrip(b"=")
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def base64_decode(string: _t_str_bytes) -> bytes:
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"""Base64 decode a URL-safe string of bytes or text. The result is
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bytes.
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"""
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string = want_bytes(string, encoding="ascii", errors="ignore")
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string += b"=" * (-len(string) % 4)
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try:
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return base64.urlsafe_b64decode(string)
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except (TypeError, ValueError) as e:
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raise BadData("Invalid base64-encoded data") from e
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# The alphabet used by base64.urlsafe_*
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_base64_alphabet = f"{string.ascii_letters}{string.digits}-_=".encode("ascii")
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_int64_struct = struct.Struct(">Q")
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_int_to_bytes = _int64_struct.pack
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_bytes_to_int = _t.cast("_t.Callable[[bytes], _t.Tuple[int]]", _int64_struct.unpack)
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def int_to_bytes(num: int) -> bytes:
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return _int_to_bytes(num).lstrip(b"\x00")
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def bytes_to_int(bytestr: bytes) -> int:
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return _bytes_to_int(bytestr.rjust(8, b"\x00"))[0]
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