sampy3/sampy/raknet/bitstream.py

from __future__ import annotations

from typing import Any, List, Literal, Optional, Type, Union

# for seek()
SEEK_SET = 0
SEEK_CUR = 1
SEEK_END = 2


def get_bit_length(value: Union[bool, List[bool], bytes, Bitstream]) -> int:
    if type(value) is bool:
        return 1
    elif type(value) is list and all(type(v) is bool for v in value):
        return len(value)
    elif type(value) is bytes:
        return len(value) << 3
    elif type(value) is Bitstream:
        return len(value)
    else:
        raise TypeError("Invalid data type")


def bits_to_int(bits: List[bool], little_endian: bool = False) -> int:
    num = 0
    if little_endian:
        bits = bits[::-1]
    for bit in bits:
        num = (num << 1) | bit
    return num


def int_to_bits(
    number: int, bit_length: int, little_endian: bool = False
) -> List[bool]:
    bits = [bool(number & (0b1 << i)) for i in range(bit_length - 1, -1, -1)]
    return bits[::-1] if little_endian else bits


class Bitstream:
    def __init__(self, *values: Union[bool, List[bool], bytes, Bitstream]):
        self._bytearray = bytearray()
        self._bit_length = 0
        self._offset = 0

        for item in values:
            if type(item) is bool:
                self.append(item)
            else:
                self.extend(item)

    @staticmethod
    def from_bytes(value: bytes) -> Bitstream:
        bitstream = Bitstream()
        bitstream._bytearray += value
        bitstream._bit_length = len(bitstream._bytearray) << 3
        return bitstream

    @staticmethod
    def from_int(value: int, bit_length: int) -> Bitstream:
        return Bitstream(
            [bool(value & (0b1 << i)) for i in range(bit_length - 1, -1, -1)]
        )

    def __len__(self) -> int:
        return self._bit_length

    def __bytes__(self) -> bytes:
        while len(self._bytearray) > ((len(self) + 7) >> 3):
            self._bytearray.pop()
        return bytes(self._bytearray)

    def __int__(self) -> int:
        num = 0
        for bit in self:
            num = (num << 1) | bit
        return num

    def __getitem__(self, bit_index: int) -> bool:
        if bit_index < 0:
            bit_index = len(self) + bit_index

        if bit_index >= self._bit_length or bit_index < 0:
            raise IndexError("bit index out of range")

        mask = 1 << (7 - (bit_index % 8))
        return bool(self._bytearray[bit_index >> 3] & mask)

    def __setitem__(
        self, bit_index: int, value: Union[bool, List[bool], bytes, Bitstream]
    ):
        if bit_index >= self._bit_length:
            raise IndexError("bit index out of range")

        if type(value) is bytes:
            self[bit_index] = Bitstream.from_bytes(value)
            return

        value_bit_length = get_bit_length(value)

        if (bit_index + value_bit_length) > self._bit_length:
            raise IndexError("Cannot write bits that extends the size of bitstream")

        if type(value) is bool:
            mask = 1 << (7 - (bit_index % 8))
            if value:
                self._bytearray[bit_index >> 3] |= mask
            else:
                self._bytearray[bit_index >> 3] &= ~mask
        elif isinstance(value, Bitstream) or (
            type(value) is list and all(type(v) is bool for v in value)
        ):
            for i in range(value_bit_length):
                self[bit_index + i] = value[i]
        else:
            raise TypeError("Expected bool, list[bool], bytes or Bitstream")

    def __eq__(self, other: Any) -> bool:
        if type(other) is bool:
            other = [other]

        if isinstance(other, Bitstream):
            pass
        elif type(other) is bytes:
            pass
        elif type(other) is list and all(type(v) is bool for v in other):
            pass
        else:
            raise TypeError("Expected Bitstream, bytes or list[bool]")

        if isinstance(other, Bitstream) or type(other) is list:
            if len(self) != len(other):
                return False
            for left, right in zip(self, other):
                if left != right:
                    return False
        else:
            if bytes(self) != other:
                return False
        return True

    def __mul__(self, number: int) -> Bitstream:
        copy = self.copy()
        for _ in range(1, number):
            copy.extend(self)
        return copy

    def __imul__(self, number: int) -> Bitstream:
        copy = self.copy()
        for _ in range(1, number):
            self.extend(copy)
        return self

    def __add__(self, value: Union[bool, List[bool], bytes, Bitstream]) -> Bitstream:
        copy = self.copy()
        if type(value) is bool:
            copy.append(value)
        else:
            copy.extend(value)
        return copy

    def __iadd__(self, value: Union[bool, List[bool], bytes, Bitstream]) -> Bitstream:
        if type(value) is bool:
            self.append(value)
        else:
            self.extend(value)
        return self

    def __iter__(self) -> Bitstream:
        for i in range(len(self)):
            yield self[i]

    def __repr__(self) -> str:
        return "<Bitstream addr:0x%012x offset:%d len:%d data:'%s'>" % (
            id(self),
            self._offset,
            len(self),
            bytes(self).hex(" "),
        )

    @property
    def bits(self) -> List[bool]:
        return [b for b in self]

    def copy(self) -> Bitstream:
        bitstream = Bitstream()
        bitstream._bytearray = self._bytearray.copy()
        bitstream._bit_length = self._bit_length
        bitstream._offset = self._offset
        return bitstream

    def append(self, value: bool):
        if type(value) is not bool:
            raise TypeError("Expected bool")

        while (len(self._bytearray) << 3) < (self._bit_length + 1):
            self._bytearray.append(0)
        prev_bit_length = self._bit_length
        self._bit_length += 1
        self[prev_bit_length] = value

    def extend(self, value: Union[List[bool], bytes, Bitstream]):
        if type(value) is bytes:
            pass
        elif isinstance(value, Bitstream):
            pass
        elif type(value) is list and all(type(v) is bool for v in value):
            pass
        else:
            raise TypeError("Expected list[bool], bytes or Bitstream")

        value_bit_length = get_bit_length(value)
        if value_bit_length == 0:
            return

        while (len(self._bytearray) << 3) < (self._bit_length + value_bit_length):
            self._bytearray.append(0)
        prev_bit_length = self._bit_length
        self._bit_length += value_bit_length
        self[prev_bit_length] = value

    def clear(self):
        self._bytearray.clear()
        self._bit_length = 0
        self._offset = 0

    def pop(self) -> bool:
        value = self[-1]
        self[-1] = False
        self._bit_length -= 1
        return value

    def read(
        self,
        type: Type[Union[bool, bytes, Bitstream, int]],
        bit_length: int,
        bit_index: Optional[int] = None,
    ) -> Union[List[bool], bytes, Bitstream, int]:
        start = self._offset if bit_index is None else bit_index

        if (start + bit_length) > self._bit_length or (start < 0):
            raise IndexError("bit index out of range")

        bits = [self[i] for i in range(start, start + bit_length)]

        if bit_index is None:
            self._offset += bit_length

        if type is bool:
            return bits

        bitstream = Bitstream(bits)
        if type is Bitstream:
            return bitstream
        elif type is bytes:
            return bytes(bitstream)
        elif type is int:
            return int(bitstream)

        raise TypeError("Invalid data type")

    def write(
        self,
        value: Union[bool, List[bool], bytes, Bitstream],
        bit_index: Optional[int] = None,
    ):
        start = self._offset if bit_index is None else bit_index

        if start < 0:
            raise IndexError("bit index out of range")

        value_bit_length = get_bit_length(value)
        if value_bit_length == 0:
            return

        while (len(self._bytearray) << 3) < (start + value_bit_length):
            self._bytearray.append(0)

        if bit_index is None:
            self._offset += value_bit_length
            _bit_length = self._offset
        else:
            _bit_length = start + value_bit_length

        if _bit_length > self._bit_length:
            self._bit_length = _bit_length
        self[start] = value

    def seek(self, position: int, whence: Literal[0, 1, 2] = 0):
        if whence == 0:
            self._offset = position
        elif whence == 1:
            self._offset += position
        elif whence == 2:
            self._offset = len(self) + position
        else:
            raise ValueError("Invalid whence")

        self._offset = min(max(self._offset, 0), len(self))