from struct import pack, unpack

_UINT_16_SIZE = 2
_UINT_32_SIZE = 4


class Decoder:
    _position: int
    _data: bytes

    def __init__(self, data: bytes):
        self._position = 0
        self._data = data

    def read_uint16(self):
        value = int.from_bytes(self._data[self._position:self._position + _UINT_16_SIZE], "big")
        self._position += _UINT_16_SIZE

        return value

    def read_uint32(self):
        value = int.from_bytes(self._data[self._position:self._position + _UINT_32_SIZE], "big")
        self._position += _UINT_32_SIZE

        return value

    def read_float(self) -> float:
        return unpack(">f", pack(">L", self.read_uint32()))[0]

    def read_str(self):
        length = self._data[self._position]
        self._position += 1

        value = self._data[self._position:self._position + length]
        self._position += length

        return value.decode()

    def read_sized_str(self, length: int):
        value = self._data[self._position:self._position + length]
        self._position += length

        return value.decode()

    @property
    def eof(self):
        return self._position >= len(self._data)