import struct

class DataInputStream:
    def __init__(self, buffer: bytes):
        self._buffer = buffer
        self._cursor = 0

    def read_bytes(self, n: int) -> bytes:
        if self._cursor + n > len(self._buffer):
            raise EOFError('stream overread')
        blob = self._buffer[self._cursor : self._cursor + n]
        self._cursor += n
        return blob

    def empty(self):
        return self._cursor >= len(self._buffer) - 1

    def end(self) -> bytes:
        return self.read_bytes(len(self._buffer) - self._cursor)

    def read_byte(self) -> int:
        if self._cursor >= len(self._buffer):
            raise EOFError('stream overread')
        self._cursor += 1
        return self._buffer[self._cursor - 1]

    def read_boolean(self) -> bool:
        return self.read_byte() != 0

    def read_short(self) -> int:
        return struct.unpack('>h', self.read_bytes(2))[0]

    def read_ushort(self) -> int:
        return struct.unpack('>H', self.read_bytes(2))[0]

    def read_int(self) -> int:
        return struct.unpack('>i', self.read_bytes(4))[0]

    def read_uint(self) -> int:
        return struct.unpack('>I', self.read_bytes(4))[0]

    def read_long(self) -> int:
        return struct.unpack('>q', self.read_bytes(8))[0]

    def read_ulong(self) -> int:
        return struct.unpack('>Q', self.read_bytes(8))[0]

    def read_float(self) -> float:
        return struct.unpack('>f', self.read_bytes(4))[0]

    def read_double(self) -> float:
        return struct.unpack('>d', self.read_bytes(8))[0]

    def read_char(self) -> str:
        return chr(self.read_ushort())

    def read_varint(self, bits: int = 32) -> int:
        value: int = 0
        position: int = 0
        while True:
            byte = self.read_byte()
            value |= (byte & 0x7F) << position
            if ((byte & 0x80) == 0):
                break
            position += 7
            if position >= bits:
                raise ValueError('varint too big')
        return value

    def read_string(self) -> str:
        size = self.read_short()
        print(f'read_bytes({size=})')
        return self.read_bytes(size).decode('utf-8')