from abc import ABC, abstractmethod


class ChunkUploadBackend(ABC):
    @abstractmethod
    def start(self, filename: str) -> None:
        """Начало загрузки нового файла"""

    @abstractmethod
    def upload_chunk(self, chunk: bytes) -> None:
        """Загрузка очередного чанка"""

    @abstractmethod
    def finish(self) -> None:
        """Завершение загрузки"""

    @abstractmethod
    def abort(self) -> None:
        """Прерывания загрузки"""


class DiskChunkUploadBackend(ChunkUploadBackend):
    def __init__(self, base_path: str):
        import os

        self.os = os

        self.base_path = base_path
        self.os.makedirs(self.base_path, exist_ok=True)
        self._file = None

    def start(self, filename):
        self._file = open(self.os.path.join(self.base_path, filename), "wb")

    def upload_chunk(self, chunk: bytes):
        self._file.write(chunk)

    def finish(self):
        self._file.close()

    def abort(self):
        if self._file:
            self._file.close()
            self._file = None