ovdashboard/api/ovdashboard_api/dav_file.py

import asyncio
import functools
import logging
import time
from io import BytesIO
from typing import Any, Optional

from async_lru import alru_cache
from webdav3.client import Resource

from . import webdav_resource

_logger = logging.getLogger(__name__)


def _run_in_executor(f):
    """
    Decorator to make blocking function call asyncio compatible
    https://stackoverflow.com/questions/41063331/how-to-use-asyncio-with-existing-blocking-library/
    """

    @functools.wraps(f)
    def inner(*args, **kwargs):
        loop = asyncio.get_running_loop()
        return loop.run_in_executor(
            None,
            functools.partial(f, *args, **kwargs),
        )

    return inner


def _get_ttl_hash(seconds: int = 20) -> int:
    """
    Return the same value within `seconds` time period
    https://stackoverflow.com/a/55900800
    """
    return round(time.time() / seconds)


@alru_cache(maxsize=20)
async def _get_buffer(
    remote_path: Any,
    ttl_hash: Optional[int] = None,
) -> BytesIO:
    del ttl_hash

    @_run_in_executor
    def buffer_inner(resource: Resource) -> BytesIO:
        _logger.info(f"updating {resource}")
        print(f"updating {resource}")
        buffer = BytesIO()
        resource.write_to(buffer)
        return buffer

    resource = webdav_resource(remote_path)
    return await buffer_inner(resource)


class DavFile:
    def __init__(self, remote_path: Any) -> None:
        self.__remote_path = remote_path

    @property
    async def __buffer(self) -> BytesIO:
        return await _get_buffer(
            remote_path=self.__remote_path,
            ttl_hash=_get_ttl_hash(20),
        )

    @property
    async def bytes(self) -> bytes:
        buffer = await self.__buffer

        buffer.seek(0)
        return buffer.read()

    @property
    async def string(self) -> str:
        bytes = await self.bytes
        return bytes.decode(encoding="utf-8")