nupes-elections/nupes/cache.py

from pathlib import Path

import requests


CACHE_DIR = Path(__file__).parent / 'cache'


def get_file(url, filename, force_etag: str = ""):
    if not CACHE_DIR.is_dir():
        CACHE_DIR.mkdir(parents=True)

    file_dir = CACHE_DIR / filename
    if not file_dir.is_dir():
        file_dir.mkdir(parents=True)

    symlink_file = file_dir / 'latest'

    etag = ""
    if symlink_file.exists():
        file = symlink_file.resolve()
        etag = file.name

    response = requests.get(url, headers={"If-None-Match": f'"{etag}'}, allow_redirects=True)
    if response.status_code == 404:
        print(url)
        return None
    response.raise_for_status()
    if response.status_code != 304:
        if force_etag:
            etag = force_etag
        else:
            etag = response.headers.get('ETag').split('/')[-1].replace('"', '')

        if symlink_file.exists():
            symlink_file.resolve().unlink()

        file = file_dir / etag

        with file.open('wb') as f:
            f.write(response.content)

        symlink_file.unlink(missing_ok=True)
        symlink_file.symlink_to(file)

    return symlink_file