svthalia/concrexit

"""Utility views."""
from datetime import timedelta

from django.core import signing
from django.core.cache import cache
from django.core.exceptions import PermissionDenied
from django.core.files.storage import get_storage_class
from django.core.signing import BadSignature
from django.http import Http404
from django.shortcuts import redirect
from django.utils import timezone

from django_sendfile import sendfile


def get_thumb_modified_time(storage, path):
    storage_value = cache.get(
        f"thumbnails_{path}", timezone.make_aware(timezone.datetime.min)
    )
    if storage_value.timestamp() <= 0:
        try:
            storage_value = storage.get_modified_time(path)
            cache.set(f"thumbnails_{path}", storage_value, 60 * 60)
        except:  # noqa: E722
            # File probably does not exist
            pass
    return storage_value


def _get_signature_info(request):
    if "sig" in request.GET:
        signature = request.GET.get("sig")
        try:
            return signing.loads(signature, max_age=timedelta(hours=3))
        except BadSignature:
            pass
    raise PermissionDenied


def private_media(request, request_path):
    """Serve private media files.

    :param request: the request
    :return: the media file
    """
    # Get image information from signature
    # raises PermissionDenied if bad signature
    sig_info = _get_signature_info(request)
    storage = get_storage_class(sig_info["storage"])()
    serve_path = sig_info["serve_path"]

    if not storage.exists(serve_path) or not serve_path == request_path:
        # 404 if the file does not exist
        raise Http404("Media not found.")

    # Serve the file, or redirect to a signed bucket url in the case of S3
    if hasattr(storage, "bucket"):
        serve_url = storage.url(sig_info["serve_path"])
        return redirect(
            f"{serve_url}",
            permanent=False,
        )
    return sendfile(
        request,
        serve_path,
        attachment=bool(sig_info.get("attachment", False)),
        attachment_filename=sig_info.get("attachment", None),
    )