# build signature for presigned urls
import base64, hashlib, datetime, os
from urllib.parse import urlencode

username = os.getenv('username')
base_url = os.getenv('BaseURL')
dav_url = f'{base_url}/remote.php/dav/files/{username}'
oc_date = datetime.datetime.now().strftime('%Y-%m-%dT%H:%M:%SZ')
data = {
  'OC-Expires': '991200',
  'OC-Verb': 'PROPFIND',
  'OC-Credential': username,
  'OC-Date': oc_date
}
sig_url = f'{dav_url}?{urlencode(data)}'
# derive signature from empty sign key
dk = hashlib.pbkdf2_hmac('sha512', sig_url.encode(), b'', 10000, dklen=32)
final_url = f'/remote.php/dav/files/{username}?{urlencode(data)}&OC-Signature={dk.hex()}'
#final_url = f'{sig_url}&OC-Signature={dk.hex()}'
print(final_url)