import base64
import json
import logging
from pathlib import Path
import time

from Crypto.Cipher import AES
from Crypto.Random import get_random_bytes
from Crypto.Util.Padding import pad

log = logging.getLogger()


SIGNATURE_KEY = Path('/secret/signature_key').read_bytes()

def _encrypt_data(data: bytes, key: bytes) -> str:
    iv = get_random_bytes(12)
    cipher = AES.new(key, AES.MODE_GCM, iv)
    ciphertext, tag = cipher.encrypt_and_digest(pad(data, AES.block_size))
    return base64.b64encode(iv + ciphertext + tag).decode('utf-8')


def makePlaybackSig(user: str, webDataPath: str, lifeSeconds=3600) -> str:
    msg = [user, webDataPath, int(time.time() + lifeSeconds)]
    return _encrypt_data(
        json.dumps(msg).encode('utf-8'), SIGNATURE_KEY)