oauth2refresh

#!/usr/bin/python3
import json
import os
import subprocess as sp
import time

cwd = os.path.dirname(os.path.abspath(__file__))

def get_config(fname):
    with open(fname, 'r') as f:
        return json.load(f)


def update_config(fname, cfg):
    with open(fname, 'w') as f:
        f.write(json.dumps(cfg, indent=4))


def refresh(account, cid, secret, refresh_token):
    cmd = (
        f'{cwd}/oauth2.py --user={account} --client_id={cid} '
        f'--client_secret={secret} --refresh_token={refresh_token} --quiet'
    )
    access_token = sp.check_output(cmd.split(' ')).decode()[:-1]  # drop newline
    return access_token


cfg_file_name = cwd + '/cfg.json'
cfg = get_config(cfg_file_name)
now = int(time.time())

if 'access_token' in cfg and cfg['expire_at'] > now:
    print(cfg['access_token'])
else:
    token = refresh(cfg['gmail_account'], cfg['cid'], cfg['secret'], cfg['refresh_token'])
    cfg['access_token'] = token
    cfg['expire_at'] = now + min(60, cfg['expire_in'] - 300)  # 5 minutes grace period
    update_config(cfg_file_name, cfg)
    print(token)