import logging
import json
import os
import subprocess
from pathlib import Path
from time import sleep
from threading import Thread


def run_kinit(
    kinit_principal: str,
    kinit_interval: int,
    keytab_path: Path,
    krb_cache: Path,
):
    """使用 kinit 保持 Kerberos 认证状态. 在 daemon 线程中调用.

    参数:
        kinit_principal: kerberos principal 名称
        kinit_interval: 执行 kinit 的时间间隔 (秒)
        keytab_path: keytab 存储路径
        krb_cache: kerberos ticket 缓存路径
    """
    while True:
        proc = subprocess.run(
            f"kinit -kt '{keytab_path}' '{kinit_principal}' && chmod go+r '{krb_cache}'",
            shell=True,
            text=True,
            capture_output=True,
            check=False,
        )
        try:
            proc.check_returncode()
        except subprocess.CalledProcessError:
            logging.warning(proc.stderr)
        sleep(kinit_interval)


def main():
    backend_base_url = os.environ.get("BACKEND_BASE_URL")
    sparkmagic_conf_dir = os.environ.get("SPARKMAGIC_CONF_DIR")
    livy_server_url = os.environ.get("LIVY_SERVER_URL")
    classpath = os.environ.get("CLASSPATH")
    hadoop_home = os.environ["HADOOP_HOME"]
    hadoop_conf_dir = os.environ["HADOOP_CONF_DIR"]
    kinit_principal = os.environ.get("KINIT_PRINCIPAL", "aidevuser")
    kinit_interval = int(os.environ.get("KINIT_INTERVAL", 6 * 60 * 60))
    keytab_path = Path(os.environ.get("KEYTAB_PATH", f"{hadoop_conf_dir}/user.keytab"))

    use_krb = keytab_path.exists()
    krb_cache = "/tmp/krb5cc"
    os.environ["KRB5CCNAME"] = f"FILE:{krb_cache}"

    if not use_krb:
        logging.info("Kerberos keytab not found, using local root")
        kinit_principal = "root"

    # 配置 backend
    if backend_base_url is not None:
        setting_dir = Path("/usr/local/share/jupyter/lab/settings/")
        if not setting_dir.exists():
            setting_dir.mkdir(exist_ok=True, parents=True)
        overrides = setting_dir / "overrides.json"
        if overrides.exists():
            overrides_conf = json.loads(overrides.read_text())
        else:
            overrides_conf = {}
        overrides_conf["@jupyterlab/jldbq-extension:plugin"] = {
            "flaskBackend": backend_base_url
        }
        overrides.write_text(json.dumps(overrides_conf, indent=2))

    # 配置 sparkmagic
    if sparkmagic_conf_dir is None:
        sparkmagic_conf_dir = "/etc/sparkmagic"
        os.environ["SPARKMAGIC_CONF_DIR"] = sparkmagic_conf_dir
    conf_file = Path(sparkmagic_conf_dir) / "config.json"
    if not conf_file.exists():
        raise FileNotFoundError(
            f"cannot find sparkmagic config file at {conf_file.resolve()}"
        )

    if livy_server_url is not None:
        conf = json.loads(conf_file.read_text())
        conf["kernel_python_credentials"]["url"] = livy_server_url
        conf_file.write_text(json.dumps(conf, indent=2))

    # 设置 hadoop classpath (for jupyter-hdfscm)
    cp_proc = subprocess.run(
        f"{hadoop_home}/bin/hadoop classpath --glob",
        shell=True,
        capture_output=True,
        check=True,
        text=True,
    )
    if classpath is None:
        os.environ["CLASSPATH"] = cp_proc.stdout.strip()
    else:
        os.environ["CLASSPATH"] = cp_proc.stdout.strip() + ":" + classpath

    # jupyter-hdfscm
    with open("/etc/jupyter/jupyter_lab_config.py", "a") as fp:
        fp.write(
            "\nc.HDFSContentsManager.root_dir_template = '/user/"
            + kinit_principal
            + "/jupyter/{username}/'\n"
        )
        fp.write("c.ServerApp.contents_manager_class = 'hdfscm.HDFSContentsManager'\n")

    # 设置 kerberos 认证
    if use_krb:
        Thread(
            daemon=True,
            target=run_kinit,
            name="run_kinit",
            args=(kinit_principal, kinit_interval, keytab_path, krb_cache),
        ).start()

    subprocess.run("jupyterhub -f /etc/jupyterhub/config.py", shell=True)


if __name__ == "__main__":
    main()