"""Patch config.yaml for the MySQL business DB + SQLite checkpointer split."""

from __future__ import annotations

import argparse
from pathlib import Path

import yaml


def _parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser(description="Switch DeerFlow config.yaml to MySQL business storage")
    parser.add_argument("--config", required=True, help="Path to config.yaml")
    parser.add_argument("--mysql-url-env", default="MYSQL_DATABASE_URL", help="Environment variable referenced by database.mysql_url")
    parser.add_argument("--checkpointer-sqlite", required=True, help="SQLite deerflow.db path used by LangGraph checkpointer")
    parser.add_argument("--pool-size", type=int, default=10)
    return parser.parse_args()


def main() -> None:
    args = _parse_args()
    config_path = Path(args.config)
    data = yaml.safe_load(config_path.read_text(encoding="utf-8")) or {}
    if not isinstance(data, dict):
        raise SystemExit(f"Expected a mapping in {config_path}")

    database = dict(data.get("database") or {})
    database["backend"] = "mysql"
    database["mysql_url"] = f"${args.mysql_url_env}"
    database.setdefault("pool_size", args.pool_size)
    database.setdefault("echo_sql", False)
    data["database"] = database

    data["checkpointer"] = {
        "type": "sqlite",
        "connection_string": args.checkpointer_sqlite,
    }

    config_path.write_text(
        yaml.safe_dump(data, allow_unicode=True, sort_keys=False),
        encoding="utf-8",
    )
    print(f"Updated {config_path}: database.backend=mysql, checkpointer.type=sqlite")


if __name__ == "__main__":
    main()