"""
Structured logging for RFCP backend.
"""

import os
import sys
import time
import threading


_log_file = None


def rfcp_log(tag: str, msg: str):
    """Log with tag prefix, timestamp, and thread name.

    Writes to stdout and a log file for reliability.
    """
    global _log_file
    ts = time.strftime('%H:%M:%S')
    thr = threading.current_thread().name
    line = f"[{tag} {ts}] [{thr}] {msg}"
    print(line, flush=True)

    try:
        if _log_file is None:
            log_dir = os.environ.get('RFCP_DATA_PATH', './data')
            os.makedirs(log_dir, exist_ok=True)
            log_path = os.path.join(log_dir, 'rfcp-backend.log')
            _log_file = open(log_path, 'a')
        _log_file.write(line + '\n')
        _log_file.flush()
    except Exception:
        pass