"""统一日志配置。

特性：
- 五级日志：DEBUG / INFO / WARNING / ERROR / CRITICAL，默认 INFO
- 同时输出到控制台和文件（RotatingFileHandler 按大小轮转）
- 通过环境变量 ``MESHSAFE_LOG_LEVEL`` 控制级别
- 通过环境变量 ``MESHSAFE_LOG_DIR`` 控制日志文件目录
- 日志文件按 10 MB 轮转，保留最近 5 份
- 自动为 FastAPI / uvicorn / sqlalchemy 等第三方库设置一致的级别
"""

from __future__ import annotations

import logging
import logging.handlers
import os
import sys
from pathlib import Path

from app.config import get_settings

_LOG_FORMAT = "%(asctime)s [%(levelname)s] %(name)s - %(message)s"
_DATE_FORMAT = "%Y-%m-%d %H:%M:%S"
_MAX_BYTES = 10 * 1024 * 1024  # 10 MB
_BACKUP_COUNT = 5


def setup_logging() -> None:
    """初始化全局日志配置。幂等：多次调用不会重复添加 handler。"""
    settings = get_settings()

    level_name = os.environ.get("MESHSAFE_LOG_LEVEL", settings.log_level).upper()
    level = getattr(logging, level_name, logging.INFO)

    log_dir = os.environ.get("MESHSAFE_LOG_DIR", "/var/log/meshsafe")
    Path(log_dir).mkdir(parents=True, exist_ok=True)

    root_logger = logging.getLogger()
    root_logger.setLevel(level)

    # 幂等：已初始化则跳过
    if root_logger.handlers:
        # 更新级别即可
        root_logger.setLevel(level)
        for handler in root_logger.handlers:
            handler.setLevel(level)
        return

    formatter = logging.Formatter(_LOG_FORMAT, datefmt=_DATE_FORMAT)

    # 控制台 handler
    console = logging.StreamHandler(sys.stdout)
    console.setLevel(level)
    console.setFormatter(formatter)
    root_logger.addHandler(console)

    # 文件 handler（按大小轮转）
    log_file = os.path.join(log_dir, "meshsafe.log")
    file_handler = logging.handlers.RotatingFileHandler(
        log_file,
        maxBytes=_MAX_BYTES,
        backupCount=_BACKUP_COUNT,
        encoding="utf-8",
    )
    file_handler.setLevel(level)
    file_handler.setFormatter(formatter)
    root_logger.addHandler(file_handler)

    # 第三方库级别收敛：避免 uvicorn.access / sqlalchemy 刷屏
    logging.getLogger("uvicorn.access").setLevel(logging.WARNING)
    logging.getLogger("sqlalchemy.engine").setLevel(logging.WARNING)
    logging.getLogger("redis").setLevel(logging.WARNING)
    logging.getLogger("pydantic").setLevel(logging.WARNING)

    # 启动日志
    root_logger.info(
        "日志系统初始化完成：级别=%s，日志文件=%s（按 %d MB 轮转，保留 %d 份）",
        logging.getLevelName(level),
        log_file,
        _MAX_BYTES // (1024 * 1024),
        _BACKUP_COUNT,
    )


def get_logger(name: str) -> logging.Logger:
    """获取模块级 logger。"""
    return logging.getLogger(name)