"""
统一配置管理器

单例模式，提供:
- 配置缓存，避免重复读取文件
- 配置热更新检测
- 类型安全的配置访问
"""

import tomllib
from pathlib import Path
from threading import Lock
from typing import Any, Dict, Optional

from loguru import logger


class ConfigManager:
    """
    配置管理器 (线程安全单例)

    使用示例:
        from utils.config_manager import get_config

        # 获取单个配置项
        admins = get_config().get("Bot", "admins", [])

        # 获取整个配置节
        bot_config = get_config().get_section("Bot")

        # 检查并重新加载
        if get_config().reload_if_changed():
            logger.info("配置已更新")
    """

    _instance: Optional["ConfigManager"] = None
    _lock = Lock()

    def __new__(cls):
        if cls._instance is None:
            with cls._lock:
                if cls._instance is None:
                    instance = super().__new__(cls)
                    instance._initialized = False
                    cls._instance = instance
        return cls._instance

    def __init__(self):
        if self._initialized:
            return

        self._config: Dict[str, Any] = {}
        self._config_path = Path("main_config.toml")
        self._file_mtime: float = 0
        self._config_lock = Lock()
        self._reload()
        self._initialized = True
        logger.debug("ConfigManager 初始化完成")

    def _reload(self) -> bool:
        """重新加载配置文件"""
        try:
            if not self._config_path.exists():
                logger.warning(f"配置文件不存在: {self._config_path}")
                return False

            current_mtime = self._config_path.stat().st_mtime
            if current_mtime == self._file_mtime and self._config:
                return False  # 文件未变化

            with self._config_lock:
                with open(self._config_path, "rb") as f:
                    self._config = tomllib.load(f)
                self._file_mtime = current_mtime

            logger.debug("配置文件已重新加载")
            return True

        except Exception as e:
            logger.error(f"加载配置文件失败: {e}")
            return False

    def get(self, section: str, key: str, default: Any = None) -> Any:
        """
        获取配置项

        Args:
            section: 配置节名称，如 "Bot"
            key: 配置项名称，如 "admins"
            default: 默认值

        Returns:
            配置值或默认值
        """
        return self._config.get(section, {}).get(key, default)

    def get_section(self, section: str) -> Dict[str, Any]:
        """
        获取整个配置节

        Args:
            section: 配置节名称

        Returns:
            配置节字典的副本
        """
        return self._config.get(section, {}).copy()

    def get_all(self) -> Dict[str, Any]:
        """获取完整配置（只读副本）"""
        return self._config.copy()

    def reload_if_changed(self) -> bool:
        """
        如果文件有变化则重新加载

        Returns:
            是否重新加载了配置
        """
        try:
            if not self._config_path.exists():
                return False
            current_mtime = self._config_path.stat().st_mtime
            if current_mtime != self._file_mtime:
                return self._reload()
        except Exception:
            pass
        return False

    def force_reload(self) -> bool:
        """强制重新加载配置"""
        self._file_mtime = 0
        return self._reload()


# ==================== 便捷函数 ====================

def get_config() -> ConfigManager:
    """获取配置管理器实例"""
    return ConfigManager()


def get_bot_config() -> Dict[str, Any]:
    """快捷获取 [Bot] 配置节"""
    return get_config().get_section("Bot")


def get_performance_config() -> Dict[str, Any]:
    """快捷获取 [Performance] 配置节"""
    return get_config().get_section("Performance")


def get_database_config() -> Dict[str, Any]:
    """快捷获取 [Database] 配置节"""
    return get_config().get_section("Database")


def get_scheduler_config() -> Dict[str, Any]:
    """快捷获取 [Scheduler] 配置节"""
    return get_config().get_section("Scheduler")


def get_queue_config() -> Dict[str, Any]:
    """快捷获取 [Queue] 配置节"""
    return get_config().get_section("Queue")


def get_concurrency_config() -> Dict[str, Any]:
    """快捷获取 [Concurrency] 配置节"""
    return get_config().get_section("Concurrency")


def get_webui_config() -> Dict[str, Any]:
    """快捷获取 [WebUI] 配置节"""
    return get_config().get_section("WebUI")


# ==================== 导出列表 ====================

__all__ = [
    'ConfigManager',
    'get_config',
    'get_bot_config',
    'get_performance_config',
    'get_database_config',
    'get_scheduler_config',
    'get_queue_config',
    'get_concurrency_config',
    'get_webui_config',
]