"""客户钩子加载器 — 从 customers/{CUSTOMER}/hooks/ 动态加载客户自定义钩子

加载逻辑：
1. 读取 CUSTOMER 环境变量
2. 查找 customers/{CUSTOMER}/hooks/__init__.py
3. 导入并返回 hooks 实例
4. 找不到则返回默认空钩子（所有方法为空操作）
"""
import importlib
import importlib.util
import logging
import os
import sys
from functools import lru_cache
from typing import Optional

from app.hooks.base import CustomerHooks
from app.core.config import get_settings

logger = logging.getLogger("hooks.loader")

_hooks_instance: Optional[CustomerHooks] = None


def _find_hooks_dir() -> Optional[str]:
    """Find the customer hooks directory, searching multiple locations."""
    settings = get_settings()
    customer = settings.CUSTOMER
    config_path = settings.customer_config_path

    hooks_dir = os.path.join(config_path, "hooks")
    if os.path.isdir(hooks_dir) and os.path.exists(os.path.join(hooks_dir, "__init__.py")):
        return hooks_dir
    return None


def _load_hooks_from_dir(hooks_dir: str) -> Optional[CustomerHooks]:
    """Load hooks module from a directory path."""
    try:
        init_path = os.path.join(hooks_dir, "__init__.py")
        spec = importlib.util.spec_from_file_location("customer_hooks", init_path)
        if spec and spec.loader:
            # Add parent dir to sys.path so relative imports work
            parent_dir = os.path.dirname(os.path.dirname(hooks_dir))
            if parent_dir not in sys.path:
                sys.path.insert(0, parent_dir)

            module = importlib.util.module_from_spec(spec)
            spec.loader.exec_module(module)

            hooks = getattr(module, "hooks", None)
            if isinstance(hooks, CustomerHooks):
                return hooks
            else:
                logger.warning(
                    f"Customer hooks module loaded but 'hooks' attribute is not a CustomerHooks instance"
                )
    except Exception as e:
        logger.error(f"Failed to load customer hooks: {e}", exc_info=True)
    return None


def get_hooks() -> CustomerHooks:
    """获取当前客户的钩子实例。线程安全，全局单例。

    Returns:
        CustomerHooks: 客户钩子实例，如果客户没有自定义钩子则返回默认空钩子
    """
    global _hooks_instance
    if _hooks_instance is not None:
        return _hooks_instance

    settings = get_settings()
    hooks_dir = _find_hooks_dir()

    if hooks_dir:
        loaded = _load_hooks_from_dir(hooks_dir)
        if loaded:
            logger.info(f"Loaded customer hooks for '{settings.CUSTOMER}' from {hooks_dir}")
            _hooks_instance = loaded
            return _hooks_instance

    logger.info(f"No custom hooks for '{settings.CUSTOMER}', using defaults")
    _hooks_instance = CustomerHooks()
    return _hooks_instance


def reload_hooks() -> CustomerHooks:
    """重新加载客户钩子（开发时热重载用）"""
    global _hooks_instance
    _hooks_instance = None
    return get_hooks()