"""
浏览器管理器模块

负责管理全局唯一的 Playwright 浏览器实例，避免频繁启动/关闭浏览器的开销。
"""
import asyncio
from typing import Optional
from playwright.async_api import async_playwright, Browser, Playwright, Page
from ..utils.logger import logger

class BrowserManager:
    """
    浏览器管理器（异步单例）
    """
    _instance = None
    _playwright: Optional[Playwright] = None
    _browser: Optional[Browser] = None

    def __new__(cls):
        if cls._instance is None:
            cls._instance = super().__new__(cls)
        return cls._instance

    async def initialize(self):
        """
        初始化 Playwright 和 Browser
        """
        if self._browser is None:
            try:
                logger.info("正在启动无头浏览器...")
                self._playwright = await async_playwright().start()
                # 启动 Chromium，headless=True 表示无头模式
                self._browser = await self._playwright.chromium.launch(headless=True)
                logger.success("无头浏览器启动成功！")
            except Exception as e:
                logger.exception(f"无头浏览器启动失败: {e}")
                self._browser = None

    async def get_new_page(self) -> Optional[Page]:
        """
        获取一个新的页面 (Page)
        
        使用完毕后，调用者应该负责关闭该页面 (await page.close())
        """
        if self._browser is None:
            logger.warning("浏览器尚未初始化，尝试重新初始化...")
            await self.initialize()
            
        if self._browser:
            try:
                return await self._browser.new_page()
            except Exception as e:
                logger.error(f"创建新页面失败: {e}")
                return None
        return None

    async def shutdown(self):
        """
        关闭浏览器和 Playwright
        """
        if self._browser:
            await self._browser.close()
            self._browser = None
            logger.info("浏览器已关闭")
            
        if self._playwright:
            await self._playwright.stop()
            self._playwright = None
            logger.info("Playwright 已停止")

# 全局浏览器管理器实例
browser_manager = BrowserManager()