import puppeteer from "puppeteer";

let browser;
const pagePool = [];
const MAX_PAGES = Number.parseInt(process.env.CHART_MAX_PAGES || "1", 10);
const DEFAULT_TIMEOUT_MS = Number.parseInt(
  process.env.CHART_RENDER_TIMEOUT_MS || "",
  10,
);
const EFFECTIVE_TIMEOUT_MS = Number.isFinite(DEFAULT_TIMEOUT_MS)
  ? DEFAULT_TIMEOUT_MS
  : 500000;

const isBrowserAlive = () => browser && browser.isConnected();

const clearPagePool = async () => {
  const pages = pagePool.splice(0, pagePool.length);
  await Promise.allSettled(
    pages.map(async (page) => {
      if (page && !page.isClosed()) await page.close();
    }),
  );
};

const createPage = async () => {
  if (!isBrowserAlive()) {
    await initBrowserPool();
  }

  const page = await browser.newPage();
  page.setDefaultTimeout(EFFECTIVE_TIMEOUT_MS);
  page.setDefaultNavigationTimeout(EFFECTIVE_TIMEOUT_MS);
  return page;
};

const isUsablePage = (page) =>
  page && !page.isClosed() && page.browser()?.isConnected();

/**
 * 初始化浏览器 + 预创建 page
 */
export const initBrowserPool = async () => {
  if (!isBrowserAlive()) {
    await clearPagePool();
    browser = null;

    browser = await puppeteer.launch({
      headless: "new",
      executablePath: process.env.CHROME_PATH || undefined,
      args: [
        "--no-sandbox",
        "--disable-setuid-sandbox",
        "--disable-dev-shm-usage",
        "--disable-background-timer-throttling",
        "--disable-backgrounding-occluded-windows",
        "--disable-renderer-backgrounding",
      ],
      // 避免渲染压力下 CDP 调用超时（对应报错：Runtime.callFunctionOn timed out）
      protocolTimeout: EFFECTIVE_TIMEOUT_MS,
    });

    browser.on("disconnected", () => {
      browser = null;
      pagePool.splice(0, pagePool.length);
    });

    console.log("✅ Browser initialized");

    // 预创建 page
    for (let i = 0; i < MAX_PAGES; i++) {
      pagePool.push(await createPage());
    }

    console.log(`✅ Page pool initialized: ${MAX_PAGES}`);
  }
};

/**
 * 获取 page（核心）
 */
export const getPage = async () => {
  if (!isBrowserAlive()) {
    await initBrowserPool();
  }

  if (pagePool.length > 0) {
    while (pagePool.length > 0) {
      const page = pagePool.pop();
      if (isUsablePage(page)) return page;
      await discardPage(page);
    }
  }

  // pool 空了就新建（兜底）
  return createPage();
};

/**
 * 释放 page
 */
export const releasePage = async (page) => {
  if (!page) return;

  try {
    if (!isUsablePage(page)) {
      await discardPage(page);
      return;
    }

    if (pagePool.length < MAX_PAGES) {
      pagePool.push(page);
    } else {
      await page.close();
    }
  } catch (err) {
    console.error("❌ releasePage error:", err);
  }
};

export const discardPage = async (page) => {
  if (!page) return;

  try {
    if (!page.isClosed()) await page.close();
  } catch (err) {
    console.warn("⚠️ discardPage failed:", err.message);
  }
};

/**
 * 关闭
 */
export const closeBrowserPool = async () => {
  try {
    await clearPagePool();

    if (browser) {
      await browser.close();
      browser = null;
    }

    console.log("🛑 Browser pool closed");
  } catch (err) {
    console.error("❌ closeBrowserPool error:", err);
  }
};