/**
 * 通过 CDP 在精确的视口尺寸下截图（含整页截图）。
 *
 * 为什么不直接用 `chrome --headless --screenshot --window-size`：
 * 该模式下截图位图宽度与 CSS 视口宽度可能不一致，导致移动端截图
 * 看起来"内容被截断"，实际测量（document.scrollWidth）却是正常的。
 * 这里用 Emulation.setDeviceMetricsOverride 明确指定视口，
 * 保证截图与真实设备表现一致。
 *
 * 用法：CDP_WS=<ws地址> node scripts/screenshot.mjs <url> <width> <height> <输出路径> [--full]
 */

import { writeFileSync } from "node:fs";

const [, , targetUrl, widthArg, heightArg, outputPath, ...flags] = process.argv;
const width = Number(widthArg ?? 1440);
const height = Number(heightArg ?? 900);
const fullPage = flags.includes("--full");

const wsUrl = process.env.CDP_WS;
if (!wsUrl || !targetUrl || !outputPath) {
	console.error(
		"用法：CDP_WS=<ws地址> node scripts/screenshot.mjs <url> <width> <height> <输出路径> [--full]",
	);
	process.exit(1);
}

const socket = new WebSocket(wsUrl);
let messageId = 0;
const pending = new Map();

function send(method, params = {}) {
	const id = ++messageId;
	socket.send(JSON.stringify({ id, method, params }));
	return new Promise((resolve, reject) => {
		pending.set(id, { resolve, reject });
		setTimeout(() => {
			if (pending.has(id)) {
				pending.delete(id);
				reject(new Error(`CDP 超时: ${method}`));
			}
		}, 40000);
	});
}

socket.addEventListener("message", (event) => {
	const message = JSON.parse(event.data);
	if (message.id && pending.has(message.id)) {
		const { resolve } = pending.get(message.id);
		pending.delete(message.id);
		resolve(message.result);
	}
});

socket.addEventListener("open", async () => {
	await send("Page.enable");
	await send("Runtime.enable");
	await send("Emulation.setDeviceMetricsOverride", {
		width,
		height,
		deviceScaleFactor: 1,
		mobile: width < 768,
	});

	await send("Page.navigate", { url: targetUrl });
	// 等待字体加载与首屏动画稳定
	await new Promise((resolve) => setTimeout(resolve, 4500));

	// 让所有延迟出现的元素（滚动动画）进入最终状态
	await send("Runtime.evaluate", {
		expression:
			"window.scrollTo(0, document.body.scrollHeight); window.scrollTo(0, 0);",
	});
	await new Promise((resolve) => setTimeout(resolve, 1200));

	const screenshot = await send("Page.captureScreenshot", {
		format: "png",
		captureBeyondViewport: fullPage,
		optimizeForSpeed: false,
	});

	writeFileSync(outputPath, Buffer.from(screenshot.data, "base64"));
	console.log(`已保存 ${outputPath} (${width}x${height}${fullPage ? ", 整页" : ""})`);
	socket.close();
	process.exit(0);
});