#!/usr/bin/env node
/**
 * cdp_eval.js —— 极简 CDP 工具: 连上**已经在跑的** Chrome(需带 --remote-debugging-port),
 * 在指定标签页里求值一段 JS 并把结果按 JSON 打印回来。
 *
 * 零依赖: 只用 Node >= 22 内置的全局 WebSocket / fetch。
 *
 * 用法:
 *   node tools/cdp_eval.js --port 9222 --match 1ms.run --file /tmp/expr.js
 *   echo 'document.title' | node tools/cdp_eval.js --port 9222 --match 1ms.run
 *   node tools/cdp_eval.js --list                 # 列出所有标签页
 *
 * 选项:
 *   --port N        调试端口 (默认 9222)
 *   --match SUBSTR  选 url 含该子串的标签页 (默认第一个 page)
 *   --file PATH     从文件读表达式 (等价 awaitPromise)
 *   --reload        求值前先 reload 一次并等待 load
 *   --timeout MS    默认 30000
 */
const fs = require('fs');

function arg(name, def) {
    const i = process.argv.indexOf('--' + name);
    if (i < 0) return def;
    const v = process.argv[i + 1];
    return (v === undefined || v.startsWith('--')) ? true : v;
}

async function listTargets(port) {
    const r = await fetch(`http://127.0.0.1:${port}/json/list`);
    return r.json();
}

class Cdp {
    constructor(ws) { this.ws = ws; this.id = 0; this.waits = new Map(); this.events = []; }
    static async connect(url) {
        const ws = new WebSocket(url);
        await new Promise((res, rej) => { ws.onopen = res; ws.onerror = rej; });
        const c = new Cdp(ws);
        ws.onmessage = ev => {
            const m = JSON.parse(ev.data);
            if (m.id && c.waits.has(m.id)) {
                const { res, rej } = c.waits.get(m.id);
                c.waits.delete(m.id);
                m.error ? rej(new Error(JSON.stringify(m.error))) : res(m.result);
            } else if (m.method) {
                c.events.push(m);
            }
        };
        return c;
    }
    send(method, params = {}) {
        const id = ++this.id;
        this.ws.send(JSON.stringify({ id, method, params }));
        return new Promise((res, rej) => this.waits.set(id, { res, rej }));
    }
    close() { try { this.ws.close(); } catch (e) {} }
}

const sleep = ms => new Promise(r => setTimeout(r, ms));

(async () => {
    const port = parseInt(arg('port', '9222'), 10);
    const timeout = parseInt(arg('timeout', '30000'), 10);

    if (arg('list', false)) {
        const t = await listTargets(port);
        for (const x of t) console.log(`${x.type}\t${(x.url || '').slice(0, 120)}\t${x.id}`);
        return;
    }

    const match = arg('match', null);
    const targets = (await listTargets(port)).filter(t => t.type === 'page' || t.type === 'iframe');
    let target = null;
    if (match) target = targets.find(t => (t.url || '').includes(match));
    if (!target) target = targets[0];
    if (!target) throw new Error('没有可用标签页');

    const cdp = await Cdp.connect(target.webSocketDebuggerUrl);
    await cdp.send('Runtime.enable');

    // --init-script FILE: 在**该文档的任何脚本之前**注入 (配合 --reload 使用)。
    // 用途: 挂钩子必须在 tdc.js 之类的目标脚本执行前就位, 否则模块系统已经初始化完/被缓存。
    const initFile = arg('init-script', null);
    if (initFile && initFile !== true) {
        await cdp.send('Page.enable');
        const src = fs.readFileSync(initFile, 'utf8');
        const added = await cdp.send('Page.addScriptToEvaluateOnNewDocument', { source: src });
        console.error(`[init-script] installed ${initFile} (${added.identifier})`);
    }

    if (arg('reload', false)) {
        await cdp.send('Page.enable');
        await cdp.send('Page.reload', { ignoreCache: true });
        await sleep(parseInt(arg('settle', '2500'), 10));
    }

    let expr;
    const file = arg('file', null);
    if (file && file !== true) expr = fs.readFileSync(file, 'utf8');
    else {
        expr = fs.readFileSync(0, 'utf8');            // stdin
    }
    if (!expr.trim()) throw new Error('表达式为空');

    const res = await cdp.send('Runtime.evaluate', {
        expression: expr,
        awaitPromise: true,
        returnByValue: true,
        timeout,
    });
    const out = {
        target: { url: target.url, title: target.title, id: target.id },
        ok: !res.exceptionDetails,
        result: res.result ? res.result.value : null,
        exception: res.exceptionDetails ? (res.exceptionDetails.exception || {}).description : null,
    };
    console.log(JSON.stringify(out, null, 2));
    cdp.close();
})().catch(e => { console.error('CDP_ERROR: ' + e.message); process.exit(1); });