#!/usr/bin/env python3
"""
通过 Chrome DevTools Protocol 下载文件。
需要 Chrome 以 --remote-debugging-port=9222 启动。

用法:
    python cdp_download.py <url> <output_path>
    python cdp_download.py https://github.com/.../vgmstream-win.zip tools/vgmstream.zip
"""

import json
import os
import sys
import time
import threading
from websocket import create_connection


class CDPClient:
    def __init__(self, ws_url: str):
        self.ws = create_connection(ws_url, origin="http://127.0.0.1:9222")
        self._id = 0
        self._lock = threading.Lock()
        self._pending = {}
        self._events = []
        self._running = True

        # Start background reader
        self._reader_thread = threading.Thread(target=self._read_loop, daemon=True)
        self._reader_thread.start()

    def _read_loop(self):
        while self._running:
            try:
                msg = json.loads(self.ws.recv())
                msg_id = msg.get('id')
                if msg_id is not None:
                    with self._lock:
                        self._pending[msg_id] = msg
                else:
                    self._events.append(msg)
            except Exception:
                if self._running:
                    time.sleep(0.1)
                else:
                    break

    def send(self, method: str, params: dict = None) -> dict:
        self._id += 1
        msg_id = self._id
        payload = json.dumps({
            'id': msg_id,
            'method': method,
            'params': params or {}
        })
        self.ws.send(payload)

        # Wait for response
        timeout = 60
        start = time.time()
        while time.time() - start < timeout:
            with self._lock:
                if msg_id in self._pending:
                    result = self._pending.pop(msg_id)
                    if 'error' in result:
                        raise Exception(f"CDP Error: {result['error']}")
                    return result.get('result', {})
            time.sleep(0.1)
        raise TimeoutError(f"CDP command {method} timed out")

    def wait_for_event(self, event_type: str, timeout: float = 60) -> dict:
        start = time.time()
        while time.time() - start < timeout:
            for i, evt in enumerate(self._events):
                if evt.get('method') == event_type:
                    return self._events.pop(i)['params']
            time.sleep(0.2)
        raise TimeoutError(f"Event {event_type} not received within {timeout}s")

    def close(self):
        self._running = False
        self.ws.close()


def download_via_cdp(url: str, output_path: str, cdp_url: str = "http://localhost:9222"):
    """
    使用 Chrome CDP 下载文件。
    """
    import urllib.request

    # 1. 创建新标签页
    print(f"[CDP] 创建标签页...")
    req = urllib.request.Request(f"{cdp_url}/json/new", method='PUT')
    resp = urllib.request.urlopen(req)
    tab = json.loads(resp.read())
    ws_url = tab['webSocketDebuggerUrl']
    print(f"[CDP] 标签页: {tab['id']}")

    client = CDPClient(ws_url)

    try:
        # 2. 启用必要的域
        print(f"[CDP] 启用 Page...")
        client.send('Page.enable')

        # 3. 设置下载目录
        download_dir = os.path.abspath(os.path.dirname(output_path))
        os.makedirs(download_dir, exist_ok=True)
        print(f"[CDP] 下载目录: {download_dir}")

        client.send('Browser.setDownloadBehavior', {
            'behavior': 'allow',
            'downloadPath': download_dir
        })

        # 4. 导航到下载 URL
        print(f"[CDP] 导航到: {url}")
        client.send('Page.navigate', {'url': url})

        # 5. 等待下载完成
        print(f"[CDP] 等待下载开始...")
        will_begin = client.wait_for_event('Browser.downloadWillBegin', timeout=30)
        guid = will_begin['guid']
        suggested_name = will_begin.get('suggestedFilename', 'unknown')
        print(f"[CDP] 下载开始: {suggested_name} (guid={guid})")

        # 等待下载进度完成
        print(f"[CDP] 等待下载完成...")
        while True:
            progress = client.wait_for_event('Browser.downloadProgress', timeout=120)
            state = progress.get('state', '')
            if state == 'completed':
                print(f"[CDP] 下载完成")
                break
            elif state == 'canceled':
                raise Exception("下载被取消")
            elif state == 'interrupted':
                print(f"[CDP] 下载中断, 重试...")
                client.send('Browser.resumeDownload', {'guid': guid})
            else:
                received = progress.get('receivedBytes', 0)
                total = progress.get('totalBytes', 0)
                if total > 0:
                    print(f"[CDP] 进度: {received}/{total} ({100*received//total}%)")

        # 6. 移动到目标路径
        downloaded_file = os.path.join(download_dir, suggested_name)
        if os.path.exists(downloaded_file) and downloaded_file != output_path:
            if os.path.exists(output_path):
                os.remove(output_path)
            os.rename(downloaded_file, output_path)
            print(f"[CDP] 文件保存到: {output_path}")

        return output_path

    finally:
        client.close()
        # 关闭标签页
        urllib.request.urlopen(urllib.request.Request(
            f"{cdp_url}/json/close/{tab['id']}", method='PUT'))


def main():
    if len(sys.argv) < 3:
        print("用法: python cdp_download.py <url> <output_path>")
        print("示例: python cdp_download.py https://example.com/file.zip tools/file.zip")
        sys.exit(1)

    url = sys.argv[1]
    output = sys.argv[2]
    download_via_cdp(url, output)


if __name__ == '__main__':
    main()