"""
练习 05: 用 Playwright 监听到的接口数据配合 requests 下载视频。

目标:
1. 用 Playwright 找到目标接口响应
2. 从 JSON 里提取第一个可下载视频
3. 用 `requests` 把 mp4 写到本地
4. 输出最终文件路径

建议:
- 浏览器负责“拿到页面里的接口数据”
- `requests` 负责“把真实 mp4 下载下来”
- 先拿第一条视频练通，不要一开始就做批量下载

运行:
    ./.venv/bin/python learning/playwright_basics/05_download_video.py
"""

from __future__ import annotations

import sys
from pathlib import Path

PROJECT_ROOT = Path(__file__).resolve().parent.parent.parent
if str(PROJECT_ROOT) not in sys.path:
    sys.path.insert(0, str(PROJECT_ROOT))

from Douyin import build_headers
from Douyin import DEFAULT_USER_URL
from Douyin import download_video
from Douyin import parse_aweme_items
from Douyin import sanitize_filename

OUTPUT_DIR = Path("learning/playwright_basics/output")
USER_DATA_DIR = PROJECT_ROOT / ".playwright-douyin-profile"
LISTEN_TARGET = "web/aweme/post/"


def build_output_path(title: str, video_id: str, output_dir: Path = OUTPUT_DIR) -> Path:
    safe_title = sanitize_filename(title, fallback="playwright-video")
    return output_dir / f"{safe_title}-{video_id}.mp4"


def extract_first_item_from_payload(payload) -> dict[str, str]:
    items = parse_aweme_items(payload)
    if not items:
        raise RuntimeError("当前接口里没有可下载视频，请先确认页面已加载出作品。")
    return items[0]


def main() -> None:
    import requests
    from playwright.sync_api import sync_playwright

    with sync_playwright() as playwright:
        context = playwright.chromium.launch_persistent_context(
            user_data_dir=str(USER_DATA_DIR),
            headless=False,
        )
        page = context.pages[0] if context.pages else context.new_page()
        page.goto(DEFAULT_USER_URL)
        print("[INFO] 页面已打开。请在必要时滚动一下，等待作品接口出现。")

        with page.expect_response(lambda response: LISTEN_TARGET in response.url, timeout=20000) as response_info:
            page.reload()

        response = response_info.value
        payload = response.json()
        first_item = extract_first_item_from_payload(payload)
        output_path = build_output_path(
            title=first_item["title"],
            video_id=first_item["video_id"],
            output_dir=OUTPUT_DIR,
        )
        headers = build_headers(page.url)
        download_video(
            requests_module=requests,
            headers=headers,
            video_url=first_item["video_url"],
            output_path=output_path,
        )
        print(f"[OK] 已下载到: {output_path}")
        context.close()


if __name__ == "__main__":
    main()