"""视频获取链 (V3-M2A).

从 play_url 下载视频(带平台下载头)→ imageio-ffmpeg 压到 ~4MB 低清 →
base64 data URL,供 GeminiVideoClient 投喂(OpenRouter image_url)。
真实下载/压缩只在 M7 live smoke 跑;单测全 mock。
2026-06-12 拍板:下载成功的原片全量落盘 data/(过没过审都存,play_url 有时效留不住)。
"""

from __future__ import annotations

import base64
import subprocess
from pathlib import Path
from typing import Any

import httpx
import imageio_ffmpeg

# platform_profiles 里写的是 "iOS UA"/"PC UA" 占位,这里映射成真实串 + Referer。
_PLATFORM_DOWNLOAD_HEADERS = {
    "douyin": {
        "User-Agent": "Mozilla/5.0 (iPhone; CPU iPhone OS 16_0 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/16.0 Mobile/15E148",
        "Referer": "https://www.douyin.com/",
    },
    "shipinhao": {
        "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120 Safari/537.36",
        "Referer": "https://channels.weixin.qq.com/",
    },
}
# 已拍板压缩档:360p / 1fps / 低清,实测 ~4MB(memory/video-multimodal-analysis)。
_FFMPEG_ARGS = ["-vf", "scale=360:-2,fps=1", "-crf", "33", "-c:a", "aac", "-b:a", "32k", "-ac", "1"]
MAX_INLINE_BYTES = 30 * 1024 * 1024  # OpenRouter inline base64 平台硬上限
COMPRESS_TIMEOUT_SECONDS = 120.0  # 实测 64MB/720p 压缩 ~8s,120s 足够余量


class VideoFetchError(RuntimeError):
    """下载/压缩/超限失败,由 GeminiVideoClient 捕获转 fail。"""


def _download_headers(platform: str, override: dict[str, str] | None) -> dict[str, str]:
    if override is not None:
        return override
    return _PLATFORM_DOWNLOAD_HEADERS.get(platform, {})


def _save_raw(save_path: str, raw: bytes) -> None:
    # 原片留档是 best-effort:磁盘问题绝不影响判定链路。
    try:
        path = Path(save_path)
        path.parent.mkdir(parents=True, exist_ok=True)
        path.write_bytes(raw)
    except OSError:
        pass


def _compress(raw: bytes, ffmpeg_exe: str) -> bytes:
    # 超时保护:坏视频会让 ffmpeg 卡死,进而挂住一个判定并发线程(实测正常压缩 ~8s)。
    try:
        proc = subprocess.run(
            [ffmpeg_exe, "-i", "pipe:0", *_FFMPEG_ARGS, "-f", "mp4",
             "-movflags", "frag_keyframe+empty_moov", "pipe:1"],
            input=raw,
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE,
            timeout=COMPRESS_TIMEOUT_SECONDS,
        )
    except subprocess.TimeoutExpired as exc:
        raise VideoFetchError("ffmpeg compression timeout") from exc
    if proc.returncode != 0 or not proc.stdout:
        raise VideoFetchError("ffmpeg compression failed")
    return proc.stdout


def fetch_and_compress(
    play_url: str,
    platform: str,
    *,
    headers: dict[str, str] | None = None,
    http_client: Any | None = None,
    ffmpeg_exe: str | None = None,
    timeout_seconds: float = 90.0,
    save_raw_to: str | None = None,
) -> str:
    if not play_url:
        raise VideoFetchError("missing play_url")
    client = http_client or httpx
    try:
        response = client.get(
            play_url,
            headers=_download_headers(platform, headers),
            follow_redirects=True,
            timeout=timeout_seconds,
        )
        response.raise_for_status()
        raw = response.content
    except httpx.HTTPError as exc:
        raise VideoFetchError(f"download failed: {type(exc).__name__}") from exc
    if not raw:
        raise VideoFetchError("empty download")
    if save_raw_to:
        _save_raw(save_raw_to, raw)

    compressed = _compress(raw, ffmpeg_exe or imageio_ffmpeg.get_ffmpeg_exe())
    if len(compressed) > MAX_INLINE_BYTES:
        raise VideoFetchError(f"compressed video oversize: {len(compressed)} bytes")
    return f"data:video/mp4;base64,{base64.b64encode(compressed).decode('ascii')}"