"""
视频处理工具模块

提供视频下载、Base64 编码等功能，用于支持视频评估
"""

import asyncio
import base64
import hashlib
import os
from pathlib import Path
from typing import Optional
import requests


# 配置
VIDEO_CACHE_DIR = Path(".video_cache")
VIDEO_MAX_SIZE_MB = 50  # 最大视频大小（MB）
VIDEO_DOWNLOAD_TIMEOUT = 120  # 下载超时（秒）
MAX_RETRIES = 2  # 最大重试次数


async def download_video(
    video_url: str,
    cache_dir: Path = VIDEO_CACHE_DIR
) -> Optional[Path]:
    """
    异步下载视频文件

    Args:
        video_url: 视频URL
        cache_dir: 缓存目录

    Returns:
        视频文件路径，失败返回 None
    """
    # 创建缓存目录
    cache_dir.mkdir(exist_ok=True)

    # 生成缓存文件名（基于URL hash）
    url_hash = hashlib.md5(video_url.encode()).hexdigest()
    cache_path = cache_dir / f"{url_hash}.mp4"

    # 检查缓存
    if cache_path.exists():
        file_size_mb = cache_path.stat().st_size / (1024 * 1024)
        print(f"      ♻️  使用缓存视频: {file_size_mb:.2f}MB")
        return cache_path

    # 异步下载
    loop = asyncio.get_event_loop()

    for attempt in range(MAX_RETRIES + 1):
        try:
            print(f"      📥 下载视频... (尝试 {attempt + 1}/{MAX_RETRIES + 1})")

            # 使用 executor 执行同步下载
            response = await loop.run_in_executor(
                None,
                lambda: requests.get(
                    video_url,
                    timeout=VIDEO_DOWNLOAD_TIMEOUT,
                    stream=True,
                    headers={"User-Agent": "Mozilla/5.0"}
                )
            )

            response.raise_for_status()

            # 检查文件大小
            content_length = response.headers.get('content-length')
            if content_length:
                size_mb = int(content_length) / (1024 * 1024)
                if size_mb > VIDEO_MAX_SIZE_MB:
                    print(f"      ⚠️  视频过大: {size_mb:.2f}MB > {VIDEO_MAX_SIZE_MB}MB")
                    return None

            # 保存到临时文件
            temp_path = cache_path.with_suffix('.tmp')

            def save_chunks():
                with open(temp_path, 'wb') as f:
                    for chunk in response.iter_content(chunk_size=8192):
                        if chunk:
                            f.write(chunk)

            await loop.run_in_executor(None, save_chunks)

            # 检查实际文件大小
            actual_size_mb = temp_path.stat().st_size / (1024 * 1024)
            if actual_size_mb > VIDEO_MAX_SIZE_MB:
                print(f"      ⚠️  视频过大: {actual_size_mb:.2f}MB > {VIDEO_MAX_SIZE_MB}MB")
                temp_path.unlink()
                return None

            # 重命名为正式文件
            temp_path.rename(cache_path)

            print(f"      ✅ 视频下载成功: {actual_size_mb:.2f}MB")
            return cache_path

        except Exception as e:
            if attempt < MAX_RETRIES:
                wait_time = 2 * (attempt + 1)
                print(f"      ⚠️  下载失败，{wait_time}秒后重试: {str(e)[:50]}")
                await asyncio.sleep(wait_time)
            else:
                print(f"      ❌ 视频下载失败: {str(e)[:100]}")
                # 清理临时文件
                if cache_path.with_suffix('.tmp').exists():
                    cache_path.with_suffix('.tmp').unlink()
                return None

    return None


async def encode_video_to_base64(video_path: Path) -> Optional[str]:
    """
    异步将视频文件编码为 Base64 data URL

    Args:
        video_path: 视频文件路径

    Returns:
        Base64 编码的 data URL，失败返回 None
    """
    try:
        loop = asyncio.get_event_loop()

        # 异步读取文件
        def read_file():
            with open(video_path, 'rb') as f:
                return f.read()

        print(f"      🔄 编码视频为 Base64...")
        video_bytes = await loop.run_in_executor(None, read_file)

        # Base64 编码
        def encode():
            base64_str = base64.b64encode(video_bytes).decode('utf-8')
            return f"data:video/mp4;base64,{base64_str}"

        data_url = await loop.run_in_executor(None, encode)

        encoded_size_mb = len(data_url) / (1024 * 1024)
        print(f"      ✅ Base64 编码完成: {encoded_size_mb:.2f}MB")

        return data_url

    except Exception as e:
        print(f"      ❌ Base64 编码失败: {str(e)[:100]}")
        return None


def cleanup_video_cache(cache_dir: Path = VIDEO_CACHE_DIR, days: int = 7):
    """
    清理超过指定天数的视频缓存

    Args:
        cache_dir: 缓存目录
        days: 保留天数
    """
    import time

    if not cache_dir.exists():
        return

    now = time.time()
    cutoff = now - (days * 24 * 60 * 60)

    removed_count = 0
    for file_path in cache_dir.glob("*.mp4"):
        if file_path.stat().st_mtime < cutoff:
            file_path.unlink()
            removed_count += 1

    if removed_count > 0:
        print(f"🗑️  清理了 {removed_count} 个过期视频缓存")