from moviepy import VideoFileClip, CompositeAudioClip

def shift_audio(video_path, output_path, shift_seconds=2.0):
    print(f"🎬 正在加载视频: {video_path}")
    
    # 加载视频和对应的音频
    video = VideoFileClip(video_path)
    audio = video.audio
    
    # 核心逻辑：让音频“时间错位”
    # shift_seconds > 0: 音频延后（开头静音）
    # shift_seconds < 0: 音频提前（结尾静音）
    print(f"⏱️ 正在将音频平移 {shift_seconds} 秒...")
    if shift_seconds >= 0:
        shifted_audio = CompositeAudioClip([audio.with_start(shift_seconds)]).with_duration(video.duration)
    else:
        advance_seconds = abs(shift_seconds)
        if advance_seconds >= video.duration:
            shifted_audio = CompositeAudioClip([]).with_duration(video.duration)
        else:
            trimmed_audio = audio.subclipped(advance_seconds, video.duration)
            shifted_audio = CompositeAudioClip([trimmed_audio.with_start(0)]).with_duration(video.duration)
    
    # 把错位的音频重新合成到视频上
    final_video = video.with_audio(shifted_audio)
    
    # 导出被“下毒”的对抗样本
    print(f"💾 正在导出对抗样本: {output_path}")
    final_video.write_videofile(output_path, codec="libx264", audio_codec="aac")
    print("✅ 搞定！CT-DPO 负样本生成成功！")

# 示例1：音频往后 2 秒（开头静音）
shift_audio(
    "/home/ubuntu/uag_oops_data/uag_oops/34 Funny Kid Nominees - FailArmy Hall Of Fame (May 2017)9.mp4",
    "/home/ubuntu/poisoned_output_delay2.mp4",
    shift_seconds=2.0,
)

# 示例2：音频往前 2 秒（结尾静音）
shift_audio(
    "/home/ubuntu/uag_oops_data/uag_oops/34 Funny Kid Nominees - FailArmy Hall Of Fame (May 2017)9.mp4",
    "/home/ubuntu/poisoned_output_early2.mp4",
    shift_seconds=-2.0,
)