import subprocess
import os

def extract_audio_ffmpeg(in_video, out_audio="temp_audio.wav"):
    """
    Extracts the audio track from the given video file using FFmpeg.
    Saves it to the specified WAV file.

    :param in_video: Path to the input video file (e.g., MP4).
    :param out_audio: Path to the output WAV file.
    :return: The path to the output WAV file (same as out_audio).
    :raises RuntimeError: If the ffmpeg command fails.
    """
    cmd = [
        "ffmpeg", "-y",
        "-i", in_video,
        "-vn",           # disable video
        "-acodec", "pcm_s16le",
        "-ar", "16000",  # sample rate
        "-ac", "1",      # mono
        out_audio
    ]
    result = subprocess.run(cmd, capture_output=True)
    if result.returncode != 0:
        raise RuntimeError(f"FFmpeg audio extraction failed: {result.stderr.decode()}")
    return out_audio


def apply_edits(original_video, edit_instructions):
    """
    Applies editing instructions (e.g., cut segments, transitions) to the original video
    and produces a final edited video file named 'edited_video.mp4'.

    :param original_video: Path to the original video file.
    :param edit_instructions: JSON/dict specifying which segments to keep,
                              transitions, or other advanced edits.
    :return: Path to the newly created 'edited_video.mp4'.
    :raises RuntimeError: If ffmpeg or any editing command fails.
    """
    # In a real implementation, you'd parse 'edit_instructions' to build an ffmpeg
    # filter or a concat script. For now, we'll just return a placeholder path.
    
    out_path = "edited_video.mp4"

    # Example placeholder: direct copy (no edits).
    # cmd = ["ffmpeg", "-y", "-i", original_video, "-c", "copy", out_path]
    # result = subprocess.run(cmd, capture_output=True)
    # if result.returncode != 0:
    #     raise RuntimeError(f"FFmpeg editing error: {result.stderr.decode()}")

    # Return the output path (in a real scenario, ensure the final file is actually created).
    return out_path