main.py

import os
import shutil
import tempfile
from fastapi import FastAPI, File, UploadFile, Form, BackgroundTasks
from fastapi.responses import FileResponse
from moviepy.editor import VideoFileClip, AudioFileClip, CompositeAudioClip, concatenate_videoclips

app = FastAPI()

def merge_videos_and_audios(video_paths, audio_paths, output_path):
    # Load video clips
    video_clips = [VideoFileClip(vp) for vp in video_paths]

    # Load audio clips (skip invalid files)
    audio_clips = []
    for ap in audio_paths:
        try:
            audio_clip = AudioFileClip(ap)
            audio_clips.append(audio_clip)
        except Exception as e:
            print(f"Warning: Could not load audio file {ap}: {e}")

    # Combine audio clips into one composite audio clip
    final_audio = CompositeAudioClip(audio_clips) if audio_clips else None

    # Concatenate video clips
    final_video = concatenate_videoclips(video_clips)

    # Set audio if exists
    if final_audio:
        final_video = final_video.set_audio(final_audio)

    # Write output video file
    final_video.write_videofile(output_path, codec="libx264", audio_codec="aac")

    # Close clips
    final_video.close()
    for vc in video_clips:
        vc.close()
    for ac in audio_clips:
        ac.close()


@app.post("/merge")
async def merge_endpoint(
    video_files: list[UploadFile] = File(...),
    audio_files: list[UploadFile] = File(None),
    background_tasks: BackgroundTasks = None
):
    # Create temporary directory for uploaded files
    temp_dir = tempfile.mkdtemp()

    try:
        # Save uploaded video files to temp_dir
        video_paths = []
        for vf in video_files:
            video_path = os.path.join(temp_dir, vf.filename)
            with open(video_path, "wb") as f:
                content = await vf.read()
                f.write(content)
            video_paths.append(video_path)

        # Save uploaded audio files to temp_dir (if any)
        audio_paths = []
        if audio_files:
            for af in audio_files:
                audio_path = os.path.join(temp_dir, af.filename)
                with open(audio_path, "wb") as f:
                    content = await af.read()
                    f.write(content)
                audio_paths.append(audio_path)

        # Prepare permanent output directory
        output_dir = os.path.abspath("output")
        os.makedirs(output_dir, exist_ok=True)

        # Define output video path
        output_file = os.path.join(output_dir, "merged_output.mp4")

        # Merge videos and audios
        merge_videos_and_audios(video_paths, audio_paths, output_file)

        # Add background task to delete temp_dir after response sent
        if background_tasks:
            background_tasks.add_task(shutil.rmtree, temp_dir)
        else:
            # If no background_tasks support, you can delete later manually or omit
            pass

        # Return merged video file
        return FileResponse(output_file, media_type="video/mp4", filename="merged_output.mp4")

    except Exception as e:
        # Cleanup temp_dir if exception occurs
        shutil.rmtree(temp_dir)
        return {"error": str(e)}