from fastapi import FastAPI, File, UploadFile, HTTPException
from fastapi.responses import StreamingResponse
import tempfile
import subprocess
import os
import io

app = FastAPI()
from fastapi.middleware.cors import CORSMiddleware
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],  # or specific origin(s)
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

def process_video(input_bytes, speed=1.5):
    """
    Process video to change playback speed and compress.
    """
    with tempfile.NamedTemporaryFile(delete=False, suffix=".mp4") as tmp_input:
        tmp_input.write(input_bytes)
        input_path = tmp_input.name

    output_path = tempfile.NamedTemporaryFile(delete=False, suffix=".mp4").name

    video_speed = 1 / speed
    audio_speed = speed

    cmd = [
        "ffmpeg", "-i", input_path,
        "-filter_complex", f"[0:v]setpts={video_speed}*PTS[v];[0:a]atempo={audio_speed}[a]",
        "-map", "[v]", "-map", "[a]",
        "-vcodec", "libx264", "-crf", "28", "-preset", "fast",
        "-movflags", "+faststart",
        "-y", output_path
    ]

    process = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, text=True)
    process.wait()

    if process.returncode != 0:
        os.remove(input_path)
        os.remove(output_path)
        raise HTTPException(status_code=500, detail="Video processing failed.")

    with open(output_path, "rb") as f:
        output_data = f.read()

    os.remove(input_path)
    os.remove(output_path)

    return output_data


@app.post("/process_video")
async def upload_video(file: UploadFile = File(...), speed: float = 1.5):
    """
    Upload a video file and return processed video.
    """
    if not (0.25 <= speed <= 4.0):
        raise HTTPException(status_code=400, detail="Speed must be between 0.25x and 4x.")

    video_bytes = await file.read()
    processed_video = process_video(video_bytes, speed)

    return StreamingResponse(
        io.BytesIO(processed_video),
        media_type="video/mp4",
        headers={"Content-Disposition": "attachment; filename=processed_video.mp4"}
    )