app.py

from fastapi import FastAPI, BackgroundTasks, HTTPException
from fastapi.responses import FileResponse
import threading
import queue
import uuid
import os
import time

import audiocraft
from audiocraft.models import MusicGen
from audiocraft.data.audio import audio_write

print("Audiocraft version:", audiocraft.__version__)

app = FastAPI()

MODEL_NAME = "facebook/musicgen-small"
OUTPUT_DIR = "outputs"
os.makedirs(OUTPUT_DIR, exist_ok=True)

print("Loading MusicGen model...")
model = MusicGen.get_pretrained(MODEL_NAME)
model.set_generation_params(
    duration=10,
    temperature=1.0,
    top_k=250,
    top_p=0.0
)

# -------------------------
# Job system (in-memory)
# -------------------------

job_queue = queue.Queue()
jobs = {}  # job_id -> metadata


class JobStatus:
    QUEUED = "queued"
    PROCESSING = "processing"
    COMPLETED = "completed"
    FAILED = "failed"


import signal

class GenerationTimeout(Exception):
    pass

def timeout_handler(signum, frame):
    raise GenerationTimeout()

MAX_RUNTIME = 600  # 10 minutes (CPU-safe)

def worker():
    while True:
        job_id = job_queue.get()
        job = jobs.get(job_id)

        if not job:
            job_queue.task_done()
            continue

        start_time = time.time()
        jobs[job_id]["status"] = JobStatus.PROCESSING

        try:
            wav = model.generate([job["prompt"]])[0]

            elapsed = time.time() - start_time
            if elapsed > MAX_RUNTIME:
                raise TimeoutError("Generation exceeded max runtime")

            base_path = os.path.join(OUTPUT_DIR, job_id)

            audio_write(
                base_path,
                wav.cpu(),
                model.sample_rate,
                strategy="loudness",
                loudness_compressor=True
            )
            
            final_path = base_path + ".wav"
            
            jobs[job_id].update({
                "status": JobStatus.COMPLETED,
                "file_path": final_path
            })


        except Exception as e:
            jobs[job_id].update({
                "status": JobStatus.FAILED,
                "error": str(e)
            })

        finally:
            job_queue.task_done()



# Start worker thread
threading.Thread(target=worker, daemon=True).start()

# -------------------------
# API endpoints
# -------------------------

@app.post("/generate")
async def generate(prompt: str):
    job_id = uuid.uuid4().hex

    jobs[job_id] = {
        "status": JobStatus.QUEUED,
        "prompt": prompt,
        "created_at": time.time(),
        "file_path": None
    }

    job_queue.put(job_id)

    return {
        "job_id": job_id,
        "status_url": f"/status/{job_id}"
    }


@app.get("/status/{job_id}")
async def status(job_id: str):
    job = jobs.get(job_id)

    if not job:
        raise HTTPException(status_code=404, detail="Job not found")

    response = {
        "job_id": job_id,
        "status": job["status"],
        "elapsed_seconds": int(time.time() - job["created_at"])
    }


    if job["status"] == JobStatus.COMPLETED:
        response["download_url"] = f"/download/{job_id}"

    if job["status"] == JobStatus.FAILED:
        response["error"] = job.get("error")

    return response


def delete_file(path: str, delay: int = 10):
    """Deletes file after response is sent"""
    time.sleep(delay)
    if os.path.exists(path):
        os.remove(path)


@app.get("/download/{job_id}")
async def download(job_id: str, background_tasks: BackgroundTasks):
    job = jobs.get(job_id)

    if not job:
        raise HTTPException(status_code=404, detail="Job not found")

    if job["status"] != JobStatus.COMPLETED:
        raise HTTPException(status_code=400, detail="Job not completed")

    path = job["file_path"]

    if not path or not os.path.exists(path):
        raise HTTPException(status_code=404, detail="File not found")

    background_tasks.add_task(delete_file, path)

    return FileResponse(
        path,
        media_type="audio/wav",
        filename=os.path.basename(path)
    )