from fastapi import FastAPI, HTTPException
from pydantic import BaseModel
from concurrent.futures import ThreadPoolExecutor
import uuid, time
import wai_service
from typing import Optional

app = FastAPI()

EXEC = ThreadPoolExecutor(max_workers=1)
JOBS = {}                        # job_id ➜ (start_ts, Future)

class InferenceRequest(BaseModel):
    word: str
    optimized_letter: str
    font: str = "KaushanScript-Regular"
    seed: int = 0
    token: Optional[str] = None

    class Config:
        extra = "allow" 

@app.post("/generate")
def enqueue(req: InferenceRequest):
    """Start a job and return its UUID immediately."""
    if req.token is None:
        raise HTTPException(422, "field 'token' is required")
    payload = req.dict(exclude_none=True)
    job_id = str(uuid.uuid4())
    fut = EXEC.submit(wai_service.handler, dict(req.__dict__))
    JOBS[job_id] = (time.time(), fut)
    return {"job_id": job_id}
    
@app.get("/result/{job_id}")
def get_result(job_id: str):
    """Poll for job completion."""
    if job_id not in JOBS:
        raise HTTPException(404, "job_id not found")

    start, fut = JOBS[job_id]
    if not fut.done():
        return {"status": "running", "elapsed": int(time.time() - start)}

    try:
        img = fut.result()
        return {"status": "finished", "image_base64": img}
    finally:
        del JOBS[job_id]          # housekeeping