"""Authenticated HTTP wrapper; Modal queues requests to one resident GPU worker."""
import hmac
import os

from fastapi import Depends, FastAPI, Header, HTTPException
from flux3_engine import GenerationRequest, LegacyRequest


def create_app(engine, startup_error=None):
    token = os.environ.get('FLUX_API_TOKEN')
    if not token:
        raise RuntimeError('FLUX_API_TOKEN must be set for the cloud API')

    def authorize(authorization: str | None = Header(default=None)):
        if not hmac.compare_digest((authorization or '').encode(), f'Bearer {token}'.encode()):
            raise HTTPException(401, 'Invalid bearer token')

    app = FastAPI(title='FLUX.3 Klein', dependencies=[Depends(authorize)])

    def ready():
        if startup_error or not engine or engine.pipe is None:
            raise HTTPException(503, startup_error or 'Model not ready')

    @app.get('/health')
    def health():
        ready()
        return engine.health()

    @app.post('/generate')
    def generate(request: GenerationRequest):
        ready()
        return engine.generate(request)

    @app.post('/sdxl')
    def legacy(request: LegacyRequest):
        ready()
        return engine.legacy(request.model_dump())

    return app