"""SAM3 engine control routes (REQ-192)."""

from fastapi import APIRouter, HTTPException

from backend import jobs

router = APIRouter(prefix="/api/sam3", tags=["sam3"])


@router.post("/release")
def release() -> dict:
    """Free the SAM3 model's VRAM now — never while the card is busy.

    The same non-blocking `gpu_lock` rule as an interactive assist (REQ-065):
    a job or assist in flight wins, and the caller is told to try again.
    """
    if not jobs.gpu_lock.acquire(blocking=False):
        raise HTTPException(409, "GPU busy — assist or job in flight, try again in a moment")
    try:
        from backend import sam3_engine

        released = sam3_engine.release_engine()
        return {"released": released, "model_loaded": sam3_engine.engine_is_loaded()}
    finally:
        jobs.gpu_lock.release()