import traceback

from fastapi import APIRouter, BackgroundTasks, HTTPException
from fastapi.responses import FileResponse

from app.models.schemas import RenderRequest, RenderAccepted, JobStatus
from app.core.jobs import new_job_id, write_status, read_status
from app.core.renderer import run_render_job
from app.core.logger import job_log

router = APIRouter()


def _run_job_safe(job_id: str, payload: dict):
    try:
        run_render_job(job_id, payload)
    except Exception as e:
        job_log(job_id, f"FAILED: {e}\n{traceback.format_exc()}", stage="error")
        write_status(job_id, status="failed", error=str(e))


@router.post("/render", response_model=RenderAccepted)
def render(req: RenderRequest, background_tasks: BackgroundTasks):
    job_id = new_job_id()
    write_status(job_id, status="queued", progress="job created")
    # Async by design (Rule #5): return immediately, render in background.
    # This is what makes the API safe to run on an HF Space free tier without
    # hitting request timeouts on multi-minute renders.
    background_tasks.add_task(_run_job_safe, job_id, req.model_dump())
    return RenderAccepted(job_id=job_id)


@router.get("/status/{job_id}", response_model=JobStatus)
def status(job_id: str):
    s = read_status(job_id)
    if s is None:
        raise HTTPException(status_code=404, detail="job_id not found")
    return s


@router.get("/outputs/{filename}")
def get_output(filename: str):
    import os
    path = os.path.join("outputs", filename)
    if not os.path.exists(path):
        raise HTTPException(status_code=404, detail="file not found")
    return FileResponse(path)


@router.get("/templates")
def list_templates():
    import os
    import json
    names = []
    for f in os.listdir("templates"):
        if f.endswith(".json"):
            with open(os.path.join("templates", f)) as fh:
                names.append(json.load(fh))
    return names