"""Synchronous conversion.

Suitable for smaller documents. Anything that does not finish within
SYNC_TIMEOUT_SECONDS is cancelled and the caller is pointed at /jobs.
"""

from __future__ import annotations

import asyncio
import logging

from fastapi import APIRouter, Response
from fastapi.responses import FileResponse
from starlette.background import BackgroundTask

from ..deps import get_container
from ..errors import ConversionError, SyncTooLongError, error_from_code
from ..models import ConvertRequest

logger = logging.getLogger(__name__)

router = APIRouter(tags=["konverze"])


CONVERT_DESCRIPTION = """
Prevede dokument a rovnou vrati `application/pdf`.

Urceno pro mensi dokumenty. Konverze, ktera presahne `SYNC_TIMEOUT_SECONDS`
(vychozi 60 s), se zrusi a sluzba vrati 413 s odkazem na POST /jobs.

**Uchovavani souboru.** Vysledek se nikam neuklada. Vznikne v docasnem adresari,
odesle se v teto odpovedi a hned po jejim odeslani se i s pracovnim adresarem
smaze. Neexistuje zadna adresa, ze ktere by sel stahnout znovu, opakovane
stazeni znamena novou konverzi. Pokud vysledek potrebujete pozdeji, pouzijte
POST /jobs.

Hlavicky odpovedi:

- `X-Page-Count` pocet stranek vysledku
- `X-Engine-Used` engine, ktery dokument vyrenderoval
- `X-Missing-Assets` pocet assetu, ktere se nepodarilo nacist, hlavicka je jen
  pri nenulove hodnote. Cely seznam vraci jen asynchronni cesta.
- `X-Warnings` pocet varovani, hlavicka je jen pri nenulove hodnote
"""


@router.post(
    "/convert",
    summary="Synchronni prevod HTML na PDF",
    description=CONVERT_DESCRIPTION,
    response_class=Response,
    responses={
        200: {"content": {"application/pdf": {}}, "description": "Hotove PDF."},
        413: {"description": "Konverze trvala dele nez limit, pouzijte POST /jobs."},
    },
)
async def convert(request: ConvertRequest):
    container = get_container()
    settings = container.settings
    manager = container.jobs

    job = manager.submit(request)

    try:
        await asyncio.wait_for(job.done.wait(), timeout=settings.sync_timeout_seconds)
    except asyncio.TimeoutError as exc:
        manager.cancel(job.id)
        logger.warning(
            "Synchronous conversion exceeded its budget",
            extra={"job_id": job.id, "limit_seconds": settings.sync_timeout_seconds},
        )
        raise SyncTooLongError(
            "Konverze presahla limit pro synchronni pozadavek. Pouzijte asynchronni endpoint POST /jobs.",
            {"limit_seconds": settings.sync_timeout_seconds},
        ) from exc

    if job.state.status != "done":
        error = job.state.error
        if error is not None:
            raise error_from_code(error.error_code, error.message, error.detail)
        raise ConversionError("Konverze skoncila ve stavu " + job.state.status + ".")

    path = container.storage.result_path(job.id)
    filename = request.filename or "dokument.pdf"

    headers = {
        "X-Page-Count": str(job.state.page_count or 0),
        "X-Engine-Used": job.state.engine_used or "",
    }
    if job.state.missing_assets:
        headers["X-Missing-Assets"] = str(len(job.state.missing_assets))
    if job.state.warnings:
        headers["X-Warnings"] = str(len(job.state.warnings))

    return FileResponse(
        path,
        media_type="application/pdf",
        filename=filename,
        headers=headers,
        background=BackgroundTask(container.storage.discard, job.id),
    )