"""Convert DOCX bytes to PDF via LibreOffice headless."""

from __future__ import annotations

import shutil
import subprocess
import tempfile
from pathlib import Path


class PdfConversionError(RuntimeError):
    pass


def find_soffice() -> str | None:
    for name in ("soffice", "libreoffice"):
        path = shutil.which(name)
        if path:
            return path
    # common Windows / Linux paths
    for candidate in (
        r"C:\Program Files\LibreOffice\program\soffice.exe",
        "/usr/bin/soffice",
        "/usr/bin/libreoffice",
    ):
        if Path(candidate).exists():
            return candidate
    return None


def docx_bytes_to_pdf(docx_bytes: bytes, timeout_sec: int = 120) -> bytes:
    soffice = find_soffice()
    if not soffice:
        raise PdfConversionError(
            "LibreOffice (soffice) не найден. Установите libreoffice-writer в контейнере API."
        )
    with tempfile.TemporaryDirectory(prefix="espd_preview_") as tmp:
        tmp_path = Path(tmp)
        src = tmp_path / "document.docx"
        src.write_bytes(docx_bytes)
        try:
            proc = subprocess.run(
                [
                    soffice,
                    "--headless",
                    "--nologo",
                    "--nofirststartwizard",
                    "--convert-to",
                    "pdf",
                    "--outdir",
                    str(tmp_path),
                    str(src),
                ],
                capture_output=True,
                text=True,
                timeout=timeout_sec,
                check=False,
            )
        except subprocess.TimeoutExpired as e:
            raise PdfConversionError("Таймаут конвертации DOCX→PDF") from e
        pdf_path = tmp_path / "document.pdf"
        if proc.returncode != 0 or not pdf_path.exists():
            detail = (proc.stderr or proc.stdout or "").strip()[:500]
            raise PdfConversionError(f"Ошибка LibreOffice: {detail or proc.returncode}")
        return pdf_path.read_bytes()