"""Jinja2 template engine for the admin panel.

Templates ship inside the package (``src/contract_check/api/admin/templates``)
so the Docker image picks them up via the wheel install. A ``dt`` filter keeps
datetime rendering consistent.
"""

from __future__ import annotations

import datetime as dt
import json
from pathlib import Path

from fastapi import Response
from fastapi.templating import Jinja2Templates

_TEMPLATES_DIR = Path(__file__).resolve().parent / "templates"

templates = Jinja2Templates(directory=str(_TEMPLATES_DIR))


def _format_dt(value: object, fmt: str = "%Y-%m-%d %H:%M UTC") -> str:
    if isinstance(value, dt.datetime):
        return value.strftime(fmt)
    if value is None:
        return "—"
    return str(value)


def _yes_no_none(value: object) -> str:
    if value is True:
        return "да"
    if value is False:
        return "нет"
    return "—"


def attach_toast(response: Response, toast: str | None) -> None:
    """Attach an HTMX toast trigger to any response that supports headers."""
    if toast:
        response.headers["HX-Trigger"] = json.dumps({"showToast": toast})


templates.env.filters["dt"] = _format_dt
templates.env.filters["yn"] = _yes_no_none