"""Project-level views every service exposes: health, timezone, legal pages."""

from __future__ import annotations

from functools import lru_cache
from zoneinfo import available_timezones

from django.contrib import messages
from django.db import connection
from django.http import JsonResponse
from django.shortcuts import redirect, render
from django.urls import reverse
from django.utils import timezone
from django.utils.http import url_has_allowed_host_and_scheme
from django.utils.translation import gettext as _

from .context_processors import DEFAULT_COMMON_TIMEZONES


@lru_cache(maxsize=1)
def _timezone_name_options():
    try:
        names = sorted(available_timezones())
    except Exception:
        names = list(DEFAULT_COMMON_TIMEZONES)

    preferred = ["UTC", "Europe/Moscow", "Asia/Yakutsk"]
    ordered = [n for n in preferred if n in names]
    ordered += [n for n in names if n not in ordered]
    return ordered


def _safe_next_url(request, candidate):
    if candidate and url_has_allowed_host_and_scheme(
        candidate,
        allowed_hosts={request.get_host()},
        require_https=request.is_secure(),
    ):
        return candidate
    return reverse("timezone-preferences")


def privacy_policy(request):
    return render(request, "privacy_policy.html")


def cookie_policy(request):
    return render(request, "cookie_policy.html")


def timezone_preferences(request):
    timezone_names = _timezone_name_options()
    timezone_set = set(timezone_names)

    selected_timezone = request.session.get("user_timezone", "UTC")
    if selected_timezone not in timezone_set:
        selected_timezone = "UTC"

    if request.method == "POST":
        selected_timezone = (request.POST.get("timezone") or "UTC").strip()
        if selected_timezone not in timezone_set:
            messages.error(request, _("Selected time zone is not supported."))
        else:
            request.session["user_timezone"] = selected_timezone
            request.session.modified = True
            messages.success(request, _("Time zone preference saved."))
            return redirect(_safe_next_url(request, request.POST.get("next")))

    return render(request, "timezone_preferences.html", {
        "timezone_names": timezone_names,
        "selected_timezone": selected_timezone,
        "next_url": _safe_next_url(
            request, request.GET.get("next") or request.META.get("HTTP_REFERER"),
        ),
    })


def health_check(request):
    """Swarm healthcheck target: it must answer without a database, not raise."""
    try:
        with connection.cursor() as cursor:
            cursor.execute("SELECT 1")
        return JsonResponse({
            "status": "healthy",
            "timestamp": timezone.now().isoformat(),
            "database": "connected",
        })
    except Exception as exc:
        return JsonResponse(
            {
                "status": "unhealthy",
                "timestamp": timezone.now().isoformat(),
                "database": "disconnected",
                "error": str(exc),
            },
            status=503,
        )