from django.contrib import messages
from django.contrib.auth.mixins import LoginRequiredMixin, UserPassesTestMixin
from django.http import HttpResponseBadRequest
from django.shortcuts import redirect, render
from django.urls import reverse
from django.utils.http import url_has_allowed_host_and_scheme
from django.views import View
from netbox.plugins import get_plugin_config
from tenancy.models import Tenant, TenantGroup

from .forms import UtilitiesSettingsForm
from .middleware import (
    SESSION_TENANT_GROUP_KEY,
    SESSION_TENANT_KEY,
    GlobalTenantFilterMiddleware,
)
from .models import NavigationPreference, UtilitiesSettings
from .navigation_helpers import get_visible_menus, normalize_preferences
from .runtime import (
    clear_runtime_settings_cache,
    navigation_customization_enabled,
    tenant_filter_enabled,
)


def _safe_return_url(request, default_name="home"):
    candidate = request.POST.get("next") or request.GET.get("next")
    if candidate and url_has_allowed_host_and_scheme(
        candidate,
        allowed_hosts={request.get_host()},
        require_https=request.is_secure(),
    ):
        return candidate
    return reverse(default_name)


class NavigationPreferencesView(LoginRequiredMixin, View):
    template_name = "netbox_utilities/navigation_preferences.html"

    def get(self, request):
        return self._render(request)

    def post(self, request):
        if not navigation_customization_enabled():
            return HttpResponseBadRequest("Die Navigationspersonalisierung ist deaktiviert.")

        preference, _ = NavigationPreference.objects.get_or_create(user=request.user)
        if "reset" in request.POST:
            preference.menu_order = []
            preference.hidden_menus = []
        else:
            descriptors = get_visible_menus(request.user)
            available_keys = [item["key"] for item in descriptors]
            order, hidden = normalize_preferences(
                request.POST.getlist("menu_order"),
                request.POST.getlist("hidden_menus"),
                available_keys,
            )
            preference.menu_order = order
            preference.hidden_menus = hidden
        preference.save()
        messages.success(request, "Die persönliche Navigation wurde gespeichert.")
        return redirect("plugins:netbox_utilities:navigation_preferences")

    def _render(self, request):
        descriptors = get_visible_menus(request.user)
        preference = NavigationPreference.objects.filter(user=request.user).first()
        order, hidden = normalize_preferences(
            preference.menu_order if preference else [],
            preference.hidden_menus if preference else [],
            [item["key"] for item in descriptors],
        )
        by_key = {item["key"]: item for item in descriptors}
        menus = [{**by_key[key], "hidden": key in hidden} for key in order]
        return render(
            request,
            self.template_name,
            {
                "menus": menus,
                "feature_enabled": navigation_customization_enabled(),
            },
        )


class UtilitiesSettingsView(LoginRequiredMixin, UserPassesTestMixin, View):
    template_name = "netbox_utilities/settings.html"
    raise_exception = True

    def test_func(self):
        return self.request.user.is_superuser

    def get(self, request):
        instance, _ = UtilitiesSettings.objects.get_or_create(singleton_id=1)
        tenant_filter_locked = not get_plugin_config("netbox_utilities", "tenant_filter_enabled")
        tenant_required_locked = not get_plugin_config("netbox_utilities", "tenant_required")
        return render(
            request,
            self.template_name,
            {
                "form": UtilitiesSettingsForm(
                    instance=instance,
                    tenant_filter_locked=tenant_filter_locked,
                    tenant_required_locked=tenant_required_locked,
                ),
                "tenant_filter_locked": tenant_filter_locked,
                "tenant_required_locked": tenant_required_locked,
            },
        )

    def post(self, request):
        instance, _ = UtilitiesSettings.objects.get_or_create(singleton_id=1)
        form = UtilitiesSettingsForm(
            request.POST,
            instance=instance,
            tenant_filter_locked=not get_plugin_config("netbox_utilities", "tenant_filter_enabled"),
            tenant_required_locked=not get_plugin_config("netbox_utilities", "tenant_required"),
        )
        if form.is_valid():
            form.save()
            clear_runtime_settings_cache()
            if not tenant_filter_enabled():
                GlobalTenantFilterMiddleware.clear_scope(request)
            messages.success(request, "Die Plugin-Einstellungen wurden gespeichert.")
            return redirect("plugins:netbox_utilities:settings")
        return render(request, self.template_name, {"form": form})


class SelectTenantView(LoginRequiredMixin, View):
    http_method_names = ["post"]

    def post(self, request):
        if not tenant_filter_enabled():
            return HttpResponseBadRequest("Der globale Mandantenfilter ist deaktiviert.")

        scope_value = request.POST.get("scope") or request.POST.get("tenant", "")
        if not scope_value:
            GlobalTenantFilterMiddleware.clear_scope(request)
            messages.success(request, "Der globale Mandantenfilter wurde aufgehoben.")
            return redirect(_safe_return_url(request))

        if ":" in scope_value:
            scope_kind, object_id = scope_value.split(":", 1)
        else:
            scope_kind, object_id = "tenant", scope_value

        if scope_kind == "tenant":
            tenant = Tenant.objects.restrict(request.user, "view").filter(pk=object_id).first()
            if tenant is None:
                return HttpResponseBadRequest("Unbekannter oder nicht erlaubter Mandant.")
            request.session.pop(SESSION_TENANT_GROUP_KEY, None)
            request.session[SESSION_TENANT_KEY] = tenant.pk
            messages.success(request, f"Globaler Mandantenfilter: {tenant}")
        elif scope_kind == "group":
            group = TenantGroup.objects.restrict(request.user, "view").filter(pk=object_id).first()
            if group is None:
                return HttpResponseBadRequest("Unbekannte oder nicht erlaubte Mandantengruppe.")
            request.session.pop(SESSION_TENANT_KEY, None)
            request.session[SESSION_TENANT_GROUP_KEY] = group.pk
            messages.success(request, f"Globale Mandantengruppe: {group}")
        else:
            return HttpResponseBadRequest("Ungültiger Mandantenfilter.")

        return redirect(_safe_return_url(request))