<?php

declare(strict_types=1);

namespace App\Filament\Pages;

use App\Support\Health\Finding;
use App\Support\Health\HealthReport;
use App\Support\Health\Severity;
use BackedEnum;
use Filament\Actions\Action;
use Filament\Notifications\Notification;
use Filament\Pages\Page;
use Filament\Support\Icons\Heroicon;
use Illuminate\Contracts\Support\Htmlable;
use Illuminate\Support\Collection;
use Illuminate\Support\Facades\Auth;
use UnitEnum;

/**
 * Everything wrong with the public site, in one place.
 *
 * This page exists because the site is somewhere else. A missing translation,
 * two records answering at the same URL, an image whose file is gone: none of
 * it is visible where the content is edited. It shows up on the frontend,
 * usually late, and usually to a visitor rather than to us.
 */
class SiteHealth extends Page
{
    protected string $view = 'filament.pages.site-health';

    protected static string|BackedEnum|null $navigationIcon = Heroicon::OutlinedShieldCheck;

    protected static ?int $navigationSort = 88;

    /**
     * Not a public Livewire property: a Finding is a plain object, and
     * Livewire can only carry types it knows how to serialise. It is
     * recomputed per render instead, which is what opening this page is for.
     *
     * @var Collection<int, Finding>|null
     */
    protected ?Collection $findings = null;

    public static function canAccess(): bool
    {
        // Anyone who edits content benefits from seeing what is wrong with it.
        // Individual checks hide themselves behind their own permission.
        return Auth::user()?->can('panel.access') ?? false;
    }

    public static function getNavigationGroup(): string|UnitEnum|null
    {
        return __('panel.groups.administration');
    }

    public static function getNavigationLabel(): string
    {
        return __('health.title');
    }

    public function getTitle(): string|Htmlable
    {
        return __('health.title');
    }

    public function getSubheading(): string|Htmlable|null
    {
        return __('health.subheading');
    }

    /**
     * @return Collection<int, Finding>
     */
    public function findings(): Collection
    {
        return $this->findings ??= app(HealthReport::class)->runFor(Auth::user());
    }

    /**
     * @return array<int, Action>
     */
    protected function getHeaderActions(): array
    {
        return [
            Action::make('refresh')
                ->label(__('health.actions.refresh'))
                ->icon('heroicon-o-arrow-path')
                ->color('gray')
                ->action(function (): void {
                    $this->refreshFindings();

                    Notification::make()
                        ->title(__('health.refreshed'))
                        ->success()
                        ->send();
                }),
        ];
    }

    public function refreshFindings(): void
    {
        // The badge is cached so that drawing it does not run ten checks on
        // every page of the panel; opening this page is the one moment we
        // definitely want fresh answers.
        app(HealthReport::class)->forget(Auth::user());

        $this->findings = null;
    }

    /**
     * @return Collection<int, Finding>
     */
    public function problems(): Collection
    {
        return $this->findings()->filter(fn (Finding $f) => $f->severity->isProblem());
    }

    /**
     * @return Collection<int, Finding>
     */
    public function passing(): Collection
    {
        return $this->findings()->reject(fn (Finding $f) => $f->severity->isProblem());
    }

    public function hasErrors(): bool
    {
        return $this->problems()->contains(fn (Finding $f) => $f->severity === Severity::Error);
    }

    /**
     * A count in the sidebar, because a diagnostics page nobody opens
     * diagnoses nothing.
     */
    public static function getNavigationBadge(): ?string
    {
        $problems = app(HealthReport::class)->problemCount(Auth::user());

        return $problems > 0 ? (string) $problems : null;
    }

    public static function getNavigationBadgeColor(): ?string
    {
        return 'warning';
    }
}