<?php

declare(strict_types=1);

namespace App\Controller;

use App\Config;
use App\Http\Request;
use App\Http\Response;
use App\Repository\DomainRepository;
use App\Repository\GroupRepository;
use App\Repository\SettingRepository;
use App\Security\Auth;
use App\Security\Csrf;
use App\Security\Session;
use App\Service\DomainChecker;
use App\Support\CheckToken;
use App\Support\ShortDomain;
use App\View;

/**
 * Verwaltung der Kurzlink-Domains.
 *
 * Ausschliesslich fuer Administratoren: eine Domain gehoert zu einer
 * Gruppe und entscheidet damit, wer die Kurzlinks darunter sehen und
 * anlegen darf. Einzige Ausnahme ist der Endpunkt der Domain-Pruefung,
 * der sich ueber ein kurzlebiges Token ausweist.
 */
final class DomainController extends Controller
{
    public function __construct(
        Config $config,
        View $view,
        private readonly Session $session,
        private readonly Csrf $csrf,
        private readonly Auth $auth,
        private readonly DomainRepository $domains,
        private readonly DomainChecker $checker,
        private readonly SettingRepository $settings,
        private readonly GroupRepository $groups,
    ) {
        parent::__construct($config, $view);
    }

    public function index(Request $request): Response
    {
        if (($response = $this->requireAdmin($this->auth, $this->session, $request)) !== null) {
            return $response;
        }

        // Stellt sicher, dass die Standarddomain existiert.
        $this->domains->defaultDomain($this->config->baseUrl());

        // Ergebnis einer eben angestossenen Pruefung einmalig anzeigen.
        $checkResult = $this->session->get('_domain_check');
        $this->session->remove('_domain_check');

        return $this->html('domains/index', [
            'domains' => $this->domains->all(),
            'groups' => $this->groups->all(),
            'requestHost' => ShortDomain::normalizeRequestHost((string) ($request->server['HTTP_HOST'] ?? '')),
            'checkResult' => is_array($checkResult) ? $checkResult : null,
            'pageTitle' => 'Domains',
        ]);
    }

    /**
     * Prueft, ob die Domain tatsaechlich bei dieser Installation ankommt.
     *
     * @param array<string,string> $args
     */
    public function check(Request $request, array $args = []): Response
    {
        if (($response = $this->requireAdmin($this->auth, $this->session, $request)) !== null) {
            return $response;
        }

        if (($response = $this->requireCsrf($this->csrf, $request)) !== null) {
            return $response;
        }

        $domain = $this->domains->find((int) ($args['id'] ?? 0));
        if ($domain === null) {
            return $this->domainNotFound();
        }

        $this->session->set('_domain_check', [
            'domain_id' => (int) $domain['id'],
            'domain' => ShortDomain::displayName((string) $domain['base_url']),
            'result' => $this->checker->check($domain),
        ]);

        return $this->redirect('/admin/domains');
    }

    /**
     * Oeffentlicher Endpunkt, den die Pruefung von aussen aufruft.
     *
     * Ohne gueltiges, kurzlebiges Token antwortet er wie eine beliebige
     * unbekannte Adresse - es wird also nichts ueber die Installation
     * preisgegeben. Kommt ein gueltiges Token an, ist damit bewiesen,
     * dass der Aufruf hier gelandet ist.
     */
    public function verify(Request $request): Response
    {
        if (!CheckToken::isValid($request->query('token'), $this->settings->secret())) {
            return Response::html('Not Found', 404);
        }

        return Response::json(['ok' => true])
            ->withHeader('Cache-Control', 'no-store');
    }

    public function create(Request $request): Response
    {
        if (($response = $this->requireAdmin($this->auth, $this->session, $request)) !== null) {
            return $response;
        }

        return $this->html('domains/form', [
            'domain' => null,
            'groups' => $this->groups->all(),
            'values' => [
                'base_url' => '',
                'label' => '',
                'is_default' => '0',
                'group_id' => (string) $this->groups->defaultGroupId(),
            ],
            'errors' => [],
            'pageTitle' => 'Neue Domain',
        ]);
    }

    public function store(Request $request): Response
    {
        if (($response = $this->requireAdmin($this->auth, $this->session, $request)) !== null) {
            return $response;
        }

        if (($response = $this->requireCsrf($this->csrf, $request)) !== null) {
            return $response;
        }

        $values = $this->readValues($request);
        $baseUrl = ShortDomain::normalizeBaseUrl($values['base_url']);
        $errors = $this->validate($baseUrl);

        if ($errors === [] && $this->domains->hostExists(ShortDomain::hostOf($baseUrl))) {
            $errors['base_url'] = 'Diese Domain ist bereits eingetragen.';
        }

        $groupId = $this->resolveGroupId($values['group_id'], $errors);

        if ($errors !== []) {
            return $this->html('domains/form', [
                'domain' => null,
                'groups' => $this->groups->all(),
                'values' => $values,
                'errors' => $errors,
                'pageTitle' => 'Neue Domain',
            ], 422);
        }

        // Die erste Domain ist zwangslaeufig die Standarddomain.
        $isDefault = $values['is_default'] === '1' || $this->domains->count() === 0;
        $this->domains->create($baseUrl, $values['label'] !== '' ? $values['label'] : null, $isDefault, $groupId);

        $this->session->flash('success', sprintf(
            'Domain "%s" wurde angelegt. Bitte daran denken, sie im DNS und beim Webserver auf diese Installation zu zeigen.',
            ShortDomain::displayName($baseUrl),
        ));

        return $this->redirect('/admin/domains');
    }

    /**
     * @param array<string,string> $args
     */
    public function edit(Request $request, array $args = []): Response
    {
        if (($response = $this->requireAdmin($this->auth, $this->session, $request)) !== null) {
            return $response;
        }

        $domain = $this->domains->find((int) ($args['id'] ?? 0));
        if ($domain === null) {
            return $this->domainNotFound();
        }

        return $this->html('domains/form', [
            'domain' => $domain,
            'groups' => $this->groups->all(),
            'values' => [
                'base_url' => (string) $domain['base_url'],
                'label' => (string) ($domain['label'] ?? ''),
                'is_default' => ((int) $domain['is_default'] === 1) ? '1' : '0',
                'group_id' => (string) $domain['group_id'],
            ],
            'errors' => [],
            'pageTitle' => 'Domain bearbeiten',
        ]);
    }

    /**
     * @param array<string,string> $args
     */
    public function update(Request $request, array $args = []): Response
    {
        if (($response = $this->requireAdmin($this->auth, $this->session, $request)) !== null) {
            return $response;
        }

        if (($response = $this->requireCsrf($this->csrf, $request)) !== null) {
            return $response;
        }

        $id = (int) ($args['id'] ?? 0);
        $domain = $this->domains->find($id);
        if ($domain === null) {
            return $this->domainNotFound();
        }

        $values = $this->readValues($request);
        $baseUrl = ShortDomain::normalizeBaseUrl($values['base_url']);
        $errors = $this->validate($baseUrl);

        if ($errors === [] && $this->domains->hostExists(ShortDomain::hostOf($baseUrl), $id)) {
            $errors['base_url'] = 'Diese Domain ist bereits eingetragen.';
        }

        $groupId = $this->resolveGroupId($values['group_id'], $errors);

        if ($errors !== []) {
            return $this->html('domains/form', [
                'domain' => $domain,
                'groups' => $this->groups->all(),
                'values' => $values,
                'errors' => $errors,
                'pageTitle' => 'Domain bearbeiten',
            ], 422);
        }

        $this->domains->update($id, $baseUrl, $values['label'] !== '' ? $values['label'] : null, $groupId);

        if ($values['is_default'] === '1') {
            $this->domains->makeDefault($id);
        }

        $this->session->flash('success', 'Die Domain wurde gespeichert.');

        return $this->redirect('/admin/domains');
    }

    /**
     * @param array<string,string> $args
     */
    public function makeDefault(Request $request, array $args = []): Response
    {
        if (($response = $this->requireAdmin($this->auth, $this->session, $request)) !== null) {
            return $response;
        }

        if (($response = $this->requireCsrf($this->csrf, $request)) !== null) {
            return $response;
        }

        $domain = $this->domains->find((int) ($args['id'] ?? 0));
        if ($domain === null) {
            return $this->domainNotFound();
        }

        $this->domains->makeDefault((int) $domain['id']);
        $this->session->flash('success', sprintf(
            '"%s" ist jetzt die Standarddomain.',
            ShortDomain::displayName((string) $domain['base_url']),
        ));

        return $this->redirect('/admin/domains');
    }

    /**
     * @param array<string,string> $args
     */
    public function destroy(Request $request, array $args = []): Response
    {
        if (($response = $this->requireAdmin($this->auth, $this->session, $request)) !== null) {
            return $response;
        }

        if (($response = $this->requireCsrf($this->csrf, $request)) !== null) {
            return $response;
        }

        $domain = $this->domains->find((int) ($args['id'] ?? 0));
        if ($domain === null) {
            return $this->domainNotFound();
        }

        $id = (int) $domain['id'];
        $name = ShortDomain::displayName((string) $domain['base_url']);

        if ((int) $domain['is_default'] === 1) {
            $this->session->flash(
                'error',
                'Die Standarddomain kann nicht gelöscht werden. Bitte zuerst eine andere Domain als Standard festlegen.',
            );

            return $this->redirect('/admin/domains');
        }

        $linkCount = $this->domains->linkCount($id);
        if ($linkCount > 0) {
            $this->session->flash('error', sprintf(
                'An "%s" hängen noch %d Kurzlink(s). Bitte diese zuerst löschen oder auf eine andere Domain umstellen.',
                $name,
                $linkCount,
            ));

            return $this->redirect('/admin/domains');
        }

        $this->domains->delete($id);
        $this->session->flash('success', sprintf('Domain "%s" wurde gelöscht.', $name));

        return $this->redirect('/admin/domains');
    }

    /**
     * @return array<string,string>
     */
    private function validate(string $baseUrl): array
    {
        $error = ShortDomain::validationError($baseUrl);

        return $error === null ? [] : ['base_url' => $error];
    }

    /**
     * Prueft die gewaehlte Gruppe. Ohne Angabe gilt die Standardgruppe -
     * eine Domain ohne Gruppe waere sonst fuer niemanden ausser
     * Administratoren nutzbar.
     *
     * @param array<string,string> $errors
     */
    private function resolveGroupId(string $value, array &$errors): int
    {
        if ($value === '') {
            return $this->groups->defaultGroupId();
        }

        $group = $this->groups->find((int) $value);

        if ($group === null) {
            $errors['group_id'] = 'Bitte eine gültige Gruppe auswählen.';

            return $this->groups->defaultGroupId();
        }

        return (int) $group['id'];
    }

    /**
     * @return array{base_url:string,label:string,is_default:string,group_id:string}
     */
    private function readValues(Request $request): array
    {
        return [
            'base_url' => $request->post('base_url'),
            'label' => mb_substr($request->post('label'), 0, 255),
            'is_default' => $request->hasPost('is_default') ? '1' : '0',
            'group_id' => $request->post('group_id'),
        ];
    }

    private function domainNotFound(): Response
    {
        return $this->html('errors/error', [
            'title' => 'Domain nicht gefunden',
            'message' => 'Die gewünschte Domain existiert nicht (mehr).',
            'pageTitle' => 'Nicht gefunden',
        ], 404);
    }
}