<?php

namespace App\Controller;

use App\Content\Consent;
use App\Content\CustomCode;
use App\Content\FormRepository;
use App\Content\MenuRepository;
use App\Content\PageRepository;
use App\Content\PartialRepository;
use App\Content\PostRepository;
use App\Content\RedirectRepository;
use App\Content\SiteSettings;
use App\Content\StyleCompiler;
use App\Content\Theme;
use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Routing\Attribute\Route;

final class PageController extends AbstractController
{
    public function __construct(private PageRepository $pages, private MenuRepository $menus, private PostRepository $posts, private FormRepository $forms, private RedirectRepository $redirects, private SiteSettings $settings, private PartialRepository $partials, private CustomCode $code, private Consent $consent, private Theme $theme, private StyleCompiler $styles, private string $secret, private string $siteOrigin)
    {
    }

    // A segment is a slug; up to four of them form the public path. The leading lookahead keeps
    // the CMS routes (/admin, /media, /assets) out of the catch-all, which matches before them.
    private const PATH = '(?!admin(?:/|$)|media/|assets/|kategorie/|schlagwort/|beitraege(?:/|$)|einwilligung$|feed\.xml$|sitemap\.xml$|robots\.txt$|llms\.txt$)[a-z0-9]+(?:-[a-z0-9]+)*(?:/[a-z0-9]+(?:-[a-z0-9]+)*){0,3}';

    #[Route('/', name: 'home', methods: ['GET'])]
    #[Route('/{path}', name: 'page', requirements: ['path' => self::PATH], methods: ['GET'])]
    public function page(Request $request, string $path = ''): Response
    {
        $home = $this->settings->homePath();
        $path = '' === $path ? $home : $path;
        // One canonical address for the root page: its own path redirects to "/".
        if ($path === $home && '/' !== $request->getPathInfo()) {
            return $this->redirectToRoute('home', status: 301);
        }
        $page = $this->pages->findPublished($path);
        $styles = '';
        $googleFonts = null;
        // The page decides which header and footer it gets - including none.
        $areas = $this->areas($page);
        if (null !== $page) {
            $theme = $this->theme->load();
            // Theme first, block styles after, so a block always wins over the site defaults.
            $sections = $this->sections($page['document'], $areas);
            $styles = $this->theme->css($theme).$this->styles->compileDocument($page['document']).$this->code->compileDocument($page['document']);
            foreach ([...array_values($areas), ...array_values($sections)] as $extra) {
                $styles .= $this->styles->compileDocument($extra).$this->code->compileDocument($extra);
            }
            $googleFonts = $this->theme->googleFontsUrl($theme);
        }
        if (null === $page) {
            // An address that moved or was deliberately removed answers before the 404 does.
            $redirect = $this->redirects->find($path);
            if (null !== $redirect && 301 === $redirect['status']) {
                return $this->shell($this->redirect('/'.$redirect['to'], 301));
            }
            $response = $this->render('not-found.html.twig', ['areas' => $areas], new Response(status: null !== $redirect ? 410 : 404));
        } else {
            $response = $this->render('page.html.twig', [
                'page' => $page,
                'canonical' => rtrim($this->siteOrigin, '/').$this->settings->publicPath($path, $home),
                'navigation' => $this->navigation($path),
                'postLists' => $this->postLists($page['document']),
                'postMeta' => 'post' === $page['type'] ? $this->posts->termsFor($page['id']) : null,
                'needsTabs' => $this->hasType($page['document'], 'tabs'),
                // Own scripts arrive as one file per page, never inline, so the policy can stay
                // hash based and no page without a script loses its strict setting.
                'pageScript' => [] === $this->code->scriptsOf($page['document']) ? null : '/assets/seite/'.$page['id'].'.js',
                'forms' => $this->formStates($page, $request->query->getString('gesendet')),
                'breadcrumbs' => $this->breadcrumbs($page),
                'structuredData' => $this->structuredData($page),
                'areas' => $areas,
                'sections' => $sections,
                'pageStyles' => $styles,
                'googleFonts' => $googleFonts,
            ]);
        }

        $wantsScript = null !== $page && ($this->hasType($page['document'], 'tabs') || [] !== $this->code->scriptsOf($page['document']));
        $frames = null === $page ? [] : $this->frameHosts($request, $page['document'], ...array_values($areas), ...array_values($sections));

        return $this->shell($response, $wantsScript, $styles, null !== $googleFonts, $frames);
    }

    /**
     * Every public response carries the same headers. Scripting stays forbidden unless the page
     * actually contains a tab group: only then may the browser load the one enhancement script,
     * and only from this origin. Inline script is never allowed.
     *
     * The generated stylesheet is inline for speed, so it is allowed by its own hash rather than
     * by 'unsafe-inline' – any other inline style, injected or not, stays blocked.
     */
    /**
     * @param list<string> $frameHosts Hosts of embeds that are actually rendered on this response.
     *                                 Nothing is added to the policy for an embed still waiting
     *                                 for consent.
     */
    private function shell(Response $response, bool $allowScript = false, string $styles = '', bool $googleFonts = false, array $frameHosts = []): Response
    {
        $styleSources = ["'self'"];
        if ('' !== $styles) {
            $styleSources[] = sprintf("'sha256-%s'", base64_encode(hash('sha256', $styles, true)));
        }
        $fontSources = ["'self'"];
        if ($googleFonts) {
            // Chosen deliberately: the stylesheet comes from Google and the files from its CDN.
            $styleSources[] = 'https://fonts.googleapis.com';
            $fontSources[] = 'https://fonts.gstatic.com';
        }
        $response->headers->set('Cache-Control', 'no-store');
        $response->headers->set('X-Content-Type-Options', 'nosniff');
        $response->headers->set('Referrer-Policy', 'strict-origin-when-cross-origin');
        $response->headers->set('Content-Security-Policy', sprintf(
            "default-src 'self'; script-src %s; style-src %s; font-src %s; img-src 'self' https: data:; frame-src %s; object-src 'none'; base-uri 'none'; frame-ancestors 'none'; form-action 'self'",
            $allowScript ? "'self'" : "'none'",
            implode(' ', $styleSources),
            implode(' ', $fontSources),
            [] === $frameHosts ? "'none'" : implode(' ', array_map(static fn (string $host): string => 'https://'.$host, $frameHosts)),
        ));

        return $response;
    }

    /**
     * Prepares one state per form block: the definition, whether this request just sent it, and a
     * signed timestamp the submission route uses to tell a person from a script.
     *
     * @return array<string, array>
     */
    private function formStates(array $page, string $sentSlug): array
    {
        $issued = time();
        $states = [];
        $walk = function (array $blocks) use (&$walk, &$states, $page, $sentSlug, $issued): void {
            foreach ($blocks as $block) {
                if ('form' === ($block['type'] ?? null)) {
                    $slug = $block['props']['form'] ?? '';
                    $states[$block['id']] = [
                        'form' => $this->forms->findBySlug($slug),
                        'sent' => '' !== $sentSlug && $sentSlug === $slug,
                        'errors' => [], 'values' => [],
                        'blockId' => $block['id'], 'page' => $page,
                        'issued' => $issued,
                        'issuedSignature' => hash_hmac('sha256', (string) $issued, $this->secret),
                    ];
                }
                $walk($block['children'] ?? []);
            }
        };
        $walk($page['document']['blocks'] ?? []);

        return $states;
    }

    /**
     * The trail from the home page down to this one, resolved from the stored hierarchy rather
     * than from content, so it cannot claim a page that does not exist.
     *
     * @return list<array{name: string, href: string}>
     */
    private function breadcrumbs(array $page): array
    {
        if ($page['path'] === $this->settings->homePath()) {
            return [];
        }
        $trail = [];
        $prefix = '';
        foreach (explode('/', (string) $page['path']) as $segment) {
            $prefix = '' === $prefix ? $segment : $prefix.'/'.$segment;
            $ancestor = $this->pages->findPublished($prefix);
            if (null !== $ancestor) {
                $trail[] = ['name' => $ancestor['document']['title'] ?? $prefix, 'href' => '/'.$prefix];
            }
        }

        return $trail;
    }

    /**
     * JSON-LD built from values that are visible on the page or maintained in the settings.
     * Nothing is invented here; a field without a maintained value is left out.
     *
     * @return list<array>
     */
    private function structuredData(array $page): array
    {
        $origin = rtrim($this->siteOrigin, '/');
        $blocks = [];
        if ($page['path'] === $this->settings->homePath()) {
            $organisation = $this->settings->organisation($this->settings->load(), $origin, (string) $page['website_name']);
            if (null !== $organisation) {
                $blocks[] = $organisation;
            }
        }
        if ('post' === $page['type']) {
            $article = [
                '@context' => 'https://schema.org',
                '@type' => 'Article',
                'headline' => mb_substr((string) ($page['document']['title'] ?? ''), 0, 110),
                'mainEntityOfPage' => $origin.'/'.$page['path'],
            ];
            foreach ([['description', $page['excerpt'] ?? $page['document']['description'] ?? ''], ['datePublished', $page['published_at'] ?? '']] as [$key, $value]) {
                if ('' !== (string) $value && null !== $value) {
                    $article[$key] = 'datePublished' === $key ? str_replace(' ', 'T', (string) $value).'Z' : (string) $value;
                }
            }
            if (null !== ($page['author'] ?? null) && '' !== $page['author']) {
                $article['author'] = ['@type' => 'Person', 'name' => $page['author']];
            }
            $blocks[] = $article;
        }
        $trail = $this->breadcrumbs($page);
        if (count($trail) > 1) {
            $blocks[] = [
                '@context' => 'https://schema.org',
                '@type' => 'BreadcrumbList',
                'itemListElement' => array_map(
                    static fn (int $index, array $item): array => ['@type' => 'ListItem', 'position' => $index + 1, 'name' => $item['name'], 'item' => $origin.$item['href']],
                    array_keys($trail),
                    $trail,
                ),
            ];
        }

        return $blocks;
    }

    /** True when the stored document contains at least one block of that type. */
    private function hasType(array $document, string $type): bool
    {
        $found = false;
        $walk = function (array $blocks) use (&$walk, &$found, $type): void {
            foreach ($blocks as $block) {
                $found = $found || $type === ($block['type'] ?? null);
                $walk($block['children'] ?? []);
            }
        };
        $walk($document['blocks'] ?? []);

        return $found;
    }

    #[Route('/beitraege', name: 'posts', methods: ['GET'])]
    #[Route('/kategorie/{slug}', name: 'category', requirements: ['slug' => '[a-z0-9-]{1,80}'], methods: ['GET'])]
    #[Route('/schlagwort/{slug}', name: 'tag', requirements: ['slug' => '[a-z0-9-]{1,80}'], methods: ['GET'])]
    public function archive(Request $request, ?string $slug = null): Response
    {
        $kind = 'category' === $request->attributes->get('_route') ? 'category' : 'tag';
        $term = null;
        if (null !== $slug) {
            $term = $this->posts->findTerm($kind, $slug);
            if (null === $term) {
                return $this->shell($this->render('not-found.html.twig', ['navigation' => $this->navigation('')], new Response(status: 404)));
            }
        }
        $page = max(1, $request->query->getInt('seite', 1));
        $result = $this->posts->published($page, $term['id'] ?? null);
        $base = null === $term ? '/beitraege' : '/'.PostRepository::ARCHIVE_PREFIX[$kind].'/'.$term['slug'];

        $frames = $this->frameHosts($request, ...array_values($this->areas()));

        return $this->shell($this->render('archive.html.twig', [
            'areas' => $this->areas(),
            'navigation' => $this->navigation(''),
            'term' => $term,
            'heading' => null === $term ? 'Beiträge' : $term['name'],
            'result' => $result,
            'base' => $base,
            'canonical' => rtrim($this->siteOrigin, '/').$base.($result['page'] > 1 ? '?seite='.$result['page'] : ''),
            'navigation' => $this->navigation(''),
        ]), frameHosts: $frames);
    }

    #[Route('/feed.xml', name: 'feed', methods: ['GET'])]
    public function feed(): Response
    {
        $result = $this->posts->published(1, null, 20);
        $response = $this->shell($this->render('feed.xml.twig', [
            'posts' => $result['posts'],
            'origin' => rtrim($this->siteOrigin, '/'),
        ]));
        $response->headers->set('Content-Type', 'application/xml; charset=UTF-8');

        return $response;
    }

    /**
     * Collects the posts each post list block needs. Stored content never carries the posts
     * themselves, so a saved document cannot claim a post it is not allowed to show.
     *
     * @return array<string, list<array>>
     */
    private function postLists(array $document): array
    {
        $lists = [];
        $walk = function (array $blocks) use (&$walk, &$lists): void {
            foreach ($blocks as $block) {
                if ('postlist' === ($block['type'] ?? null)) {
                    $props = $block['props'] ?? [];
                    $term = null;
                    foreach (['category', 'tag'] as $kind) {
                        if ('' !== ($props[$kind] ?? '')) {
                            $term = $this->posts->findTerm($kind, $props[$kind]);
                        }
                    }
                    $lists[$block['id']] = $this->posts->published(1, $term['id'] ?? null, $props['count'])['posts'];
                }
                $walk($block['children'] ?? []);
            }
        };
        $walk($document['blocks'] ?? []);

        return $lists;
    }

    /**
     * The own scripts of one published page, as a single file.
     *
     * A file instead of inline markup, so the policy stays hash based and every page without a
     * script keeps `script-src 'none'`. Only published content is served: a draft script must not
     * run for a visitor.
     */
    #[Route('/assets/seite/{id}.js', name: 'page_script', requirements: ['id' => '[a-zA-Z0-9_-]{1,64}'], methods: ['GET'])]
    public function pageScript(string $id): Response
    {
        $row = $this->pages->findPublishedById($id);
        $script = null === $row ? '' : $this->code->compileScript($row['document']);
        if ('' === $script) {
            throw $this->createNotFoundException('Diese Seite hat kein eigenes Skript.');
        }
        $response = new Response($script, 200, ['Content-Type' => 'text/javascript; charset=UTF-8']);
        $response->headers->set('X-Content-Type-Options', 'nosniff');
        $response->headers->set('Cache-Control', 'no-store');

        return $response;
    }

    /**
     * The hosts of embeds that may load on this request.
     *
     * An embed whose group is not granted contributes nothing: its host must not appear in the
     * policy, because the frame is not rendered either.
     *
     * @return list<string>
     */
    private function frameHosts(Request $request, array ...$documents): array
    {
        $hosts = [];
        $walk = function (array $blocks) use (&$walk, &$hosts, $request): void {
            foreach ($blocks as $block) {
                if ('embed' === ($block['type'] ?? null) && $this->consent->granted($request, $block['props']['group'] ?? '')) {
                    $host = parse_url($block['props']['url'] ?? '', PHP_URL_HOST);
                    if (is_string($host)) {
                        $hosts[$host] = true;
                    }
                }
                $walk($block['children'] ?? []);
            }
        };
        foreach ($documents as $document) {
            $walk($document['blocks'] ?? []);
        }

        return array_keys($hosts);
    }

    /**
     * The header and footer documents. Absent areas simply render nothing, so a site without a
     * header is a valid site rather than a broken one.
     *
     * @return array<string, array>
     */
    private function areas(?array $page = null): array
    {
        $areas = [];
        foreach (['header', 'footer'] as $kind) {
            // A page may ask for another area or for none at all: a landing page without a
            // navigation is a normal wish, and it must not need a second header document that
            // happens to be empty.
            $choice = $page[$kind.'_area'] ?? null;
            if ('none' === $choice) {
                continue;
            }
            $partial = $this->partials->findByKind($kind, is_string($choice) && '' !== $choice ? $choice : 'default');
            // A page pointing at an area that no longer exists falls back to the standard one
            // rather than losing its header without saying so.
            $partial ??= $this->partials->findByKind($kind);
            if (null !== $partial) {
                $areas[$kind] = $partial['document'];
            }
        }

        return $areas;
    }

    /**
     * Resolves every linked section a page or one of its areas refers to, including sections that
     * link further sections. A missing section is left out; the renderer shows a placeholder only
     * in the editor, so a visitor never sees a gap explained.
     *
     * @return array<string, array>
     */
    private function sections(array $document, array $areas): array
    {
        $resolved = [];
        $pending = $this->partials->referencedSlugs($document);
        foreach ($areas as $area) {
            $pending = [...$pending, ...$this->partials->referencedSlugs($area)];
        }
        for ($depth = 0; $depth < PartialRepository::MAX_NESTING && [] !== $pending; ++$depth) {
            $next = [];
            foreach (array_unique($pending) as $slug) {
                if (isset($resolved[$slug])) {
                    continue;
                }
                $section = $this->partials->resolveSection($slug);
                if (null === $section) {
                    continue;
                }
                $resolved[$slug] = $section['document'];
                $next = [...$next, ...$this->partials->referencedSlugs($section['document'])];
            }
            $pending = $next;
        }

        return $resolved;
    }

    /**
     * @return array<string, list<array>>
     */
    private function navigation(string $currentPath): array
    {
        $links = [];
        foreach ($this->menus->all() as $slot => $menu) {
            $links[$slot] = $this->menus->resolve($menu['items'], $currentPath);
        }

        return $links;
    }
}