<?php
declare(strict_types=1);

namespace NeonBlog;

use Throwable;

final class App
{
    private Config $config;
    private ContentRepository $repository;
    private CommentService $comments;
    private Stats $stats;

    public function __construct(Config $config, ContentRepository $repository, CommentService $comments, Stats $stats)
    {
        $this->config = $config;
        $this->repository = $repository;
        $this->comments = $comments;
        $this->stats = $stats;
        View::setBasePath($this->config->basePath());
    }

    public function handle(): void
    {
        try {
            $path = $this->path();
            if (($_SERVER['REQUEST_METHOD'] ?? 'GET') === 'POST' && preg_match('#^comment/([a-z0-9-]+)$#', $path, $matches)) {
                $this->handleComment($matches[1]);
                return;
            }

            if (($_SERVER['REQUEST_METHOD'] ?? 'GET') !== 'GET') {
                $this->render('error', ['title' => 'Method not allowed', 'message' => 'This route only accepts GET requests.'], 405, 'error');
                return;
            }

            $this->route($path);
        } catch (Throwable $error) {
            $this->render('error', [
                'title' => 'Server error',
                'message' => 'Something went wrong while rendering this page.',
                'debug' => $error->getMessage(),
            ], 500, 'error');
        }
    }

    public function repository(): ContentRepository
    {
        return $this->repository;
    }

    public function comments(): CommentService
    {
        return $this->comments;
    }

    public function stats(): Stats
    {
        return $this->stats;
    }

    public function config(): Config
    {
        return $this->config;
    }

    private function route(string $path): void
    {
        if ($this->servePublicFile($path)) {
            return;
        }

        if ($path === '' || $path === 'home') {
            $this->home(1);
            return;
        }
        if (preg_match('#^page/(\d+)$#', $path, $matches)) {
            $this->home((int) $matches[1]);
            return;
        }
        if ($path === 'search') {
            $this->search();
            return;
        }
        if ($path === 'feed.xml') {
            $this->feed();
            return;
        }
        if ($path === 'sitemap.xml') {
            $this->sitemap();
            return;
        }
        if (preg_match('#^post/([a-z0-9-]+)$#', $path, $matches)) {
            $this->single($matches[1], 'post');
            return;
        }
        if (preg_match('#^category/([a-z0-9-]+)(?:/page/(\d+))?$#', $path, $matches)) {
            $this->taxonomy('category', $matches[1], isset($matches[2]) ? (int) $matches[2] : 1);
            return;
        }
        if (preg_match('#^tag/([a-z0-9-]+)(?:/page/(\d+))?$#', $path, $matches)) {
            $this->taxonomy('tag', $matches[1], isset($matches[2]) ? (int) $matches[2] : 1);
            return;
        }
        if (preg_match('#^archive/(\d{4})(?:/(\d{2}))?(?:/page/(\d+))?$#', $path, $matches)) {
            $this->archive((int) $matches[1], isset($matches[2]) ? (int) $matches[2] : null, isset($matches[3]) ? (int) $matches[3] : 1);
            return;
        }

        $item = $this->repository->find($path);
        if ($item !== null) {
            $this->single($path, (string) $item['type']);
            return;
        }

        $this->render('error', ['title' => 'Not found', 'message' => 'That page does not exist.'], 404, 'not_found');
    }

    private function home(int $page): void
    {
        $perPage = (int) $this->config->get('posts_per_page', 6);
        $result = $this->repository->paginate($this->repository->posts(false), $page, $perPage);
        $this->render('listing', [
            'title' => (string) $this->config->get('site.title'),
            'heading' => (string) $this->config->get('site.tagline'),
            'items' => $result['items'],
            'pagination' => $result['pagination'],
            'pagination_url' => static fn (int $target): string => $target === 1 ? View::url('') : View::url('page/' . $target),
        ], 200, 'home');
    }

    private function search(): void
    {
        $query = trim((string) ($_GET['q'] ?? ''));
        $page = max(1, (int) ($_GET['page'] ?? 1));
        $perPage = (int) $this->config->get('posts_per_page', 6);
        $result = $this->repository->search($query, $page, $perPage);
        $this->render('listing', [
            'title' => $query === '' ? 'Search' : 'Search: ' . $query,
            'heading' => $query === '' ? 'Search the archive' : 'Search results for "' . $query . '"',
            'items' => $result['items'],
            'pagination' => $result['pagination'],
            'search_query' => $query,
            'empty_message' => $query === '' ? 'Enter a word or phrase to search posts and pages.' : 'No matching posts were found.',
            'pagination_url' => static fn (int $target): string => View::url('search', ['q' => $query, 'page' => $target]),
        ], 200, 'search');
    }

    private function taxonomy(string $type, string $slug, int $page): void
    {
        $items = $type === 'category' ? $this->repository->byCategory($slug) : $this->repository->byTag($slug);
        $label = $this->termLabel($items, $type, $slug);
        $perPage = (int) $this->config->get('posts_per_page', 6);
        $result = $this->repository->paginate($items, $page, $perPage);

        $this->render('listing', [
            'title' => ucfirst($type) . ': ' . $label,
            'heading' => ucfirst($type) . ': ' . $label,
            'items' => $result['items'],
            'pagination' => $result['pagination'],
            'empty_message' => 'No posts live here yet.',
            'pagination_url' => static fn (int $target): string => $target === 1
                ? View::url($type . '/' . $slug)
                : View::url($type . '/' . $slug . '/page/' . $target),
        ], 200, $type);
    }

    private function archive(int $year, ?int $month, int $page): void
    {
        $items = $this->repository->byArchive($year, $month);
        $perPage = (int) $this->config->get('posts_per_page', 6);
        $result = $this->repository->paginate($items, $page, $perPage);
        $label = $month === null ? (string) $year : date('F Y', strtotime(sprintf('%04d-%02d-01', $year, $month)));
        $base = $month === null ? 'archive/' . $year : sprintf('archive/%04d/%02d', $year, $month);

        $this->render('listing', [
            'title' => 'Archive: ' . $label,
            'heading' => 'Archive: ' . $label,
            'items' => $result['items'],
            'pagination' => $result['pagination'],
            'empty_message' => 'No posts were published in this window.',
            'pagination_url' => static fn (int $target): string => $target === 1 ? View::url($base) : View::url($base . '/page/' . $target),
        ], 200, 'archive');
    }

    private function single(string $slug, string $type): void
    {
        $item = $this->repository->find($slug);
        if ($item === null || $item['type'] !== $type) {
            $this->render('error', ['title' => 'Not found', 'message' => 'That content is not published.'], 404, 'not_found');
            return;
        }

        $approved = $this->comments->approvedFor((string) $item['slug']);
        $captcha = $this->config->get('comments.captcha', true) ? Captcha::challenge() : ['token' => '', 'question' => ''];
        $this->render('single', [
            'title' => $item['title'],
            'item' => $item,
            'approved_comments' => $approved,
            'captcha' => $captcha,
        ], 200, (string) $item['type'], (string) $item['slug']);
    }

    private function feed(): void
    {
        $base = $this->config->baseUrl();
        $items = array_slice($this->repository->posts(false), 0, 20);
        $xml = [
            '<?xml version="1.0" encoding="UTF-8"?>',
            '<rss version="2.0">',
            '<channel>',
            '<title>' . $this->xml((string) $this->config->get('site.title')) . '</title>',
            '<link>' . $this->xml($base . View::url('')) . '</link>',
            '<description>' . $this->xml((string) $this->config->get('site.description')) . '</description>',
        ];
        foreach ($items as $item) {
            $xml[] = '<item>';
            $xml[] = '<title>' . $this->xml((string) $item['title']) . '</title>';
            $xml[] = '<link>' . $this->xml($base . View::itemUrl($item)) . '</link>';
            $xml[] = '<guid>' . $this->xml($base . View::itemUrl($item)) . '</guid>';
            $xml[] = '<pubDate>' . gmdate(DATE_RSS, strtotime((string) $item['date']) ?: time()) . '</pubDate>';
            $xml[] = '<description>' . $this->xml((string) $item['summary']) . '</description>';
            $xml[] = '</item>';
        }
        $xml[] = '</channel>';
        $xml[] = '</rss>';

        $this->respond(implode("\n", $xml), 'application/rss+xml; charset=utf-8', 200, 'feed');
    }

    private function sitemap(): void
    {
        $base = $this->config->baseUrl();
        $xml = [
            '<?xml version="1.0" encoding="UTF-8"?>',
            '<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">',
            '<url><loc>' . $this->xml($base . View::url('')) . '</loc></url>',
        ];
        foreach ($this->repository->all(false) as $item) {
            $xml[] = '<url>';
            $xml[] = '<loc>' . $this->xml($base . View::itemUrl($item)) . '</loc>';
            $xml[] = '<lastmod>' . $this->xml(date('Y-m-d', strtotime((string) $item['modified']) ?: time())) . '</lastmod>';
            $xml[] = '</url>';
        }
        $xml[] = '</urlset>';

        $this->respond(implode("\n", $xml), 'application/xml; charset=utf-8', 200, 'sitemap');
    }

    private function handleComment(string $slug): void
    {
        $item = $this->repository->find($slug);
        if ($item === null || !$item['allow_comments'] || !$this->config->get('comments.enabled', true)) {
            $this->flash('error', 'Comments are closed for that post.');
            $this->redirect(View::url(''));
            return;
        }

        if ($this->config->get('comments.captcha', true)) {
            $valid = Captcha::verify((string) ($_POST['captcha_token'] ?? ''), (string) ($_POST['captcha_answer'] ?? ''));
            if (!$valid) {
                $this->flash('error', 'The captcha answer was not correct.');
                $this->redirect(View::itemUrl($item) . '#comments');
                return;
            }
        }

        $result = $this->comments->add((string) $item['slug'], $_POST);
        $this->flash($result['ok'] ? 'success' : 'error', $result['message']);
        $this->redirect(View::itemUrl($item) . '#comments');
    }

    /** @param array<string, mixed> $data */
    private function render(string $template, array $data, int $statusCode, string $routeType, string $slug = ''): void
    {
        http_response_code($statusCode);
        header('Content-Type: text/html; charset=utf-8');

        $theme = preg_replace('/[^a-z0-9_-]/', '', (string) $this->config->get('theme', 'neon')) ?: 'neon';
        $layout = BLOG_ROOT . '/themes/' . $theme . '/layout.php';
        $config = $this->config;
        $repository = $this->repository;
        $facets = $this->repository->facets();
        $navPages = $this->repository->pages(false);
        usort($navPages, static fn (array $a, array $b): int => ((int) $a['menu_order']) <=> ((int) $b['menu_order']));
        $flash = $this->consumeFlash();

        extract($data, EXTR_SKIP);
        ob_start();
        require $layout;
        $body = (string) ob_get_clean();
        $this->stats->record($routeType, $slug, $statusCode);
        echo $body;
    }

    private function respond(string $body, string $contentType, int $statusCode, string $routeType): void
    {
        http_response_code($statusCode);
        header('Content-Type: ' . $contentType);
        $this->stats->record($routeType, '', $statusCode);
        echo $body;
    }

    private function servePublicFile(string $path): bool
    {
        if (!preg_match('#^(themes/[a-z0-9_-]+/assets/.+|bl-content/uploads/.+)$#', $path)) {
            return false;
        }

        $file = realpath(BLOG_ROOT . '/' . $path);
        $allowedRoots = [
            realpath(BLOG_ROOT . '/themes'),
            realpath(BLOG_ROOT . '/bl-content/uploads'),
        ];
        $insideAllowedRoot = false;
        foreach ($allowedRoots as $root) {
            if (is_string($root) && is_string($file) && str_starts_with($file, $root . DIRECTORY_SEPARATOR)) {
                $insideAllowedRoot = true;
                break;
            }
        }
        if (!$insideAllowedRoot || !is_file((string) $file)) {
            return false;
        }

        $extension = strtolower(pathinfo((string) $file, PATHINFO_EXTENSION));
        $types = [
            'css' => 'text/css; charset=utf-8',
            'js' => 'application/javascript; charset=utf-8',
            'svg' => 'image/svg+xml',
            'png' => 'image/png',
            'jpg' => 'image/jpeg',
            'jpeg' => 'image/jpeg',
            'gif' => 'image/gif',
            'webp' => 'image/webp',
            'avif' => 'image/avif',
            'ico' => 'image/x-icon',
            'woff' => 'font/woff',
            'woff2' => 'font/woff2',
        ];

        http_response_code(200);
        header('Content-Type: ' . ($types[$extension] ?? 'application/octet-stream'));
        header('Content-Length: ' . filesize((string) $file));
        header('Cache-Control: public, max-age=3600');
        $this->stats->record('asset', $path, 200);
        readfile((string) $file);

        return true;
    }

    private function path(): string
    {
        $route = (string) ($_GET['route'] ?? '');
        if ($route === '') {
            $route = (string) parse_url((string) ($_SERVER['REQUEST_URI'] ?? '/'), PHP_URL_PATH);
        }

        $scriptDir = str_replace('\\', '/', dirname((string) ($_SERVER['SCRIPT_NAME'] ?? '')));
        $route = '/' . ltrim($route, '/');
        $basePath = $this->config->basePath();
        if ($basePath !== '' && ($route === $basePath || str_starts_with($route, $basePath . '/'))) {
            $route = substr($route, strlen($basePath));
        } elseif ($scriptDir !== '/' && str_starts_with($route, $scriptDir . '/')) {
            $route = substr($route, strlen($scriptDir));
        }

        return trim($route, '/');
    }

    private function termLabel(array $items, string $type, string $slug): string
    {
        foreach ($items as $item) {
            if ($type === 'category') {
                return (string) $item['category'];
            }
            foreach ($item['tags'] as $tag) {
                if (ContentRepository::slugify((string) $tag) === $slug) {
                    return (string) $tag;
                }
            }
        }

        return ucwords(str_replace('-', ' ', $slug));
    }

    private function flash(string $type, string $message): void
    {
        if (session_status() === PHP_SESSION_ACTIVE) {
            $_SESSION['flash'] = ['type' => $type, 'message' => $message];
        }
    }

    /** @return array{type: string, message: string}|null */
    private function consumeFlash(): ?array
    {
        if (session_status() !== PHP_SESSION_ACTIVE || !isset($_SESSION['flash'])) {
            return null;
        }
        $flash = $_SESSION['flash'];
        unset($_SESSION['flash']);

        return is_array($flash) ? $flash : null;
    }

    private function redirect(string $url): void
    {
        header('Location: ' . $url, true, 303);
    }

    private function xml(string $value): string
    {
        return htmlspecialchars($value, ENT_XML1 | ENT_COMPAT, 'UTF-8');
    }
}