<?php
namespace Zadex\Library;

defined('ABSPATH') || exit;

use Zadex\Documents\Sanitizer;
use Zadex\Settings;
use Zadex\Widgets\WidgetRegistry;

/**
 * Starter kits (ready-made sections and pages) shown in the editor's template library.
 *
 * Source: the JSON file at the URL stored in `zadex_settings.library_url` (filter `zadex/library/remote_url`),
 * falling back to the bundled `library/kits.json`. Remote responses are cached in a transient for 12 hours.
 *
 * Format: { "version": 1, "kits": [ { slug, title, type: section|page, tags[], thumbnail (inline SVG),
 * elements[], pageSettings? } ] }. `{{library}}` inside the file is replaced with the plugin's library URL
 * (bundled assets such as the Link in bio avatar).
 */
final class Kits
{
    public const TRANSIENT_PREFIX = 'zadex_library_remote_';
    public const CACHE_TTL = 43200; // 12 h
    public const MAX_BYTES = 5242880; // 5 MB

    private WidgetRegistry $widgets;
    private Settings $settings;
    /** @var array<int, array<string, mixed>>|null */
    private ?array $loaded = null;

    public function __construct(WidgetRegistry $widgets, Settings $settings)
    {
        $this->widgets = $widgets;
        $this->settings = $settings;
    }

    public static function bundled_path(): string
    {
        return (defined('ZADEX_PATH') ? ZADEX_PATH : dirname(__DIR__, 2) . '/') . 'library/kits.json';
    }

    public static function library_url(): string
    {
        return (defined('ZADEX_URL') ? ZADEX_URL : '') . 'library';
    }

    /** The configured remote index URL ('' = bundled file). */
    public function remote_url(): string
    {
        $url = (string) $this->settings->get('library_url', '');
        $url = (string) apply_filters('zadex/library/remote_url', $url);
        return $url !== '' && preg_match('#^https?://#i', $url) ? $url : '';
    }

    /** Kit summaries (no element trees) for the library grid. */
    public function index(): array
    {
        $out = [];
        foreach ($this->kits() as $kit) {
            $out[] = [
                'slug'      => $kit['slug'],
                'title'     => $kit['title'],
                'type'      => $kit['type'],
                'tags'      => $kit['tags'],
                'thumbnail' => $kit['thumbnail'],
            ];
        }
        return $out;
    }

    /** One kit with its sanitized element tree, or null. */
    public function get(string $slug): ?array
    {
        foreach ($this->kits() as $kit) {
            if ($kit['slug'] !== $slug) {
                continue;
            }
            $sanitizer = new Sanitizer($this->widgets);
            $kit['elements'] = $sanitizer->sanitize_elements($kit['elements']);
            $kit['pageSettings'] = $kit['pageSettings'] ? $sanitizer->sanitize_settings_generic($kit['pageSettings']) : (object) [];
            return $kit;
        }
        return null;
    }

    /** @return array<int, array<string, mixed>> validated kits */
    public function kits(): array
    {
        if ($this->loaded !== null) {
            return $this->loaded;
        }
        $data = null;
        $url = $this->remote_url();
        if ($url !== '') {
            $data = $this->fetch_remote($url);
        }
        if (!is_array($data)) {
            $data = $this->read_bundled();
        }
        $this->loaded = self::validate($data);
        return $this->loaded;
    }

    public function flush_cache(): void
    {
        $url = $this->remote_url();
        if ($url !== '') {
            delete_transient(self::TRANSIENT_PREFIX . md5($url));
        }
        $this->loaded = null;
    }

    private function read_bundled(): ?array
    {
        $path = self::bundled_path();
        if (!is_file($path) || (int) filesize($path) > self::MAX_BYTES) {
            return null;
        }
        $data = wp_json_file_decode($path, ['associative' => true]);
        return is_array($data) ? self::with_library_url($data) : null;
    }

    /** Replaces the `{{library}}` placeholder in every string of a decoded kit list (like decode() does on raw JSON). */
    public static function with_library_url(array $data): array
    {
        $url = self::library_url();
        array_walk_recursive($data, static function (&$value) use ($url): void {
            if (is_string($value)) {
                $value = str_replace('{{library}}', $url, $value);
            }
        });
        return $data;
    }

    private function fetch_remote(string $url): ?array
    {
        $key = self::TRANSIENT_PREFIX . md5($url);
        $cached = get_transient($key);
        if (is_array($cached)) {
            return $cached;
        }
        $response = wp_remote_get($url, ['timeout' => 8, 'redirection' => 3, 'limit_response_size' => self::MAX_BYTES]);
        if (is_wp_error($response) || (int) wp_remote_retrieve_response_code($response) !== 200) {
            return null;
        }
        $data = self::decode((string) wp_remote_retrieve_body($response));
        if (!is_array($data) || !self::validate($data)) {
            return null;
        }
        set_transient($key, $data, self::CACHE_TTL);
        return $data;
    }

    public static function decode(string $json): ?array
    {
        if ($json === '' || strlen($json) > self::MAX_BYTES) {
            return null;
        }
        $json = str_replace('{{library}}', self::library_url(), $json);
        $data = json_decode($json, true);
        return is_array($data) ? $data : null;
    }

    /**
     * Keeps well-formed kits only. Thumbnails are inline SVG, cleaned through the SVG sanitizer.
     *
     * @return array<int, array<string, mixed>>
     */
    public static function validate(?array $data): array
    {
        $list = is_array($data['kits'] ?? null) ? $data['kits'] : [];
        $out = [];
        $seen = [];
        foreach ($list as $kit) {
            if (!is_array($kit)) {
                continue;
            }
            $slug = isset($kit['slug']) && is_string($kit['slug']) ? $kit['slug'] : '';
            if (!preg_match('/^[a-z0-9][a-z0-9\-]{0,63}$/', $slug) || isset($seen[$slug])) {
                continue;
            }
            if (!is_array($kit['elements'] ?? null) || !$kit['elements']) {
                continue;
            }
            $seen[$slug] = true;
            $thumb = isset($kit['thumbnail']) && is_string($kit['thumbnail']) ? $kit['thumbnail'] : '';
            $out[] = [
                'slug'         => $slug,
                'title'        => isset($kit['title']) && is_string($kit['title']) ? sanitize_text_field($kit['title']) : $slug,
                'type'         => Store::sanitize_type($kit['type'] ?? 'section'),
                'tags'         => Store::sanitize_tags($kit['tags'] ?? []),
                'thumbnail'    => $thumb !== '' ? Sanitizer::clean_svg($thumb) : '',
                'elements'     => array_values($kit['elements']),
                'pageSettings' => is_array($kit['pageSettings'] ?? null) ? $kit['pageSettings'] : [],
            ];
        }
        return $out;
    }
}