<?php
namespace Zadex;

defined('ABSPATH') || exit;

/**
 * Resolves built assets from build/manifest.json (production) or the Vite dev server (development).
 *
 * Development mode is enabled by defining ZADEX_DEV = true in wp-config.php or by creating an empty
 * `.vite-dev` file in the plugin root while `npm run dev` is running.
 */
final class Assets
{
    public const ENTRY_EDITOR = 'src/editor/main.ts';
    public const ENTRY_FRONTEND = 'src/frontend/main.ts';
    /** Font Awesome 6 Free (solid/regular/brands). Loaded only when a rendered widget declares `"assets": ["icons"]`. */
    public const ENTRY_ICONS = 'src/frontend/icons.ts';
    /** Site-wide floating buttons (structural CSS + scroll-to-top). Loaded only when a button is printed. */
    public const ENTRY_FLOATING = 'src/frontend/floating.ts';
    /** Popups (structural CSS + triggers / rules / actions runtime). Loaded only when a popup is printed. */
    public const ENTRY_POPUP = 'src/frontend/popup.ts';
    /** Scrolling / mouse effects + sticky runtime (T160-T162). Loaded only when a rendered element uses them. */
    public const ENTRY_MOTION = 'src/frontend/motion.ts';
    /** Page transitions + preloader runtime (T163). Loaded only when enabled in the site settings. */
    public const ENTRY_TRANSITIONS = 'src/frontend/transitions.ts';

    private ?array $manifest = null;
    private string $dev_server;

    public function __construct(?string $manifest_path = null, string $dev_server = 'http://localhost:5173')
    {
        $this->manifest_path = $manifest_path ?? (defined('ZADEX_BUILD_PATH') ? ZADEX_BUILD_PATH . 'manifest.json' : '');
        $this->dev_server = defined('ZADEX_DEV_SERVER') ? ZADEX_DEV_SERVER : $dev_server;
    }

    private string $manifest_path;

    public function is_dev(): bool
    {
        if (defined('ZADEX_DEV')) {
            return (bool) ZADEX_DEV;
        }
        return defined('ZADEX_PATH') && file_exists(ZADEX_PATH . '.vite-dev');
    }

    private ?bool $dev_reachable = null;

    /**
     * Whether the Vite dev server accepts connections (cached per request, 500 ms timeout). A stale
     * `.vite-dev` marker or a forgotten ZADEX_DEV constant must never leave the editor blank.
     */
    public function dev_server_reachable(): bool
    {
        if ($this->dev_reachable !== null) {
            return $this->dev_reachable;
        }
        $parts = wp_parse_url($this->dev_server);
        $host = isset($parts['host']) ? (string) $parts['host'] : 'localhost';
        $port = isset($parts['port']) ? (int) $parts['port'] : (($parts['scheme'] ?? 'http') === 'https' ? 443 : 80);
        $socket = @stream_socket_client('tcp://' . $host . ':' . $port, $errno, $errstr, 0.5);
        $this->dev_reachable = is_resource($socket);
        if (is_resource($socket)) {
            fclose($socket); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_fclose -- closes the TCP probe socket, not a file.
        }
        return $this->dev_reachable;
    }

    /**
     * Dev mode is only used when Vite answers; otherwise the production build (when present) is served so
     * the editor keeps working. With neither, print_entry() explains what to do instead of a blank page.
     */
    public function uses_dev_server(): bool
    {
        return $this->is_dev() && ($this->dev_server_reachable() || !$this->has_build());
    }

    /** Explanation printed by print_entry() when dev mode is on but nothing can be loaded ('' otherwise). */
    public function dev_problem(): string
    {
        if (!$this->is_dev() || $this->dev_server_reachable() || $this->has_build()) {
            return '';
        }
        return sprintf(
            /* translators: %s: dev server URL */
            __('Zadex is in development mode (ZADEX_DEV or the .vite-dev marker file) but the Vite dev server at %s is not running and there is no production build. Run "npm run dev" or "npm run build", or remove the marker.', 'zadex'),
            $this->dev_server
        );
    }

    public function manifest(): array
    {
        if ($this->manifest === null) {
            $this->manifest = [];
            if ($this->manifest_path && is_readable($this->manifest_path)) {
                $decoded = wp_json_file_decode($this->manifest_path, ['associative' => true]);
                if (is_array($decoded)) {
                    $this->manifest = $decoded;
                }
            }
        }
        return $this->manifest;
    }

    public function has_build(): bool
    {
        return !empty($this->manifest()[self::ENTRY_EDITOR]['file']);
    }

    /**
     * Returns ['js' => [urls], 'css' => [urls]] for an entry, following imported chunks.
     */
    public function entry(string $entry): array
    {
        if ($this->uses_dev_server()) {
            return [
                'js'  => [$this->dev_server . '/@vite/client', $this->dev_server . '/' . $entry],
                'css' => [],
            ];
        }
        $manifest = $this->manifest();
        $js = [];
        $css = [];
        $seen = [];
        $walk = function (string $key) use (&$walk, &$js, &$css, &$seen, $manifest): void {
            if (isset($seen[$key]) || empty($manifest[$key])) {
                return;
            }
            $seen[$key] = true;
            $chunk = $manifest[$key];
            foreach ($chunk['imports'] ?? [] as $import) {
                $walk($import);
            }
            foreach ($chunk['css'] ?? [] as $file) {
                $css[] = ZADEX_BUILD_URL . $file;
            }
            // Only entries are loaded as scripts; shared chunks are pulled in through ES imports.
            if (!empty($chunk['file']) && !empty($chunk['isEntry'])) {
                $js[] = ZADEX_BUILD_URL . $chunk['file'];
            }
        };
        $walk($entry);
        return ['js' => array_values(array_unique($js)), 'css' => array_values(array_unique($css))];
    }

    /** Prints the stylesheets + module scripts of an entry through the WP APIs (used by the editor shell). */
    public function print_entry(string $entry): void
    {
        $problem = $this->dev_problem();
        if ($problem !== '') {
            // Nothing can be loaded: replace the (empty) editor root with the explanation once the body exists.
            $html = '<div class="zadex-dev-error" role="alert" style="max-width:640px;margin:15vh auto;padding:24px;font:15px/1.5 system-ui,sans-serif;border:1px solid #f59e0b;border-radius:8px;background:#fffbeb;color:#78350f">' . esc_html($problem) . '</div>';
            wp_register_script('zadex-dev-error', false, [], ZADEX_VERSION, false);
            wp_add_inline_script('zadex-dev-error', 'document.addEventListener("DOMContentLoaded",function(){var r=document.getElementById("zadex-editor");if(r){r.innerHTML=' . wp_json_encode($html, JSON_HEX_TAG | JSON_HEX_AMP) . ';}});');
            wp_print_scripts(['zadex-dev-error']);
            return;
        }
        $assets = $this->entry($entry);
        $handle = 'zadex-entry-' . substr(md5($entry), 0, 8);
        foreach ($assets['css'] as $i => $href) {
            wp_register_style($handle . '-' . $i, $href, [], ZADEX_VERSION);
            wp_print_styles([$handle . '-' . $i]);
        }
        foreach ($assets['js'] as $src) {
            wp_print_script_tag(['type' => 'module', 'src' => $src]);
        }
    }

    /** Enqueue an entry through the WP script/style APIs (used on the frontend). */
    public function enqueue_entry(string $entry, string $handle): void
    {
        $assets = $this->entry($entry);
        foreach ($assets['css'] as $i => $href) {
            wp_enqueue_style($handle . ($i ? "-$i" : ''), $href, [], ZADEX_VERSION);
        }
        foreach ($assets['js'] as $i => $src) {
            // Script modules (WordPress 6.5+, the minimum version).
            wp_enqueue_script_module($handle . ($i ? "-$i" : ''), $src, [], ZADEX_VERSION);
        }
    }

    public function dev_server(): string
    {
        return $this->dev_server;
    }
}