<?php
/**
 * Plugin Name: Chinaready WordPress CDN
 * Description: Rewrites enqueued WordPress core, plugin, and theme static asset URLs to Chinaready WordPress CDN when the installed version matches the CDN snapshot.
 * Version: 1.0.0
 * Author: Chinaready
 * License: GPL-2.0-or-later
 *
 * Install: copy this file to wp-content/mu-plugins/chinaready-wp-cdn.php
 * Optional: define CHINAREADY_WP_CDN_ORIGIN in wp-config.php (default https://wp-cdn.launchready.cn)
 */

if (!defined('ABSPATH')) {
    exit;
}

if (!defined('CHINAREADY_WP_CDN_ORIGIN')) {
    define('CHINAREADY_WP_CDN_ORIGIN', 'https://wp-cdn.launchready.cn');
}

/**
 * @return string CDN origin without trailing slash
 */
function chinaready_wp_cdn_origin(): string
{
    return rtrim(CHINAREADY_WP_CDN_ORIGIN, '/');
}

/**
 * @return array<string,string>|null slug => version from manifest.json when cached
 */
function chinaready_wp_cdn_manifest_versions(string $type): ?array
{
    static $manifest = null;
    if ($manifest === null) {
        $response = wp_remote_get(chinaready_wp_cdn_origin() . '/manifest.json', ['timeout' => 5]);
        if (is_wp_error($response)) {
            $manifest = false;
            return null;
        }
        $body = wp_remote_retrieve_body($response);
        $decoded = json_decode($body, true);
        $manifest = is_array($decoded) ? $decoded : false;
    }
    if ($manifest === false || !is_array($manifest)) {
        return null;
    }
    if ($type === 'plugin') {
        $items = $manifest['plugins'] ?? [];
    } elseif ($type === 'theme') {
        $items = $manifest['themes'] ?? [];
    } else {
        return null;
    }
    $map = [];
    foreach ($items as $item) {
        if (!is_array($item) || empty($item['slug']) || empty($item['version'])) {
            continue;
        }
        $map[$item['slug']] = $item['version'];
    }
    return $map;
}

/**
 * @return string|null Installed plugin version for slug
 */
function chinaready_wp_cdn_installed_plugin_version(string $slug): ?string
{
    if (!function_exists('get_plugins')) {
        require_once ABSPATH . 'wp-admin/includes/plugin.php';
    }
    foreach (get_plugins() as $file => $data) {
        if (strpos($file, $slug . '/') === 0) {
            return $data['Version'] ?? null;
        }
    }
    return null;
}

/**
 * @return string|null Installed theme version for slug
 */
function chinaready_wp_cdn_installed_theme_version(string $slug): ?string
{
    $theme = wp_get_theme($slug);
    if (!$theme->exists()) {
        return null;
    }
    return $theme->get('Version') ?: null;
}

/**
 * Rewrite a local WordPress asset URL to the CDN when version matches snapshot.
 */
function chinaready_wp_cdn_rewrite_src(string $src): string
{
    if ($src === '' || strpos($src, 'wp-includes') === false && strpos($src, 'wp-content') === false) {
        return $src;
    }

    $parts = wp_parse_url($src);
    if (!is_array($parts) || empty($parts['path'])) {
        return $src;
    }

    $path = $parts['path'];
    $query = [];
    if (!empty($parts['query'])) {
        parse_str($parts['query'], $query);
    }

    $origin = chinaready_wp_cdn_origin();

    if (preg_match('#/wp-includes/(.+)$#', $path, $matches)) {
        $core_version = get_bloginfo('version');
        if (!$core_version) {
            return $src;
        }
        return $origin . '/wp/' . rawurlencode($core_version) . '/wp-includes/' . $matches[1];
    }

    if (preg_match('#/wp-content/plugins/([^/]+)/(.+)$#', $path, $matches)) {
        $slug = $matches[1];
        $rest = $matches[2];
        $version = $query['ver'] ?? chinaready_wp_cdn_installed_plugin_version($slug);
        if (!$version) {
            return $src;
        }
        $manifest = chinaready_wp_cdn_manifest_versions('plugin');
        if ($manifest !== null && (!isset($manifest[$slug]) || $manifest[$slug] !== $version)) {
            return $src;
        }
        return $origin . '/wp-content/plugins/' . rawurlencode($slug) . '@' . rawurlencode($version) . '/' . $rest;
    }

    if (preg_match('#/wp-content/themes/([^/]+)/(.+)$#', $path, $matches)) {
        $slug = $matches[1];
        $rest = $matches[2];
        $version = $query['ver'] ?? chinaready_wp_cdn_installed_theme_version($slug);
        if (!$version) {
            return $src;
        }
        $manifest = chinaready_wp_cdn_manifest_versions('theme');
        if ($manifest !== null && (!isset($manifest[$slug]) || $manifest[$slug] !== $version)) {
            return $src;
        }
        return $origin . '/wp-content/themes/' . rawurlencode($slug) . '@' . rawurlencode($version) . '/' . $rest;
    }

    return $src;
}

add_filter('script_loader_src', 'chinaready_wp_cdn_rewrite_src', 20);
add_filter('style_loader_src', 'chinaready_wp_cdn_rewrite_src', 20);