<?php

/**
 * Helper Functions List
 *
 * Can be called via Singleton. Since Singleton uses magic method __call().
 * Example:
 *
 * Add Media to GS storage:
 * ud_get_stateless_media()->add_media( false, $post_id );
 *
 * @class Utility
 */

namespace wpCloud\StatelessMedia {

  use wpCloud\StatelessMedia\Sync\BackgroundSync;
  use \Firebase\JWT\JWT;
  use \Firebase\JWT\Key;

  if (!class_exists('wpCloud\StatelessMedia\Utility')) {

    class Utility {

      static $can_delete_attachment = [];

      /**
       * ChromeLogger
       *
       * @author potanin@UD
       * @param $data
       */
      static public function log($data) {

        if (!class_exists('wpCloud\StatelessMedia\Logger')) {
          include_once(__DIR__ . '/class-logger.php');
        }

        if (!class_exists('wpCloud\StatelessMedia\Logger')) {
          return;
        }

        if (defined('WP_STATELESS_CONSOLE_LOG') && WP_STATELESS_CONSOLE_LOG) {
          Logger::log('[wp-stateless]', $data);
        }
      }

      /**
       * wp_normalize_path was added in 3.9.0
       *
       * @param $path
       * @return mixed|string
       *
       */
      public static function normalize_path($path) {

        if (function_exists('wp_normalize_path')) {
          return wp_normalize_path($path);
        }

        $path = str_replace('\\', '/', $path);
        $path = preg_replace('|/+|', '/', $path);
        return $path;
      }

      /**
       * Randomize file name
       * @param $filename
       * @return string
       */
      public static function randomize_filename($filename) {
        $return = apply_filters('stateless_skip_cache_busting', null, $filename);
        if ($return) {
          return $return;
        }

        if (preg_match('/^[a-f0-9]{8}-/', $filename)) {
          return $filename;
        }

        $info = pathinfo($filename);
        $ext = empty($info['extension']) ? '' : '' . $info['extension'];
        $_parts = array();
        $rand = substr(md5(time()), 0, 8);

        if (strpos($info['filename'], '@')) {
          $_cleanName = explode('@', $info['filename'])[0];
          $_retna = explode('@', $info['filename'])[1];
          $_parts[] = $rand;
          $_parts[] = '-';
          $_parts[] = strtolower($_cleanName);
          $_parts[] = '@' . strtolower($_retna);
        } else {
          $_parts[] = $rand;
          $_parts[] = '-';
          $_parts[] = strtolower($info['filename']);
        }

        $filename = join('', $_parts);
        if (!empty($ext)) {
          $filename .= '.' . $ext;
        }

        return $filename;
      }

      /**
       * Get Media Item Content Disposition
       *
       * @param null $attachment_id
       * @param array $metadata
       * @param array $data
       * @return string
       */
      public static function getContentDisposition($attachment_id = null, $metadata = array(), $data = array()) {
        // return 'Content-Disposition: attachment; filename=some-file.sql';
        return apply_filters('sm:item:contentDisposition', null, array('attachment_id' => $attachment_id, 'mime_type' => get_post_mime_type($attachment_id), 'metadata' => $metadata, 'data' => $data));
      }

      /**
       * @param null $attachment_id
       * @param array $metadata
       * @param array $data
       * @return string
       */
      public static function getCacheControl($attachment_id = null, $metadata = array(), $data = array()) {
        if (!$attachment_id) {
          return apply_filters('sm:item:cacheControl', 'private, no-cache, no-store', $attachment_id, array('attachment_id' => null, 'mime_type' => null, 'metadata' => $metadata, 'data' => $data));
        }

        $_mime_type = get_post_mime_type($attachment_id);

        // Treat SQL as non-public.
        if (strpos($_mime_type, 'sql') !== false) {
          return apply_filters('sm:item:cacheControl', 'private, no-cache, no-store', array('attachment_id' => $attachment_id, 'mime_type' => null, 'metadata' => $metadata, 'data' => $data));
        }

        // Treat all other files as public.
        return apply_filters('sm:item:cacheControl', ud_get_stateless_media()->get_default_cache_control(), array('attachment_id' => $attachment_id, 'mime_type' => null, 'metadata' => $metadata, 'data' => $data));
      }

      /**
       * Add/Update Media to Bucket
       * Fired for every action with image add or update
       *
       * $force and $args params will no be passed on media library uploads.
       * This two will be passed on by compatibility.
       *
       * @action wp_generate_attachment_metadata
       * @author peshkov@UD
       * @param $metadata
       * @param $attachment_id
       * @param boolean $force Whether to force the upload incase of it's already exists.
       * @param array $args Whether to only sync the full size image.
       * @return bool|string
       */
      public static function add_media($metadata, $attachment_id, $force = false, $args = array()) {
        $sm_mode = ud_get_stateless_media()->get('sm.mode');
        $file = '';
        $upload_dir = wp_upload_dir();
        $args = wp_parse_args($args, array(
          'is_webp' => '', // expected value ".webp";
        ));

        /* Get metadata in case if method is called directly. */
        if (current_filter() !== 'wp_generate_attachment_metadata' && current_filter() !== 'wp_update_attachment_metadata' && current_filter() !== 'intermediate_image_sizes_advanced') {
          $metadata = wp_get_attachment_metadata($attachment_id);
        }

        // making sure meta data isn't null.
        if (empty($metadata)) {
          $metadata = array();
        }

        /**
         * To skip the sync process.
         *
         * Returning a non-null value
         * will effectively short-circuit the function.
         *
         * $force and $args params will no be passed on non media library uploads.
         * This two will be passed on by compatibility.
         *
         * @since 2.2.4
         *
         * @param bool              $value          This should return true if want to skip the sync.
         * @param int               $metadata       Metadata for the attachment.
         * @param string            $attachment_id  Attachment ID.
         * @param bool              $force          (optional) Whether to force the sync even the file already exist in GCS.
         * @param bool              $args           (optional) Whether to only sync the full size image.
         */
        $check = apply_filters('wp_stateless_skip_add_media', null, $metadata, $attachment_id, $force, $args);

        $client = ud_get_stateless_media()->get_client();

        if ((!is_wp_error($client) || ($sm_mode == 'stateless' && !wp_doing_ajax())) && !$check) {

          $image_host          = ud_get_stateless_media()->get_gs_host();
          $bucketLink          = apply_filters('wp_stateless_bucket_link', $image_host);
          $fullsizepath        = wp_normalize_path(get_attached_file($attachment_id));
          $_cacheControl       = self::getCacheControl($attachment_id, $metadata, null);
          $_contentDisposition = self::getContentDisposition($attachment_id, $metadata, null);

          // Ensure image upload to GCS when attachment is updated,
          // by checking if the attachment metadata is changed.
          if ($attachment_id && !empty($metadata) && !$force) {
            $db_metadata = get_post_meta($attachment_id, '_wp_attachment_metadata', true);
            if ($db_metadata != $metadata) {
              $force = true;
            }
          }

          /**
           * To skip removing files from server
           *
           * Returning a non-null value
           * will effectively short-circuit the function.
           *
           * $force and $args params will no be passed on non media library uploads.
           * This two will be passed on by compatibility.
           *
           * @since 3.0
           *
           * @param bool              $value          This should return true if want to skip the sync.
           * @param int               $metadata       Metadata for the attachment.
           * @param string            $attachment_id  Attachment ID.
           * @param bool              $force          (optional) Whether to force the sync even the file already exist in GCS.
           * @param bool              $args           (optional) Whether to only sync the full size image.
           */
          $skip_remove_media = apply_filters('wp_stateless_skip_remove_media', false, $metadata, $attachment_id, $force, $args);

          // Make non-images uploadable.
          // empty $metadata['file'] can cause problem, so we need to generate it.
          if (empty($metadata['file']) && $attachment_id) {
            $mime_type = get_post_mime_type($attachment_id);
            $file = str_replace(wp_normalize_path(trailingslashit($upload_dir['basedir'])), '', $fullsizepath);

            // We shouldn't create $metadata["file"] if it's PDF file.
            if ($mime_type != "application/pdf") {
              $metadata["file"] = $file;
            }
          }

          $cloud_meta = apply_filters('wp_stateless_get_file', [], $attachment_id, true);

          $cloud_meta = wp_parse_args($cloud_meta, array(
            'name'               => '',
            'bucket'             => ud_get_stateless_media()->get('sm.bucket'),
            'fileLink'           => '',
            'mediaLink'          => '',
            'cacheControl'       => $_cacheControl,
            'contentDisposition' => $_contentDisposition,
            'sizes'              => array(),
          ));

          /**
           * Storing file size to sm_cloud first,
           * Because assigning directly to $metadata['filesize'] don't work.
           * Maybe filesize gets removed in first run (when file exists).
           */
          if (file_exists($fullsizepath)) {
            $cloud_meta['filesize'] = filesize($fullsizepath);
          }
          // Getting file size from sm_cloud.
          if (!empty($cloud_meta['filesize'])) {
            $metadata['filesize'] = $cloud_meta['filesize'];
          }

          $image_sizes = self::get_path_and_url($metadata, $attachment_id);

          foreach ($image_sizes as $size => $img) {
            if ((isset($_REQUEST['size']) && $_REQUEST['size'] == $size) || empty($_REQUEST['size'])) {
              // GCS metadata
              $_metadata = array(
                "width"     => $img['width'],
                "height"    => $img['height'],
                'child-of'  => $attachment_id,
                'file-hash' => md5($file),
                'size'      => $size,
              );

              // adding extra GCS meta for full size image.
              if (!$img['is_thumb']) {
                unset($_metadata['child-of']); // no need in full size image.
                $_metadata['object-id'] = $attachment_id;
                $_metadata['source-id'] = md5($attachment_id . ud_get_stateless_media()->get('sm.bucket'));
              }

              $media_args = array_filter(array(
                'force'              => $force,
                'name'               => $img['gs_name'],
                'is_webp'            => $args['is_webp'],
                'mimeType'           => $img['mime_type'],
                'metadata'           => $_metadata,
                'absolutePath'       => $img['path'],
                'cacheControl'       => $_cacheControl,
                'contentDisposition' => $_contentDisposition,
              ));

              if ($sm_mode == 'stateless' && !wp_doing_ajax() && !wp_doing_cron() 
                || ($sm_mode == 'stateless' && wp_doing_ajax()) ) {
                global $gs_client;

                $media_args = wp_parse_args($media_args, array(
                  'use_root' => true,
                  'force' => false,
                  'name' => false,
                  'absolutePath' => false,
                  'mimeType' => 'image/jpeg',
                  'metadata' => array(),
                  'is_webp' => '',
                ));
                $media_args = apply_filters('wp_stateless_add_media_args', $media_args);

                //Bucket
                $bucket = ud_get_stateless_media()->get('sm.bucket');

                $bucket = $gs_client->bucket($bucket);
                $object = $bucket->object($media_args['name']);

                /**
                 * Updating object metadata, ACL, CacheControl and contentDisposition
                 * @return media object
                 */
                try {
                  $mediaOptions = array(
                    'cacheControl' => $_cacheControl,
                    'contentDisposition' => $_contentDisposition
                  );

                  if ( !defined('WP_STATELESS_SKIP_ACL_SET') || !WP_STATELESS_SKIP_ACL_SET) {
                    $mediaOptions['predefinedAcl'] = 'publicRead';
                  }
      
                  $media = $object->update(array('metadata' => $media_args['metadata']) + $mediaOptions);

                  $cloud_meta = self::generate_cloud_meta($cloud_meta, $media, $size, $img, $bucketLink);
                } catch (\Throwable $th) {
                  //throw $th;
                }
              } else {
                /* Add default image */
                $media = $client->add_media($media_args);

                /* Break if we have errors. */
                if (!is_wp_error($media)) {
                  // @note We don't add storageClass because it's same as parent...
                  $cloud_meta = self::generate_cloud_meta($cloud_meta, $media, $size, $img, $bucketLink);

                  /**
                   * Ephemeral and stateless mode: we don't need the local version.
                   * Except when uploading the full size image first.
                   */
                  if (self::can_delete_attachment($attachment_id, $args) && !$skip_remove_media) {
                    @unlink($img['path']);
                  }
                }
              }
            }
          }
          // End of image sync loop
          if (!$args['is_webp']) {
            update_post_meta($attachment_id, 'sm_cloud', $cloud_meta);
          }

          /**
           * Triggers when the media and it's thumbs are synced.
           *
           * $force and $args params will no be passed on non media library uploads.
           * This two will be passed on by compatibility.
           *
           * @since 2.2.5
           *
           * @param int               $metadata       Metadata for the attachment.
           * @param string            $attachment_id  Attachment ID.
           * @param bool              $force          (optional) Whether to force the sync even the file already exist in GCS.
           * @param bool              $args           (optional) Whether to only sync the full size image.
           */
          $metadata = apply_filters('wp_stateless_media_synced', $metadata, $attachment_id, $force, $args);
        }

        return $metadata;
      }

      /**
       * Remove Media from Bucket by post ID
       * Fired on calling function wp_delete_attachment()
       *
       * @todo: add error logging. peshkov@UD
       * @see wp_delete_attachment()
       * @action delete_attachment
       * @author peshkov@UD
       * @param $post_id
       */
      public static function remove_media($post_id) {
        /* Get attachments metadata */
        $metadata = wp_get_attachment_metadata($post_id);

        /* Be sure we have the same bucket in settings and have GS object's name before proceed. */
        if (isset($metadata['gs_name']) && isset($metadata['gs_bucket']) && $metadata['gs_bucket'] == ud_get_stateless_media()->get('sm.bucket')) {
          $client = ud_get_stateless_media()->get_client();
          if (!is_wp_error($client)) {

            /* Remove default image */
            $client->remove_media($metadata['gs_name'], $post_id);
            $client->remove_media(get_attached_file($post_id), $post_id);

            // Remove webp
            $client->remove_media($metadata['gs_name'] . '.webp', $post_id, true, "", true);

            /* Now, go through all sizes and remove 'image sizes' images from Bucket too. */
            if (!empty($metadata['sizes']) && is_array($metadata['sizes'])) {
              foreach ($metadata['sizes'] as $k => $v) {
                if (!empty($v['gs_name'])) {
                  $client->remove_media($v['gs_name'], $post_id, true, $k);
                  $client->remove_media($v['gs_name'] . '.webp', $post_id, true, $k, true);
                }
              }
            }
          }
        }
      }

      /**
       * Return URL and path for all image sizes of a attachment.
       * @param $metadata
       * @param $attachment_id
       * @return mixed
       */
      public static function get_path_and_url($metadata, $attachment_id) {
        /* Get metadata in case if method is called directly. */
        if (empty($metadata) && current_filter() !== 'wp_generate_attachment_metadata' && current_filter() !== 'wp_update_attachment_metadata') {
          $metadata = wp_get_attachment_metadata($attachment_id);
        }

        $gs_name_path = array();
        $full_size_path = get_attached_file($attachment_id);
        $base_dir = dirname($full_size_path);

        $gs_name = apply_filters('wp_stateless_file_name', $full_size_path, true, $attachment_id, '');
        $gs_base_dir = dirname($gs_name) == '.' ? '' : trailingslashit(dirname($gs_name));

        if (!isset($metadata['width']) && file_exists($full_size_path)) {
          try {
            $_image_size = getimagesize($full_size_path);
            if ($_image_size !== false && is_array($_image_size)) {
              $metadata['width'] = $_image_size[0];
              $metadata['height'] = $_image_size[1];
            }
          } catch (\Exception $e) {
            // lets do nothing.
          }
        }

        $gs_name_path['__full'] = array(
          'gs_name'   => $gs_name,
          'path'      => $full_size_path,
          'sm_meta'   => true,
          'is_thumb'  => false,
          'mime_type' => get_post_mime_type($attachment_id),
          'width'     => isset($metadata['width']) ? $metadata['width'] : null,
          'height'    => isset($metadata['height']) ? $metadata['height'] : null,
        );

        /* Now we go through all available image sizes and upload them to Google Storage */
        if (!empty($metadata['sizes']) && is_array($metadata['sizes'])) {
          foreach ($metadata['sizes'] as $image_size => $data) {
            if (empty($data['file'])) continue;
            $absolutePath = wp_normalize_path($base_dir . '/' . $data['file']);
            $gs_name = $gs_base_dir . $data['file'];
            $gs_name = apply_filters('wp_stateless_file_name', $gs_name, true, $attachment_id, $image_size);

            $gs_name_path[$image_size] = array(
              'gs_name'   => $gs_name,
              'path'      => $absolutePath,
              'sm_meta'   => true,
              'is_thumb'  => true,
              'mime_type' => $data['mime-type'],
              'width'     => $data['width'],
              'height'    => $data['height'],
            );
          }
        }

        return apply_filters('wp_stateless_get_path_and_url', $gs_name_path, $metadata, $attachment_id);
      }

      /**
       * Return URL and path for all image sizes of a attachment.
       * @param $cloud_meta
       * @param $media
       * @param $image_size
       * @param $img
       * @param $bucketLink
       * @return mixed
       */
      public static function generate_cloud_meta($cloud_meta, $media, $image_size, $img, $bucketLink) {
        $gs_name = !empty($media['name']) ? $media['name'] : $img['gs_name'];
        $fileLink = trailingslashit($bucketLink) . $gs_name;
        $version = get_option('wp_sm_version', false);

        if ($img['is_thumb']) {
          // Cloud meta for thumbs.
          $cloud_meta['sizes'][$image_size]['name']         = $gs_name;
          $cloud_meta['sizes'][$image_size]['fileLink']     = $fileLink;
          $cloud_meta['sizes'][$image_size]['mediaLink']    = $media['mediaLink'];
          $cloud_meta['sizes'][$image_size]['width']        = ($media['metadata']['width']) ? $media['metadata']['width'] : $img['width'];
          $cloud_meta['sizes'][$image_size]['height']       = ($media['metadata']['height']) ? $media['metadata']['height'] : $img['height'];
        } else {
          // cloud meta for full size image.
          $cloud_meta['name']                   = $gs_name;
          $cloud_meta['fileLink']               = $fileLink;
          $cloud_meta['mediaLink']              = $media['mediaLink'];
          $cloud_meta['width']                  = isset($media['metadata']['width']) ? $media['metadata']['width'] : ($img['width'] ? $img['width'] : 0);
          $cloud_meta['height']                 = isset($media['metadata']['height']) ? $media['metadata']['height'] : ($img['height'] ? $img['height'] : 0);
          $cloud_meta['bucket']                 = ud_get_stateless_media()->get('sm.bucket');
          $cloud_meta['sm_version']             = $version;
        }
        return apply_filters('wp_stateless_generate_cloud_meta', $cloud_meta, $media, $image_size, $img, $bucketLink);
      }

      /**
       * join_url
       *
       * @param array $parts
       * @param boolean $encode
       * @return string $url
       */
      public static function join_url($parts, $encode = TRUE) {
        if ($encode) {
          if (isset($parts['user']))
            $parts['user']     = rawurlencode($parts['user']);
          if (isset($parts['pass']))
            $parts['pass']     = rawurlencode($parts['pass']);
          if (
            isset($parts['host']) &&
            !preg_match('!^(\[[\da-f.:]+\]])|([\da-f.:]+)$!ui', $parts['host'])
          )
            $parts['host']     = rawurlencode($parts['host']);
          if (!empty($parts['path']))
            $parts['path']     = preg_replace(
              '!%2F!ui',
              '/',
              rawurlencode($parts['path'])
            );
          if (isset($parts['query']))
            $parts['query']    = rawurlencode($parts['query']);
          if (isset($parts['fragment']))
            $parts['fragment'] = rawurlencode($parts['fragment']);
        }

        $url = '';
        if (!empty($parts['scheme']))
          $url .= $parts['scheme'] . ':';
        if (isset($parts['host'])) {
          $url .= '//';
          if (isset($parts['user'])) {
            $url .= $parts['user'];
            if (isset($parts['pass']))
              $url .= ':' . $parts['pass'];
            $url .= '@';
          }
          if (preg_match('!^[\da-f]*:[\da-f.:]+$!ui', $parts['host']))
            $url .= '[' . $parts['host'] . ']'; // IPv6
          else
            $url .= $parts['host'];             // IPv4 or name
          if (isset($parts['port']))
            $url .= ':' . $parts['port'];
          if (!empty($parts['path']) && $parts['path'][0] != '/')
            $url .= '/';
        }
        if (!empty($parts['path']))
          $url .= $parts['path'];
        if (isset($parts['query']))
          $url .= '?' . $parts['query'];
        if (isset($parts['fragment']))
          $url .= '#' . $parts['fragment'];
        return $url;
      }

      /**
       * add_webp_mime
       * @param $t
       * @param $user
       * @return mixed
       */
      public function add_webp_mime($t, $user) {
        $t['webp'] = 'image/webp';
        return $t;
      }

      /**
       * Store attachment id in a static variable on 'intermediate_image_sizes_advanced' filter.
       * To indicate that we can now delete attachment from server now.
       *
       * @param array $new_sizes
       * @param array $image_meta
       * @param int $attachment_id
       * @return array $new_sizes
       */
      public static function store_can_delete_attachment($new_sizes, $image_meta, $attachment_id) {
        if (!in_array($attachment_id, self::$can_delete_attachment)) {
          self::$can_delete_attachment[] = $attachment_id;
        }
        return $new_sizes;
      }

      /**
       * Check whether to delete attachment from server or not.
       *
       * @param int $attachment_id
       * @param array $args
       * @return boolean
       */
      public static function can_delete_attachment($attachment_id, $args) {
        $sm_mode = ud_get_stateless_media()->get('sm.mode');

        if (in_array($sm_mode, array('ephemeral', 'stateless'))) {
          // checks whether it's WP 5.3 and 'intermediate_image_sizes_advanced' is passed.
          // To be sure that we don't delete full size image before thumbnails are generated.
          if (
            wp_attachment_is_image($attachment_id) &&
            function_exists('is_wp_version_compatible') &&
            is_wp_version_compatible('5.3-RC4-46673') &&
            !in_array($attachment_id, self::$can_delete_attachment)
          ) {
            return false;
          }
          return true;
        }
        return false;
      }

      /**
       * Useful when there is a need to do things depending on a call stack.
       * Returns true if any of the conditions met. Returns false otherwise.
       *
       * @param $callstack array Result of debug_backtrace function.
       * @param $conditions array CallStack fingerprint with `stack_level` integer.
       *
       * Example:
       * array(
       *  array(
       *    'stack_level' => 4,
       *    'function' => '__construct',
       *    'class' => 'ET_Core_PageResource'
       *  ),
       *  array(
       *    'stack_level' => 4,
       *    'function' => 'get_cache_filename',
       *    'class' => 'ET_Builder_Element'
       *  )
       * )
       *
       * @return bool
       */
      public static function isCallStackMatches($callstack, $conditions) {
        if (!is_array($conditions)) {
          $conditions = array($conditions);
        }

        foreach ($conditions as $condition) {
          $condition['stack_level'] = $condition['stack_level'] ? $condition['stack_level'] : 0;

          $levelData = $callstack[$condition['stack_level']];

          unset($condition['stack_level']);

          $levelMatches = false;
          foreach ($condition as $key => $value) {
            if (isset($levelData[$key]) && $levelData[$key] === $value) {
              $levelMatches = true;
            } else {
              $levelMatches = false;
            }
          }

          if ($levelMatches) return true;
        }

        return false;
      }

      /**
       * Fail over to image URL if not found on disk
       * In case image not available on both local and bucket
       * try to pull image from image URL in case it is accessible by some sort of proxy.
       *
       * @param:
       * $url (int/string): URL of the image.
       * $save_to (string): Path where to save the image.
       *
       * @return bool|int
       * @throws \Exception
       */
      public static function sync_get_attachment_if_exist($url, $save_to) {
        if (is_int($url)) $url = wp_get_attachment_url($url);

        $response = wp_remote_get($url);
        if (!is_wp_error($response) && is_array($response)) {
          if (!empty($response['response']['code']) && $response['response']['code'] == 200) {
            try {
              if (wp_mkdir_p(dirname($save_to))) {
                return file_put_contents($save_to, $response['body']);
              }
            } catch (\Exception $e) {
              throw $e;
            }
          }
        }
        return false;
      }

      /**
       * Get a secure JWT signing key
       * Priority: AUTH_SALT (if valid length) > Plugin-specific stored key > Generated key
       *
       * @return string A key suitable for HS256 (minimum 32 bytes)
       */
      public static function get_jwt_signing_key() {
        // Minimum key length for HS256 (256 bits = 32 bytes)
        $min_key_length = 32;
        
        // Try AUTH_SALT first if it's long enough
        if (defined('AUTH_SALT') && !empty(AUTH_SALT) && strlen(AUTH_SALT) >= $min_key_length) {
          return AUTH_SALT;
        }
        
        // Try to get stored plugin-specific key
        $stored_key = get_option('wp_stateless_jwt_key');
        
        if ($stored_key && strlen($stored_key) >= $min_key_length) {
          return $stored_key;
        }
        
        // Generate a new secure key
        $new_key = self::generate_secure_key($min_key_length);
        update_option('wp_stateless_jwt_key', $new_key, false);
        
        return $new_key;
      }
      
      /**
       * Generate a cryptographically secure random key
       *
       * @param int $length Key length in bytes
       * @return string Base64-encoded key
       */
      private static function generate_secure_key($length = 32) {
        try {
          // Use random_bytes for PHP 7+
          $random_bytes = random_bytes($length);
          return base64_encode($random_bytes);
        } catch (\Exception $e) {
          // Fallback: use wp_generate_password
          return wp_generate_password($length * 2, true, true);
        }
      }

      /**
       * Generate JWT token signed by secure key
       * Uses AUTH_SALT if valid, otherwise uses plugin-specific stored key
       *
       * @param $payload
       * @param int $ttl
       * @return string
       */
      public static function generate_jwt_token($payload, $ttl = 3600) {
        $payload = wp_parse_args($payload, [
          'iat' => $now = time(),
          'iss' => $site_url = get_site_url(),
          'aud' => $site_url,
          'exp' => $now + $ttl
        ]);

        $key = self::get_jwt_signing_key();
        return JWT::encode($payload, $key, 'HS256');
      }

      /**
       * Verify and decode token
       * Uses the same secure key retrieval as generation
       * Throws exceptions if cannot decode
       *
       * @param $token
       * @return object
       * @throws \Exception
       */
      public static function verify_jwt_token($token) {
        $key = self::get_jwt_signing_key();
        return JWT::decode($token, new Key($key, 'HS256'));
      }

      /**
       * Generate auth token for wizard iframe
       *
       * @param int $ttl
       * @return string
       */
      public static function generate_wizard_auth_token($ttl = 3600) {
        $payload = [
          'is_network' => is_network_admin(),
          'user_id' => get_current_user_id()
        ];
        return self::generate_jwt_token($payload, $ttl);
      }

      /**
       * Maps a file extensions to a mimetype.
       *
       * @param $extension string The file extension.
       *
       * @return string|null
       * @link http://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x/conf/mime.types
       */
      public static function mimetype_from_extension($extension) {
        $file_type = wp_check_filetype($extension);
        if (!empty($file_type['type'])) {
          return $file_type['type'];
        }
        static $mimetypes = [
          '7z' => 'application/x-7z-compressed',
          'aac' => 'audio/x-aac',
          'ai' => 'application/postscript',
          'aif' => 'audio/x-aiff',
          'asc' => 'text/plain',
          'asf' => 'video/x-ms-asf',
          'atom' => 'application/atom+xml',
          'avi' => 'video/x-msvideo',
          'bmp' => 'image/bmp',
          'bz2' => 'application/x-bzip2',
          'cer' => 'application/pkix-cert',
          'crl' => 'application/pkix-crl',
          'crt' => 'application/x-x509-ca-cert',
          'css' => 'text/css',
          'csv' => 'text/csv',
          'cu' => 'application/cu-seeme',
          'deb' => 'application/x-debian-package',
          'doc' => 'application/msword',
          'docx' => 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
          'dvi' => 'application/x-dvi',
          'eot' => 'application/vnd.ms-fontobject',
          'eps' => 'application/postscript',
          'epub' => 'application/epub+zip',
          'etx' => 'text/x-setext',
          'flac' => 'audio/flac',
          'flv' => 'video/x-flv',
          'gif' => 'image/gif',
          'gz' => 'application/gzip',
          'htm' => 'text/html',
          'html' => 'text/html',
          'ico' => 'image/x-icon',
          'ics' => 'text/calendar',
          'ini' => 'text/plain',
          'iso' => 'application/x-iso9660-image',
          'jar' => 'application/java-archive',
          'jpe' => 'image/jpeg',
          'jpeg' => 'image/jpeg',
          'jpg' => 'image/jpeg',
          'js' => 'text/javascript',
          'json' => 'application/json',
          'latex' => 'application/x-latex',
          'log' => 'text/plain',
          'm4a' => 'audio/mp4',
          'm4v' => 'video/mp4',
          'mid' => 'audio/midi',
          'midi' => 'audio/midi',
          'mov' => 'video/quicktime',
          'mp3' => 'audio/mpeg',
          'mp4' => 'video/mp4',
          'mp4a' => 'audio/mp4',
          'mp4v' => 'video/mp4',
          'mpe' => 'video/mpeg',
          'mpeg' => 'video/mpeg',
          'mpg' => 'video/mpeg',
          'mpg4' => 'video/mp4',
          'oga' => 'audio/ogg',
          'ogg' => 'audio/ogg',
          'ogv' => 'video/ogg',
          'ogx' => 'application/ogg',
          'pbm' => 'image/x-portable-bitmap',
          'pdf' => 'application/pdf',
          'pgm' => 'image/x-portable-graymap',
          'png' => 'image/png',
          'pnm' => 'image/x-portable-anymap',
          'ppm' => 'image/x-portable-pixmap',
          'ppt' => 'application/vnd.ms-powerpoint',
          'pptx' => 'application/vnd.openxmlformats-officedocument.presentationml.presentation',
          'ps' => 'application/postscript',
          'qt' => 'video/quicktime',
          'rar' => 'application/x-rar-compressed',
          'ras' => 'image/x-cmu-raster',
          'rss' => 'application/rss+xml',
          'rtf' => 'application/rtf',
          'sgm' => 'text/sgml',
          'sgml' => 'text/sgml',
          'svg' => 'image/svg+xml',
          'swf' => 'application/x-shockwave-flash',
          'tar' => 'application/x-tar',
          'tif' => 'image/tiff',
          'tiff' => 'image/tiff',
          'torrent' => 'application/x-bittorrent',
          'ttf' => 'application/x-font-ttf',
          'txt' => 'text/plain',
          'wav' => 'audio/x-wav',
          'webm' => 'video/webm',
          'webp' => 'image/webp',
          'wma' => 'audio/x-ms-wma',
          'wmv' => 'video/x-ms-wmv',
          'woff' => 'application/x-font-woff',
          'wsdl' => 'application/wsdl+xml',
          'xbm' => 'image/x-xbitmap',
          'xls' => 'application/vnd.ms-excel',
          'xlsx' => 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
          'xml' => 'application/xml',
          'xpm' => 'image/x-xpixmap',
          'xwd' => 'image/x-xwindowdump',
          'yaml' => 'text/yaml',
          'yml' => 'text/yaml',
          'zip' => 'application/zip',
        ];

        $extension = strtolower($extension);

        return isset($mimetypes[$extension]) ? $mimetypes[$extension] : false;
      }

      /**
       * @param $size
       * @return float|int
       */
      public static function convert_to_byte($size) {
        $lastCharacter = \substr($size, -1);
        $base = \strtoupper($lastCharacter);
        if (!\ctype_digit($lastCharacter)) {
          switch ($base) {
            case 'B':
              $size = (int) $size;
              break;
            case 'K':
              $size = (int) $size * 1024;
              break;
            case 'M':
              $size = (int) $size * pow(1024, 2);
              break;
            case 'G':
              $size = (int) $size * pow(1024, 3);
              break;
          }
        }
        return $size;
      }

      /**
       * Get stateless data, count of stateless media
       * @return mixed
       */
      public static function get_stateless_media_data_count() {
        global $wpdb;

        if ( !ud_get_stateless_media()->get('sm.use_postmeta') ) {
          try {
            return ud_stateless_db()->get_total_files();
          } catch (\Throwable $th) {
          }
        }

        $stateless_media = $wpdb->get_var($wpdb->prepare("
          SELECT COUNT(meta_id)
          FROM " . $wpdb->postmeta . "
          WHERE meta_key = %s
        ", 'sm_cloud'));

        return $stateless_media;
      }

      /**
       * Get a list of instances of all available sync methods
       */
      public static function get_available_sync_classes() {
        return array_filter(array_map(function ($class) {
          if (class_exists($class)) {
            try {
              $class = $class::instance();
              if (is_a($class, BackgroundSync::class)) {
                return $class;
              }
              return null;
            } catch (\Throwable $e) {
              error_log($e->getMessage());
              return null;
            }
          }
          return null;
        }, apply_filters('wp_stateless_sync_types', [])));
      }

      /**
       * Process single image attachment by id
       * 
       * @param mixed $id Attachment ID
       * @return \WP_Post
       * @throws FatalException
       * @throws UnprocessableException
       */
      public static function process_image_by_id($id) {
        if (ud_get_stateless_media()->is_connected_to_gs() !== true) {
          throw new FatalException(__('Not connected to GCS', ud_get_stateless_media()->domain));
        }

        $image = get_post($id);

        if (!$image || 'attachment' != $image->post_type || 'image/' != substr($image->post_mime_type, 0, 6))
          throw new UnprocessableException(sprintf(__('Failed to process item: %s is an invalid image ID.', ud_get_stateless_media()->domain), $id));

        $fullsizepath = get_attached_file($image->ID);

        // If no file found
        if (false === $fullsizepath || !file_exists($fullsizepath)) {

          // Try get it and save
          $result_code = ud_get_stateless_media()->get_client()->get_media(apply_filters('wp_stateless_file_name', $fullsizepath, true, "", ""), true, $fullsizepath);

          if ($result_code !== 200) {
            if (!Utility::sync_get_attachment_if_exist($image->ID, $fullsizepath)) {
              throw new UnprocessableException(sprintf(__('Both local and remote files are missing. Unable to process. (%s)', ud_get_stateless_media()->domain), $image->guid));
            }
          }
        }

        do_action('sm:pre::synced::image', $id);
        if (!function_exists('wp_generate_attachment_metadata')) {
          require_once ABSPATH . '/wp-admin/includes/image.php';
        }
        $metadata = wp_generate_attachment_metadata($image->ID, $fullsizepath);

        if (get_post_mime_type($image->ID) !== 'image/svg+xml') {
          if (is_wp_error($metadata)) {
            throw new UnprocessableException($metadata->get_error_message());
          }

          if (empty($metadata)) {
            throw new UnprocessableException(sprintf(__('No metadata generated for %1$s (ID %2$s).', ud_get_stateless_media()->domain), esc_html(get_the_title($image->ID)), $image->ID));
          }
        }

        // trigger processing filters
        wp_update_attachment_metadata($image->ID, $metadata);
        do_action('sm:synced::image', $id, $metadata);

        return $image;
      }

      /**
       * Process single attachment file by id
       * 
       * @param mixed $id Attachment ID
       * @return \WP_Post
       * @throws FatalException
       * @throws UnprocessableException
       */
      public static function process_file_by_id($id) {
        if (ud_get_stateless_media()->is_connected_to_gs() !== true) {
          throw new FatalException(__('Not connected to GCS', ud_get_stateless_media()->domain));
        }

        $file = get_post($id);

        if (!$file || 'attachment' != $file->post_type) {
          throw new UnprocessableException(sprintf(__('Attachment not found: %s is an invalid file ID.', ud_get_stateless_media()->domain), $id));
        }

        $fullsizepath = get_attached_file($file->ID);
        $local_file_exists = file_exists($fullsizepath);

        if (false === $fullsizepath || !$local_file_exists) {

          // Try get it and save
          $result_code = ud_get_stateless_media()->get_client()->get_media(apply_filters('wp_stateless_file_name', $fullsizepath, true, "", ""), true, $fullsizepath);

          if ($result_code !== 200) {
            if (!Utility::sync_get_attachment_if_exist($file->ID, $fullsizepath)) { // Save file to local from proxy.
              throw new UnprocessableException(sprintf(__('File not found (%s)', ud_get_stateless_media()->domain), $file->guid));
            } else {
              $local_file_exists = true;
            }
          } else {
            $local_file_exists = true;
          }
        }

        if ($local_file_exists) {

          if (!ud_get_stateless_media()->get_client()->media_exists(apply_filters('wp_stateless_file_name', $fullsizepath, true, "", ""))) {

            if (!function_exists('wp_generate_attachment_metadata')) {
              require_once ABSPATH . '/wp-admin/includes/media.php';
              require_once ABSPATH . '/wp-admin/includes/image.php';
            }
            $metadata = wp_generate_attachment_metadata($file->ID, $fullsizepath);

            if (is_wp_error($metadata)) {
              throw new UnprocessableException($metadata->get_error_message());
            }

            wp_update_attachment_metadata($file->ID, $metadata);
            do_action('sm:synced::nonImage', $id, $metadata);
          } else {
            // Ephemeral and Stateless modes: we don't need the local version.
            if (ud_get_stateless_media()->get('sm.mode') === 'ephemeral' || ud_get_stateless_media()->get('sm.mode') === 'stateless') {
              @unlink($fullsizepath);

              $metadata = wp_get_attachment_metadata($file->ID);
              /**
               * removing thumbnails
               * https://github.com/udx/wp-stateless/issues/577
               */
              if (!empty($metadata['sizes'])) {
                $base_dir = dirname($fullsizepath);
                foreach ($metadata['sizes'] as $image_size => $data) {
                  $gs_name = $base_dir . '/' . $data['file'];
                  if (file_exists($gs_name)) {
                    @unlink($gs_name);
                  }
                }
              }
            }
          }
        }

        return $file;
      }

      /**
       * Return list of files in a dir.
       * @param string $dir: Directory path
       * @return array - Lists of files in the directory and subdirectory.
       */
      public static function get_files($dir) {
        $return = array();
        if (is_dir($dir) && $dh = opendir($dir)) {
          while ($file = readdir($dh)) {
            if ($file != '.' && $file != '..') {
              if (is_dir($dir . $file)) {
                // since it is a directory we recursively get files.
                $arr = self::get_files($dir . $file . '/');
                $return = array_merge($return, $arr);
              } else {
                $return[] = $dir . $file;
              }
            }
          }
          closedir($dh);
        }
        
        return $return;
      }
    }
  }
}