public static function download($sURL, $iTimeOut = 300)
 {
     if (false === filter_var($sURL, FILTER_VALIDATE_URL)) {
         return false;
     }
     $_sTmpFileName = self::setTempPath(self::getBaseNameOfURL($sURL));
     if (!$_sTmpFileName) {
         return false;
     }
     $_aoResponse = wp_safe_remote_get($sURL, array('timeout' => $iTimeOut, 'stream' => true, 'filename' => $_sTmpFileName));
     if (is_wp_error($_aoResponse)) {
         unlink($_sTmpFileName);
         return false;
     }
     if (200 != wp_remote_retrieve_response_code($_aoResponse)) {
         unlink($_sTmpFileName);
         return false;
     }
     $_sContent_md5 = wp_remote_retrieve_header($_aoResponse, 'content-md5');
     if ($_sContent_md5) {
         $_boIsMD5 = verify_file_md5($_sTmpFileName, $_sContent_md5);
         if (is_wp_error($_boIsMD5)) {
             unlink($_sTmpFileName);
             return false;
         }
     }
     return $_sTmpFileName;
 }

/**
 * Downloads a url to a local temporary file using the WordPress HTTP Class.
 * Please note, That the calling function must unlink() the file.
 *
 * @since 2.5.0
 *
 * @param string $url the URL of the file to download
 * @param int $timeout The timeout for the request to download the file default 300 seconds
 * @return mixed WP_Error on failure, string Filename on success.
 */
function download_url( $url, $timeout = 300 ) {
	//WARNING: The file is not automatically deleted, The script must unlink() the file.
	if ( ! $url )
		return new WP_Error('http_no_url', __('Invalid URL Provided.'));

	$tmpfname = wp_tempnam($url);
	if ( ! $tmpfname )
		return new WP_Error('http_no_file', __('Could not create Temporary file.'));

	$response = wp_safe_remote_get( $url, array( 'timeout' => $timeout, 'stream' => true, 'filename' => $tmpfname ) );

	if ( is_wp_error( $response ) ) {
		unlink( $tmpfname );
		return $response;
	}

	if ( 200 != wp_remote_retrieve_response_code( $response ) ){
		unlink( $tmpfname );
		return new WP_Error( 'http_404', trim( wp_remote_retrieve_response_message( $response ) ) );
	}

	$content_md5 = wp_remote_retrieve_header( $response, 'content-md5' );
	if ( $content_md5 ) {
		$md5_check = verify_file_md5( $tmpfname, $content_md5 );
		if ( is_wp_error( $md5_check ) ) {
			unlink( $tmpfname );
			return $md5_check;
		}
	}

	return $tmpfname;
}

 /**
  * Downloads a resource identified by the parameters.
  *
  * If only the first parameter is passed, and it is an instance of a cache
  * file, downloads the resource described by it.
  * If it is a URL, the request timeout and target path will be computed by this instance.
  * Otherwise, they will be overridden by the specified values, respectively.
  *
  * If the 'content-md5' header is present in the responce, MD5 checksum
  * verification will take place.
  *
  * @since 4.7.3
  * @see get_download_request_timeout()
  * @see WPRSS_Image_Cache_Image::get_download_request_timeout()
  * @see get_unique_filename()
  * @see WPRSS_Image_Cache_Image::get_current_path()
  * @see get_tmp_dir()
  * @see wp_mkdir_p()
  * @see wp_safe_remote_get()
  * @see verify_file_md5()
  * @param WPRSS_Image_Cache_Image|string $image An instance of a cache file, or the URL to download.
  * @param int|null $request_timeout The timeout for the download request.
  * @param string|null $target_path The relative path to the target file.
  * @return string| The absolute local path to the downloaded file,
  *  or false if checksum verification failed.
  * @throws Exception If the URL is invalid, or the destination path is not writable,
  *  or the file download library cannot be read, or any other error happens during download.
  */
 public function download_image($image, $request_timeout = null, $target_path = null)
 {
     if ($image instanceof WPRSS_Image_Cache_Image) {
         $url = $image->get_url();
         $timeout = $image->get_download_request_timeout();
         $path = $image->get_current_path();
     } else {
         $url = $image;
         $timeout = $this->get_download_request_timeout();
         $path = $this->get_unique_filename($url);
     }
     if (!$url) {
         throw new Exception(sprintf(__('Invalid URL provided: "%1$s"'), $url));
     }
     if (!is_null($target_path)) {
         $path = $target_path;
     }
     if (is_null($request_timeout)) {
         $timeout = $request_timeout;
     }
     // Absolute path to the cache file
     $tmpfname = $image instanceof WPRSS_Image_Cache_Image ? $image->get_tmp_dir($path) : $this->get_tmp_dir($path);
     //WARNING: The file is not automatically deleted, The script must unlink() the file.
     $dirname = dirname($tmpfname);
     if (!wp_mkdir_p($dirname)) {
         throw new Exception(sprintf(__('Could not create directory: "%1$s". Filename: "%2$s"'), $dirname, $tmpfname));
     }
     // Getting file download lib
     $file_lib_path = ABSPATH . 'wp-admin/includes/file.php';
     if (!is_readable($file_lib_path)) {
         throw new Exception(sprintf(__('The file library cannot be read from %1$s'), $file_lib_path));
     }
     require_once $file_lib_path;
     // Retrieving the remote resource
     $response = wp_safe_remote_get($url, array('timeout' => $timeout, 'stream' => true, 'filename' => $tmpfname));
     // Could not retrieve
     if (is_wp_error($response)) {
         @unlink($tmpfname);
         throw new Exception($response->get_error_message());
     }
     // Retrieved, but remote server served error instead of resource
     if (200 != wp_remote_retrieve_response_code($response)) {
         @unlink($tmpfname);
         throw new Exception(trim(wp_remote_retrieve_response_message($response)));
     }
     // Checksum verification
     $content_md5 = wp_remote_retrieve_header($response, 'content-md5');
     if ($content_md5) {
         $md5_check = verify_file_md5($tmpfname, $content_md5);
         if (is_wp_error($md5_check)) {
             unlink($tmpfname);
             return $md5_check;
         }
     }
     return $tmpfname;
 }

 public function sideload()
 {
     //setup temp dir
     $temp_file = wp_tempnam($this->_upload_from);
     if (!$temp_file) {
         EE_Error::add_error(__('Something went wrong with the upload.  Unable to create a tmp file for the uploaded file on the server', 'event_espresso'), __FILE__, __FUNCTION__, __LINE__);
         return false;
     }
     do_action('AHEE__EEH_Sideloader__sideload__before', $this, $temp_file);
     $wp_remote_args = apply_filters('FHEE__EEH_Sideloader__sideload__wp_remote_args', array('timeout' => 500, 'stream' => true, 'filename' => $temp_file), $this, $temp_file);
     $response = wp_safe_remote_get($this->_upload_from, $wp_remote_args);
     if (is_wp_error($response) || 200 != wp_remote_retrieve_response_code($response)) {
         unlink($temp_file);
         if (defined('WP_DEBUG') && WP_DEBUG) {
             EE_Error::add_error(sprintf(__('Unable to upload the file.  Either the path given to upload from is incorrect, or something else happened.  Here is the response returned:<br />%s<br />Here is the path given: %s', 'event_espresso'), var_export($response, true), $this->_upload_from), __FILE__, __FUNCTION__, __LINE__);
         }
         return false;
     }
     //possible md5 check
     $content_md5 = wp_remote_retrieve_header($response, 'content-md5');
     if ($content_md5) {
         $md5_check = verify_file_md5($temp_file, $content_md5);
         if (is_wp_error($md5_check)) {
             unlink($temp_file);
             EE_Error::add_error($md5_check->get_error_message(), __FILE__, __FUNCTION__, __LINE__);
             return false;
         }
     }
     $file = $temp_file;
     //now we have the file, let's get it in the right directory with the right name.
     $path = apply_filters('FHEE__EEH_Sideloader__sideload__new_path', $this->_upload_to . $this->_new_file_name, $this);
     //move file in
     if (false === @rename($file, $path)) {
         unlink($temp_file);
         EE_Error::add_error(sprintf(__('Unable to move the file to new location (possible permissions errors). This is the path the class attempted to move the file to: %s', 'event_espresso'), $path), __FILE__, __FUNCTION__, __LINE__);
         return false;
     }
     //set permissions
     $permissions = apply_filters('FHEE__EEH_Sideloader__sideload__permissions_applied', $this->_permissions, $this);
     chmod($path, $permissions);
     //that's it.  let's allow for actions after file uploaded.
     do_action('AHEE__EE_Sideloader__sideload_after', $this, $path);
     //unlink tempfile
     @unlink($temp_file);
     return true;
 }