src/wp-admin/includes/class-theme-upgrader.php

<?php
/**
 * Upgrade API: Theme_Upgrader class
 *
 * @package WordPress
 * @subpackage Upgrader
 * @since 4.6.0
 */

/**
 * Core class used for upgrading/installing themes.
 *
 * It is designed to upgrade/install themes from a local zip, remote zip URL,
 * or uploaded zip file.
 *
 * @since 2.8.0
 * @since 4.6.0 Moved to its own file from wp-admin/includes/class-wp-upgrader.php.
 *
 * @see WP_Upgrader
 */
class Theme_Upgrader extends WP_Upgrader {

	/**
	 * Result of the theme upgrade offer.
	 *
	 * @since 2.8.0
	 * @var array|WP_Error $result
	 * @see WP_Upgrader::$result
	 */
	public $result;

	/**
	 * Whether multiple themes are being upgraded/installed in bulk.
	 *
	 * @since 2.9.0
	 * @var bool $bulk
	 */
	public $bulk = false;

	/**
	 * New theme info.
	 *
	 * @since 5.5.0
	 * @var array $new_theme_data
	 *
	 * @see check_package()
	 */
	public $new_theme_data = array();

	/**
	 * Initializes the upgrade strings.
	 *
	 * @since 2.8.0
	 */
	public function upgrade_strings() {
		$this->strings['up_to_date'] = __( 'The theme is at the latest version.' );
		$this->strings['no_package'] = __( 'Update package not available.' );
		/* translators: %s: Package URL. */
		$this->strings['downloading_package'] = sprintf( __( 'Downloading update from %s&#8230;' ), '<span class="code pre">%s</span>' );
		$this->strings['unpack_package']      = __( 'Unpacking the update&#8230;' );
		$this->strings['remove_old']          = __( 'Removing the old version of the theme&#8230;' );
		$this->strings['remove_old_failed']   = __( 'Could not remove the old theme.' );
		$this->strings['process_failed']      = __( 'Theme update failed.' );
		$this->strings['process_success']     = __( 'Theme updated successfully.' );
	}

	/**
	 * Initializes the installation strings.
	 *
	 * @since 2.8.0
	 */
	public function install_strings() {
		$this->strings['no_package'] = __( 'Installation package not available.' );
		/* translators: %s: Package URL. */
		$this->strings['downloading_package'] = sprintf( __( 'Downloading installation package from %s&#8230;' ), '<span class="code pre">%s</span>' );
		$this->strings['unpack_package']      = __( 'Unpacking the package&#8230;' );
		$this->strings['installing_package']  = __( 'Installing the theme&#8230;' );
		$this->strings['remove_old']          = __( 'Removing the old version of the theme&#8230;' );
		$this->strings['remove_old_failed']   = __( 'Could not remove the old theme.' );
		$this->strings['no_files']            = __( 'The theme contains no files.' );
		$this->strings['process_failed']      = __( 'Theme installation failed.' );
		$this->strings['process_success']     = __( 'Theme installed successfully.' );
		/* translators: 1: Theme name, 2: Theme version. */
		$this->strings['process_success_specific'] = __( 'Successfully installed the theme <strong>%1$s %2$s</strong>.' );
		$this->strings['parent_theme_search']      = __( 'This theme requires a parent theme. Checking if it is installed&#8230;' );
		/* translators: 1: Theme name, 2: Theme version. */
		$this->strings['parent_theme_prepare_install'] = __( 'Preparing to install <strong>%1$s %2$s</strong>&#8230;' );
		/* translators: 1: Theme name, 2: Theme version. */
		$this->strings['parent_theme_currently_installed'] = __( 'The parent theme, <strong>%1$s %2$s</strong>, is currently installed.' );
		/* translators: 1: Theme name, 2: Theme version. */
		$this->strings['parent_theme_install_success'] = __( 'Successfully installed the parent theme, <strong>%1$s %2$s</strong>.' );
		/* translators: %s: Theme name. */
		$this->strings['parent_theme_not_found'] = sprintf( __( '<strong>The parent theme could not be found.</strong> You will need to install the parent theme, %s, before you can use this child theme.' ), '<strong>%s</strong>' );
		/* translators: %s: Theme error. */
		$this->strings['current_theme_has_errors'] = __( 'The active theme has the following error: "%s".' );

		if ( ! empty( $this->skin->overwrite ) ) {
			if ( 'update-theme' === $this->skin->overwrite ) {
				$this->strings['installing_package'] = __( 'Updating the theme&#8230;' );
				$this->strings['process_failed']     = __( 'Theme update failed.' );
				$this->strings['process_success']    = __( 'Theme updated successfully.' );
			}

			if ( 'downgrade-theme' === $this->skin->overwrite ) {
				$this->strings['installing_package'] = __( 'Downgrading the theme&#8230;' );
				$this->strings['process_failed']     = __( 'Theme downgrade failed.' );
				$this->strings['process_success']    = __( 'Theme downgraded successfully.' );
			}
		}
	}

	/**
	 * Checks if a child theme is being installed and its parent also needs to be installed.
	 *
	 * Hooked to the {@see 'upgrader_post_install'} filter by Theme_Upgrader::install().
	 *
	 * @since 3.4.0
	 *
	 * @param bool  $install_result
	 * @param array $hook_extra
	 * @param array $child_result
	 * @return bool
	 */
	public function check_parent_theme_filter( $install_result, $hook_extra, $child_result ) {
		// Check to see if we need to install a parent theme.
		$theme_info = $this->theme_info();

		if ( ! $theme_info->parent() ) {
			return $install_result;
		}

		$this->skin->feedback( 'parent_theme_search' );

		if ( ! $theme_info->parent()->errors() ) {
			$this->skin->feedback( 'parent_theme_currently_installed', $theme_info->parent()->display( 'Name' ), $theme_info->parent()->display( 'Version' ) );
			// We already have the theme, fall through.
			return $install_result;
		}

		// We don't have the parent theme, let's install it.
		$api = themes_api(
			'theme_information',
			array(
				'slug'   => $theme_info->get( 'Template' ),
				'fields' => array(
					'sections' => false,
					'tags'     => false,
				),
			)
		); // Save on a bit of bandwidth.

		if ( ! $api || is_wp_error( $api ) ) {
			$this->skin->feedback( 'parent_theme_not_found', $theme_info->get( 'Template' ) );
			// Don't show activate or preview actions after installation.
			add_filter( 'install_theme_complete_actions', array( $this, 'hide_activate_preview_actions' ) );
			return $install_result;
		}

		// Backup required data we're going to override:
		$child_api             = $this->skin->api;
		$child_success_message = $this->strings['process_success'];

		// Override them.
		$this->skin->api = $api;

		$this->strings['process_success_specific'] = $this->strings['parent_theme_install_success'];

		$this->skin->feedback( 'parent_theme_prepare_install', $api->name, $api->version );

		add_filter( 'install_theme_complete_actions', '__return_false', 999 ); // Don't show any actions after installing the theme.

		// Install the parent theme.
		$parent_result = $this->run(
			array(
				'package'           => $api->download_link,
				'destination'       => get_theme_root(),
				'clear_destination' => false, // Do not overwrite files.
				'clear_working'     => true,
			)
		);

		if ( is_wp_error( $parent_result ) ) {
			add_filter( 'install_theme_complete_actions', array( $this, 'hide_activate_preview_actions' ) );
		}

		// Start cleaning up after the parent's installation.
		remove_filter( 'install_theme_complete_actions', '__return_false', 999 );

		// Reset child's result and data.
		$this->result                     = $child_result;
		$this->skin->api                  = $child_api;
		$this->strings['process_success'] = $child_success_message;

		return $install_result;
	}

	/**
	 * Don't display the activate and preview actions to the user.
	 *
	 * Hooked to the {@see 'install_theme_complete_actions'} filter by
	 * Theme_Upgrader::check_parent_theme_filter() when installing
	 * a child theme and installing the parent theme fails.
	 *
	 * @since 3.4.0
	 *
	 * @param array $actions Preview actions.
	 * @return array
	 */
	public function hide_activate_preview_actions( $actions ) {
		unset( $actions['activate'], $actions['preview'] );
		return $actions;
	}

	/**
	 * Install a theme package.
	 *
	 * @since 2.8.0
	 * @since 3.7.0 The `$args` parameter was added, making clearing the update cache optional.
	 *
	 * @param string $package The full local path or URI of the package.
	 * @param array  $args {
	 *     Optional. Other arguments for installing a theme package. Default empty array.
	 *
	 *     @type bool $clear_update_cache Whether to clear the updates cache if successful.
	 *                                    Default true.
	 * }
	 *
	 * @return bool|WP_Error True if the installation was successful, false or a WP_Error object otherwise.
	 */
	public function install( $package, $args = array() ) {
		$defaults    = array(
			'clear_update_cache' => true,
			'overwrite_package'  => false, // Do not overwrite files.
		);
		$parsed_args = wp_parse_args( $args, $defaults );

		$this->init();
		$this->install_strings();

		add_filter( 'upgrader_source_selection', array( $this, 'check_package' ) );
		add_filter( 'upgrader_post_install', array( $this, 'check_parent_theme_filter' ), 10, 3 );

		if ( $parsed_args['clear_update_cache'] ) {
			// Clear cache so wp_update_themes() knows about the new theme.
			add_action( 'upgrader_process_complete', 'wp_clean_themes_cache', 9, 0 );
		}

		$this->run(
			array(
				'package'           => $package,
				'destination'       => get_theme_root(),
				'clear_destination' => $parsed_args['overwrite_package'],
				'clear_working'     => true,
				'hook_extra'        => array(
					'type'   => 'theme',
					'action' => 'install',
				),
			)
		);

		remove_action( 'upgrader_process_complete', 'wp_clean_themes_cache', 9 );
		remove_filter( 'upgrader_source_selection', array( $this, 'check_package' ) );
		remove_filter( 'upgrader_post_install', array( $this, 'check_parent_theme_filter' ) );

		if ( ! $this->result || is_wp_error( $this->result ) ) {
			return $this->result;
		}

		// Refresh the Theme Update information.
		wp_clean_themes_cache( $parsed_args['clear_update_cache'] );

		if ( $parsed_args['overwrite_package'] ) {
			/** This action is documented in wp-admin/includes/class-plugin-upgrader.php */
			do_action( 'upgrader_overwrote_package', $package, $this->new_theme_data, 'theme' );
		}

		return true;
	}

	/**
	 * Upgrades a theme.
	 *
	 * @since 2.8.0
	 * @since 3.7.0 The `$args` parameter was added, making clearing the update cache optional.
	 *
	 * @param string $theme The theme slug.
	 * @param array  $args {
	 *     Optional. Other arguments for upgrading a theme. Default empty array.
	 *
	 *     @type bool $clear_update_cache Whether to clear the update cache if successful.
	 *                                    Default true.
	 * }
	 * @return bool|WP_Error True if the upgrade was successful, false or a WP_Error object otherwise.
	 */
	public function upgrade( $theme, $args = array() ) {
		$defaults    = array(
			'clear_update_cache' => true,
		);
		$parsed_args = wp_parse_args( $args, $defaults );

		$this->init();
		$this->upgrade_strings();

		// Is an update available?
		$current = get_site_transient( 'update_themes' );
		if ( ! isset( $current->response[ $theme ] ) ) {
			$this->skin->before();
			$this->skin->set_result( false );
			$this->skin->error( 'up_to_date' );
			$this->skin->after();
			return false;
		}

		$r = $current->response[ $theme ];

		add_filter( 'upgrader_pre_install', array( $this, 'current_before' ), 10, 2 );
		add_filter( 'upgrader_post_install', array( $this, 'current_after' ), 10, 2 );
		add_filter( 'upgrader_clear_destination', array( $this, 'delete_old_theme' ), 10, 4 );
		if ( $parsed_args['clear_update_cache'] ) {
			// Clear cache so wp_update_themes() knows about the new theme.
			add_action( 'upgrader_process_complete', 'wp_clean_themes_cache', 9, 0 );
		}

		$this->run(
			array(
				'package'           => $r['package'],
				'destination'       => get_theme_root( $theme ),
				'clear_destination' => true,
				'clear_working'     => true,
				'hook_extra'        => array(
					'theme'       => $theme,
					'type'        => 'theme',
					'action'      => 'update',
					'temp_backup' => array(
						'slug' => $theme,
						'src'  => get_theme_root( $theme ),
						'dir'  => 'themes',
					),
				),
			)
		);

		remove_action( 'upgrader_process_complete', 'wp_clean_themes_cache', 9 );
		remove_filter( 'upgrader_pre_install', array( $this, 'current_before' ) );
		remove_filter( 'upgrader_post_install', array( $this, 'current_after' ) );
		remove_filter( 'upgrader_clear_destination', array( $this, 'delete_old_theme' ) );

		if ( ! $this->result || is_wp_error( $this->result ) ) {
			return $this->result;
		}

		wp_clean_themes_cache( $parsed_args['clear_update_cache'] );

		/*
		 * Ensure any future auto-update failures trigger a failure email by removing
		 * the last failure notification from the list when themes update successfully.
		 */
		$past_failure_emails = get_option( 'auto_plugin_theme_update_emails', array() );

		if ( isset( $past_failure_emails[ $theme ] ) ) {
			unset( $past_failure_emails[ $theme ] );
			update_option( 'auto_plugin_theme_update_emails', $past_failure_emails );
		}

		return true;
	}

	/**
	 * Upgrades several themes at once.
	 *
	 * @since 3.0.0
	 * @since 3.7.0 The `$args` parameter was added, making clearing the update cache optional.
	 *
	 * @global string $wp_version The WordPress version string.
	 *
	 * @param string[] $themes Array of the theme slugs.
	 * @param array    $args {
	 *     Optional. Other arguments for upgrading several themes at once. Default empty array.
	 *
	 *     @type bool $clear_update_cache Whether to clear the update cache if successful.
	 *                                    Default true.
	 * }
	 * @return array[]|false An array of results, or false if unable to connect to the filesystem.
	 */
	public function bulk_upgrade( $themes, $args = array() ) {
		global $wp_version;

		$defaults    = array(
			'clear_update_cache' => true,
		);
		$parsed_args = wp_parse_args( $args, $defaults );

		$this->init();
		$this->bulk = true;
		$this->upgrade_strings();

		$current = get_site_transient( 'update_themes' );

		add_filter( 'upgrader_pre_install', array( $this, 'current_before' ), 10, 2 );
		add_filter( 'upgrader_post_install', array( $this, 'current_after' ), 10, 2 );
		add_filter( 'upgrader_clear_destination', array( $this, 'delete_old_theme' ), 10, 4 );

		$this->skin->header();

		// Connect to the filesystem first.
		$res = $this->fs_connect( array( WP_CONTENT_DIR ) );
		if ( ! $res ) {
			$this->skin->footer();
			return false;
		}

		$this->skin->bulk_header();

		/*
		 * Only start maintenance mode if:
		 * - running Multisite and there are one or more themes specified, OR
		 * - a theme with an update available is currently in use.
		 * @todo For multisite, maintenance mode should only kick in for individual sites if at all possible.
		 */
		$maintenance = ( is_multisite() && ! empty( $themes ) );
		foreach ( $themes as $theme ) {
			$maintenance = $maintenance || get_stylesheet() === $theme || get_template() === $theme;
		}
		if ( $maintenance ) {
			$this->maintenance_mode( true );
		}

		$results = array();

		$this->update_count   = count( $themes );
		$this->update_current = 0;
		foreach ( $themes as $theme ) {
			++$this->update_current;

			$this->skin->theme_info = $this->theme_info( $theme );

			if ( ! isset( $current->response[ $theme ] ) ) {
				$this->skin->set_result( true );
				$this->skin->before();
				$this->skin->feedback( 'up_to_date' );
				$this->skin->after();
				$results[ $theme ] = true;
				continue;
			}

			// Get the URL to the zip file.
			$r = $current->response[ $theme ];

			if ( isset( $r['requires'] ) && ! is_wp_version_compatible( $r['requires'] ) ) {
				$result = new WP_Error(
					'incompatible_wp_required_version',
					sprintf(
						/* translators: 1: Current WordPress version, 2: WordPress version required by the new theme version. */
						__( 'Your WordPress version is %1$s, however the new theme version requires %2$s.' ),
						$wp_version,
						$r['requires']
					)
				);

				$this->skin->before( $result );
				$this->skin->error( $result );
				$this->skin->after();
			} elseif ( isset( $r['requires_php'] ) && ! is_php_version_compatible( $r['requires_php'] ) ) {
				$result = new WP_Error(
					'incompatible_php_required_version',
					sprintf(
						/* translators: 1: Current PHP version, 2: PHP version required by the new theme version. */
						__( 'The PHP version on your server is %1$s, however the new theme version requires %2$s.' ),
						PHP_VERSION,
						$r['requires_php']
					)
				);

				$this->skin->before( $result );
				$this->skin->error( $result );
				$this->skin->after();
			} else {
				add_filter( 'upgrader_source_selection', array( $this, 'check_package' ) );
				$result = $this->run(
					array(
						'package'           => $r['package'],
						'destination'       => get_theme_root( $theme ),
						'clear_destination' => true,
						'clear_working'     => true,
						'is_multi'          => true,
						'hook_extra'        => array(
							'theme'       => $theme,
							'temp_backup' => array(
								'slug' => $theme,
								'src'  => get_theme_root( $theme ),
								'dir'  => 'themes',
							),
						),
					)
				);
				remove_filter( 'upgrader_source_selection', array( $this, 'check_package' ) );
			}

			$results[ $theme ] = $result;

			// Prevent credentials auth screen from displaying multiple times.
			if ( false === $result ) {
				break;
			}
		} // End foreach $themes.

		$this->maintenance_mode( false );

		// Refresh the Theme Update information.
		wp_clean_themes_cache( $parsed_args['clear_update_cache'] );

		/** This action is documented in wp-admin/includes/class-wp-upgrader.php */
		do_action(
			'upgrader_process_complete',
			$this,
			array(
				'action' => 'update',
				'type'   => 'theme',
				'bulk'   => true,
				'themes' => $themes,
			)
		);

		$this->skin->bulk_footer();

		$this->skin->footer();

		// Cleanup our hooks, in case something else does an upgrade on this connection.
		remove_filter( 'upgrader_pre_install', array( $this, 'current_before' ) );
		remove_filter( 'upgrader_post_install', array( $this, 'current_after' ) );
		remove_filter( 'upgrader_clear_destination', array( $this, 'delete_old_theme' ) );

		/*
		 * Ensure any future auto-update failures trigger a failure email by removing
		 * the last failure notification from the list when themes update successfully.
		 */
		$past_failure_emails = get_option( 'auto_plugin_theme_update_emails', array() );

		foreach ( $results as $theme => $result ) {
			// Maintain last failure notification when themes failed to update manually.
			if ( ! $result || is_wp_error( $result ) || ! isset( $past_failure_emails[ $theme ] ) ) {
				continue;
			}

			unset( $past_failure_emails[ $theme ] );
		}

		update_option( 'auto_plugin_theme_update_emails', $past_failure_emails );

		return $results;
	}

	/**
	 * Checks that the package source contains a valid theme.
	 *
	 * Hooked to the {@see 'upgrader_source_selection'} filter by Theme_Upgrader::install().
	 *
	 * @since 3.3.0
	 *
	 * @global WP_Filesystem_Base $wp_filesystem WordPress filesystem subclass.
	 * @global string             $wp_version    The WordPress version string.
	 *
	 * @param string $source The path to the downloaded package source.
	 * @return string|WP_Error The source as passed, or a WP_Error object on failure.
	 */
	public function check_package( $source ) {
		global $wp_filesystem, $wp_version;

		$this->new_theme_data = array();

		if ( is_wp_error( $source ) ) {
			return $source;
		}

		// Check that the folder contains a valid theme.
		$working_directory = str_replace( $wp_filesystem->wp_content_dir(), trailingslashit( WP_CONTENT_DIR ), $source );
		if ( ! is_dir( $working_directory ) ) { // Confidence check, if the above fails, let's not prevent installation.
			return $source;
		}

		// A proper archive should have a style.css file in the single subdirectory.
		if ( ! file_exists( $working_directory . 'style.css' ) ) {
			return new WP_Error(
				'incompatible_archive_theme_no_style',
				$this->strings['incompatible_archive'],
				sprintf(
					/* translators: %s: style.css */
					__( 'The theme is missing the %s stylesheet.' ),
					'<code>style.css</code>'
				)
			);
		}

		// All these headers are needed on Theme_Installer_Skin::do_overwrite().
		$info = get_file_data(
			$working_directory . 'style.css',
			array(
				'Name'        => 'Theme Name',
				'Version'     => 'Version',
				'Author'      => 'Author',
				'Template'    => 'Template',
				'RequiresWP'  => 'Requires at least',
				'RequiresPHP' => 'Requires PHP',
			)
		);

		if ( empty( $info['Name'] ) ) {
			return new WP_Error(
				'incompatible_archive_theme_no_name',
				$this->strings['incompatible_archive'],
				sprintf(
					/* translators: %s: style.css */
					__( 'The %s stylesheet does not contain a valid theme header.' ),
					'<code>style.css</code>'
				)
			);
		}

		/*
		 * Parent themes must contain an index file:
		 * - classic themes require /index.php
		 * - block themes require /templates/index.html or block-templates/index.html (deprecated 5.9.0).
		 */
		if (
			empty( $info['Template'] ) &&
			! file_exists( $working_directory . 'index.php' ) &&
			! file_exists( $working_directory . 'templates/index.html' ) &&
			! file_exists( $working_directory . 'block-templates/index.html' )
		) {
			return new WP_Error(
				'incompatible_archive_theme_no_index',
				$this->strings['incompatible_archive'],
				sprintf(
					/* translators: 1: templates/index.html, 2: index.php, 3: Documentation URL, 4: Template, 5: style.css */
					__( 'Template is missing. Standalone themes need to have a %1$s or %2$s template file. <a href="%3$s">Child themes</a> need to have a %4$s header in the %5$s stylesheet.' ),
					'<code>templates/index.html</code>',
					'<code>index.php</code>',
					__( 'https://developer.wordpress.org/themes/advanced-topics/child-themes/' ),
					'<code>Template</code>',
					'<code>style.css</code>'
				)
			);
		}

		$requires_php = isset( $info['RequiresPHP'] ) ? $info['RequiresPHP'] : null;
		$requires_wp  = isset( $info['RequiresWP'] ) ? $info['RequiresWP'] : null;

		if ( ! is_php_version_compatible( $requires_php ) ) {
			$error = sprintf(
				/* translators: 1: Current PHP version, 2: Version required by the uploaded theme. */
				__( 'The PHP version on your server is %1$s, however the uploaded theme requires %2$s.' ),
				PHP_VERSION,
				$requires_php
			);

			return new WP_Error( 'incompatible_php_required_version', $this->strings['incompatible_archive'], $error );
		}
		if ( ! is_wp_version_compatible( $requires_wp ) ) {
			$error = sprintf(
				/* translators: 1: Current WordPress version, 2: Version required by the uploaded theme. */
				__( 'Your WordPress version is %1$s, however the uploaded theme requires %2$s.' ),
				$wp_version,
				$requires_wp
			);

			return new WP_Error( 'incompatible_wp_required_version', $this->strings['incompatible_archive'], $error );
		}

		$this->new_theme_data = $info;

		return $source;
	}

	/**
	 * Turns on maintenance mode before attempting to upgrade the active theme.
	 *
	 * Hooked to the {@see 'upgrader_pre_install'} filter by Theme_Upgrader::upgrade() and
	 * Theme_Upgrader::bulk_upgrade().
	 *
	 * @since 2.8.0
	 *
	 * @param bool|WP_Error $response The installation response before the installation has started.
	 * @param array         $theme    Theme arguments.
	 * @return bool|WP_Error The original `$response` parameter or WP_Error.
	 */
	public function current_before( $response, $theme ) {
		if ( is_wp_error( $response ) ) {
			return $response;
		}

		$theme = isset( $theme['theme'] ) ? $theme['theme'] : '';

		// Only run if active theme.
		if ( get_stylesheet() !== $theme ) {
			return $response;
		}

		// Change to maintenance mode. Bulk edit handles this separately.
		if ( ! $this->bulk ) {
			$this->maintenance_mode( true );
		}

		return $response;
	}

	/**
	 * Turns off maintenance mode after upgrading the active theme.
	 *
	 * Hooked to the {@see 'upgrader_post_install'} filter by Theme_Upgrader::upgrade()
	 * and Theme_Upgrader::bulk_upgrade().
	 *
	 * @since 2.8.0
	 *
	 * @param bool|WP_Error $response The installation response after the installation has finished.
	 * @param array         $theme    Theme arguments.
	 * @return bool|WP_Error The original `$response` parameter or WP_Error.
	 */
	public function current_after( $response, $theme ) {
		if ( is_wp_error( $response ) ) {
			return $response;
		}

		$theme = isset( $theme['theme'] ) ? $theme['theme'] : '';

		// Only run if active theme.
		if ( get_stylesheet() !== $theme ) {
			return $response;
		}

		// Ensure stylesheet name hasn't changed after the upgrade:
		if ( get_stylesheet() === $theme && $theme !== $this->result['destination_name'] ) {
			wp_clean_themes_cache();
			$stylesheet = $this->result['destination_name'];
			switch_theme( $stylesheet );
		}

		// Time to remove maintenance mode. Bulk edit handles this separately.
		if ( ! $this->bulk ) {
			$this->maintenance_mode( false );
		}
		return $response;
	}

	/**
	 * Deletes the old theme during an upgrade.
	 *
	 * Hooked to the {@see 'upgrader_clear_destination'} filter by Theme_Upgrader::upgrade()
	 * and Theme_Upgrader::bulk_upgrade().
	 *
	 * @since 2.8.0
	 *
	 * @global WP_Filesystem_Base $wp_filesystem Subclass
	 *
	 * @param bool   $removed
	 * @param string $local_destination
	 * @param string $remote_destination
	 * @param array  $theme
	 * @return bool
	 */
	public function delete_old_theme( $removed, $local_destination, $remote_destination, $theme ) {
		global $wp_filesystem;

		if ( is_wp_error( $removed ) ) {
			return $removed; // Pass errors through.
		}

		if ( ! isset( $theme['theme'] ) ) {
			return $removed;
		}

		$theme      = $theme['theme'];
		$themes_dir = trailingslashit( $wp_filesystem->wp_themes_dir( $theme ) );
		if ( $wp_filesystem->exists( $themes_dir . $theme ) ) {
			if ( ! $wp_filesystem->delete( $themes_dir . $theme, true ) ) {
				return false;
			}
		}

		return true;
	}

	/**
	 * Gets the WP_Theme object for a theme.
	 *
	 * @since 2.8.0
	 * @since 3.0.0 The `$theme` argument was added.
	 *
	 * @param string $theme The directory name of the theme. This is optional, and if not supplied,
	 *                      the directory name from the last result will be used.
	 * @return WP_Theme|false The theme's info object, or false `$theme` is not supplied
	 *                        and the last result isn't set.
	 */
	public function theme_info( $theme = null ) {
		if ( empty( $theme ) ) {
			if ( ! empty( $this->result['destination_name'] ) ) {
				$theme = $this->result['destination_name'];
			} else {
				return false;
			}
		}

		$theme = wp_get_theme( $theme );
		$theme->cache_delete();

		return $theme;
	}
}