WP_Automatic_Updater::send_plugin_theme_email

	protected function send_plugin_theme_email( $type, $successful_updates, $failed_updates ) {
		// No updates were attempted.
		if ( empty( $successful_updates ) && empty( $failed_updates ) ) {
			return;
		}

		$unique_failures     = false;
		$past_failure_emails = get_option( 'auto_plugin_theme_update_emails', array() );

		/*
		 * When only failures have occurred, an email should only be sent if there are unique failures.
		 * A failure is considered unique if an email has not been sent for an update attempt failure
		 * to a plugin or theme with the same new_version.
		 */
		if ( 'fail' === $type ) {
			foreach ( $failed_updates as $update_type => $failures ) {
				foreach ( $failures as $failed_update ) {
					if ( ! isset( $past_failure_emails[ $failed_update->item->{$update_type} ] ) ) {
						$unique_failures = true;
						continue;
					}

					// Check that the failure represents a new failure based on the new_version.
					if ( version_compare( $past_failure_emails[ $failed_update->item->{$update_type} ], $failed_update->item->new_version, '<' ) ) {
						$unique_failures = true;
					}
				}
			}

			if ( ! $unique_failures ) {
				return;
			}
		}

		$body               = array();
		$successful_plugins = ( ! empty( $successful_updates['plugin'] ) );
		$successful_themes  = ( ! empty( $successful_updates['theme'] ) );
		$failed_plugins     = ( ! empty( $failed_updates['plugin'] ) );
		$failed_themes      = ( ! empty( $failed_updates['theme'] ) );

		switch ( $type ) {
			case 'success':
				if ( $successful_plugins && $successful_themes ) {
					/* translators: %s: Site title. */
					$subject = __( '[%s] Some plugins and themes have automatically updated' );
					$body[]  = sprintf(
						/* translators: %s: Home URL. */
						__( 'Howdy! Some plugins and themes have automatically updated to their latest versions on your site at %s. No further action is needed on your part.' ),
						home_url()
					);
				} elseif ( $successful_plugins ) {
					/* translators: %s: Site title. */
					$subject = __( '[%s] Some plugins were automatically updated' );
					$body[]  = sprintf(
						/* translators: %s: Home URL. */
						__( 'Howdy! Some plugins have automatically updated to their latest versions on your site at %s. No further action is needed on your part.' ),
						home_url()
					);
				} else {
					/* translators: %s: Site title. */
					$subject = __( '[%s] Some themes were automatically updated' );
					$body[]  = sprintf(
						/* translators: %s: Home URL. */
						__( 'Howdy! Some themes have automatically updated to their latest versions on your site at %s. No further action is needed on your part.' ),
						home_url()
					);
				}

				break;
			case 'fail':
			case 'mixed':
				if ( $failed_plugins && $failed_themes ) {
					/* translators: %s: Site title. */
					$subject = __( '[%s] Some plugins and themes have failed to update' );
					$body[]  = sprintf(
						/* translators: %s: Home URL. */
						__( 'Howdy! Plugins and themes failed to update on your site at %s.' ),
						home_url()
					);
				} elseif ( $failed_plugins ) {
					/* translators: %s: Site title. */
					$subject = __( '[%s] Some plugins have failed to update' );
					$body[]  = sprintf(
						/* translators: %s: Home URL. */
						__( 'Howdy! Plugins failed to update on your site at %s.' ),
						home_url()
					);
				} else {
					/* translators: %s: Site title. */
					$subject = __( '[%s] Some themes have failed to update' );
					$body[]  = sprintf(
						/* translators: %s: Home URL. */
						__( 'Howdy! Themes failed to update on your site at %s.' ),
						home_url()
					);
				}

				break;
		}

		if ( in_array( $type, array( 'fail', 'mixed' ), true ) ) {
			$body[] = "\n";
			$body[] = __( 'Please check your site now. It’s possible that everything is working. If there are updates available, you should update.' );
			$body[] = "\n";

			// List failed plugin updates.
			if ( ! empty( $failed_updates['plugin'] ) ) {
				$body[] = __( 'These plugins failed to update:' );

				foreach ( $failed_updates['plugin'] as $item ) {
					$body[] = sprintf(
						/* translators: 1: Plugin name, 2: Version number. */
						__( '- %1$s version %2$s' ),
						$item->name,
						$item->item->new_version
					);

					$past_failure_emails[ $item->item->plugin ] = $item->item->new_version;
				}

				$body[] = "\n";
			}

			// List failed theme updates.
			if ( ! empty( $failed_updates['theme'] ) ) {
				$body[] = __( 'These themes failed to update:' );

				foreach ( $failed_updates['theme'] as $item ) {
					$body[] = sprintf(
						/* translators: 1: Theme name, 2: Version number. */
						__( '- %1$s version %2$s' ),
						$item->name,
						$item->item->new_version
					);

					$past_failure_emails[ $item->item->theme ] = $item->item->new_version;
				}

				$body[] = "\n";
			}
		}

		// List successful updates.
		if ( in_array( $type, array( 'success', 'mixed' ), true ) ) {
			$body[] = "\n";

			// List successful plugin updates.
			if ( ! empty( $successful_updates['plugin'] ) ) {
				$body[] = __( 'These plugins are now up to date:' );

				foreach ( $successful_updates['plugin'] as $item ) {
					$body[] = sprintf(
						/* translators: 1: Plugin name, 2: Version number. */
						__( '- %1$s version %2$s' ),
						$item->name,
						$item->item->new_version
					);

					unset( $past_failure_emails[ $item->item->plugin ] );
				}

				$body[] = "\n";
			}

			// List successful theme updates.
			if ( ! empty( $successful_updates['theme'] ) ) {
				$body[] = __( 'These themes are now up to date:' );

				foreach ( $successful_updates['theme'] as $item ) {
					$body[] = sprintf(
						/* translators: 1: Theme name, 2: Version number. */
						__( '- %1$s version %2$s' ),
						$item->name,
						$item->item->new_version
					);

					unset( $past_failure_emails[ $item->item->theme ] );
				}

				$body[] = "\n";
			}
		}

		if ( $failed_plugins ) {
			$body[] = sprintf(
				/* translators: %s: Plugins screen URL. */
				__( 'To manage plugins on your site, visit the Plugins page: %s' ),
				admin_url( 'plugins.php' )
			);
			$body[] = "\n";
		}

		if ( $failed_themes ) {
			$body[] = sprintf(
				/* translators: %s: Themes screen URL. */
				__( 'To manage themes on your site, visit the Themes page: %s' ),
				admin_url( 'themes.php' )
			);
			$body[] = "\n";
		}

		// Add a note about the support forums.
		$body[] = __( 'If you experience any issues or need support, the volunteers in the WordPress.org support forums may be able to help.' );
		$body[] = __( 'https://wordpress.org/support/forums/' );
		$body[] = "\n" . __( 'The WordPress Team' );

		$body    = implode( "\n", $body );
		$to      = get_site_option( 'admin_email' );
		$subject = sprintf( $subject, wp_specialchars_decode( get_option( 'blogname' ), ENT_QUOTES ) );
		$headers = '';

		$email = compact( 'to', 'subject', 'body', 'headers' );

		/**
		 * Filters the email sent following an automatic background update for plugins and themes.
		 *
		 * @since 5.5.0
		 *
		 * @param array  $email {
		 *     Array of email arguments that will be passed to wp_mail().
		 *
		 *     @type string $to      The email recipient. An array of emails
		 *                           can be returned, as handled by wp_mail().
		 *     @type string $subject The email's subject.
		 *     @type string $body    The email message body.
		 *     @type string $headers Any email headers, defaults to no headers.
		 * }
		 * @param string $type               The type of email being sent. Can be one of 'success', 'fail', 'mixed'.
		 * @param array  $successful_updates A list of updates that succeeded.
		 * @param array  $failed_updates     A list of updates that failed.
		 */
		$email = apply_filters( 'auto_plugin_theme_update_email', $email, $type, $successful_updates, $failed_updates );

		$result = wp_mail( $email['to'], wp_specialchars_decode( $email['subject'] ), $email['body'], $email['headers'] );

		if ( $result ) {
			update_option( 'auto_plugin_theme_update_emails', $past_failure_emails );
		}
	}