<?php
/*
	Plugin Name: Health Check Troubleshooting Mode
	Description: Conditionally disabled themes or plugins on your site for a given session, used to rule out conflicts during troubleshooting.
	Version: 1.8.1
 */

if ( ! defined( 'ABSPATH' ) ) {
	die( 'We\'re sorry, but you can not directly access this file.' );
}

// Set the MU plugin version.
define( 'HEALTH_CHECK_TROUBLESHOOTING_MODE_PLUGIN_VERSION', '1.8.1' );

class Health_Check_Troubleshooting_MU {
	private $disable_hash    = null;
	private $override_active = true;
	private $default_theme   = true;
	private $active_plugins  = array();
	private $allowed_plugins = array();
	private $current_theme;
	private $current_theme_details;
	private $self_fetching_theme = false;

	private $available_query_args = array(
		'wp-health-check-disable-plugins',
		'health-check-disable-plugins-hash',
		'health-check-disable-troubleshooting',
		'health-check-change-active-theme',
		'health-check-troubleshoot-enable-plugin',
		'health-check-troubleshoot-disable-plugin',
		'health-check-plugin-force-enable',
		'health-check-plugin-force-disable',
		'health-check-theme-force-switch',
	);

	private $default_themes = array(
		'twentytwentytwo',
		'twentytwentyone',
		'twentytwenty',
		'twentynineteen',
		'twentyseventeen',
		'twentysixteen',
		'twentyfifteen',
		'twentyfourteen',
		'twentythirteen',
		'twentytwelve',
		'twentyeleven',
		'twentyten',
	);

	/**
	 * Health_Check_Troubleshooting_MU constructor.
	 */
	public function __construct() {
		$this->init();
	}

	/**
	 * Actually initiation of the plugin.
	 *
	 * @return void
	 */
	public function init() {
		add_filter( 'option_active_plugins', array( $this, 'health_check_loopback_test_disable_plugins' ) );
		add_filter( 'option_active_sitewide_plugins', array( $this, 'health_check_loopback_test_disable_plugins' ) );

		add_filter( 'pre_option_template', array( $this, 'health_check_troubleshoot_theme_template' ) );
		add_filter( 'pre_option_stylesheet', array( $this, 'health_check_troubleshoot_theme_stylesheet' ) );

		add_filter( 'bulk_actions-plugins', array( $this, 'remove_plugin_bulk_actions' ) );
		add_filter( 'handle_bulk_actions-plugins', array( $this, 'handle_plugin_bulk_actions' ), 10, 3 );

		$this->load_options();

		// If troubleshooting mode is enabled, add special filters and actions.
		if ( $this->is_troubleshooting() ) {
			// Attempt to avoid cache entries from a troubleshooting session.
			wp_suspend_cache_addition( true );

			// Add nocache headers for browser caches.
			add_action( 'init', 'nocache_headers' );
			add_action( 'admin_init', 'nocache_headers' );

			add_action( 'admin_enqueue_scripts', array( $this, 'enqueue_assets' ) );

			add_action( 'admin_bar_menu', array( $this, 'health_check_troubleshoot_menu_bar' ), 999 );

			add_filter( 'wp_fatal_error_handler_enabled', '__return_false' );

			add_action( 'admin_notices', array( $this, 'prompt_install_default_theme' ) );
			add_filter( 'user_has_cap', array( $this, 'remove_plugin_theme_install' ) );

			add_action( 'plugin_action_links', array( $this, 'plugin_actions' ), 50, 4 );

			add_action( 'admin_notices', array( $this, 'display_dashboard_widget' ) );
			add_action( 'admin_footer', array( $this, 'dashboard_widget_scripts' ) );

			add_action( 'wp_logout', array( $this, 'health_check_troubleshooter_mode_logout' ) );
			add_action( 'init', array( $this, 'health_check_troubleshoot_get_captures' ) );

			/*
			 * Plugin activations can be forced by other tools in things like themes, so let's
			 * attempt to work around that by forcing plugin lists back and forth.
			 *
			 * This is not an ideal scenario, but one we must accept as reality.
			 */
			add_action( 'activated_plugin', array( $this, 'plugin_activated' ) );
		}
	}

	/**
	 * Set up the class variables based on option table entries.
	 *
	 * @return void
	 */
	public function load_options() {
		$this->disable_hash    = get_option( 'health-check-disable-plugin-hash', null );
		$this->allowed_plugins = get_option( 'health-check-allowed-plugins', array() );
		$this->default_theme   = ( 'yes' === get_option( 'health-check-default-theme', 'yes' ) ? true : false );
		$this->active_plugins  = $this->get_unfiltered_plugin_list();
		$this->current_theme   = get_option( 'health-check-current-theme', false );
	}

	/**
	 * Enqueue styles and scripts used by the MU plugin if applicable.
	 *
	 * @return void
	 */
	public function enqueue_assets() {
		if ( ! is_admin() ) {
			return;
		}

		wp_enqueue_style( 'health-check', plugins_url( '/health-check/build/health-check.css' ), array(), HEALTH_CHECK_TROUBLESHOOTING_MODE_PLUGIN_VERSION );

		if ( ! wp_script_is( 'site-health', 'registered' ) ) {
			wp_enqueue_script( 'site-health', plugins_url( '/health-check/build/health-check.js' ), array( 'jquery', 'wp-a11y', 'wp-util' ), HEALTH_CHECK_TROUBLESHOOTING_MODE_PLUGIN_VERSION, true );
		}

		wp_enqueue_script( 'health-check', plugins_url( '/health-check/build/troubleshooting-mode.js' ), array( 'site-health' ), HEALTH_CHECK_TROUBLESHOOTING_MODE_PLUGIN_VERSION, true );
	}

	/**
	 * Add a prompt to install a default theme.
	 *
	 * If no default theme exists, we can't reliably assert if an issue is
	 * caused by the theme. In these cases we should provide an easy step
	 * to get to, and install, one of the default themes.
	 *
	 * @return void
	 */
	public function prompt_install_default_theme() {
		if ( $this->has_default_theme() ) {
			return;
		}

		printf(
			'<div class="notice notice-warning dismissable"><p>%s</p><p><a href="%s" class="button button-primary">%s</a></p></div>',
			esc_html__( 'You don\'t have any of the default themes installed. A default theme helps you determine if your current theme is causing conflicts.', 'health-check' ),
			esc_url(
				admin_url(
					sprintf(
						'theme-install.php?theme=%s',
						$this->default_themes[0]
					)
				)
			),
			esc_html__( 'Install a default theme', 'health-check' )
		);
	}

	/**
	 * Remove the `Add` option for plugins and themes.
	 *
	 * When troubleshooting, adding or changing themes and plugins can
	 * lead to unexpected results. Remove these menu items to make it less
	 * likely that a user breaks their site through these.
	 *
	 * @param  array $caps Array containing the current users capabilities.
	 *
	 * @return array
	 */
	public function remove_plugin_theme_install( $caps ) {
		$caps['switch_themes'] = false;

		/*
		 * This is to early for `get_current_screen()`, so we have to do it the
		 * old fashioned way with `$_SERVER`.
		 */
		if ( 'plugin-install.php' === substr( $_SERVER['REQUEST_URI'], -18 ) ) {
			$caps['activate_plugins'] = false;
		}

		return $caps;
	}

	/**
	 * Fire on plugin activation.
	 *
	 * When in Troubleshooting Mode, plugin activations
	 * will clear out the DB entry for `active_plugins`, this is bad.
	 *
	 * We fix this by re-setting the DB entry if anything tries
	 * to modify it during troubleshooting.
	 *
	 * @return void
	 */
	public function plugin_activated() {
		// Force the database entry for active plugins if someone tried changing plugins while in Troubleshooting Mode.
		update_option( 'active_plugins', $this->active_plugins );
	}

	public function handle_plugin_bulk_actions( $sendback, $action, $plugins ) {
		if ( ! $this->is_troubleshooting() && 'health-check-troubleshoot' !== $action ) {
			return $sendback;
		}

		$sendback = self_admin_url( 'plugins.php' );

		if ( 'health-check-troubleshoot' === $action ) {
			foreach ( $plugins as $single_plugin ) {
				$plugin_slug = explode( '/', $single_plugin );
				$plugin_slug = $plugin_slug[0];

				if ( in_array( $single_plugin, $this->active_plugins, true ) ) {
					$this->allowed_plugins[ $plugin_slug ] = $plugin_slug;
				}
			}

			Health_Check_Troubleshoot::initiate_troubleshooting_mode( $this->allowed_plugins );

			if ( ! $this->test_site_state() ) {
				$this->allowed_plugins = array();
				update_option( 'health-check-allowed-plugins', $this->allowed_plugins );

				$this->add_dashboard_notice(
					__( 'When enabling troubleshooting on the selected plugins, a site failure occurred. Because of this the selected plugins were kept disabled while troubleshooting mode started.', 'health-check' ),
					'warning'
				);
			}
		}

		if ( 'health-check-enable' === $action ) {
			$old_allowed_plugins = $this->allowed_plugins;

			foreach ( $plugins as $single_plugin ) {
				$plugin_slug = explode( '/', $single_plugin );
				$plugin_slug = $plugin_slug[0];

				if ( in_array( $single_plugin, $this->active_plugins, true ) ) {
					$this->allowed_plugins[ $plugin_slug ] = $plugin_slug;
				}
			}

			update_option( 'health-check-allowed-plugins', $this->allowed_plugins );

			if ( ! $this->test_site_state() ) {
				$this->allowed_plugins = $old_allowed_plugins;
				update_option( 'health-check-allowed-plugins', $old_allowed_plugins );

				$this->add_dashboard_notice(
					__( 'When bulk-enabling plugins, a site failure occurred. Because of this the change was automatically reverted.', 'health-check' ),
					'warning'
				);
			}
		}

		if ( 'health-check-disable' === $action ) {
			$old_allowed_plugins = $this->allowed_plugins;

			foreach ( $plugins as $single_plugin ) {
				$plugin_slug = explode( '/', $single_plugin );
				$plugin_slug = $plugin_slug[0];

				if ( in_array( $single_plugin, $this->active_plugins, true ) ) {
					unset( $this->allowed_plugins[ $plugin_slug ] );
				}
			}

			update_option( 'health-check-allowed-plugins', $this->allowed_plugins );

			if ( ! $this->test_site_state() ) {
				$this->allowed_plugins = $old_allowed_plugins;
				update_option( 'health-check-allowed-plugins', $old_allowed_plugins );

				$this->add_dashboard_notice(
					__( 'When bulk-disabling plugins, a site failure occurred. Because of this the change was automatically reverted.', 'health-check' ),
					'warning'
				);
			}
		}

		return $sendback;
	}

	public function remove_plugin_bulk_actions( $actions ) {
		if ( ! $this->is_troubleshooting() ) {
			$actions['health-check-troubleshoot'] = __( 'Troubleshoot', 'health-check' );

			return $actions;
		}

		$actions = array(
			'health-check-enable'  => __( 'Enable while troubleshooting', 'health-check' ),
			'health-check-disable' => __( 'Disable while troubleshooting', 'health-check' ),
		);

		return $actions;
	}

	/**
	 * Modify plugin actions.
	 *
	 * While in Troubleshooting Mode, weird things will happen if you start
	 * modifying your plugin list. Prevent this, but also add in the ability
	 * to enable or disable a plugin during troubleshooting from this screen.
	 *
	 * @param $actions
	 * @param $plugin_file
	 * @param $plugin_data
	 * @param $context
	 *
	 * @return array
	 */
	public function plugin_actions( $actions, $plugin_file, $plugin_data, $context ) {
		if ( 'mustuse' === $context ) {
			return $actions;
		}

		/*
		 * Disable all plugin actions when in Troubleshooting Mode.
		 *
		 * We intentionally remove all plugin actions to avoid accidental clicking, activating or deactivating plugins
		 * while our plugin is altering plugin data may lead to unexpected behaviors, so to keep things sane we do
		 * not allow users to perform any actions during this time.
		 */
		$actions = array();

		// This isn't an active plugin, so does not apply to our troubleshooting scenarios.
		if ( ! in_array( $plugin_file, $this->active_plugins, true ) ) {
			return $actions;
		}

		// Set a slug if the plugin lives in the plugins directory root.
		if ( ! stristr( $plugin_file, '/' ) ) {
			$plugin_slug = $plugin_file;
		} else { // Set the slug for plugin inside a folder.
			$plugin_slug = explode( '/', $plugin_file );
			$plugin_slug = $plugin_slug[0];
		}

		if ( in_array( $plugin_slug, $this->allowed_plugins, true ) ) {
			$actions['troubleshoot-disable'] = sprintf(
				'<a href="%s">%s</a>',
				esc_url(
					add_query_arg(
						array(
							'health-check-troubleshoot-disable-plugin' => $plugin_slug,
						),
						admin_url( 'plugins.php' )
					)
				),
				esc_html__( 'Disable while troubleshooting', 'health-check' )
			);
		} else {
			$actions['troubleshoot-disable'] = sprintf(
				'<a href="%s">%s</a>',
				esc_url(
					add_query_arg(
						array(
							'health-check-troubleshoot-enable-plugin' => $plugin_slug,
						),
						admin_url( 'plugins.php' )
					)
				),
				esc_html__( 'Enable while troubleshooting', 'health-check' )
			);
		}

		return $actions;
	}

	/**
	 * Get the actual list of active plugins.
	 *
	 * When in Troubleshooting Mode we override the list of plugins,
	 * this function lets us grab the active plugins list without
	 * any interference.
	 *
	 * @return array Array of active plugins.
	 */
	public function get_unfiltered_plugin_list() {
		$this->override_active = false;
		$all_plugins           = get_option( 'active_plugins' );
		$this->override_active = true;

		return $all_plugins;
	}

	/**
	 * Check if the user is currently in Troubleshooting Mode or not.
	 *
	 * @return bool
	 */
	public function is_troubleshooting() {
		// Check if a session cookie to disable plugins has been set.
		if ( isset( $_COOKIE['wp-health-check-disable-plugins'] ) ) {
			$_GET['health-check-disable-plugin-hash'] = $_COOKIE['wp-health-check-disable-plugins'] . md5( $_SERVER['REMOTE_ADDR'] );
		}

		// If the disable hash isn't set, no need to interact with things.
		if ( ! isset( $_GET['health-check-disable-plugin-hash'] ) ) {
			return false;
		}

		if ( empty( $this->disable_hash ) ) {
			return false;
		}

		// If the plugin hash is not valid, we also break out
		if ( $this->disable_hash !== $_GET['health-check-disable-plugin-hash'] ) {
			return false;
		}

		return true;
	}

	/**
	 * Filter the plugins that are activated in WordPress.
	 *
	 * @param array $plugins An array of plugins marked as active.
	 *
	 * @return array
	 */
	function health_check_loopback_test_disable_plugins( $plugins ) {
		if ( ! $this->is_troubleshooting() || ! $this->override_active ) {
			return $plugins;
		}

		// If we've received a comma-separated list of allowed plugins, we'll add them to the array of allowed plugins.
		if ( isset( $_GET['health-check-allowed-plugins'] ) ) {
			$this->allowed_plugins = explode( ',', $_GET['health-check-allowed-plugins'] );
		}

		foreach ( $plugins as $plugin_no => $plugin_path ) {
			// Split up the plugin path, [0] is the slug and [1] holds the primary plugin file.
			$plugin_parts = explode( '/', $plugin_path );

			// We may want to allow individual, or groups of plugins, so introduce a skip-mechanic for those scenarios.
			if ( in_array( $plugin_parts[0], $this->allowed_plugins, true ) ) {
				continue;
			}

			// Remove the reference to this plugin.
			unset( $plugins[ $plugin_no ] );
		}

		// Return a possibly modified list of activated plugins.
		return $plugins;
	}

	/**
	 * Check if a default theme exists.
	 *
	 * If a default theme exists, return the most recent one, if not return `false`.
	 *
	 * @return bool|string
	 */
	function has_default_theme() {
		foreach ( $this->default_themes as $default_theme ) {
			if ( $this->theme_exists( $default_theme ) ) {
				return $default_theme;
			}
		}

		return false;
	}

	/**
	 * Check if a theme exists by looking for the slug.
	 *
	 * @param string $theme_slug
	 *
	 * @return bool
	 */
	function theme_exists( $theme_slug ) {
		return is_dir( WP_CONTENT_DIR . '/themes/' . $theme_slug );
	}

	/**
	 * Check if theme overrides are active.
	 *
	 * @return bool
	 */
	function override_theme() {
		if ( ! $this->is_troubleshooting() ) {
			return false;
		}

		return true;
	}

	/**
	 * Override the default theme.
	 *
	 * Attempt to set one of the default themes, or a theme of the users choosing, as the active one
	 * during Troubleshooting Mode.
	 *
	 * @param $default
	 *
	 * @return bool|string
	 */
	function health_check_troubleshoot_theme_stylesheet( $default ) {
		if ( $this->self_fetching_theme ) {
			return $default;
		}

		if ( ! $this->override_theme() ) {
			return $default;
		}

		if ( empty( $this->current_theme_details ) ) {
			$this->self_fetching_theme   = true;
			$this->current_theme_details = wp_get_theme( $this->current_theme );
			$this->self_fetching_theme   = false;
		}

		// If no theme has been chosen, start off by troubleshooting as a default theme if one exists.
		$default_theme = $this->has_default_theme();
		if ( false === $this->current_theme ) {
			if ( $default_theme ) {
				return $default_theme;
			}
		}

		return $this->current_theme;
	}

	/**
	 * Override the default parent theme.
	 *
	 * If this is a child theme, override the parent and provide our users chosen themes parent instead.
	 *
	 * @param $default
	 *
	 * @return bool|string
	 */
	function health_check_troubleshoot_theme_template( $default ) {
		if ( $this->self_fetching_theme ) {
			return $default;
		}

		if ( ! $this->override_theme() ) {
			return $default;
		}

		if ( empty( $this->current_theme_details ) ) {
			$this->self_fetching_theme   = true;
			$this->current_theme_details = wp_get_theme( $this->current_theme );
			$this->self_fetching_theme   = false;
		}

		// If no theme has been chosen, start off by troubleshooting as a default theme if one exists.
		$default_theme = $this->has_default_theme();
		if ( false === $this->current_theme ) {
			if ( $default_theme ) {
				return $default_theme;
			}
		}

		if ( $this->current_theme_details->parent() ) {
			return $this->current_theme_details->get_template();
		}

		return $this->current_theme;
	}

	/**
	 * Disable Troubleshooting Mode on logout.
	 *
	 * If logged in, disable the Troubleshooting Mode when the logout
	 * event is fired, this ensures we start with a clean slate on
	 * the next login.
	 *
	 * @return void
	 */
	function health_check_troubleshooter_mode_logout() {
		if ( isset( $_COOKIE['wp-health-check-disable-plugins'] ) ) {
			$this->disable_troubleshooting_mode();
		}
	}

	function disable_troubleshooting_mode() {
		unset( $_COOKIE['wp-health-check-disable-plugins'] );
		setcookie( 'wp-health-check-disable-plugins', null, 0, COOKIEPATH, COOKIE_DOMAIN );
		delete_option( 'health-check-allowed-plugins' );
		delete_option( 'health-check-default-theme' );
		delete_option( 'health-check-current-theme' );

		delete_option( 'health-check-backup-plugin-list' );
	}

	/**
	 * Catch query arguments.
	 *
	 * When in Troubleshooting Mode, look for various GET variables that trigger
	 * various plugin actions.
	 *
	 * @return void
	 */
	function health_check_troubleshoot_get_captures() {
		// Disable Troubleshooting Mode.
		if ( isset( $_GET['health-check-disable-troubleshooting'] ) ) {
			$this->disable_troubleshooting_mode();

			wp_redirect( remove_query_arg( $this->available_query_args ) );
			die();
		}

		// Dismiss notices.
		if ( isset( $_GET['health-check-dismiss-notices'] ) && $this->is_troubleshooting() && is_admin() ) {
			update_option( 'health-check-dashboard-notices', array() );

			wp_redirect( admin_url() );
			die();
		}

		// Enable an individual plugin.
		if ( isset( $_GET['health-check-troubleshoot-enable-plugin'] ) ) {
			$old_allowed_plugins = $this->allowed_plugins;

			$this->allowed_plugins[ $_GET['health-check-troubleshoot-enable-plugin'] ] = $_GET['health-check-troubleshoot-enable-plugin'];

			update_option( 'health-check-allowed-plugins', $this->allowed_plugins );

			if ( isset( $_GET['health-check-plugin-force-enable'] ) ) {
				$this->add_dashboard_notice(
					sprintf(
						// translators: %s: The plugin slug.
						'The %s plugin was forcefully enabled.',
						$_GET['health-check-troubleshoot-enable-plugin']
					),
					'info'
				);
			}

			if ( ! $this->test_site_state() && ! isset( $_GET['health-check-plugin-force-enable'] ) ) {
				$this->allowed_plugins = $old_allowed_plugins;
				update_option( 'health-check-allowed-plugins', $old_allowed_plugins );

				$notice = sprintf(
					// Translators: %1$s: The link-button markup to force enable the plugin. %2$s: The force-enable link markup.
					__( 'When enabling the plugin, %1$s, a site failure occurred. Because of this the change was automatically reverted. %2$s', 'health-check' ),
					$_GET['health-check-troubleshoot-enable-plugin'],
					sprintf(
						'<a href="%s" aria-label="%s">%s</a>',
						esc_url(
							add_query_arg(
								array(
									'health-check-troubleshoot-enable-plugin' => $_GET['health-check-troubleshoot-enable-plugin'],
									'health-check-plugin-force-enable' => 'true',
								)
							)
						),
						esc_attr(
							sprintf(
								// translators: %s: Plugin name.
								__( 'Force-enable the plugin, %s, even though the loopback checks failed.', 'health-check' ),
								$_GET['health-check-troubleshoot-enable-plugin']
							)
						),
						__( 'Enable anyway', 'health-check' )
					)
				);

				$this->add_dashboard_notice(
					$notice,
					'warning'
				);
			}

			wp_redirect( remove_query_arg( $this->available_query_args ) );
			die();
		}

		// Disable an individual plugin.
		if ( isset( $_GET['health-check-troubleshoot-disable-plugin'] ) ) {
			$old_allowed_plugins = $this->allowed_plugins;

			unset( $this->allowed_plugins[ $_GET['health-check-troubleshoot-disable-plugin'] ] );

			update_option( 'health-check-allowed-plugins', $this->allowed_plugins );

			if ( isset( $_GET['health-check-plugin-force-disable'] ) ) {
				$this->add_dashboard_notice(
					sprintf(
						// translators: %s: The plugin slug.
						'The %s plugin was forcefully disabled.',
						$_GET['health-check-troubleshoot-disable-plugin']
					),
					'info'
				);
			}

			if ( ! $this->test_site_state() && ! isset( $_GET['health-check-plugin-force-disable'] ) ) {
				$this->allowed_plugins = $old_allowed_plugins;
				update_option( 'health-check-allowed-plugins', $old_allowed_plugins );

				$notice = sprintf(
					// Translators: %1$s: The plugin slug that was disabled. %2$s: The force-disable link markup.
					__( 'When disabling the plugin, %1$s, a site failure occurred. Because of this the change was automatically reverted. %2$s', 'health-check' ),
					$_GET['health-check-troubleshoot-disable-plugin'],
					sprintf(
						'<a href="%1$s" aria-label="%2$s">%3$s</a>',
						esc_url(
							add_query_arg(
								array(
									'health-check-troubleshoot-disable-plugin' => $_GET['health-check-troubleshoot-disable-plugin'],
									'health-check-plugin-force-disable' => 'true',
								)
							)
						),
						esc_attr(
							sprintf(
								// translators: %s: Plugin name.
								__( 'Force-disable the plugin, %s, even though the loopback checks failed.', 'health-check' ),
								$_GET['health-check-troubleshoot-disable-plugin']
							)
						),
						__( 'Disable anyway', 'health-check' )
					)
				);

				$this->add_dashboard_notice(
					$notice,
					'warning'
				);
			}

			wp_redirect( remove_query_arg( $this->available_query_args ) );
			die();
		}

		// Change the active theme for this session.
		if ( isset( $_GET['health-check-change-active-theme'] ) ) {
			$old_theme = get_option( 'health-check-current-theme' );

			update_option( 'health-check-current-theme', $_GET['health-check-change-active-theme'] );

			if ( isset( $_GET['health-check-theme-force-switch'] ) ) {
				$this->add_dashboard_notice(
					sprintf(
						// translators: %s: The theme slug.
						'The theme was forcefully switched to %s.',
						$_GET['health-check-change-active-theme']
					),
					'info'
				);
			}

			if ( ! $this->test_site_state() && ! isset( $_GET['health-check-theme-force-switch'] ) ) {
				update_option( 'health-check-current-theme', $old_theme );

				$notice = sprintf(
					// Translators: %1$s: The theme slug that was switched to.. %2$s: The force-enable link markup.
					__( 'When switching the active theme to %1$s, a site failure occurred. Because of this we reverted the theme to the one you used previously. %2$s', 'health-check' ),
					$_GET['health-check-change-active-theme'],
					sprintf(
						'<a href="%s" aria-label="%s">%s</a>',
						esc_url(
							add_query_arg(
								array(
									'health-check-change-active-theme' => $_GET['health-check-change-active-theme'],
									'health-check-theme-force-switch' => 'true',
								)
							)
						),
						esc_attr(
							sprintf(
								// translators: %s: Plugin name.
								__( 'Force-switch to the %s theme, even though the loopback checks failed.', 'health-check' ),
								$_GET['health-check-change-active-theme']
							)
						),
						__( 'Switch anyway', 'health-check' )
					)
				);

				$this->add_dashboard_notice(
					$notice,
					'warning'
				);
			}

			wp_redirect( remove_query_arg( $this->available_query_args ) );
			die();
		}
	}

	private function add_dashboard_notice( $message, $severity = 'notice' ) {
		$notices = get_option( 'health-check-dashboard-notices', array() );

		$notices[] = array(
			'severity' => $severity,
			'message'  => $message,
			'time'     => gmdate( 'Y-m-d H:i' ),
		);

		update_option( 'health-check-dashboard-notices', $notices );
	}

	/**
	 * Extend the admin bar.
	 *
	 * When in Troubleshooting Mode, introduce a new element to the admin bar to show
	 * enabled and disabled plugins (if conditions are met), switch between themes
	 * and disable Troubleshooting Mode altogether.
	 *
	 * @param WP_Admin_Bar $wp_menu
	 *
	 * @return void
	 */
	function health_check_troubleshoot_menu_bar( $wp_menu ) {
		// We need some admin functions to make this a better user experience, so include that file.
		if ( ! is_admin() ) {
			require_once( trailingslashit( ABSPATH ) . 'wp-admin/includes/plugin.php' );
		}

		// Make sure the updater tools are available since WordPress 5.5.0 auto-updates were introduced.
		if ( ! function_exists( 'wp_is_auto_update_enabled_for_type' ) ) {
			require_once( trailingslashit( ABSPATH ) . 'wp-admin/includes/update.php' );
		}

		// Ensure the theme functions are available to us on every page.
		include_once( trailingslashit( ABSPATH ) . 'wp-admin/includes/theme.php' );

		// Add top-level menu item.
		$wp_menu->add_menu(
			array(
				'id'    => 'health-check',
				'title' => esc_html__( 'Troubleshooting Mode', 'health-check' ),
				'href'  => admin_url( '/' ),
			)
		);

		// Add a link to manage plugins if there are more than 20 set to be active.
		if ( count( $this->active_plugins ) > 20 ) {
			$wp_menu->add_node(
				array(
					'id'     => 'health-check-plugins',
					'title'  => esc_html__( 'Manage active plugins', 'health-check' ),
					'parent' => 'health-check',
					'href'   => admin_url( 'plugins.php' ),
				)
			);
		} else {
			$wp_menu->add_node(
				array(
					'id'     => 'health-check-plugins',
					'title'  => esc_html__( 'Plugins', 'health-check' ),
					'parent' => 'health-check',
					'href'   => admin_url( 'plugins.php' ),
				)
			);

			$wp_menu->add_group(
				array(
					'id'     => 'health-check-plugins-enabled',
					'parent' => 'health-check-plugins',
				)
			);
			$wp_menu->add_group(
				array(
					'id'     => 'health-check-plugins-disabled',
					'parent' => 'health-check-plugins',
				)
			);

			foreach ( $this->active_plugins as $single_plugin ) {
				$plugin_slug = explode( '/', $single_plugin );
				$plugin_slug = $plugin_slug[0];

				$plugin_data = get_plugin_data( trailingslashit( WP_PLUGIN_DIR ) . $single_plugin );

				$enabled = true;

				if ( in_array( $plugin_slug, $this->allowed_plugins, true ) ) {
					$label = sprintf(
						// Translators: %s: Plugin slug.
						esc_html__( 'Disable %s', 'health-check' ),
						sprintf(
							'<strong>%s</strong>',
							$plugin_data['Name']
						)
					);
					$url = add_query_arg(
						array(
							'health-check-troubleshoot-disable-plugin' => $plugin_slug,
						)
					);
				} else {
					$enabled = false;
					$label   = sprintf(
						// Translators: %s: Plugin slug.
						esc_html__( 'Enable %s', 'health-check' ),
						sprintf(
							'<strong>%s</strong>',
							$plugin_data['Name']
						)
					);
					$url = add_query_arg(
						array(
							'health-check-troubleshoot-enable-plugin' => $plugin_slug,
						)
					);
				}

				$wp_menu->add_node(
					array(
						'id'     => sprintf(
							'health-check-plugin-%s',
							$plugin_slug
						),
						'title'  => $label,
						'parent' => ( $enabled ? 'health-check-plugins-enabled' : 'health-check-plugins-disabled' ),
						'href'   => $url,
					)
				);
			}
		}

		$wp_menu->add_node(
			array(
				'id'     => 'health-check-theme',
				'title'  => esc_html__( 'Themes', 'health-check' ),
				'parent' => 'health-check',
				'href'   => admin_url( 'themes.php' ),
			)
		);

		$themes = wp_prepare_themes_for_js();

		foreach ( $themes as $theme ) {
			$node = array(
				'id'     => sprintf(
					'health-check-theme-%s',
					sanitize_title( $theme['id'] )
				),
				'title'  => sprintf(
					'%s %s',
					( $theme['active'] ? esc_html_x( 'Active:', 'Prefix for the active theme in troubleshooting mode', 'health-check' ) : esc_html_x( 'Switch to', 'Prefix for inactive themes in troubleshooting mode', 'health-check' ) ),
					$theme['name']
				),
				'parent' => 'health-check-theme',
			);

			if ( ! $theme['active'] ) {
				$node['href'] = add_query_arg(
					array(
						'health-check-change-active-theme' => $theme['id'],
					)
				);
			}

			$wp_menu->add_node( $node );
		}

		// Add a link to disable Troubleshooting Mode.
		$wp_menu->add_node(
			array(
				'id'     => 'health-check-disable',
				'title'  => esc_html__( 'Disable Troubleshooting Mode', 'health-check' ),
				'parent' => 'health-check',
				'href'   => add_query_arg(
					array(
						'health-check-disable-troubleshooting' => true,
					)
				),
			)
		);
	}

	public function test_site_state() {

		// Make sure the Health_Check_Loopback class is available to us, in case the primary plugin is disabled.
		if ( ! method_exists( 'Health_Check_Loopback', 'can_perform_loopback' ) ) {
			$plugin_file = trailingslashit( WP_PLUGIN_DIR ) . 'health-check/HealthCheck/class-health-check-loopback.php';

			// Make sure the file exists, in case someone deleted the plugin manually, we don't want any errors.
			if ( ! file_exists( $plugin_file ) ) {

				// If the plugin files are inaccessible, we can't guarantee for the state of the site, so the default is a bad response.
				return false;
			}

			require_once( $plugin_file );
		}

		$loopback_state = Health_Check_Loopback::can_perform_loopback();

		if ( 'good' !== $loopback_state->status ) {
			return false;
		}

		return true;
	}

	public function dashboard_widget_scripts() {
		// Check that it's the dashboard page, we don't want to disturb any other pages.
		$screen = get_current_screen();
		if ( 'dashboard' !== $screen->id && 'plugins' !== $screen->id ) {
			return;
		}
	}

	public function display_dashboard_widget() {
		// Check that it's the dashboard page, we don't want to disturb any other pages.
		$screen = get_current_screen();
		if ( 'dashboard' !== $screen->id && 'plugins' !== $screen->id ) {
			return;
		}

		$notices = get_option( 'health-check-dashboard-notices', array() );

		$active_plugins   = array();
		$inactive_plugins = array();

		$themes = wp_prepare_themes_for_js();
		?>
		<div class="wrap">
			<div id="health-check-dashboard-widget">
				<div class="welcome-panel-content health-check-column">
					<h2>
						<?php
							printf(
								// translators: %s: The running status of Troubleshooting Mode.
								esc_html__( 'Troubleshooting Mode - %s', 'health-check' ),
								sprintf(
									'<span class="green">%s</span>',
									esc_html__( 'enabled', 'health-check' )
								)
							);
						?>
					</h2>

					<?php
					printf(
						'<a href="%s" class="button button-primary">%s</a>',
						esc_url(
							add_query_arg(
								array(
									'health-check-disable-troubleshooting' => true,
								)
							)
						),
						esc_html__( 'Disable Troubleshooting Mode', 'health-check' )
					);
					?>

					<div class="about-description">
						<p>
							<?php _e( 'Your site is currently in Troubleshooting Mode. This has <strong>no effect on your site visitors</strong>, they will continue to view your site as usual, but for you it will look as if you had just installed WordPress for the first time.', 'health-check' ); ?>
						</p>

						<p>
							<?php _e( 'Here you can enable individual plugins or themes, helping you to find out what might be causing strange behaviors on your site. Do note that <strong>any changes you make to settings will be kept</strong> when you disable Troubleshooting Mode.', 'health-check' ); ?>
						</p>

						<p>
							<?php _e( 'The Health Check plugin will attempt to disable cache solutions on your site, but if you are using a custom caching solution, you may need to disable it manually when troubleshooting.', 'health-check' ); ?>
						</p>
					</div>
				</div>

				<div class="health-check-column">
					<dl role="presentation" class="health-check-accordion">
						<dt role="heading" aria-level="3">
							<button aria-expanded="false" class="health-check-accordion-trigger" aria-controls="health-check-accordion-block-plugins" id="health-check-accordion-heading-plugins" type="button">
								<span class="title">
									<?php
									printf(
										// translators: %d: The amount of available plugins.
										esc_html__( 'Available plugins (%d)', 'health-check' ),
										esc_html( is_countable( $this->active_plugins ) ? count( $this->active_plugins ) : 0 )
									);
									?>
								</span>
								<span class="icon"></span>
							</button>
						</dt>
						<dd id="health-check-accordion-block-plugins" role="region" aria-labelledby="health-check-accordion-heading-plugins" class="health-check-accordion-panel" hidden="hidden">
							<ul id="health-check-plugins" role="list">
								<?php
								$has_toggle = false;

								foreach ( $this->active_plugins as $count => $single_plugin ) {
									$plugin_slug = explode( '/', $single_plugin );
									$plugin_slug = $plugin_slug[0];

									$plugin_is_visible = true;
									if ( $count >= 5 ) {
										$plugin_is_visible = false;
									}

									$plugin_data = get_plugin_data( trailingslashit( WP_PLUGIN_DIR ) . $single_plugin );

									$actions = array();

									if ( in_array( $plugin_slug, $this->allowed_plugins, true ) ) {
										$actions[] = sprintf(
											'<a href="%s" aria-label="%s">%s</a>',
											esc_url(
												add_query_arg(
													array(
														'health-check-troubleshoot-disable-plugin' => $plugin_slug,
													)
												)
											),
											esc_attr(
												sprintf(
													// translators: %s: Plugin name.
													__( 'Disable the plugin, %s, while troubleshooting.', 'health-check' ),
													$plugin_data['Name']
												)
											),
											esc_html__( 'Disable', 'health-check' )
										);
									} else {
										$actions[] = sprintf(
											'<a href="%s" aria-label="%s">%s</a>',
											esc_url(
												add_query_arg(
													array(
														'health-check-troubleshoot-enable-plugin' => $plugin_slug,
													)
												)
											),
											esc_attr(
												sprintf(
													// translators: %s: Plugin name.
													__( 'Enable the plugin, %s, while troubleshooting.', 'health-check' ),
													$plugin_data['Name']
												)
											),
											esc_html__( 'Enable', 'health-check' )
										);
									}

									if ( ! $plugin_is_visible && ! $has_toggle ) {
										$has_toggle = true;

										printf(
											'<li><button type="button" class="show-remaining button button-link">%s</button></li>',
											sprintf(
												// translators: %d: Amount of hidden plugins.
												_n(
													'Show %d remaining plugin',
													'Show %d remaining plugins',
													( is_countable( $this->active_plugins ) ? ( count( $this->active_plugins ) - 5 ) : 0 ),
													'health-check'
												),
												( is_countable( $this->active_plugins ) ? ( count( $this->active_plugins ) - 5 ) : 0 )
											)
										);
									}

									printf(
										'<li class="%s">%s - %s</li>',
										( ! $plugin_is_visible ? 'toggle-visibility hidden' : '' ),
										esc_html( $plugin_data['Name'] ),
										implode( ' | ', $actions )
									);
								}
								?>
							</ul>
						</dd>

						<dt role="heading" aria-level="3">
							<button aria-expanded="false" class="health-check-accordion-trigger" aria-controls="health-check-accordion-block-themes" id="health-check-accordion-heading-themes" type="button">
								<span class="title">
									<?php
									printf(
										// translators: %d: The amount of available themes.
										esc_html__( 'Available themes (%d)', 'health-check' ),
										esc_html( is_countable( $themes ) ? count( $themes ) : 0 )
									);
									?>
								</span>
								<span class="icon"></span>
							</button>
						</dt>
						<dd id="health-check-accordion-block-themes" role="region" aria-labelledby="health-check-accordion-heading-themes" class="health-check-accordion-panel" hidden="hidden">
							<ul id="health-check-themes" role="list">
								<?php
								$has_toggle = false;

								foreach ( $themes as $count => $theme ) {
									$theme_is_visible = true;
									if ( $count >= 5 ) {
										$theme_is_visible = false;
									}

									$actions = sprintf(
										'<a href="%s" aria-label="%s">%s</a>',
										esc_url(
											add_query_arg(
												array(
													'health-check-change-active-theme' => $theme['id'],
												)
											)
										),
										esc_attr(
											sprintf(
												// translators: %s: Theme name.
												__( 'Switch the active theme to %s', 'health-check' ),
												$theme['name']
											)
										),
										esc_html__( 'Switch to this theme', 'health-check' )
									);

									$plugin_label = sprintf(
										'%s %s',
										// translators: Prefix for the active theme in a listing.
										( $theme['active'] ? esc_html__( 'Active:', 'health-check' ) : '' ),
										$theme['name']
									);

									if ( ! $theme['active'] ) {
										$plugin_label .= ' - ' . $actions;
									}

									if ( ! $theme_is_visible && ! $has_toggle ) {
										$has_toggle = true;

										printf(
											'<li><button type="button" class="show-remaining button button-link">%s</button></li>',
											sprintf(
												// translators: %d: Amount of hidden themes.
												_n(
													'Show %d remaining theme',
													'Show %d remaining themes',
													( is_countable( $themes ) ? ( count( $themes ) - 5 ) : 0 ),
													'health-check'
												),
												( is_countable( $themes ) ? ( count( $themes ) - 5 ) : 0 )
											)
										);
									}

									printf(
										'<li class="%s">%s</li>',
										( ! $theme_is_visible ? 'toggle-visibility hidden' : '' ),
										$plugin_label
									);
								}
								?>
							</ul>
						</dd>

						<dt role="heading" aria-level="3">
							<button aria-expanded="true" class="health-check-accordion-trigger" aria-controls="health-check-accordion-block-notices" id="health-check-accordion-heading-notices" type="button">
								<span class="title">
									<?php
									printf(
										// translators: %d: The amount of notices that are visible.
										esc_html__( 'Notices (%d)', 'health-check' ),
										esc_html( is_countable( $notices ) ? count( $notices ) : 0 )
									);
									?>
								</span>
								<span class="icon"></span>
							</button>
						</dt>
						<dd id="health-check-accordion-block-notices" role="region" aria-labelledby="health-check-accordion-heading-notices" class="health-check-accordion-panel">
							<?php if ( empty( $notices ) && 'plugins' !== $screen->id ) : ?>
								<div class="no-notices">
									<p>
										<?php esc_html_e( 'There are no notices to show.', 'health-check' ); ?>
									</p>
								</div>
							<?php endif; ?>

							<?php if ( 'plugins' === $screen->id ) : ?>
								<div class="notice notice-warning inline">
									<p>
										<?php esc_html_e( 'Plugin actions, such as activating and deactivating, are not available while in Troubleshooting Mode.', 'health-check' ); ?>
									</p>
								</div>
							<?php endif; ?>

							<?php
							foreach ( $notices as $notice ) {
								printf(
									'<div class="notice notice-%s inline"><p>%s</p></div>',
									esc_attr( $notice['severity'] ),
									wp_kses(
										$notice['message'],
										array(
											'a' => array(
												'class' => true,
												'href'  => true,
												'aria-label' => true,
											),
										)
									)
								);
							}
							?>

							<?php
							if ( ! empty( $notices ) ) {
								printf(
									'<div class="dismiss-notices"><a href="%s" class="">%s</a></div>',
									esc_url(
										add_query_arg(
											array(
												'health-check-dismiss-notices' => true,
											)
										)
									),
									esc_html__( 'Dismiss notices', 'health-check' )
								);
							}
							?>
						</dd>
					</dl>
				</div>
			</div>
		</div>
		<?php
	}

}

new Health_Check_Troubleshooting_MU();