As the sun rises and the forest mist clears, and the clouds return and the caves darken, these changes of light and shadow are the morning and evening in the mountains. Wildflowers bloom with their subtle fragrance, fine trees flourish with their dense shade, the wind and frost are pure and clean, and the water recedes to reveal the rocks—these are the four seasons in the mountains. Going out in the morning and returning in the evening, the scenery of the four seasons is different, and the joy is endless.至于负者歌于途,行者休于树,前者呼,后者应,伛偻提携,往来而不绝者,滁人游也。临溪而渔,溪深而鱼肥,酿泉为酒,泉香而酒洌,山肴野蔌,杂然而前陈者,太守宴也。宴酣之乐,非丝非竹,射者中,弈者胜,觥筹交错,起坐而喧哗者,众宾欢也。苍颜白发,颓然乎其间者,太守醉也。 HEX
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File: /home/labeautef/piscines-services.com/wp-includes/class-wp-plugin-dependencies.php
<?php
/**
 * WordPress Plugin Administration API: WP_Plugin_Dependencies class
 *
 * @package WordPress
 * @subpackage Administration
 * @since 6.5.0
 */

/**
 * Core class for installing plugin dependencies.
 *
 * It is designed to add plugin dependencies as designated in the
 * `Requires Plugins` header to a new view in the plugins install page.
 */
class WP_Plugin_Dependencies {

	/**
	 * Holds 'get_plugins()'.
	 *
	 * @since 6.5.0
	 *
	 * @var array
	 */
	protected static $plugins;

	/**
	 * Holds plugin directory names to compare with cache.
	 *
	 * @since 6.5.0
	 *
	 * @var array
	 */
	protected static $plugin_dirnames;

	/**
	 * Holds sanitized plugin dependency slugs.
	 *
	 * Keyed on the dependent plugin's filepath,
	 * relative to the plugins directory.
	 *
	 * @since 6.5.0
	 *
	 * @var array
	 */
	protected static $dependencies;

	/**
	 * Holds an array of sanitized plugin dependency slugs.
	 *
	 * @since 6.5.0
	 *
	 * @var array
	 */
	protected static $dependency_slugs;

	/**
	 * Holds an array of dependent plugin slugs.
	 *
	 * Keyed on the dependent plugin's filepath,
	 * relative to the plugins directory.
	 *
	 * @since 6.5.0
	 *
	 * @var array
	 */
	protected static $dependent_slugs;

	/**
	 * Holds 'plugins_api()' data for plugin dependencies.
	 *
	 * @since 6.5.0
	 *
	 * @var array
	 */
	protected static $dependency_api_data;

	/**
	 * Holds plugin dependency filepaths, relative to the plugins directory.
	 *
	 * Keyed on the dependency's slug.
	 *
	 * @since 6.5.0
	 *
	 * @var string[]
	 */
	protected static $dependency_filepaths;

	/**
	 * An array of circular dependency pairings.
	 *
	 * @since 6.5.0
	 *
	 * @var array[]
	 */
	protected static $circular_dependencies_pairs;

	/**
	 * An array of circular dependency slugs.
	 *
	 * @since 6.5.0
	 *
	 * @var string[]
	 */
	protected static $circular_dependencies_slugs;

	/**
	 * Whether Plugin Dependencies have been initialized.
	 *
	 * @since 6.5.0
	 *
	 * @var bool
	 */
	protected static $initialized = false;

	/**
	 * Initializes by fetching plugin header and plugin API data.
	 *
	 * @since 6.5.0
	 */
	public static function initialize() {
		if ( false === self::$initialized ) {
			self::read_dependencies_from_plugin_headers();
			self::get_dependency_api_data();
			self::$initialized = true;
		}
	}

	/**
	 * Determines whether the plugin has plugins that depend on it.
	 *
	 * @since 6.5.0
	 *
	 * @param string $plugin_file The plugin's filepath, relative to the plugins directory.
	 * @return bool Whether the plugin has plugins that depend on it.
	 */
	public static function has_dependents( $plugin_file ) {
		return in_array( self::convert_to_slug( $plugin_file ), (array) self::$dependency_slugs, true );
	}

	/**
	 * Determines whether the plugin has plugin dependencies.
	 *
	 * @since 6.5.0
	 *
	 * @param string $plugin_file The plugin's filepath, relative to the plugins directory.
	 * @return bool Whether a plugin has plugin dependencies.
	 */
	public static function has_dependencies( $plugin_file ) {
		return isset( self::$dependencies[ $plugin_file ] );
	}

	/**
	 * Determines whether the plugin has active dependents.
	 *
	 * @since 6.5.0
	 *
	 * @param string $plugin_file The plugin's filepath, relative to the plugins directory.
	 * @return bool Whether the plugin has active dependents.
	 */
	public static function has_active_dependents( $plugin_file ) {
		require_once ABSPATH . 'wp-admin/includes/plugin.php';

		$dependents = self::get_dependents( self::convert_to_slug( $plugin_file ) );
		foreach ( $dependents as $dependent ) {
			if ( is_plugin_active( $dependent ) ) {
				return true;
			}
		}

		return false;
	}

	/**
	 * Gets filepaths of plugins that require the dependency.
	 *
	 * @since 6.5.0
	 *
	 * @param string $slug The dependency's slug.
	 * @return array An array of dependent plugin filepaths, relative to the plugins directory.
	 */
	public static function get_dependents( $slug ) {
		$dependents = array();

		foreach ( (array) self::$dependencies as $dependent => $dependencies ) {
			if ( in_array( $slug, $dependencies, true ) ) {
				$dependents[] = $dependent;
			}
		}

		return $dependents;
	}

	/**
	 * Gets the slugs of plugins that the dependent requires.
	 *
	 * @since 6.5.0
	 *
	 * @param string $plugin_file The dependent plugin's filepath, relative to the plugins directory.
	 * @return array An array of dependency plugin slugs.
	 */
	public static function get_dependencies( $plugin_file ) {
		if ( isset( self::$dependencies[ $plugin_file ] ) ) {
			return self::$dependencies[ $plugin_file ];
		}

		return array();
	}

	/**
	 * Gets a dependent plugin's filepath.
	 *
	 * @since 6.5.0
	 *
	 * @param string $slug  The dependent plugin's slug.
	 * @return string|false The dependent plugin's filepath, relative to the plugins directory,
	 *                      or false if the plugin has no dependencies.
	 */
	public static function get_dependent_filepath( $slug ) {
		$filepath = array_search( $slug, self::$dependent_slugs, true );

		return $filepath ? $filepath : false;
	}

	/**
	 * Determines whether the plugin has unmet dependencies.
	 *
	 * @since 6.5.0
	 *
	 * @param string $plugin_file The plugin's filepath, relative to the plugins directory.
	 * @return bool Whether the plugin has unmet dependencies.
	 */
	public static function has_unmet_dependencies( $plugin_file ) {
		if ( ! isset( self::$dependencies[ $plugin_file ] ) ) {
			return false;
		}

		require_once ABSPATH . 'wp-admin/includes/plugin.php';

		foreach ( self::$dependencies[ $plugin_file ] as $dependency ) {
			$dependency_filepath = self::get_dependency_filepath( $dependency );

			if ( false === $dependency_filepath || is_plugin_inactive( $dependency_filepath ) ) {
				return true;
			}
		}

		return false;
	}

	/**
	 * Determines whether the plugin has a circular dependency.
	 *
	 * @since 6.5.0
	 *
	 * @param string $plugin_file The plugin's filepath, relative to the plugins directory.
	 * @return bool Whether the plugin has a circular dependency.
	 */
	public static function has_circular_dependency( $plugin_file ) {
		if ( ! is_array( self::$circular_dependencies_slugs ) ) {
			self::get_circular_dependencies();
		}

		if ( ! empty( self::$circular_dependencies_slugs ) ) {
			$slug = self::convert_to_slug( $plugin_file );

			if ( in_array( $slug, self::$circular_dependencies_slugs, true ) ) {
				return true;
			}
		}

		return false;
	}

	/**
	 * Gets the names of plugins that require the plugin.
	 *
	 * @since 6.5.0
	 *
	 * @param string $plugin_file The plugin's filepath, relative to the plugins directory.
	 * @return array An array of dependent names.
	 */
	public static function get_dependent_names( $plugin_file ) {
		$dependent_names = array();
		$plugins         = self::get_plugins();
		$slug            = self::convert_to_slug( $plugin_file );

		foreach ( self::get_dependents( $slug ) as $dependent ) {
			$dependent_names[ $dependent ] = $plugins[ $dependent ]['Name'];
		}
		sort( $dependent_names );

		return $dependent_names;
	}

	/**
	 * Gets the names of plugins required by the plugin.
	 *
	 * @since 6.5.0
	 *
	 * @param string $plugin_file The dependent plugin's filepath, relative to the plugins directory.
	 * @return array An array of dependency names.
	 */
	public static function get_dependency_names( $plugin_file ) {
		$dependency_api_data = self::get_dependency_api_data();
		$dependencies        = self::get_dependencies( $plugin_file );
		$plugins             = self::get_plugins();

		$dependency_names = array();
		foreach ( $dependencies as $dependency ) {
			// Use the name if it's available, otherwise fall back to the slug.
			if ( isset( $dependency_api_data[ $dependency ]['name'] ) ) {
				$name = $dependency_api_data[ $dependency ]['name'];
			} else {
				$dependency_filepath = self::get_dependency_filepath( $dependency );
				if ( false !== $dependency_filepath ) {
					$name = $plugins[ $dependency_filepath ]['Name'];
				} else {
					$name = $dependency;
				}
			}

			$dependency_names[ $dependency ] = $name;
		}

		return $dependency_names;
	}

	/**
	 * Gets the filepath for a dependency, relative to the plugin's directory.
	 *
	 * @since 6.5.0
	 *
	 * @param string $slug The dependency's slug.
	 * @return string|false If installed, the dependency's filepath relative to the plugins directory, otherwise false.
	 */
	public static function get_dependency_filepath( $slug ) {
		$dependency_filepaths = self::get_dependency_filepaths();

		if ( ! isset( $dependency_filepaths[ $slug ] ) ) {
			return false;
		}

		return $dependency_filepaths[ $slug ];
	}

	/**
	 * Returns API data for the dependency.
	 *
	 * @since 6.5.0
	 *
	 * @param string $slug The dependency's slug.
	 * @return array|false The dependency's API data on success, otherwise false.
	 */
	public static function get_dependency_data( $slug ) {
		$dependency_api_data = self::get_dependency_api_data();

		if ( isset( $dependency_api_data[ $slug ] ) ) {
			return $dependency_api_data[ $slug ];
		}

		return false;
	}

	/**
	 * Displays an admin notice if dependencies are not installed.
	 *
	 * @since 6.5.0
	 */
	public static function display_admin_notice_for_unmet_dependencies() {
		if ( in_array( false, self::get_dependency_filepaths(), true ) ) {
			$error_message = __( 'Some required plugins are missing or inactive.' );

			if ( is_multisite() ) {
				if ( current_user_can( 'manage_network_plugins' ) ) {
					$error_message .= ' ' . sprintf(
						/* translators: %s: Link to the network plugins page. */
						__( '<a href="%s">Manage plugins</a>.' ),
						esc_url( network_admin_url( 'plugins.php' ) )
					);
				} else {
					$error_message .= ' ' . __( 'Please contact your network administrator.' );
				}
			} elseif ( 'plugins' !== get_current_screen()->base ) {
				$error_message .= ' ' . sprintf(
					/* translators: %s: Link to the plugins page. */
					__( '<a href="%s">Manage plugins</a>.' ),
					esc_url( admin_url( 'plugins.php' ) )
				);
			}

			wp_admin_notice(
				$error_message,
				array(
					'type' => 'warning',
				)
			);
		}
	}

	/**
	 * Displays an admin notice if circular dependencies are installed.
	 *
	 * @since 6.5.0
	 */
	public static function display_admin_notice_for_circular_dependencies() {
		$circular_dependencies = self::get_circular_dependencies();
		if ( ! empty( $circular_dependencies ) && count( $circular_dependencies ) > 1 ) {
			$circular_dependencies = array_unique( $circular_dependencies, SORT_REGULAR );
			$plugins               = self::get_plugins();
			$plugin_dirnames       = self::get_plugin_dirnames();

			// Build output lines.
			$circular_dependency_lines = '';
			foreach ( $circular_dependencies as $circular_dependency ) {
				$first_filepath             = $plugin_dirnames[ $circular_dependency[0] ];
				$second_filepath            = $plugin_dirnames[ $circular_dependency[1] ];
				$circular_dependency_lines .= sprintf(
					/* translators: 1: First plugin name, 2: Second plugin name. */
					'<li>' . _x( '%1$s requires %2$s', 'The first plugin requires the second plugin.' ) . '</li>',
					'<strong>' . esc_html( $plugins[ $first_filepath ]['Name'] ) . '</strong>',
					'<strong>' . esc_html( $plugins[ $second_filepath ]['Name'] ) . '</strong>'
				);
			}

			wp_admin_notice(
				sprintf(
					'<p>%1$s</p><ul>%2$s</ul><p>%3$s</p>',
					__( 'These plugins cannot be activated because their requirements are invalid.' ),
					$circular_dependency_lines,
					__( 'Please contact the plugin authors for more information.' )
				),
				array(
					'type'           => 'warning',
					'paragraph_wrap' => false,
				)
			);
		}
	}

	/**
	 * Checks plugin dependencies after a plugin is installed via AJAX.
	 *
	 * @since 6.5.0
	 */
	public static function check_plugin_dependencies_during_ajax() {
		check_ajax_referer( 'updates' );

		if ( empty( $_POST['slug'] ) ) {
			wp_send_json_error(
				array(
					'slug'         => '',
					'pluginName'   => '',
					'errorCode'    => 'no_plugin_specified',
					'errorMessage' => __( 'No plugin specified.' ),
				)
			);
		}

		$slug   = sanitize_key( wp_unslash( $_POST['slug'] ) );
		$status = array( 'slug' => $slug );

		self::get_plugins();
		self::get_plugin_dirnames();

		if ( ! isset( self::$plugin_dirnames[ $slug ] ) ) {
			$status['errorCode']    = 'plugin_not_installed';
			$status['errorMessage'] = __( 'The plugin is not installed.' );
			wp_send_json_error( $status );
		}

		$plugin_file          = self::$plugin_dirnames[ $slug ];
		$status['pluginName'] = self::$plugins[ $plugin_file ]['Name'];
		$status['plugin']     = $plugin_file;

		if ( current_user_can( 'activate_plugin', $plugin_file ) && is_plugin_inactive( $plugin_file ) ) {
			$status['activateUrl'] = add_query_arg(
				array(
					'_wpnonce' => wp_create_nonce( 'activate-plugin_' . $plugin_file ),
					'action'   => 'activate',
					'plugin'   => $plugin_file,
				),
				is_multisite() ? network_admin_url( 'plugins.php' ) : admin_url( 'plugins.php' )
			);
		}

		if ( is_multisite() && current_user_can( 'manage_network_plugins' ) ) {
			$status['activateUrl'] = add_query_arg( array( 'networkwide' => 1 ), $status['activateUrl'] );
		}

		self::initialize();
		$dependencies = self::get_dependencies( $plugin_file );
		if ( empty( $dependencies ) ) {
			$status['message'] = __( 'The plugin has no required plugins.' );
			wp_send_json_success( $status );
		}

		require_once ABSPATH . 'wp-admin/includes/plugin.php';

		$inactive_dependencies = array();
		foreach ( $dependencies as $dependency ) {
			if ( false === self::$plugin_dirnames[ $dependency ] || is_plugin_inactive( self::$plugin_dirnames[ $dependency ] ) ) {
				$inactive_dependencies[] = $dependency;
			}
		}

		if ( ! empty( $inactive_dependencies ) ) {
			$inactive_dependency_names = array_map(
				function ( $dependency ) {
					if ( isset( self::$dependency_api_data[ $dependency ]['Name'] ) ) {
						$inactive_dependency_name = self::$dependency_api_data[ $dependency ]['Name'];
					} else {
						$inactive_dependency_name = $dependency;
					}
					return $inactive_dependency_name;
				},
				$inactive_dependencies
			);

			$status['errorCode']    = 'inactive_dependencies';
			$status['errorMessage'] = sprintf(
				/* translators: %s: A list of inactive dependency plugin names. */
				__( 'The following plugins must be activated first: %s.' ),
				implode( ', ', $inactive_dependency_names )
			);
			$status['errorData'] = array_combine( $inactive_dependencies, $inactive_dependency_names );

			wp_send_json_error( $status );
		}

		$status['message'] = __( 'All required plugins are installed and activated.' );
		wp_send_json_success( $status );
	}

	/**
	 * Gets data for installed plugins.
	 *
	 * @since 6.5.0
	 *
	 * @return array An array of plugin data.
	 */
	protected static function get_plugins() {
		if ( is_array( self::$plugins ) ) {
			return self::$plugins;
		}

		require_once ABSPATH . 'wp-admin/includes/plugin.php';
		self::$plugins = get_plugins();

		return self::$plugins;
	}

	/**
	 * Reads and stores dependency slugs from a plugin's 'Requires Plugins' header.
	 *
	 * @since 6.5.0
	 */
	protected static function read_dependencies_from_plugin_headers() {
		self::$dependencies     = array();
		self::$dependency_slugs = array();
		self::$dependent_slugs  = array();
		$plugins                = self::get_plugins();
		foreach ( $plugins as $plugin => $header ) {
			if ( '' === $header['RequiresPlugins'] ) {
				continue;
			}

			$dependency_slugs              = self::sanitize_dependency_slugs( $header['RequiresPlugins'] );
			self::$dependencies[ $plugin ] = $dependency_slugs;
			self::$dependency_slugs        = array_merge( self::$dependency_slugs, $dependency_slugs );

			$dependent_slug                   = self::convert_to_slug( $plugin );
			self::$dependent_slugs[ $plugin ] = $dependent_slug;
		}
		self::$dependency_slugs = array_unique( self::$dependency_slugs );
	}

	/**
	 * Sanitizes slugs.
	 *
	 * @since 6.5.0
	 *
	 * @param string $slugs A comma-separated string of plugin dependency slugs.
	 * @return array An array of sanitized plugin dependency slugs.
	 */
	protected static function sanitize_dependency_slugs( $slugs ) {
		$sanitized_slugs = array();
		$slugs           = explode( ',', $slugs );

		foreach ( $slugs as $slug ) {
			$slug = trim( $slug );

			/**
			 * Filters a plugin dependency's slug before matching to
			 * the WordPress.org slug format.
			 *
			 * Can be used to switch between free and premium plugin slugs, for example.
			 *
			 * @since 6.5.0
			 *
			 * @param string $slug The slug.
			 */
			$slug = apply_filters( 'wp_plugin_dependencies_slug', $slug );

			// Match to WordPress.org slug format.
			if ( preg_match( '/^[a-z0-9]+(-[a-z0-9]+)*$/mu', $slug ) ) {
				$sanitized_slugs[] = $slug;
			}
		}
		$sanitized_slugs = array_unique( $sanitized_slugs );
		sort( $sanitized_slugs );

		return $sanitized_slugs;
	}

	/**
	 * Gets the filepath of installed dependencies.
	 * If a dependency is not installed, the filepath defaults to false.
	 *
	 * @since 6.5.0
	 *
	 * @return array An array of install dependencies filepaths, relative to the plugins directory.
	 */
	protected static function get_dependency_filepaths() {
		if ( is_array( self::$dependency_filepaths ) ) {
			return self::$dependency_filepaths;
		}

		if ( null === self::$dependency_slugs ) {
			return array();
		}

		self::$dependency_filepaths = array();

		$plugin_dirnames = self::get_plugin_dirnames();
		foreach ( self::$dependency_slugs as $slug ) {
			if ( isset( $plugin_dirnames[ $slug ] ) ) {
				self::$dependency_filepaths[ $slug ] = $plugin_dirnames[ $slug ];
				continue;
			}

			self::$dependency_filepaths[ $slug ] = false;
		}

		return self::$dependency_filepaths;
	}

	/**
	 * Retrieves and stores dependency plugin data from the WordPress.org Plugin API.
	 *
	 * @since 6.5.0
	 *
	 * @global string $pagenow The filename of the current screen.
	 *
	 * @return array|void An array of dependency API data, or void on early exit.
	 */
	protected static function get_dependency_api_data() {
		global $pagenow;

		if ( ! is_admin() || ( 'plugins.php' !== $pagenow && 'plugin-install.php' !== $pagenow ) ) {
			return;
		}

		if ( is_array( self::$dependency_api_data ) ) {
			return self::$dependency_api_data;
		}

		$plugins                   = self::get_plugins();
		self::$dependency_api_data = (array) get_site_transient( 'wp_plugin_dependencies_plugin_data' );
		foreach ( self::$dependency_slugs as $slug ) {
			// Set transient for individual data, remove from self::$dependency_api_data if transient expired.
			if ( ! get_site_transient( "wp_plugin_dependencies_plugin_timeout_{$slug}" ) ) {
				unset( self::$dependency_api_data[ $slug ] );
				set_site_transient( "wp_plugin_dependencies_plugin_timeout_{$slug}", true, 12 * HOUR_IN_SECONDS );
			}

			if ( isset( self::$dependency_api_data[ $slug ] ) ) {
				if ( false === self::$dependency_api_data[ $slug ] ) {
					$dependency_file = self::get_dependency_filepath( $slug );

					if ( false === $dependency_file ) {
						self::$dependency_api_data[ $slug ] = array( 'Name' => $slug );
					} else {
						self::$dependency_api_data[ $slug ] = array( 'Name' => $plugins[ $dependency_file ]['Name'] );
					}
					continue;
				}

				// Don't hit the Plugin API if data exists.
				if ( ! empty( self::$dependency_api_data[ $slug ]['last_updated'] ) ) {
					continue;
				}
			}

			if ( ! function_exists( 'plugins_api' ) ) {
				require_once ABSPATH . 'wp-admin/includes/plugin-install.php';
			}

			$information = plugins_api(
				'plugin_information',
				array(
					'slug'   => $slug,
					'fields' => array(
						'short_description' => true,
						'icons'             => true,
					),
				)
			);

			if ( is_wp_error( $information ) ) {
				continue;
			}

			self::$dependency_api_data[ $slug ] = (array) $information;
			// plugins_api() returns 'name' not 'Name'.
			self::$dependency_api_data[ $slug ]['Name'] = self::$dependency_api_data[ $slug ]['name'];
			set_site_transient( 'wp_plugin_dependencies_plugin_data', self::$dependency_api_data, 0 );
		}

		// Remove from self::$dependency_api_data if slug no longer a dependency.
		$differences = array_diff( array_keys( self::$dependency_api_data ), self::$dependency_slugs );
		foreach ( $differences as $difference ) {
			unset( self::$dependency_api_data[ $difference ] );
		}

		ksort( self::$dependency_api_data );
		// Remove empty elements.
		self::$dependency_api_data = array_filter( self::$dependency_api_data );
		set_site_transient( 'wp_plugin_dependencies_plugin_data', self::$dependency_api_data, 0 );

		return self::$dependency_api_data;
	}

	/**
	 * Gets plugin directory names.
	 *
	 * @since 6.5.0
	 *
	 * @return array An array of plugin directory names.
	 */
	protected static function get_plugin_dirnames() {
		if ( is_array( self::$plugin_dirnames ) ) {
			return self::$plugin_dirnames;
		}

		self::$plugin_dirnames = array();

		$plugin_files = array_keys( self::get_plugins() );
		foreach ( $plugin_files as $plugin_file ) {
			$slug                           = self::convert_to_slug( $plugin_file );
			self::$plugin_dirnames[ $slug ] = $plugin_file;
		}

		return self::$plugin_dirnames;
	}

	/**
	 * Gets circular dependency data.
	 *
	 * @since 6.5.0
	 *
	 * @return array[] An array of circular dependency pairings.
	 */
	protected static function get_circular_dependencies() {
		if ( is_array( self::$circular_dependencies_pairs ) ) {
			return self::$circular_dependencies_pairs;
		}

		if ( null === self::$dependencies ) {
			return array();
		}

		self::$circular_dependencies_slugs = array();

		self::$circular_dependencies_pairs = array();
		foreach ( self::$dependencies as $dependent => $dependencies ) {
			/*
			 * $dependent is in 'a/a.php' format. Dependencies are stored as slugs, i.e. 'a'.
			 *
			 * Convert $dependent to slug format for checking.
			 */
			$dependent_slug = self::convert_to_slug( $dependent );

			self::$circular_dependencies_pairs = array_merge(
				self::$circular_dependencies_pairs,
				self::check_for_circular_dependencies( array( $dependent_slug ), $dependencies )
			);
		}

		return self::$circular_dependencies_pairs;
	}

	/**
	 * Checks for circular dependencies.
	 *
	 * @since 6.5.0
	 *
	 * @param array $dependents   Array of dependent plugins.
	 * @param array $dependencies Array of plugins dependencies.
	 * @return array A circular dependency pairing, or an empty array if none exists.
	 */
	protected static function check_for_circular_dependencies( $dependents, $dependencies ) {
		$circular_dependencies_pairs = array();

		// Check for a self-dependency.
		$dependents_location_in_its_own_dependencies = array_intersect( $dependents, $dependencies );
		if ( ! empty( $dependents_location_in_its_own_dependencies ) ) {
			foreach ( $dependents_location_in_its_own_dependencies as $self_dependency ) {
				self::$circular_dependencies_slugs[] = $self_dependency;
				$circular_dependencies_pairs[]       = array( $self_dependency, $self_dependency );

				// No need to check for itself again.
				unset( $dependencies[ array_search( $self_dependency, $dependencies, true ) ] );
			}
		}

		/*
		 * Check each dependency to see:
		 * 1. If it has dependencies.
		 * 2. If its list of dependencies includes one of its own dependents.
		 */
		foreach ( $dependencies as $dependency ) {
			// Check if the dependency is also a dependent.
			$dependency_location_in_dependents = array_search( $dependency, self::$dependent_slugs, true );

			if ( false !== $dependency_location_in_dependents ) {
				$dependencies_of_the_dependency = self::$dependencies[ $dependency_location_in_dependents ];

				foreach ( $dependents as $dependent ) {
					// Check if its dependencies includes one of its own dependents.
					$dependent_location_in_dependency_dependencies = array_search(
						$dependent,
						$dependencies_of_the_dependency,
						true
					);

					if ( false !== $dependent_location_in_dependency_dependencies ) {
						self::$circular_dependencies_slugs[] = $dependent;
						self::$circular_dependencies_slugs[] = $dependency;
						$circular_dependencies_pairs[]       = array( $dependent, $dependency );

						// Remove the dependent from its dependency's dependencies.
						unset( $dependencies_of_the_dependency[ $dependent_location_in_dependency_dependencies ] );
					}
				}

				$dependents[] = $dependency;

				/*
				 * Now check the dependencies of the dependency's dependencies for the dependent.
				 *
				 * Yes, that does make sense.
				 */
				$circular_dependencies_pairs = array_merge(
					$circular_dependencies_pairs,
					self::check_for_circular_dependencies( $dependents, array_unique( $dependencies_of_the_dependency ) )
				);
			}
		}

		return $circular_dependencies_pairs;
	}

	/**
	 * Converts a plugin filepath to a slug.
	 *
	 * @since 6.5.0
	 *
	 * @param string $plugin_file The plugin's filepath, relative to the plugins directory.
	 * @return string The plugin's slug.
	 */
	protected static function convert_to_slug( $plugin_file ) {
		if ( 'hello.php' === $plugin_file ) {
			return 'hello-dolly';
		}
		return str_contains( $plugin_file, '/' ) ? dirname( $plugin_file ) : str_replace( '.php', '', $plugin_file );
	}
}