<?php
/**
 * Pending core, plugin and theme updates.
 *
 * @package Keepwatch
 */

namespace Keepwatch\Checks;

defined( 'ABSPATH' ) || exit;

/**
 * Reads the update information WordPress already fetched (site transients). It never triggers a
 * remote update check itself.
 */
final class UpdatesCheck implements Check {

	/**
	 * {@inheritDoc}
	 */
	public function group(): string {
		return 'updates';
	}

	/**
	 * {@inheritDoc}
	 */
	public function run(): array {
		return self::evaluate(
			get_site_transient( 'update_core' ),
			get_site_transient( 'update_plugins' ),
			get_site_transient( 'update_themes' )
		);
	}

	/**
	 * Pure evaluation of the three update transients.
	 *
	 * @param mixed $core    update_core transient.
	 * @param mixed $plugins update_plugins transient.
	 * @param mixed $themes  update_themes transient.
	 * @return Result[]
	 */
	public static function evaluate( $core, $plugins, $themes ): array {
		$url = admin_url( 'update-core.php' );

		if ( ! is_object( $plugins ) && ! is_object( $core ) ) {
			return array(
				new Result(
					'updates.unknown',
					Result::RECOMMENDED,
					__( 'Update information is not available yet', 'keepwatch' ),
					__( 'WordPress has not checked for updates recently. Open the Updates screen once to refresh it.', 'keepwatch' ),
					$url,
					__( 'Open Updates', 'keepwatch' )
				),
			);
		}

		$results = array();

		$core_version = self::core_upgrade( $core );
		if ( null !== $core_version ) {
			$results[] = new Result(
				'updates.core',
				Result::CRITICAL,
				/* translators: %s: WordPress version */
				sprintf( __( 'WordPress %s is available', 'keepwatch' ), $core_version ),
				__( 'Core updates include security fixes. Back up the site and update WordPress.', 'keepwatch' ),
				$url,
				__( 'Update WordPress', 'keepwatch' )
			);
		}

		$plugin_count = self::count_responses( $plugins );
		if ( $plugin_count > 0 ) {
			$results[] = new Result(
				'updates.plugins',
				$plugin_count >= 5 ? Result::CRITICAL : Result::RECOMMENDED,
				/* translators: %d: number of plugins */
				sprintf( _n( '%d plugin has an update', '%d plugins have updates', $plugin_count, 'keepwatch' ), $plugin_count ),
				__( 'Outdated plugins are the most common way sites get compromised.', 'keepwatch' ),
				admin_url( 'plugins.php?plugin_status=upgrade' ),
				__( 'Review plugins', 'keepwatch' )
			);
		}

		$theme_count = self::count_responses( $themes );
		if ( $theme_count > 0 ) {
			$results[] = new Result(
				'updates.themes',
				Result::RECOMMENDED,
				/* translators: %d: number of themes */
				sprintf( _n( '%d theme has an update', '%d themes have updates', $theme_count, 'keepwatch' ), $theme_count ),
				__( 'Keep installed themes up to date, or delete the ones you do not use.', 'keepwatch' ),
				admin_url( 'themes.php' ),
				__( 'Review themes', 'keepwatch' )
			);
		}

		if ( array() === $results ) {
			$results[] = new Result( 'updates.all', Result::GOOD, __( 'WordPress, plugins and themes are up to date', 'keepwatch' ) );
		}

		return $results;
	}

	/**
	 * Version offered as an upgrade, if any.
	 *
	 * @param mixed $core update_core transient.
	 */
	private static function core_upgrade( $core ): ?string {
		if ( ! is_object( $core ) || ! isset( $core->updates ) || ! is_array( $core->updates ) ) {
			return null;
		}
		foreach ( $core->updates as $update ) {
			if ( is_object( $update ) && isset( $update->response ) && 'upgrade' === $update->response ) {
				return isset( $update->current ) ? (string) $update->current : '';
			}
		}
		return null;
	}

	/**
	 * Number of entries in a plugin/theme update transient's "response" list.
	 *
	 * @param mixed $transient Transient value.
	 */
	private static function count_responses( $transient ): int {
		if ( is_object( $transient ) && isset( $transient->response ) && is_array( $transient->response ) ) {
			return count( $transient->response );
		}
		return 0;
	}
}