<?php
/**
 * Scanner.
 *
 * @package OvanapAdminToolkit
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Scans the WordPress environment and returns detection results
 * for each feature — is it relevant? safe? already handled?
 */
class OVKIT_Scanner {

	/**
	 * Singleton instance.
	 *
	 * @var self|null
	 */
	private static $instance = null;

	/**
	 * Cached detection results (null until scanned).
	 *
	 * @var array|null
	 */
	private $results = null;

	/**
	 * Instance.
	 *
	 * @return self
	 */
	public static function instance(): self {
		if ( ! self::$instance ) {
			self::$instance = new self();
		}
		return self::$instance;
	}

	/**
	 * Run all feature detections. Cached per request.
	 */
	public function scan(): array {
		if ( null !== $this->results ) {
			return $this->results;
		}

		// Ensure plugin functions are available (needed by detect callbacks).
		if ( ! function_exists( 'is_plugin_active' ) ) {
			include_once ABSPATH . 'wp-admin/includes/plugin.php';
		}

		$this->results = array();
		$features      = OVKIT_Feature_Registry::instance()->get_all();

		foreach ( $features as $key => $f ) {
			$detection = array(
				'detected' => null,   // true = issue found, false = not relevant, null = unknown.
				'message'  => '',     // human-readable detection result.
				'safe'     => true,   // is it safe to enable right now?
				'savings'  => '',     // estimated savings (e.g. "~10KB", "1 HTTP request").
			);

			// Run feature-specific detection if defined.
			if ( ! empty( $f['detect'] ) && is_callable( $f['detect'] ) ) {
				try {
					$detection = array_merge( $detection, call_user_func( $f['detect'] ) );
				} catch ( \Throwable $e ) {
					$detection['message'] = 'Detection failed';
				}
			}

			$this->results[ $key ] = $detection;
		}

		// Cache for 1 hour as transient.
		set_transient( 'ovkit_scan_results', $this->results, HOUR_IN_SECONDS );

		return $this->results;
	}

	/**
	 * Get cached scan results (don't re-scan).
	 */
	public function get_cached(): array {
		if ( null !== $this->results ) {
			return $this->results;
		}
		$cached = get_transient( 'ovkit_scan_results' );
		if ( is_array( $cached ) ) {
			$this->results = $cached;
			return $cached;
		}
		return $this->scan();
	}

	/**
	 * Force re-scan (clear cache).
	 */
	public function rescan(): array {
		delete_transient( 'ovkit_scan_results' );
		$this->results = null;
		return $this->scan();
	}

	/**
	 * Get summary stats.
	 */
	public function get_summary(): array {
		$results  = $this->get_cached();
		$features = OVKIT_Feature_Registry::instance()->get_all();

		$issues     = 0;
		$safe_fixes = 0;
		$active     = 0;
		$risky      = 0;

		foreach ( $features as $key => $f ) {
			if ( ovkit_is_enabled( $key ) ) {
				++$active;
			}

			$risk = $f['risk'] ?? 'safe';
			$det  = $results[ $key ] ?? array();

			if ( ! empty( $det['detected'] ) ) {
				++$issues;
				if ( 'safe' === $risk || 'recommended' === $risk ) {
					++$safe_fixes;
				}
			}

			if ( ovkit_is_enabled( $key ) && ( 'advanced' === $risk || 'risky' === $risk ) ) {
				++$risky;
			}
		}

		return array(
			'issues'     => $issues,
			'safe_fixes' => $safe_fixes,
			'active'     => $active,
			'risky'      => $risky,
			'total'      => count( $features ),
		);
	}
}