<?php
/**
 * Database size, autoload bloat and expired transients.
 *
 * @package Keepwatch
 */

namespace Keepwatch\Checks;

defined( 'ABSPATH' ) || exit;

/**
 * Read-only queries against the options table. Safe for the dashboard widget.
 */
final class DatabaseCheck implements Check {

	/** Autoload payload above this is a warning (bytes). */
	public const AUTOLOAD_WARN = 1048576; // 1 MB

	/** Autoload payload above this is critical (bytes). */
	public const AUTOLOAD_CRIT = 2097152; // 2 MB

	/** Expired transient count that triggers a recommendation. */
	public const EXPIRED_WARN = 50;

	public const CACHE_KEY = 'keepwatch_db_facts';

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

	/**
	 * {@inheritDoc}
	 */
	public function run(): array {
		// information_schema can be slow on shared hosting; measure at most once per hour (CLAUDE.md rule 22).
		$facts = get_transient( self::CACHE_KEY );
		if ( ! is_array( $facts ) ) {
			$facts = $this->facts();
			set_transient( self::CACHE_KEY, $facts, HOUR_IN_SECONDS );
		}
		return self::evaluate(
			array(
				'autoload_bytes'     => isset( $facts['autoload_bytes'] ) ? (int) $facts['autoload_bytes'] : null,
				'expired_transients' => isset( $facts['expired_transients'] ) ? (int) $facts['expired_transients'] : null,
				'db_bytes'           => isset( $facts['db_bytes'] ) ? (int) $facts['db_bytes'] : null,
			)
		);
	}

	/**
	 * Pure evaluation.
	 *
	 * @param array{autoload_bytes: int|null, expired_transients: int|null, db_bytes: int|null} $facts Measured facts.
	 * @return Result[]
	 */
	public static function evaluate( array $facts ): array {
		$results = array();

		if ( null !== $facts['autoload_bytes'] ) {
			$bytes = $facts['autoload_bytes'];
			if ( $bytes >= self::AUTOLOAD_CRIT ) {
				$results[] = new Result(
					'database.autoload',
					Result::CRITICAL,
					/* translators: %s: human size */
					sprintf( __( 'Autoloaded options are %s', 'keepwatch' ), size_format( $bytes ) ),
					__( 'Large autoloaded options slow every page load. Remove leftover options from unused plugins or convert heavy rows to autoload=no.', 'keepwatch' )
				);
			} elseif ( $bytes >= self::AUTOLOAD_WARN ) {
				$results[] = new Result(
					'database.autoload',
					Result::RECOMMENDED,
					/* translators: %s: human size */
					sprintf( __( 'Autoloaded options are %s', 'keepwatch' ), size_format( $bytes ) ),
					__( 'Keeping autoload under about 1 MB is a common performance target.', 'keepwatch' )
				);
			} else {
				$results[] = new Result(
					'database.autoload',
					Result::GOOD,
					/* translators: %s: human size */
					sprintf( __( 'Autoloaded options look healthy (%s)', 'keepwatch' ), size_format( $bytes ) )
				);
			}
		}

		if ( null !== $facts['expired_transients'] ) {
			$count = $facts['expired_transients'];
			if ( $count >= self::EXPIRED_WARN ) {
				$results[] = new Result(
					'database.transients',
					Result::RECOMMENDED,
					/* translators: %d: number of expired transients */
					sprintf( _n( '%d expired transient is sitting in the database', '%d expired transients are sitting in the database', $count, 'keepwatch' ), $count ),
					__( 'Expired transients are harmless but waste space. A cleanup plugin or WP-CLI can purge them.', 'keepwatch' )
				);
			} else {
				$results[] = new Result(
					'database.transients',
					Result::GOOD,
					__( 'No significant pile of expired transients', 'keepwatch' )
				);
			}
		}

		if ( null !== $facts['db_bytes'] && $facts['db_bytes'] > 0 ) {
			$results[] = new Result(
				'database.size',
				Result::GOOD,
				/* translators: %s: human size */
				sprintf( __( 'Database size is about %s', 'keepwatch' ), size_format( $facts['db_bytes'] ) )
			);
		}

		return $results;
	}

	/**
	 * Collect measurements (also used for the cloud report metrics, SiteInventory).
	 *
	 * @return array{autoload_bytes: int|null, expired_transients: int|null, db_bytes: int|null}
	 */
	public function facts(): array {
		global $wpdb;

		$autoload = null;
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- admin/dashboard read-only health check.
		$sum = $wpdb->get_var(
			"SELECT SUM(LENGTH(option_value)) FROM {$wpdb->options} WHERE autoload IN ( 'yes', 'on', 'auto', 'auto-on' )"
		);
		if ( null !== $sum ) {
			$autoload = (int) $sum;
		}

		$expired = null;
		$timeout = $wpdb->esc_like( '_transient_timeout_' ) . '%';
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- see above.
		$count = $wpdb->get_var(
			$wpdb->prepare(
				"SELECT COUNT(*) FROM {$wpdb->options} WHERE option_name LIKE %s AND option_value < %d",
				$timeout,
				time()
			)
		);
		if ( null !== $count ) {
			$expired = (int) $count;
		}

		$db_bytes = null;
		$name     = $wpdb->dbname;
		if ( is_string( $name ) && '' !== $name ) {
			// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- optional size hint.
			$size = $wpdb->get_var(
				$wpdb->prepare(
					'SELECT SUM(data_length + index_length) FROM information_schema.TABLES WHERE table_schema = %s',
					$name
				)
			);
			if ( null !== $size && '' !== $size ) {
				$db_bytes = (int) $size;
			}
		}

		return array(
			'autoload_bytes'     => $autoload,
			'expired_transients' => $expired,
			'db_bytes'           => $db_bytes,
		);
	}
}