<?php
/**
 * Fail closed when the operational table namespace is not ready.
 *
 * @package ABeCeBooking
 */
namespace ABeCe\Booking\Infrastructure\Database;

/** Read-only preflight shared by web registration, activation and the CLI workflow. */
final class DatabaseState {
	public const JOURNAL = 'abece_booking_schema13_journal';
	public const FRESH   = 'abece_booking_schema13_fresh_install';

	/** @param \wpdb $wpdb Site connection. @return array<string, int|string> */
	public static function layout( \wpdb $wpdb ): array {
		$new          = Tables::all( $wpdb );
		$old          = Tables::legacy( $wpdb );
		$names        = array_merge( array_values( $new ), array_values( $old ) );
		$placeholders = implode( ',', array_fill( 0, count( $names ), '%s' ) );
		$actual       = $wpdb->get_results( $wpdb->prepare( 'SELECT TABLE_NAME,TABLE_TYPE FROM information_schema.TABLES WHERE TABLE_SCHEMA=DATABASE() AND TABLE_NAME IN (' . $placeholders . ')', ...$names ), ARRAY_A );
		if ( $wpdb->last_error ) {
			throw new \RuntimeException( 'ABECE_BOOKING_DATABASE_PREFLIGHT_FAILED' );
		}
		$old_count = 0;
		$new_count = 0;
		foreach ( $actual as $row ) {
			if ( $row['TABLE_TYPE'] !== 'BASE TABLE' ) {
				return array(
					'state' => 'unsafe',
					'old'   => 0,
					'new'   => 0,
				);
			}
			$old_count += (int) in_array( $row['TABLE_NAME'], $old, true );
			$new_count += (int) in_array( $row['TABLE_NAME'], $new, true );
		}
		$state = match ( true ) {
			$old_count === 0 && $new_count === 0 => 'empty',
			$old_count === 24 && $new_count === 0 => 'legacy',
			$old_count === 0 && $new_count === 24 => 'current',
			default => 'unsafe',
		};
		return array(
			'state' => $state,
			'old'   => $old_count,
			'new'   => $new_count,
		);
	}

	/** @param \wpdb $wpdb Site connection. @return int */
	public static function version( \wpdb $wpdb ): int {
		// An uncached read also sees a version committed by a different PHP worker.
		$value = $wpdb->get_var( $wpdb->prepare( 'SELECT option_value FROM %i WHERE option_name=%s', $wpdb->options, Installer::VERSION_OPTION ) );
		if ( $value === null ) {
			$value = $wpdb->get_var( $wpdb->prepare( 'SELECT option_value FROM %i WHERE option_name=%s', $wpdb->options, 'asb_db_version' ) );
		}
		if ( $wpdb->last_error || ( $value !== null && ( ! ctype_digit( (string) $value ) || (int) $value > 13 ) ) ) {
			throw new \RuntimeException( 'ABECE_BOOKING_UNKNOWN_SCHEMA' );
		}
		return $value === null ? 0 : (int) $value;
	}

	/**
	 * Missing version/tables do not imply a new site when prior installation markers survive.
	 *
	 * @param \wpdb $wpdb Site connection.
	 * @return bool
	 */
	public static function has_history( \wpdb $wpdb ): bool {
		$name = $wpdb->get_var( $wpdb->prepare( 'SELECT option_name FROM %i WHERE option_name IN (%s,%s,%s,%s) LIMIT 1', $wpdb->options, self::JOURNAL, 'abece_booking_identifier_migration_version', 'abece_booking_capabilities_version', 'asb_capabilities_version' ) );
		if ( $wpdb->last_error ) {
			throw new \RuntimeException( 'ABECE_BOOKING_PRIOR_SCHEMA_INSPECTION_FAILED' );
		}
		return $name !== null;
	}

	/** @param \wpdb $wpdb Site connection. @return bool */
	public static function ready( \wpdb $wpdb ): bool {
		if ( self::version( $wpdb ) !== 13 ) {
			return false;
		}
		$journal = get_option( self::JOURNAL, array() );
		if ( $journal && ( $journal['phase'] ?? '' ) !== 'complete' ) {
			return false;
		}
		return self::layout( $wpdb )['state'] === 'current';
	}
}