<?php


namespace Vizyt\Support;

defined( 'ABSPATH' ) || exit;

/**
 * Storage engine of Vizyt's tables. Vizyt\Support\Tx needs InnoDB to undo a
 * half-done save, and a host whose default engine is MyISAM would create
 * every table without transactions, so CREATE TABLE asks for InnoDB.
 *
 * dbDelta() runs the CREATE TABLE text as written when the table is new and
 * ignores the table options when it already exists — existing MyISAM tables
 * are converted from Vizyt\Admin\EngineNotice ("Convert tables to InnoDB").
 */
final class DbEngine {

    /** Whether the server has InnoDB (null = not asked yet). */
    private static ?bool $innodb = null;

    public static function innodb_available(): bool {
        if ( null === self::$innodb ) {
            global $wpdb;
            // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- information_schema has no API; the answer is kept in a static for the request.
            $support      = $wpdb->get_var( "SELECT SUPPORT FROM information_schema.ENGINES WHERE ENGINE = 'InnoDB'" );
            self::$innodb = in_array( strtoupper( (string) $support ), [ 'YES', 'DEFAULT' ], true );
        }

        return self::$innodb;
    }

    /**
     * Table options for CREATE TABLE: "ENGINE=InnoDB DEFAULT CHARACTER SET … COLLATE …".
     * Without InnoDB on the server (or when the server cannot be asked) only
     * the charset, as before: the host's default engine applies.
     */
    public static function table_options(): string {
        global $wpdb;

        $charset = $wpdb->get_charset_collate();

        return self::innodb_available() ? trim( 'ENGINE=InnoDB ' . $charset ) : $charset;
    }
}