<?php
/**
 * Table-name parsing and metadata probes for database error handling.
 */

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

// allow-no-test-found: covered through DatabaseErrorClassifier facade by tests/MissingTableErrorDoubleReportingTest.php and tests/DataAccessRetrySemanticsTest.php
class ABJ_404_Solution_DatabaseErrorTableInspector {

    /** @var ABJ_404_Solution_Logging */
    private $logger;

    /** @var (callable(string): bool)|null */
    private $confirmedTableAbsenceProbe;

    /**
     * @param ABJ_404_Solution_Logging $logger
     * @param (callable(string): bool)|null $confirmedTableAbsenceProbe
     *   Returns true only when the database positively confirms absence.
     */
    public function __construct($logger, $confirmedTableAbsenceProbe = null) {
        $this->logger = $logger;
        $this->confirmedTableAbsenceProbe = is_callable($confirmedTableAbsenceProbe)
            ? $confirmedTableAbsenceProbe : null;
    }

    /**
     * Extract a table name from a MySQL "table is full" error message.
     *
     * @param string $errorText
     * @return string|null
     */
    public function extractTableNameFromFullError(string $errorText): ?string {
        if (preg_match("/table '([^']+)' is full/i", $errorText, $m)) {
            return $m[1];
        }
        return null;
    }

    /**
     * Extract the table name from a MySQL "doesn't exist" error message.
     *
     * @param string $errorText
     * @return string
     */
    public function extractMissingTableNameFromError(string $errorText): string {
        if ($errorText === '') {
            return '';
        }
        if (!preg_match("/Table '([^']+)' doesn't exist/i", $errorText, $matches)) {
            return '';
        }
        $fullName = $matches[1];
        $dotPos = strrpos($fullName, '.');
        return $dotPos !== false ? substr($fullName, $dotPos + 1) : $fullName;
    }

    /**
     * Whether WordPress recognizes the missing table and the database also
     * positively confirms that WordPress's authoritative name is absent.
     *
     * A failed query against a generated prefix remains a plugin ERROR when
     * WordPress's own table exists: that means our name resolution drifted.
     * An inconclusive SHOW TABLES probe also remains an ERROR because failure
     * to prove presence is not evidence of absence.
     *
     * @param string $errorText
     * @return bool
     */
    public function isConfirmedMissingWordPressTableError(string $errorText): bool {
        if ($this->confirmedTableAbsenceProbe === null) {
            return false;
        }

        $missingTable = $this->extractMissingTableNameFromError($errorText);
        if ($missingTable === '') {
            return false;
        }

        global $wpdb;
        if (!isset($wpdb) || !is_object($wpdb)) {
            return false;
        }

        $tableSuffixes = isset($wpdb->tables) && is_array($wpdb->tables)
            ? $wpdb->tables : array();
        $tableSuffixes[] = 'users';
        $prefix = isset($wpdb->prefix) && is_scalar($wpdb->prefix)
            ? (string)$wpdb->prefix : '';

        foreach (array_unique($tableSuffixes, SORT_REGULAR) as $tableSuffix) {
            if (!is_scalar($tableSuffix) || (string)$tableSuffix === '') {
                continue;
            }
            $property = (string)$tableSuffix;
            if (!isset($wpdb->{$property}) || !is_scalar($wpdb->{$property})) {
                continue;
            }
            $wordpressTable = (string)$wpdb->{$property};
            if ($wordpressTable === '') {
                continue;
            }
            $generatedTable = $prefix . $property;
            if ($missingTable !== $generatedTable && $missingTable !== $wordpressTable) {
                continue;
            }
            return (bool)call_user_func($this->confirmedTableAbsenceProbe, $wordpressTable);
        }

        return false;
    }

    /**
     * Check if a given table uses the InnoDB storage engine.
     *
     * @param string $tableName
     * @return bool
     */
    public function isInnoDBTable(string $tableName): bool {
        global $wpdb;
        /** @var wpdb $wpdb */
        if (!is_object($wpdb) || !method_exists($wpdb, 'get_var') || !method_exists($wpdb, 'prepare')) {
            return false;
        }
        if (defined('DB_NAME')) {
            $dbName = (string)DB_NAME;
        } else {
            static $warnedNoDbName = false;
            if (!$warnedNoDbName) {
                $warnedNoDbName = true;
                $this->logger->warn(__METHOD__ . ': DB_NAME undefined; using empty schema in InnoDB probe');
            }
            $dbName = '';
        }
        // DAO-bypass-approved: read-only information_schema engine probe for classifying table-full DB errors.
        $engine = $wpdb->get_var(
            // DAO-bypass-approved: prepare call for read-only information_schema engine probe placeholders.
            $wpdb->prepare(
                "SELECT ENGINE FROM information_schema.TABLES WHERE TABLE_SCHEMA = %s AND TABLE_NAME = %s",
                $dbName,
                $tableName
            )
        );
        return is_string($engine) && strtolower($engine) === 'innodb';
    }
}