<?php
/**
 * Copyright 2026 Adobe
 * All Rights Reserved.
 */

declare(strict_types=1);

namespace Magento\Framework\DB\Helper;

/**
 * Helper class to remove deprecated 'SET NAMES utf8;' or 'SET NAMES utf8 COLLATE ...;'
 * from database connection initStatements in env.php during setup/upgrade operations.
 */
class InitStatementsCleanup
{
    /**
     * Remove 'SET NAMES utf8;' or 'SET NAMES utf8 COLLATE utf8_general_ci;' from initStatements string
     *
     * Rules:
     * - If initStatements contains only such a statement, returns null
     *   (indicating the entire initStatements key should be removed)
     * - If initStatements contains it along with other statements,
     *   removes only that statement and returns the cleaned string
     * - Does not remove 'SET NAMES utf8mb4' or similar
     *
     * @param string $initStatements The initStatements string from connection config
     * @return string|null Returns cleaned string, or null if nothing remains
     */
    public function removeSetNamesUtf8(string $initStatements): ?string
    {
        // Skip if empty
        if (empty(trim($initStatements))) {
            return null;
        }

        // Check if it contains 'SET NAMES utf8'
        if (stripos($initStatements, 'SET NAMES utf8') === false) {
            return $initStatements;
        }

        // Remove deprecated 'SET NAMES utf8;' or 'SET NAMES utf8 COLLATE utf8_general_ci;'.
        // (?!mb4) ensures we never match 'utf8' inside 'SET NAMES utf8mb4'
        // (only the utf8mb3 form is removed).
        $cleaned = preg_replace(
            '/\s*SET\s+NAMES\s+utf8(?!mb4)(?:\s*;|\s+COLLATE\s+[\w_]+\s*;?)\s*/i',
            '',
            $initStatements
        );

        // Clean up any extra semicolons or whitespace
        $cleaned = trim($cleaned);
        $cleaned = preg_replace('/;\s*;+/', ';', $cleaned);  // Remove duplicate semicolons
        $cleaned = trim($cleaned, ';');  // Remove leading/trailing semicolons
        $cleaned = preg_replace('/\s+/', ' ', $cleaned);  // Normalize whitespace

        // If nothing left after removing SET NAMES utf8, return null
        if (empty($cleaned)) {
            return null;
        }

        // Return cleaned value with semicolon at the end
        return $cleaned . ';';
    }

    /**
     * Process connection configuration array and remove deprecated SET NAMES utf8
     *
     * This method modifies the connection config array in-place.
     * - Removes entire 'initStatements' key if it only contains 'SET NAMES utf8;' or 'SET NAMES utf8 COLLATE ...;'
     * - Updates 'initStatements' with cleaned value if it contains other statements
     *
     * @param array &$connectionConfig Database connection configuration array (passed by reference)
     * @return bool True if configuration was modified
     */
    public function processConnectionConfig(array &$connectionConfig): bool
    {
        if (!isset($connectionConfig['initStatements'])) {
            return false;
        }

        $initStatements = $connectionConfig['initStatements'];

        // Skip if not a string
        if (!is_string($initStatements)) {
            return false;
        }

        $cleaned = $this->removeSetNamesUtf8($initStatements);

        // If cleaned is null, remove the entire initStatements key
        if ($cleaned === null) {
            unset($connectionConfig['initStatements']);
            return true;
        }

        // If cleaned is different from original, update it
        if ($cleaned !== $initStatements) {
            $connectionConfig['initStatements'] = $cleaned;
            return true;
        }

        return false;
    }

    /**
     * Process all database connections in env.php config array
     *
     * This method processes both regular connections (db/connection) and slave connections
     * (db/slave_connection) to remove deprecated 'SET NAMES utf8;' or 'SET NAMES utf8 COLLATE ...;' statements.
     *
     * @param array &$envConfig The full env.php configuration array (passed by reference)
     * @return bool True if any configuration was modified
     */
    public function processEnvConfig(array &$envConfig): bool
    {
        $modified = false;

        // Process regular database connections
        if (isset($envConfig['db']['connection']) && is_array($envConfig['db']['connection'])) {
            foreach ($envConfig['db']['connection'] as &$connectionConfig) {
                if ($this->processConnectionConfig($connectionConfig)) {
                    $modified = true;
                }
            }
            unset($connectionConfig); // Break reference
        }

        // Process slave connections
        if (isset($envConfig['db']['slave_connection']) && is_array($envConfig['db']['slave_connection'])) {
            foreach ($envConfig['db']['slave_connection'] as &$slaveConfig) {
                if ($this->processConnectionConfig($slaveConfig)) {
                    $modified = true;
                }
            }
            unset($slaveConfig); // Break reference
        }

        return $modified;
    }
}