<?php

/**
 * WKVS Database User Generator & Manager Script
 * 
 * Functions:
 * 1. Reads database configuration from config/.env.db, config/.env.db-wkvs-user, config/.env.db-guest
 * 2. Connects to MariaDB/MySQL using Root credentials
 * 3. Auto-creates or updates DB users (Normal User with CRUD & Guest User with Read-only)
 * 4. Updates the respective .env files so PHP application stays in sync
 * 
 * Can be run via CLI: php setup/database/generate-users.php
 * Or included in web endpoints to change user credentials dynamically.
 */

// Helper to parse simple key=value .env files without requiring composer packages
function parse_env_file_simple(string $filepath): array {
    $env = [];
    if (!file_exists($filepath)) {
        return $env;
    }
    $lines = file($filepath, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
    foreach ($lines as $line) {
        $line = trim($line);
        if (empty($line) || str_starts_with($line, '#')) {
            continue;
        }
        $parts = explode('=', $line, 2);
        if (count($parts) === 2) {
            $key = trim($parts[0]);
            $val = trim($parts[1], " \t\n\r\0\x0B\"'");
            $env[$key] = $val;
        }
    }
    return $env;
}

// Helper to write key=value pairs back to a .env file safely
function write_env_file_simple(string $filepath, array $data): bool {
    $content = "";
    foreach ($data as $key => $val) {
        $content .= "{$key}={$val}\n";
    }
    return file_put_contents($filepath, $content) !== false;
}

// Main logic wrapped in a reusable function
function sync_and_create_db_users(
    ?string $overrideUser = null,
    ?string $overrideUserPass = null,
    ?string $overrideGuest = null,
    ?string $overrideGuestPass = null
): array {
    $baseDir = dirname(__DIR__, 2);
    $configDir = $baseDir . '/config';

    $dbEnvFile       = $configDir . '/.env.db';
    $userEnvFile     = $configDir . '/.env.db-wkvs-user';
    $guestEnvFile    = $configDir . '/.env.db-guest';

    // 1. Load Root DB config
    $dbEnv = parse_env_file_simple($dbEnvFile);
    $rootPass = $dbEnv['MYSQL_ROOT_PASSWORD'] ?? '';
    $dbName   = $dbEnv['MYSQL_DATABASE'] ?? 'devdb_';

    // Target host for MySQL connection from PHP script
    // If running inside Docker container or host, determine host
    $dbHost = getenv('DB_HOST') ?: ($dbEnv['DB_HOST'] ?? 'mariadb');
    $dbPort = (int)($dbEnv['DB_PORT'] ?? 3306);

    // Fallback connection attempt hosts
    $hostsToTry = [$dbHost, '127.0.0.1', 'mariadb', 'localhost'];

    $mysqli = null;
    $connectedHost = null;

    foreach ($hostsToTry as $tryHost) {
        try {
            $testConn = @new mysqli($tryHost, 'root', $rootPass, '', $dbPort);
            if (!$testConn->connect_error) {
                $mysqli = $testConn;
                $connectedHost = $tryHost;
                break;
            }
        } catch (Throwable $e) {
            continue;
        }
    }

    if (!$mysqli) {
        return [
            'success' => false,
            'message' => "Konnte keine Verbindung als 'root' zu MariaDB herstellen. Bitte prüfen Sie MYSQL_ROOT_PASSWORD in config/.env.db."
        ];
    }

    // 2. Load existing user env files or generate defaults
    $userEnv = parse_env_file_simple($userEnvFile);
    $guestEnv = parse_env_file_simple($guestEnvFile);

    // Prefix helper for usernames if creating new
    $dbUser     = $overrideUser     ?: ($userEnv['DB_USER'] ?? 'wkvs_user');
    $dbPass     = $overrideUserPass ?: ($userEnv['DB_PASSWORD'] ?? bin2hex(random_bytes(16)));
    
    $dbGuestUser = $overrideGuest    ?: ($guestEnv['DB_GUEST_USER'] ?? 'wkvs_guest');
    $dbGuestPass = $overrideGuestPass?: ($guestEnv['DB_GUEST_PASSWORD'] ?? bin2hex(random_bytes(16)));

    $appDbHost  = $userEnv['DB_HOST'] ?? 'mariadb';
    $appDbPort  = $userEnv['DB_PORT'] ?? 3306;

    // 3. Create database if it does not exist
    $mysqli->query("CREATE DATABASE IF NOT EXISTS `$dbName` CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci");

    // 4. Create or Update Normal User (SELECT, INSERT, UPDATE, DELETE)
    // Access is isolated to the Docker network container level via compose.yaml
    $escapedUser = $mysqli->real_escape_string($dbUser);
    $escapedPass = $mysqli->real_escape_string($dbPass);
    $escapedDb   = $mysqli->real_escape_string($dbName);

    // Clean up legacy per-host entries if present
    $mysqli->query("DROP USER IF EXISTS '{$escapedUser}'@'%'");
    

    // Normal User (1 user entry)
    $mysqli->query("CREATE USER IF NOT EXISTS '{$escapedUser}'@'%' IDENTIFIED BY '{$escapedPass}'");
    $mysqli->query("ALTER USER '{$escapedUser}'@'%' IDENTIFIED BY '{$escapedPass}'");
    $mysqli->query("GRANT SELECT, INSERT, UPDATE, DELETE ON `{$escapedDb}`.* TO '{$escapedUser}'@'%'");

    // Guest User (SELECT only)
    $escapedGuest     = $mysqli->real_escape_string($dbGuestUser);
    $escapedGuestPass = $mysqli->real_escape_string($dbGuestPass);

    // Clean up legacy per-host entries if present
    foreach (['127.0.0.1', 'localhost', '172.%.%.%', '10.%.%.%', '192.168.%.%.%'] as $oldHost) {
        $mysqli->query("DROP USER IF EXISTS '{$escapedGuest}'@'{$oldHost}'");
    }

    // Guest User (1 user entry)
    $mysqli->query("CREATE USER IF NOT EXISTS '{$escapedGuest}'@'%' IDENTIFIED BY '{$escapedGuestPass}'");
    $mysqli->query("ALTER USER '{$escapedGuest}'@'%' IDENTIFIED BY '{$escapedGuestPass}'");
    $mysqli->query("GRANT SELECT ON `{$escapedDb}`.* TO '{$escapedGuest}'@'%'");

    $mysqli->query("FLUSH PRIVILEGES");
    $mysqli->close();

    // 5. Update .env files
    $newUserEnvData = [
        'DB_USER'     => $dbUser,
        'DB_PASSWORD' => $dbPass,
        'DB_NAME'     => $dbName,
        'DB_HOST'     => $appDbHost,
        'DB_PORT'     => $appDbPort,
    ];

    $newGuestEnvData = [
        'DB_GUEST_USER'     => $dbGuestUser,
        'DB_GUEST_PASSWORD' => $dbGuestPass,
        'DB_NAME'           => $dbName,
        'DB_HOST'           => $appDbHost,
        'DB_PORT'           => $appDbPort,
    ];

    write_env_file_simple($userEnvFile, $newUserEnvData);
    write_env_file_simple($guestEnvFile, $newGuestEnvData);

    return [
        'success' => true,
        'message' => 'Datenbank-Benutzer erfolgreich erstellt/aktualisiert.',
        'normal_user' => [
            'username' => $dbUser,
            'password' => $dbPass,
        ],
        'guest_user' => [
            'username' => $dbGuestUser,
            'password' => $dbGuestPass,
        ]
    ];
}

// If invoked directly from CLI
if (php_sapi_name() === 'cli' && realpath($argv[0] ?? '') === __FILE__) {
    echo "=== WKVS Database User Auto-Generator ===\n";

    $user      = $argv[1] ?? null;
    $userPass  = $argv[2] ?? null;
    $guest     = $argv[3] ?? null;
    $guestPass = $argv[4] ?? null;

    $result = sync_and_create_db_users($user, $userPass, $guest, $guestPass);

    if ($result['success']) {
        echo "✓ " . $result['message'] . "\n\n";
        echo "Normal User (SELECT, INSERT, UPDATE, DELETE):\n";
        echo "  Benutzername: " . $result['normal_user']['username'] . "\n";
        echo "  Passwort:     " . $result['normal_user']['password'] . "\n\n";
        echo "Guest User (SELECT only):\n";
        echo "  Benutzername: " . $result['guest_user']['username'] . "\n";
        echo "  Passwort:     " . $result['guest_user']['password'] . "\n";
    } else {
        echo "❌ Fehler: " . $result['message'] . "\n";
        exit(1);
    }
}