Update -> refactor and optimize UI , code ,...

app/core/db.php

@@ -1,13 +1,21 @@
 <?php
 $config = require __DIR__ . '/../config/config.php';
+
 try {
-    $pdo = new PDO(
-        "mysql:host={$config['db']['host']};dbname={$config['db']['name']};charset=utf8mb4",
-        $config['db']['user'],
-        $config['db']['pass'],
-        [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION]
+    $dsn = sprintf(
+        'mysql:host=%s;dbname=%s;charset=%s',
+        $config['db']['host'],
+        $config['db']['name'],
+        $config['db']['charset']
     );
-} catch (Exception $e) {
-    die('Database connection error');
+    $pdo = new PDO($dsn, $config['db']['user'], $config['db']['pass'], [
+        PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
+        PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
+        PDO::ATTR_EMULATE_PREPARES   => false,
+    ]);
+} catch (PDOException $e) {
+    http_response_code(503);
+    die(json_encode(['success' => false, 'message' => 'Database connection error.']));
 }
+
 return $pdo;

app/core/redis.php

@@ -1,13 +1,14 @@
 <?php
 
-function redisClient()
+function redisClient(): Redis
 {
     static $redis = null;
     if ($redis === null) {
         $config = require __DIR__ . '/../config/config.php';
-
-        $redis = new Redis();
-        $redis->connect($config['redis']['host'], $config['redis']['port']);
+        $redis  = new Redis();
+        if (!@$redis->connect($config['redis']['host'], $config['redis']['port'])) {
+            throw new RuntimeException('Redis connection failed.');
+        }
     }
     return $redis;
 }

app/core/security.php

@@ -1,15 +1,32 @@
 <?php
-function encryptText($text, $key) {
-    $iv = random_bytes(16);
+
+function encryptText(string $text, string $key): array
+{
+    $iv     = random_bytes(16);
     $cipher = openssl_encrypt($text, 'AES-256-CBC', $key, 0, $iv);
+    if ($cipher === false) {
+        throw new RuntimeException('Encryption failed.');
+    }
     return [
         'cipher' => $cipher,
-        'iv' => base64_encode($iv)
+        'iv'     => base64_encode($iv),
     ];
 }
-function decryptText($cipher, $iv, $key) {
+
+function decryptText(string $cipher, string $iv, string $key): string|false
+{
     return openssl_decrypt($cipher, 'AES-256-CBC', $key, 0, base64_decode($iv));
 }
-function generateId() {
+
+function generateId(): string
+{
     return bin2hex(random_bytes(16));
 }
+
+function jsonResponse(array $data, int $status = 200): void
+{
+    http_response_code($status);
+    header('Content-Type: application/json');
+    echo json_encode($data);
+    exit;
+}