First working version with non working routes

src/Container/GenericContainer.php

@@ -0,0 +1,54 @@
+<?php
+
+namespace Ardent\Undercurrent\Container;
+
+use Exception;
+
+class GenericContainer
+{
+    private array $definitions = [];
+
+    private array $instances = [];
+
+    public function add(string $className, ?callable $definition = null, bool $singleton = true): self
+    {
+        if (!$definition) {
+            $definition = function () use ($className) {
+                return new $className();
+            };
+        }
+
+        $this->definitions[$className] = [
+            'definition' => $definition,
+            'singleton' => $singleton,
+        ];
+
+        return $this;
+    }
+
+    /**
+     * @template TClassName
+     * @param class-string<TClassName> $className
+     * @return TClassName
+     * @throws Exception
+     */
+    public function get(string $className): object
+    {
+        if (!isset($this->definitions[$className])) {
+            throw new Exception("Class $className not found in container");
+        }
+
+        $definition = $this->definitions[$className]['definition'];
+        if ($this->definitions[$className]['singleton']) {
+            if (isset($this->instances[$className])) {
+                return $this->instances[$className];
+            }
+            $instance = $definition();
+            $this->instances[$className] = $instance;
+        } else {
+            $instance = $definition();
+        }
+
+        return $instance;
+    }
+}