feat: implement command bus with attribute-based handler resolution and add example command and handler (#27)

Reviewed-on: #27
Co-authored-by: Ron Rise <ron@siteworxpro.com>
Co-committed-by: Ron Rise <ron@siteworxpro.com>

src/CommandBus/AttributeLocator.php

@@ -0,0 +1,49 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Siteworxpro\App\CommandBus;
+
+use League\Tactician\Exception\CanNotInvokeHandlerException;
+use League\Tactician\Handler\Locator\HandlerLocator;
+use Siteworxpro\App\Attributes\CommandBus\HandlesCommand;
+
+class AttributeLocator implements HandlerLocator
+{
+    private const string HANDLER_NAMESPACE = 'Siteworxpro\\App\\CommandBus\\Handlers\\';
+
+    private array $handlers;
+
+    public function __construct()
+    {
+        $directory = __DIR__ . '/Handlers';
+        $files = scandir($directory);
+        foreach ($files as $file) {
+            if (pathinfo($file, PATHINFO_EXTENSION) === 'php') {
+                $className = pathinfo($file, PATHINFO_FILENAME);
+                $fullClassName = self::HANDLER_NAMESPACE . $className;
+
+                if (class_exists($fullClassName)) {
+                    $reflectionClass = new \ReflectionClass($fullClassName);
+                    $attributes = $reflectionClass->getAttributes(HandlesCommand::class);
+
+                    foreach ($attributes as $attribute) {
+                        $instance = $attribute->newInstance();
+                        $commandClass = $instance->commandClass;
+                        $this->handlers[$commandClass] = $fullClassName;
+                    }
+                }
+            }
+        }
+    }
+
+    public function getHandlerForCommand($commandName)
+    {
+        if (isset($this->handlers[$commandName])) {
+            $handlerClass = $this->handlers[$commandName];
+            return new $handlerClass();
+        }
+
+        throw new CanNotInvokeHandlerException("No handler found for command: " . $commandName);
+    }
+}