Allow providing manual signature hint to commands

src/Command.php

@@ -2,6 +2,8 @@
 
 namespace NoccyLabs\React\CommandBus;
 
+use ReflectionFunction;
+use ReflectionNamedType;
 use React\Promise\Deferred;
 use React\Promise\Promise;
 use React\Promise\PromiseInterface;
@@ -17,10 +19,13 @@ class Command
     /** @var callable $handler The handler */
     private $handler;
 
-    public function __construct(string $name, callable $handler)
+    private ?array $signature;
+
+    public function __construct(string $name, callable $handler, ?array $signature = null)
     {
         $this->name = $name;
         $this->handler = $handler;
+        $this->signature = $signature;
     }
 
     public function getName(): string
@@ -38,5 +43,36 @@ class Command
         });
     }
 
+    public function parameters(): array
+    {
+        $refl = new ReflectionFunction($this->handler);
+        $args = [];
+
+        foreach ($refl->getParameters() as $parameter) {
+            $name = $parameter->getName();
+            $type = null;
+            if (!$parameter->hasType()) {
+                $type = 'any';
+            } else {
+                $type = $parameter->getType();
+                if ($type instanceof ReflectionNamedType && $type->isBuiltin()) {
+                    $type = ($type->allowsNull() ? "?" : "") . $type->getName();
+                } else {
+                    $type = null;
+                }
+            }
+            
+            if ($parameter->isDefaultValueAvailable()) $type = "{$type}=".\json_encode($parameter->getDefaultValue(),\JSON_UNESCAPED_SLASHES);
+            if ($type !== null) $args[$name] = $type;
+        }
+
+        return $args;
+    }
+
+    public function getSignature(): array
+    {
+        return $this->signature ?? $this->parameters();
+    }
+
 }
 

src/CommandResolverTrait.php

@@ -8,9 +8,8 @@ use Evenement\EventEmitterTrait;
  * A collection of commands that can be executed via CommandBusInterface
  *
  */
-trait CommandResolverTrait implements EventEmitterInterface
+trait CommandResolverTrait
 {
-    use EventEmitterTrait;
 
     const EVENT_REGISTERED = 'registered';
     const EVENT_UNREGISTERED = 'unregistered';

tests/CommandTest.php

@@ -26,4 +26,14 @@ class CommandTest extends \PHPUnit\Framework\TestCase
         $this->assertEquals(true, $hit);
     }
 
+    public function testCommandReflection()
+    {
+        $command = new Command("test", function (string $a, ?int $b, bool $c = false) { });
+        $expect = [
+            'a' => 'string',
+            'b' => '?int',
+            'c' => 'bool=false'
+        ];
+        $this->assertEquals($expect, $command->parameters());
+    }
 }