Add basic event system

src/Event.php

@@ -0,0 +1,47 @@
+<?php declare(strict_types=1);
+
+namespace Aviat\Kilo;
+
+use Aviat\Kilo\Enum\Event as EventEnum;
+
+class Event {
+	private static $subscribeMap = [];
+
+	public static function fire(string $eventName, $value): void
+	{
+		static::validateEvent($eventName);
+
+		if (array_key_exists($eventName, static::$subscribeMap))
+		{
+			foreach (static::$subscribeMap[$eventName] as $fn)
+			{
+				$fn($value);
+			}
+		}
+	}
+
+	public static function bind(string $eventName, callable $fn): void
+	{
+		static::validateEvent($eventName);
+
+		if ( ! array_key_exists($eventName, static::$subscribeMap))
+		{
+			static::$subscribeMap[$eventName] = [];
+		}
+
+		if ( ! in_array($fn, static::$subscribeMap[$eventName], TRUE))
+		{
+			static::$subscribeMap[$eventName][] = $fn;
+		}
+	}
+
+	private static function validateEvent(string $eventName): void
+	{
+		$validEvents = EventEnum::getConstList();
+
+		if ( ! array_key_exists($eventName, $validEvents))
+		{
+			throw new \InvalidArgumentException("Invalid event '{$eventName}'. Event const must exist in Aviat\\Kilo\\Enum\\Event.");
+		}
+	}
+}

tests/EventTest.php

@@ -0,0 +1,28 @@
+<?php declare(strict_types=1);
+
+namespace Aviat\Kilo\Tests;
+
+use Aviat\Kilo\Event;
+use Aviat\Kilo\Enum\Event as EventType;
+use InvalidArgumentException;
+use PHPUnit\Framework\TestCase;
+
+class EventTest extends TestCase {
+	public function testRequiresValidEvent(): void
+	{
+		$this->expectException(InvalidArgumentException::class);
+		Event::bind('badEventName', fn () => null);
+
+		$this->expectException(InvalidArgumentException::class);
+		Event::fire('badEventName', []);
+	}
+
+	public function testBindAndFire(): void
+	{
+		$fn = static function($value = false) {
+			static::assertTrue($value);
+		};
+		Event::bind(EventType::INPUT_KEY, $fn);
+		Event::fire(EventType::INPUT_KEY, TRUE);
+	}
+}