php-kilo/src/Event.php

<?php declare(strict_types=1);

namespace Aviat\Kilo;

class Event {
	use Traits\ConstList;

	// ------------------------------------------------------------------------
	// Valid Events
	// ------------------------------------------------------------------------
	public const INPUT_KEY = 'INPUT_KEY';
	public const PAGE_CHANGE = 'PAGE_CHANGE';
	public const MOVE_CURSOR = 'MOVE_CURSOR';
	public const QUIT_ATTEMPT = 'QUIT_ATTEMPT';

	// Mapping of events to handlers
	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 on(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 = self::getConstList();

		if ( ! array_key_exists($eventName, $validEvents))
		{
			throw new \InvalidArgumentException("Invalid event '{$eventName}'. Event const must exist in Aviat\\Kilo\\Event.");
		}
	}
}