<?php

namespace NoccyLabs\Ipc\Interop\Async;

use NoccyLabs\Ipc\Signal\SignalHandler;


/**
 * Simple second-granularity timer for asynchronous events
 * 
 */
class Timer
{
    private static $timers = null;

    private $callback;

    /**
     * Constructor
     *
     * @param callable $callback
     */
    public function __construct(callable $callback)
    {
        $this->callback = $callback;
        self::registerTimer($this->callback);
    }

    /**
     * Destructor
     */
    public function __destruct()
    {
        self::clearTimer($this->callback);
    }

    /**
     * Register a timer callback function
     *
     * @param callable $timer
     * @return void
     */
    private static function registerTimer(callable $timer)
    {
        if (self::$timers === null) {
            $handler = new SignalHandler(SIGALRM, [ __CLASS__."::onSignal" ]);
            pcntl_alarm(1);
        }
        self::$timers[] = $timer;
    }

    /**
     * Remove a timer callback function
     *
     * @param callable $timer
     * @return void
     */
    private static function clearTimer(callable $timer)
    {
        self::$timers = array_filter(self::$timers, function ($t) use ($timer) {
            return $t !== $timer;
        });
    }

    /**
     * Handle signals when the alarm fires
     *
     * @return void
     */
    public static function onSignal()
    {
        foreach (self::$timers as $timer) {
            call_user_func($timer);
        }
        pcntl_alarm(1);
    }

}