<?php
namespace Libs;

use React\ChildProcess\Process;
use React\Promise\Deferred;
use React\EventLoop\Loop;

final class ExecLib
{
    public static function exec(string $cmd, ?float $timeoutSecs = null)
    {
        $process  = new Process($cmd);
        $deferred = new Deferred();

        $bufferOut = '';
        $bufferErr = '';
        $timers    = [];

        $process->start(Loop::get());

        if ($process->stdin !== null) {
            $process->stdin->end();
        }

        if ($process->stdout) {
            $process->stdout->on('data', function ($chunk) use (&$bufferOut) {
                $bufferOut .= (string)$chunk;
            });
        }
        if ($process->stderr) {
            $process->stderr->on('data', function ($chunk) use (&$bufferErr) {
                $bufferErr .= (string)$chunk;
            });
        }

        if ($timeoutSecs !== null && $timeoutSecs > 0) {
            $timers['timeout'] = Loop::addTimer($timeoutSecs, function () use ($process, $deferred) {
                if ($process->isRunning()) {
                    $process->terminate(); // SIGTERM
                    Loop::addTimer(1.0, function () use ($process) {
                        if ($process->isRunning()) {
                            $process->terminate(\defined('SIGKILL') ? \SIGKILL : null);
                        }
                    });
                }
                $deferred->reject(new \RuntimeException('CLI timeout'));
            });
        }

        $process->on('exit', function ($exitCode) use (&$bufferOut, &$bufferErr, $deferred, &$timers) {
            foreach ($timers as $t) {
                if ($t) {
                    Loop::cancelTimer($t);
                }
            }
            $output = trim($bufferOut !== '' ? $bufferOut : $bufferErr);
            $deferred->resolve([(int)$exitCode, $output]);
        });

        $process->on('error', function (\Throwable $e) use ($deferred, &$timers) {
            foreach ($timers as $t) {
                if ($t) {
                    Loop::cancelTimer($t);
                }
            }
            $deferred->reject($e);
        });

        return $deferred->promise();
    }
}