I have this code which returns the best move using Stockfish Engine. I provide it with a skill level for the engine and the fen string of the position and it should return the best move.

<?php

namespace App;
use SymfonyComponentProcessProcess;

class StockfishService
{
    public function getBestMove(int $skillLevel, string $fen): string
    {
        $output = $this->runCommand("ucinucinewgamenposition startpos moves 10000nsetoption name Skill Level value $skillLevelnposition fen $fenngo movetime 10000n");
        $bestMove = $this->extractBestMove($output);

        return $bestMove;
    }

    private function runCommand(string $command): string
    {
        $process = new Process(['stockfish']);
        $process->setInput($command);
        $process->start();
        $process->wait();

        if (!$process->isSuccessful()) {
            throw new RuntimeException($process->getErrorOutput());
        }

        return $process->getIncrementalOutput();
    }

    private function extractBestMove(string $output): string
    {
        $lines = explode("n", $output);
        foreach ($lines as $line) {
            if (strpos($line, 'bestmove') !== false) {
                $parts = explode(' ', $line);
                return $parts[1]; // Assuming bestmove is the second part
            }
        }

        throw new RuntimeException('Best move not found in engine output');
    }
}

But whenever this code gets exectued it returns basically one of the worst moves in the position no matter the skill level. For example for fen position rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQqk e3 1 1(White pawn to e3) it returns a7a6 which is a bad move. I figured out that the problem is that process ends too soon so I added movetime 10000 after the go command but this didn’t solve anything. Any ideas on how can I fix this?

The only thing I tried is to use $process->start() and $process->wait() instead of $process->run()