class Brainfuck {
	private string $code;
	private int $code_pointer;
	private int[] $cells;
	private int $pointer;
	private string $input;
	private int $input_pointer;
	private int[] $buffer;
	private string $output;

	public void __construct(string $code, string $input = NULL) {
		$this->code = $code;
		$this->input = $input;
	}

	public void run() {
		while ($this->code_pointer < strlen($this->code)) {
			$this->interpret($this->code[$this->code_pointer]);
			$this->code_pointer++;
		}
		print($this->output);
	}

	private void interpret(string $command) {
		if(!$this->cells[$this->pointer]) {
			$this->cells[$this->pointer] = 0;
		}
		switch ($command) {
			case '>' :
				$this->pointer++;
				break;
			case '<' :
				$this->pointer--;
				break;
			case '+' :
				$this->cells[$this->pointer]++;
				if($this->cells[$this->pointer] > 255) {
					$this->cells[$this->pointer] = 0;
				}
				break;
			case '-' :
				$this->cells[$this->pointer]--;
				if($this->cells[$this->pointer] < 0) {
					$this->cells[$this->pointer] = 255;
				}
				break;
			case '.' :
				$this->output += chr($this->cells[$this->pointer]);
				break;
			case ',' :
				$this->cells[$this->pointer] = $this->input[$this->input_pointer] ? ord($this->input[$this->input_pointer]) : 0;
				$this->input_pointer++;
				break;
			case '[' :
				if($this->cells[$this->pointer] == 0) {
					int $delta = 1;
					while($delta && $this->code_pointer++ < strlen($this->code)) {
						switch ($this->code[$this->code_pointer]) {
							case '[' :
								$delta++;
								break;
							case ']' :
								$delta--;
								break;
						}
					}
				} else {
					$this->buffer[] = $this->code_pointer;
				}
				break;
			case ']' :
				$this->code_pointer = array_pop($this->buffer) - 1;
		}
	}

}


class Program {

	void main() {
		object $bf;
		string $code;
		resource $dir;
		string $file;
		string[] $files;
		string $input;
		$dir = opendir('tests/data/brainfuck');
		while($file = readdir($dir)) {
			if($file == '.' || $file == '..') {
				continue;
			}
			$files[] = $file;
		}
		sort($files);
		unset($file);
		for(int $n = 0; $n < sizeof($files); $n++) {
			print('Executing "' + $files[$n] + '"' + "\n");
			$code = file_get_contents('tests/data/brainfuck/' + $files[$n]);
			$bf = new Brainfuck($code, $input);
			$bf->run();
			print("\n");
		}
		closedir($dir);
	}

}