fixed

<?php

class BreakPieces
{
    public function process($shape): array
    {
        $lines = explode("\n", $shape);
        $plusPositions = $this->findPlusPositions($lines);
        $rectangles = $this->findRectangles($plusPositions, $lines);
        return array_map([$this, 'generateRectangle'], $rectangles);
    }

    private function findPlusPositions($lines): array
    {
        $positions = [];
        foreach ($lines as $x => $line) {
            foreach (str_split($line) as $y => $char) {
                if ($char === '+') {
                    $positions[] = new Pos($x, $y);
                }
            }
        }
        return $positions;
    }

    private function findRectangles($plusPositions, $lines): array
    {
        $rectangles = [];
        foreach ($plusPositions as $p1) {
            foreach ($plusPositions as $p2) {
                if ($p1->x === $p2->x && $p1->y < $p2->y) {
                    foreach ($plusPositions as $p3) {
                        if ($p1->y === $p3->y && $p1->x < $p3->x) {
                            $p4 = new Pos($p3->x, $p2->y);
                            if (in_array($p4, $plusPositions, false) && $this->isValidRectangle($lines, $p1, $p2, $p3, $p4)) {
                                // Rechteck nur hinzufügen, wenn es die richtige Struktur hat
                                $rectangles[] = [$p1, $p2, $p3, $p4];
                            }
                        }
                    }
                }
            }
        }
        return $rectangles;
    }

	private function isValidRectangle($lines, $p1, $p2, $p3, $p4): bool
	{
		// Überprüfen, ob die Mitte des Rechtecks nur aus Leerzeichen besteht
		for ($x = $p1->x + 1; $x < $p3->x; $x++) {
			for ($y = $p1->y + 1; $y < $p2->y; $y++) {
				if ($lines[$x][$y] !== ' ') {
					return false;
				}
			}
		}
	
		return true;
	}
	
	

    private function generateRectangle($rectangle): string
    {
        [$p1, $p2, $p3, $p4] = $rectangle;
        $width = $p2->y - $p1->y + 1; // Korrekte Berechnung der Breite
        $height = $p3->x - $p1->x + 1; // Korrekte Berechnung der Höhe

        $output = "+" . str_repeat("-", $width - 2) . "+\n"; // Formatierung der oberen Grenze
        for ($i = 0; $i < $height - 2; $i++) {
            $output .= "|" . str_repeat(" ", $width - 2) . "|\n"; // Leere Linien für die Höhe
        }
        $output .= "+" . str_repeat("-", $width - 2) . "+"; // Formatierung der unteren Grenze
        return $output;
    }
}

class Pos
{
    public int $x, $y;
    public function __construct(int $x, int $y) { $this->x = $x; $this->y = $y; }
}


$shape = implode("\n", [
	"+------------+",
	"|            |",
	"|            |",
	"|            |",
	"|            |",
	"+-----+------+",
	"|     |      |",
	"+-----+------+"
]);

var_dump((new BreakPieces())->process($shape));

$result = [
	[
		"+------------+",
		"|            |",
		"|            |",
		"|            |",
		"|            |",
		"+------------+"
	],
	[
		"+-----+",
		"|     |",
		"+-----+"
	],
	[
		"+------+",
		"|      |",
		"+------+"
	]
];