public function nextGrid(AnimatedLightingGrid $grid)
{
$verticalSize = $grid->verticalSize();
$horizontalSize = $grid->horizontalSize();
$lights = [];
$existingLights = $grid->getLights();
$brokenLights = $grid instanceof BrokenAnimatedLightingGrid ? $grid->getBrokenLights() : [];
//loop through grid checking each light for its status + neighbours
for ($y = 1; $y <= $verticalSize; $y++) {
for ($x = 1; $x <= $horizontalSize; $x++) {
if (in_array($x . "-" . $y, $brokenLights)) {
$lights[] = $x . "-" . $y;
continue;
}
//find out how many neighbour lights are switched on
$onNeighbours = 0;
foreach ($grid->neighbours($x, $y) as $neighbour) {
if (in_array($neighbour[0] . "-" . $neighbour[1], $existingLights)) {
$onNeighbours++;
}
}
//work out state for this light for next step
$currentlyOn = in_array("{$x}-{$y}", $existingLights);
if ($currentlyOn && ($onNeighbours == 2 || $onNeighbours == 3)) {
$lights[] = "{$x}-{$y}";
} elseif (!$currentlyOn && $onNeighbours == 3) {
$lights[] = "{$x}-{$y}";
}
}
}
$grid->lights($lights);
return $grid;
}
public function lights(array $lights)
{
parent::lights(array_merge($lights, $this->getBrokenLights()));
}