/**
* Generate a new galaxy.
*
* @return \Illuminate\Http\RedirectResponse
*/
public function generate()
{
// Start with a clean slate.
DB::table('stars')->delete();
DB::table('star_links')->delete();
// Create new stars.
$starCount = 200;
/**
* @var Star[] $unvisitedStars
* @var Star[] $visitedStars
* @var Star[] $allStars
*/
$unvisitedStars = [];
$visitedStars = [];
$allStars = [];
for ($i = 0; $i < $starCount; $i++) {
$star = new Star(['name' => $this->generateName()]);
$star->save();
$unvisitedStars[$star->getKey()] = true;
$allStars[$star->getKey()] = $star;
}
// Create links between stars.
$totalLinks = 0;
$starId = array_rand($allStars);
$visitedStars[$starId] = $allStars[$starId];
unset($unvisitedStars[$starId]);
// Random walk to generate a uniform spanning tree.
while (!empty($unvisitedStars)) {
$star = $visitedStars[$starId];
$otherStarId = array_rand($allStars);
$otherStar = $allStars[$otherStarId];
if (!isset($visitedStars[$otherStarId])) {
$star->exits()->attach($otherStar);
$otherStar->exits()->attach($star);
$visitedStars[$otherStarId] = $allStars[$otherStarId];
unset($unvisitedStars[$otherStarId]);
$totalLinks++;
}
$starId = $otherStarId;
}
// Add some extra links to create cycles.
for ($i = 0; $i < $totalLinks / 10; $i++) {
$star = $allStars[array_rand($allStars)];
$otherStar = $allStars[array_rand($allStars)];
if ($star != $otherStar) {
$star->exits()->attach($otherStar);
$otherStar->exits()->attach($star);
$totalLinks++;
}
}
return redirect()->back()->with('status', 'Generated ' . $starCount . ' stars and ' . $totalLinks . ' star links.');
}
