3dealer/app/Services/Wishlist.php

<?php

namespace App\Services;

use App\Models\WishlistItem;
use Illuminate\Contracts\Auth\Authenticatable;
use Illuminate\Support\Facades\Auth;
use Illuminate\Support\Facades\Cookie;

/**
 * The current shopper's wishlist, product ids only.
 *
 * Logged in: rows in wishlist_items. Guest: a 1-year cookie holding the ids
 * (encrypted like every cookie, by the web group's EncryptCookies), so nothing
 * is written to the database for anonymous visitors. On login the cookie is
 * merged into the account and cleared (MergeGuestWishlistOnLogin).
 */
class Wishlist
{
    public const COOKIE = 'wishlist';

    private const COOKIE_MINUTES = 60 * 24 * 365;

    // Keeps the cookie well under the 4KB browser limit.
    private const GUEST_MAX = 100;

    /** @var array<int>|null ids for this request, including a toggle just made */
    private ?array $guestIds = null;

    /** @return array<int> newest first */
    public function ids(): array
    {
        if ($user = Auth::user()) {
            return WishlistItem::where('user_id', $user->id)
                ->latest('id')
                ->pluck('product_id')
                ->all();
        }

        return $this->guestIds();
    }

    public function has(int $productId): bool
    {
        return in_array($productId, $this->ids(), true);
    }

    /**
     * @return bool whether the product is on the wishlist afterwards
     */
    public function toggle(int $productId): bool
    {
        if ($user = Auth::user()) {
            $deleted = WishlistItem::where('user_id', $user->id)->where('product_id', $productId)->delete();

            if ($deleted) {
                return false;
            }

            WishlistItem::create(['user_id' => $user->id, 'product_id' => $productId]);

            return true;
        }

        $ids = $this->guestIds();

        if (in_array($productId, $ids, true)) {
            $this->storeGuestIds(array_values(array_diff($ids, [$productId])));

            return false;
        }

        $this->storeGuestIds(array_slice([$productId, ...$ids], 0, self::GUEST_MAX));

        return true;
    }

    public function remove(int $productId): void
    {
        if ($this->has($productId)) {
            $this->toggle($productId);
        }
    }

    /**
     * Moves the guest cookie's products onto $user's wishlist and clears it.
     */
    public function mergeGuestInto(Authenticatable $user): void
    {
        $ids = $this->guestIds();

        if ($ids === []) {
            return;
        }

        // Oldest first, so the newest cookie item also ends up newest here.
        foreach (array_reverse($ids) as $productId) {
            WishlistItem::firstOrCreate(['user_id' => $user->id, 'product_id' => $productId]);
        }

        $this->guestIds = [];
        Cookie::queue(Cookie::forget(self::COOKIE));
    }

    /** @return array<int> */
    private function guestIds(): array
    {
        if ($this->guestIds !== null) {
            return $this->guestIds;
        }

        $decoded = json_decode((string) request()->cookie(self::COOKIE), true);

        return $this->guestIds = is_array($decoded)
            ? array_values(array_unique(array_filter(array_map('intval', $decoded))))
            : [];
    }

    /** @param  array<int>  $ids */
    private function storeGuestIds(array $ids): void
    {
        $this->guestIds = $ids;

        Cookie::queue(self::COOKIE, json_encode($ids), self::COOKIE_MINUTES);
    }
}