add to cart

public function add_to_cart(Request $request)
    {
        // session()->forget('cart');
        try{
            if(session()->has('cart.session_id')) //cart update code
            {
                
                if(!session()->has('user.id'))//if user not logged in 
                {
                    $prev_rec = ShoppingCart::where(['cart_session_id' => session()->get('cart.session_id'), 'product_id' => $request->product_id])->first();
                    
                    if($prev_rec != null)//if product existed in session id, shopping cart, upgrading the cart value
                    {
                        $res = $prev_rec->update([
                            'product_id' => $request->product_id,
                            'price' => $request->price,
                            'net_price' => $prev_rec->net_price + ($request->order_qty * $request->price),
                            'quantity' => $prev_rec->quantity + $request->order_qty,
                            'discount' => null,
                            'status' => 'A',
                        ]);
                    }
                    else //if adding a new product which wasn't in session id, shopping cart
                    {
                        $res = ShoppingCart::create([
                            'cart_session_id' => session()->get('cart.session_id'),
                            'product_id' => $request->product_id,
                            'price' => $request->price,
                            'net_price' => $request->order_qty * $request->price,
                            'quantity' => $request->order_qty,
                            'discount' => null,
                            'status' => 'A',
                        ]);
                    }

                }
                elseif(session()->has('user.id'))//if user logged in
                {
                    $prev_rec = ShoppingCart::where(['user_id' => session()->get('user.id'), 'product_id' => $request->product_id])->first();
                    if($prev_rec != null)
                    {
                        $res = $prev_rec->update([
                            'product_id' => $request->product_id,
                            'price' => $request->price,
                            'net_price' => $request->order_qty * $request->price,
                            'quantity' => $request->order_qty,
                            'discount' => null,
                            'status' => 'A',
                        ]);
                    }
                    else
                    {
                        $res = ShoppingCart::create([
                            'user_id' => session()->get('user.id'),
                            'cart_session_id' => session()->get('cart.session_id'),
                            'product_id' => $request->product_id,
                            'price' => $request->price,
                            'net_price' => $request->order_qty * $request->price,
                            'quantity' => $request->order_qty,
                            'discount' => null,
                            'status' => 'A',
                        ]);
                    }
                }

                return response()->json([
                    'status'=>'Cart updated',
                ], 200);

            }
            elseif(!session()->has('cart.session_id')) //creating new cart
            {
                
                $cart_id = $this->generate_cart_id();
                session()->put([
                    'cart.session_id' => $cart_id,
                ]);

                if(!session()->has('user.id')) //if user not logged in
                {
                    $res = ShoppingCart::create([
                        'cart_session_id' => $cart_id,
                        'product_id' => $request->product_id,
                        'price' => $request->price,
                        'net_price' => $request->order_qty * $request->price,
                        'quantity' => $request->order_qty,
                        'discount' => null,
                        'status' => 'A',
                    ]);
                }
                elseif(session()->has('user.id')) //if user logged in
                {
                    $res = ShoppingCart::create([
                        'user_id' => session()->get('user.id'),
                        'cart_session_id' => $cart_id,
                        'product_id' => $request->product_id,
                        'price' => $request->price,
                        'net_price' => $request->order_qty * $request->price,
                        'quantity' => $request->order_qty,
                        'discount' => null,
                        'status' => 'A',
                    ]);
                }

                return response()->json([
                    'status'=>'Cart created',
                ], 200);
            }
        }
        catch(Exception $e1)
        {
            return response()->json([
                'status' => $e1->getMessage(),
            ], 400);
        }
    }