<?php

namespace App\Http\Controllers;

use App\Http\Requests\StoreCartRequest;
use App\Http\Requests\UpdateCartRequest;
use App\Models\Cart;
use App\Models\Product;
use Illuminate\Http\JsonResponse;
use Illuminate\Http\Request;

class CartController extends Controller
{
    public function store(StoreCartRequest $request): JsonResponse
    {
        $cart = $this->resolveCart();

        $existing = $cart->products()->wherePivot('product_id', $request->product_id)->first();

        if ($existing) {
            $cart->products()->updateExistingPivot($request->product_id, [
                'quantity' => $existing->pivot->quantity + 1,
            ]);
        } else {
            $cart->products()->attach($request->product_id, ['quantity' => 1]);
        }

        return response()->json($this->cartItems($cart));
    }

    public function update(UpdateCartRequest $request, Product $product): JsonResponse
    {
        $cart = $this->resolveCart();

        $cart->products()->updateExistingPivot($product->id, [
            'quantity' => $request->quantity,
        ]);

        return response()->json($this->cartItems($cart));
    }

    public function destroy(Request $request, Product $product): JsonResponse
    {
        $cart = $this->resolveCart();

        $cart->products()->detach($product->id);

        return response()->json($this->cartItems($cart));
    }

    private function resolveCart(): Cart
    {
        $cartId = session('cart_id');

        if ($cartId) {
            $cart = Cart::find($cartId);
            if ($cart) {
                return $cart;
            }
        }

        $cart = Cart::create(['user_id' => request()->user()?->id]);
        session(['cart_id' => $cart->id]);

        return $cart;
    }

    /**
     * @return array<int, array{product_id: int, quantity: int}>
     */
    private function cartItems(Cart $cart): array
    {
        return $cart->products()->get()->map(fn ($p) => [
            'product_id' => $p->id,
            'quantity' => $p->pivot->quantity,
        ])->all();
    }
}