<?php

namespace App\Http\Controllers\Checkout;

use App\Http\Controllers\Controller;
use Illuminate\Http\JsonResponse;
use Illuminate\Http\Request;
use Illuminate\View\View;
use Lunar\Exceptions\Carts\CartException;
use Lunar\Models\CartLine;
use Lunar\Models\ProductVariant;
use Modules\Core\Cart\Exceptions\InvalidCouponException;
use Modules\Core\Cart\Services\CartService;

/**
 * Thin storefront cart endpoints for the checkout module. Every action mutates
 * the session cart via boboko-core's CartService and returns the same
 * server-rendered `cart-body` partial — the drawer's Stimulus controller swaps
 * that fragment in place (no JSON, no client-side templating). $cart / $lines
 * for the partial come from the view composer in CheckoutModuleServiceProvider.
 */
class CartController extends Controller
{
    public function __construct(
        private readonly CartService $cart,
    ) {}

    /**
     * CartException here is Lunar's own add_to_cart validation pipeline
     * (CartLineQuantity/CartLineStock) rejecting the line — most commonly
     * "not enough stock at this quantity" for a tracked (purchasable =
     * in_stock) variant. Its own message is an untranslated, hardcoded
     * English string not meant for storefront display, so this returns our
     * own translated one instead rather than passing it through — a
     * storefront.* key rather than checkout.*, since this is a catalog/stock
     * concern the storefront owns, not something specific to the portable
     * checkout module.
     */
    public function add(string $locale, Request $request): View|JsonResponse
    {
        $data = $request->validate([
            'purchasable_id' => ['required', 'integer'],
            'quantity' => ['nullable', 'integer', 'min:1'],
        ]);

        $variant = ProductVariant::findOrFail($data['purchasable_id']);

        try {
            $this->cart->addLine($variant, $data['quantity'] ?? 1);
        } catch (CartException) {
            return $this->stockError($variant);
        }

        return view('checkout::partials.cart-body');
    }

    public function updateLine(string $locale, Request $request, int $line): View|JsonResponse
    {
        $quantity = (int) $request->validate([
            'quantity' => ['required', 'integer', 'min:0'],
        ])['quantity'];

        try {
            $quantity === 0
                ? $this->cart->removeLine($line)
                : $this->cart->updateLine($line, $quantity);
        } catch (CartException) {
            $variant = CartLine::find($line)?->purchasable;

            return $this->stockError($variant instanceof ProductVariant ? $variant : null);
        }

        return view('checkout::partials.cart-body');
    }

    /**
     * getTotalInventory() is the same number canBeFulfilledAtQuantity()
     * checked against (stock, for a tracked in_stock variant) — telling the
     * shopper how many are actually left beats a generic "not enough stock"
     * they'd otherwise have to guess around by trial and error.
     */
    private function stockError(?ProductVariant $variant): JsonResponse
    {
        $available = $variant?->getTotalInventory() ?? 0;

        return response()->json([
            'error' => trans_choice('storefront.product.add_to_cart_failed', $available, ['count' => $available]),
        ], 422);
    }

    public function remove(string $locale, int $line): View
    {
        $this->cart->removeLine($line);

        return view('checkout::partials.cart-body');
    }

    /**
     * A bad code is a normal, expected outcome here (typo, expired code), not
     * an error state for the request — it re-renders the same cart-body
     * partial with $couponError set, rather than a 4xx/redirect, so the fetch
     * + swap in bbk-cart-controller stays the one code path for every cart
     * mutation.
     */
    public function applyCoupon(string $locale, Request $request): View
    {
        $code = $request->validate([
            'code' => ['required', 'string'],
        ])['code'];

        $couponError = false;

        try {
            $this->cart->applyCoupon($code);
        } catch (InvalidCouponException) {
            $couponError = true;
        }

        return view('checkout::partials.cart-body', ['couponError' => $couponError]);
    }

    public function removeCoupon(string $locale): View
    {
        $this->cart->removeCoupon();

        return view('checkout::partials.cart-body');
    }
}