<?php

namespace App\Domains\Purchase\Services;

use App\Domains\Catalog\Models\ProductVariant;
use App\Domains\Purchase\Models\Purchase;
use App\Domains\Tenant\Models\Tenant;
use Illuminate\Support\Facades\DB;
use Illuminate\Validation\ValidationException;

class CheckoutService
{
    public function processCheckout(Tenant $tenant, int $userId, array $purchaseData): Purchase
    {
        // 1. Preparar items de la compra
        $items = $purchaseData['items'];
        unset($purchaseData['items']);

        $variants = $this->resolveTenantVariants($tenant, $items);
        $purchaseItemsPayload = $this->buildPurchaseItemsPayload($items, $variants);

        // 2. Crear la orden de compra y vaciar carrito
        return DB::transaction(function () use ($tenant, $userId, $purchaseData, $purchaseItemsPayload): Purchase {
            /** @var Purchase $purchase */
            $purchase = Purchase::query()->create([
                ...$purchaseData,
                'tenant_codigo' => $tenant->codigo,
                'user_id' => $userId,
            ]);

            $purchase->items()->createMany($purchaseItemsPayload);

            // Vaciar y eliminar el carrito activo del usuario
            $cart = \App\Domains\Cart\Models\Cart::query()
                ->where('tenant_codigo', $tenant->codigo)
                ->where('user_id', $userId)
                ->first();
            if ($cart) {
                $cart->items()->delete();
                $cart->delete();
            }

            return $purchase->load(['items.variant.product', 'items.variant.definitions.productAttribute.attribute']);
        });
    }

    /**
     * @param  array<int, array<string, mixed>>  $items
     * @return \Illuminate\Support\Collection<int, ProductVariant>
     */
    protected function resolveTenantVariants(Tenant $tenant, array $items)
    {
        $variantIds = collect($items)
            ->pluck('producto_variante_id')
            ->filter()
            ->map(static fn (mixed $id): int => (int) $id)
            ->unique()
            ->values();

        $variants = ProductVariant::query()
            ->with('product')
            ->whereIn('id', $variantIds)
            ->whereHas('product', fn ($query) => $query->where('tenant_codigo', $tenant->codigo))
            ->get()
            ->keyBy('id');

        if ($variants->count() !== $variantIds->count()) {
            throw ValidationException::withMessages([
                'items' => 'One or more product variants do not belong to the tenant.',
            ]);
        }

        return $variants;
    }

    /**
     * @param  array<int, array<string, mixed>>  $items
     * @param  \Illuminate\Support\Collection<int, ProductVariant>  $variants
     * @return array<int, array<string, mixed>>
     */
    protected function buildPurchaseItemsPayload(array $items, $variants): array
    {
        return collect($items)
            ->map(function (array $item) use ($variants): array {
                /** @var ProductVariant $variant */
                $variant = $variants->get((int) $item['producto_variante_id']);
                $quantity = (int) $item['cantidad'];
                $unitPrice = (float) ($variant->product?->precio ?? 0);

                return [
                    'producto_variante_id' => $variant->getKey(),
                    'cantidad' => $quantity,
                    'precio_unitario' => $unitPrice,
                    'discount_total' => null,
                    'tax_total' => null,
                    'total' => $unitPrice * $quantity,
                ];
            })
            ->all();
    }
}