<?php

namespace App\Services;

use App\Endpoint\Api\Http\Resources\ProductSkuSimpleResource;
use App\Endpoint\Api\Http\Resources\ShippingAddressResource;
use App\Endpoint\Api\Http\Resources\UserCouponResource;
use App\Exceptions\BizException;
use App\Exceptions\ShippingNotSupportedException;
use App\Helpers\Numeric;
use App\Helpers\Order as OrderHelper;
use App\Models\Order;
use App\Models\OrderProduct;
use App\Models\ProductSku;
use App\Models\ShippingAddress;
use App\Models\User;
use App\Models\UserCoupon;
use Illuminate\Support\Facades\DB;

class OrderService
{
    /**
     * 快速下单
     *
     * @param \App\Models\User $user
     * @param int $skuId
     * @param int $quantity
     * @param int $shippingAddressId
     * @param int|null $couponId
     * @param string|null $note
     * @return \App\Models\Order
     */
    public function createQuickOrder(
        User $user,
        int $skuId,
        int $quantity,
        int $shippingAddressId,
        ?int $couponId = null,
        ?string $note = null
    ): Order {
        $sku = ProductSku::online()->findOrFail($skuId);

        $product = [
            'sku' => $sku,
            'quantity' => $quantity,
        ];

        return $this->createOrder($user, [$product], $shippingAddressId, $couponId, $note);
    }

    /**
     * 购物车下单
     *
     * @param \App\Models\User $user
     * @param int $skuId
     * @param int $quantity
     * @param int $shippingAddressId
     * @param int|null $couponId
     * @param string|null $note
     * @return \App\Models\Order
     */
    public function createShoppingCartOrder(
        User $user,
        array $shoppingCartItemIds,
        int $shippingAddressId,
        ?int $couponId = null,
        ?string $note = null,
    ): Order {
        $order = $this->createOrder(
            $user,
            $this->getProductsByShoppingCart($user, $shoppingCartItemIds),
            $shippingAddressId,
            $couponId,
            $note
        );

        $user->shoppingCartItems()->whereIn('id', $shoppingCartItemIds)->delete();

        return $order;
    }

    /**
     * 确认快速下单
     *
     * @param \App\Models\User $user
     * @param int $skuId
     * @param int $quantity
     * @param int|null $shippingAddressId
     * @param int|null $couponId
     * @return array
     */
    public function verifyQuickOrder(User $user, int $skuId, int $quantity, ?int $shippingAddressId = null, ?int $couponId = null)
    {
        $sku = ProductSku::online()->findOrFail($skuId);

        $product = [
            'sku' => $sku,
            'quantity' => $quantity,
        ];

        return $this->verifyOrder($user, [$product], $shippingAddressId, $couponId);
    }

    /**
     * 确认购物车订单
     *
     * @param \App\Models\User $user
     * @param array $shoppingCartItemIds
     * @param int|null $shippingAddressId
     * @param int|null $couponId
     * @return array
     */
    public function verifyShoppingCartOrder(User $user, array $shoppingCartItemIds, ?int $shippingAddressId = null, ?int $couponId = null)
    {
        // 获取购买商品
        $products = $this->getProductsByShoppingCart($user, $shoppingCartItemIds);

        return $this->verifyOrder($user, $products, $shippingAddressId, $couponId);
    }

    /**
     * 创建订单
     *
     * @param \App\Models\User $user
     * @param array $products
     * @param int $shippingAddressId
     * @param int|null $couponId
     * @param string|null $note
     * @return \App\Models\Order
     */
    protected function createOrder(
        User $user,
        array $products,
        int $shippingAddressId,
        ?int $couponId = null,
        ?string $note = null,
    ): Order {
        foreach ($products as $product) {
            $sku = $product['sku'];

            if ($product['quantity'] > $sku->saleable_stock) {
                throw new BizException('商品库存不足');
            }
        }

        $shippingAddress = $this->getShippingAddress($user, $shippingAddressId);

        // 优惠券
        $coupon = null;

        if ($couponId) {
            $coupon = $user->coupons()->onlyAvailable()->lockForUpdate()->findOrFail($couponId);
        }

        $mapProducts = $this->mapProducts($user, $products, $coupon);

        // 计算运费
        $shippingFee = $this->calculateShippingFee($mapProducts, $shippingAddress);

        list(
            $productsTotalAmount,
            $vipDiscountAmount,
            $couponDiscountAmount,
            $totalAmount,
        ) = $this->calculateFees($mapProducts);

        // 订单总费用
        $totalAmount += $shippingFee;

        $order = $user->orders()->create([
            'sn' => OrderHelper::serialNumber(),
            'user_coupon_id' => $coupon?->id,
            'coupon_discount_amount' => $couponDiscountAmount,
            'vip_discount_amount' => $vipDiscountAmount,
            'shipping_fee' => $shippingFee,
            'products_total_amount' => $productsTotalAmount,
            'total_amount' => $totalAmount,
            'status' => $totalAmount > 0 ? Order::STATUS_PENDING : Order::STATUS_PAID,
            'note' => $note,
            // 收货地址
            'consignee_name' => $shippingAddress->consignee,
            'consignee_telephone' => $shippingAddress->telephone,
            'consignee_zone' => $shippingAddress->zone,
            'consignee_address' => $shippingAddress->address,
        ]);

        $data = [];

        foreach ($mapProducts as $product) {
            $sku = $product['sku'];

            // 支付金额 = 商品总额 - 优惠券折扣金额- 会员折扣金额
            $totalAmount = $product['total_amount'] - $product['coupon_discount_amount'] - $product['vip_discount_amount'];

            $data[] = [
                'user_id' => $order->user_id,
                'order_id' => $order->id,
                'spu_id' => $sku->spu_id,
                'sku_id' => $sku->id,
                'category_id' => $sku->category_id,
                'name' => $sku->name,
                'specs' => json_encode($sku->specs),
                'cover' => $sku->cover,
                'weight' => $sku->weight,
                'sell_price' => $sku->sell_price,
                'vip_price' => $sku->vip_price,
                'quantity' => $product['quantity'],
                'coupon_discount_amount' => $product['coupon_discount_amount'],
                'vip_discount_amount' => $product['vip_discount_amount'],
                'total_amount' => $totalAmount,
                'created_at' => $order->created_at,
                'updated_at' => $order->updated_at,
            ];

            $this->deductSkuStock($sku, $product['quantity']);
        }

        OrderProduct::insert($data);

        // 将优惠券标记为已使用
        $coupon?->markAsUse();

        return $order;
    }

    /**
     * 扣除商品库存
     *
     * @param \App\Models\ProductSku $sku
     * @param int $quantity
     * @return void
     */
    protected function deductSkuStock(ProductSku $sku, int $quantity): void
    {
        $sku->update([
            'stock' => DB::raw("stock - {$quantity}"),   // 库存
            'sales' => DB::raw("sales + {$quantity}"),   // 销量
        ]);

        $sku->spu->update([
            'sales' => DB::raw("sales + {$quantity}"),   // 销量
        ]);
    }

    /**
     * 确认订单
     *
     * @param \App\Models\User $user
     * @param array $products
     * @param int|null $shippingAddressId
     * @param int|null $couponId
     * @return array
     */
    protected function verifyOrder(User $user, array $products, ?int $shippingAddressId = null, ?int $couponId = null): array
    {
        // 获取收货地址
        $shippingAddress = $this->getShippingAddress($user, $shippingAddressId);

        // 优惠券
        $coupon = null;

        if ($couponId) {
            $coupon = $user->coupons()->onlyAvailable()->findOrFail($couponId);
        }

        $mapProducts = $this->mapProducts($user, $products, $coupon);

        // 是否支持配送
        $shippingSupported = true;
        // 运费
        $shippingFee = 0;

        if ($shippingAddress) {
            try {
                $shippingFee = $this->calculateShippingFee($mapProducts, $shippingAddress);
            } catch (ShippingNotSupportedException $e) {
                $shippingFee = 0;
                $shippingSupported = false;
            }
        }

        list(
            $productsTotalAmount,
            $vipDiscountAmount,
            $couponDiscountAmount,
            $totalAmount,
        ) = $this->calculateFees($mapProducts);

        // 订单总费用
        $totalAmount += $shippingFee;

        return [
            'products' => collect($mapProducts)->map(function ($item) {
                return [
                    'sku' => ProductSkuSimpleResource::make($item['sku']),
                    'quantity' => $item['quantity'],
                ];
            }),
            'coupons' => UserCouponResource::collection((new CouponService())->getAvailableCoupons($user, $products)),
            'shipping_address' => $shippingAddress ? ShippingAddressResource::make($shippingAddress) : null, // 收货地址
            'shipping_supported' => $shippingSupported,
            'shipping_fee' => Numeric::trimTrailingZero(bcdiv($shippingFee, 100, 2)), // 运费
            'products_total_amount' => Numeric::trimTrailingZero(bcdiv($productsTotalAmount, 100, 2)), // 商品总额
            'vip_discount_amount' => Numeric::trimTrailingZero(bcdiv($vipDiscountAmount, 100, 2)), // 会员折扣金额
            'coupon_discount_amount' => Numeric::trimTrailingZero(bcdiv($couponDiscountAmount, 100, 2)), // 优惠券折扣金额
            'total_amount' => Numeric::trimTrailingZero(bcdiv($totalAmount, 100, 2)), // 实付金额
        ];
    }

    /**
     * 计算费用
     *
     * @param array $products
     * @return array
     */
    protected function calculateFees(array $products)
    {
        $productsTotalAmount = 0;
        $vipDiscountAmount = 0;
        $couponDiscountAmount = 0;


        foreach ($products as $product) {
            $productsTotalAmount += $product['total_amount'];
            $vipDiscountAmount += $product['vip_discount_amount'];
            $couponDiscountAmount += $product['coupon_discount_amount'];
        }

        // 订单总额
        $totalAmount = $productsTotalAmount - $vipDiscountAmount - $couponDiscountAmount;

        return [
            $productsTotalAmount,
            $vipDiscountAmount,
            $couponDiscountAmount,
            $totalAmount,
        ];
    }

    /**
     * 计算运费
     *
     * @param array $products
     * @param \App\Models\ShippingAddress $shippingAddress
     * @return int
     */
    protected function calculateShippingFee(array $products, ShippingAddress $shippingAddress): int
    {
        // 运费
        $shippingFee = 0;

        $shippings = [];

        foreach ($products as $product) {
            $sku = $product['sku'];

            if (is_null($sku->shipping_template_id)) {
                continue;
            }

            $shipping = $shippings[$sku->shipping_template_id] ?? [
                'total_weight' => 0,
                'total_amount' => 0,
            ];
            $shipping['total_weight'] += $sku->weight * $product['quantity'];
            $shipping['total_amount'] += $product['total_amount'] - $product['vip_discount_amount'] - $product['coupon_discount_amount'];

            $shippings[$sku->shipping_template_id] = $shipping;
        }

        $shippingService = new ShippingService();

        foreach ($shippings as $templateId => $shipping) {
            $shippingFee += $shippingService->countShippingAmount(
                $shipping['total_weight'],
                $shipping['total_amount'],
                $templateId,
                $shippingAddress->zone_id
            );
        }

        return $shippingFee;
    }

    /**
     * 准备商品信息
     *
     * @param \App\Models\User $user
     * @param array $products
     * @param \App\Models\UserCoupon|null $coupon
     * @return array
     *
     * @throws \App\Exceptions\BizException
     */
    protected function mapProducts(User $user, array $products, ?UserCoupon $coupon): array
    {
        $_products = collect($products)->map(function ($item) use ($user) {
            $sku = $item['sku'];

            return array_merge($item, [
                // 优惠券折扣金额
                'coupon_discount_amount' => 0,
                // 会员折扣金额
                'vip_discount_amount' => $this->calculateVipDiscountAmount(
                    $user, $sku, $item['quantity']
                ),
                // 总金额
                'total_amount' => $sku->sell_price * $item['quantity'],
            ]);
        });

        if ($coupon === null) {
            return $_products->all();
        }

        $couponDiscountAmounts = $this->getCouponDiscountAmounts($coupon, $_products->all());

        return $_products->map(function ($item) use ($couponDiscountAmounts) {
            $item['coupon_discount_amount'] = $couponDiscountAmounts[$item['sku']->id] ?? 0;

            return $item;
        })->all();
    }

    /**
     * 计算会员折扣金额
     *
     * @param \App\Models\User $user
     * @param \App\Models\ProductSku $sku
     * @param int $quantity
     * @return int
     */
    protected function calculateVipDiscountAmount(User $user, ProductSku $sku, int $quantity)
    {
        $price = $sku->getRealPrice($user);

        if ($price > $sku->sell_price) {
            return 0;
        }

        return ($sku->sell_price - $price) * $quantity;
    }

    /**
     * 获取商品的优惠券折扣金额
     *
     * @param \App\Models\UserCoupon $coupon
     * @param array $products
     * @return array
     *
     * @throws \App\Exceptions\BizException
     */
    protected function getCouponDiscountAmounts(UserCoupon $coupon, array $products): array
    {
        // 启用的券的使用规则
        $coupon->loadMissing(['ranges' => function ($query) {
            $query->isEnable();
        }]);

        // 可使用优惠券的商品总额
        $amounts = [];

        foreach ($products as $item) {
            $sku = $item['sku'];

            if (! $coupon->isSupport($sku)) {
                throw new BizException('优惠券不满足使用条件');
            }

            $amount = $item['total_amount'] - $item['vip_discount_amount'];

            // 仅保留商品真实总额大于0的商品
            if ($amount > 0) {
                $amounts[$sku->id] = $amount;
            }
        }

        // 全部商品总额
        $totalAmount = array_sum($amounts);

        if ($coupon->coupon_threshold > $totalAmount) {
            throw new BizException('优惠券不满足使用条件');
        }

        // 商品的券折扣金额
        $discountAmounts = [];
        // 优惠券折扣总额
        $discountTotalAmount = 0;
        // 未计算优惠金额的商品总数
        $lastCount = count($amounts);

        foreach ($amounts as $skuId => $amount) {
            if ($coupon->isDiscountCoupon()) {
                /*
                |----------------------------------------
                | 计算折扣券的折扣金额
                |----------------------------------------
                */

                $discountAmounts[$skuId] = (int) bcmul($amount, bcdiv(100 - $coupon->coupon_amount, 100, 2));
            } else {
                /*
                |----------------------------------------
                | 计算抵扣券的抵扣金额
                |----------------------------------------
                */

                $couponAmount = $coupon->coupon_amount;

                // 如果券的抵用金额大于商品的实际金额，则以商品实际金额作为抵扣金额
                if ($couponAmount > $totalAmount) {
                    $couponAmount = $totalAmount;
                }

                $discountAmounts[$skuId] = (int) ($couponAmount * $amount / $totalAmount);
                $discountTotalAmount += $discountAmounts[$skuId];

                $lastCount--;

                // 将券的剩余抵扣金额给最后一个商品
                if ($lastCount === 0) {
                    $discountAmounts[$skuId] += $couponAmount - $discountTotalAmount;
                }
            }
        }

        return $discountAmounts;
    }

    /**
     * 根据购物车获取商品
     *
     * @param \App\Models\User $user
     * @param array $shoppingCartItemIds
     * @return array
     *
     * @throws \App\Exceptions\BizException
     */
    protected function getProductsByShoppingCart(User $user, array $shoppingCartItemIds): array
    {
        $shoppingCartItems = $user->shoppingCartItems()->findMany($shoppingCartItemIds);

        if ($shoppingCartItems->count() !== count($shoppingCartItemIds)) {
            throw new BizException('购物车商品已丢失');
        }

        $shoppingCartItems->load('sku');

        $lostShoppingCartItems = $shoppingCartItems->filter(function ($item) {
            return $item->sku === null;
        });

        if ($lostShoppingCartItems->count() > 0) {
            throw new BizException('购物车商品已失效');
        }

        return $shoppingCartItems->map(function ($item) {
            return [
                'sku' => $item->sku,
                'quantity' => $item->quantity,
            ];
        })->all();
    }

    /**
     * 获取收货地址
     *
     * @param \App\Models\User $user
     * @param int|null $shippingAddressId
     * @return \App\Models\ShippingAddress|null
     *
     * @throws \Illuminate\Database\Eloquent\ModelNotFoundException
     */
    protected function getShippingAddress(User $user, ?int $shippingAddressId = null): ?ShippingAddress
    {
        if ($shippingAddressId) {
            return $user->shippingAddresses()->findOrFail($shippingAddressId);
        }

        return $user->shippingAddresses()->where('is_default', true)->first();
    }
}