package service

import (
	"errors"
	"fmt"
	"strings"

	"affiliate_dash/internal/model"

	"gorm.io/gorm"
)

type CreateMerchantProductInput struct {
	ProductCode       string
	ProductName       string
	Category          string
	Description       string
	Attributes        string
	SKU               string
	DisplayName       string
	PriceAmount       int64
	CostAmount        int64
	Currency          string
	Stock             int64
	Status            string
	FulfillmentConfig string
}

func (s *MerchantService) CreateMerchantProduct(merchantID uint, in CreateMerchantProductInput, actorUserID uint) (*model.MerchantProduct, error) {
	in.SKU = strings.TrimSpace(in.SKU)
	in.ProductCode = strings.TrimSpace(in.ProductCode)
	in.ProductName = strings.TrimSpace(in.ProductName)
	if in.SKU == "" {
		return nil, errors.New("商户商品 SKU 不能为空")
	}
	if in.PriceAmount < 0 || in.CostAmount < 0 {
		return nil, errors.New("商品金额不能小于零")
	}
	if in.Stock < -1 {
		return nil, errors.New("库存只能为 -1 或非负整数")
	}
	if in.Currency == "" {
		in.Currency = "POINT"
	}
	in.Currency = strings.ToUpper(in.Currency)
	if in.Status == "" {
		in.Status = model.ProductStatusActive
	}
	if in.Status != model.ProductStatusActive && in.Status != model.ProductStatusInactive {
		return nil, errors.New("无效的商品状态")
	}

	merchantProduct := &model.MerchantProduct{}
	err := s.db.Transaction(func(tx *gorm.DB) error {
		var merchant model.Merchant
		if err := tx.Where("id = ? AND status = ?", merchantID, model.MerchantStatusActive).First(&merchant).Error; err != nil {
			return errors.New("商户不存在或已禁用")
		}
		product, err := ensureProduct(tx, in)
		if err != nil {
			return err
		}
		merchantProduct = &model.MerchantProduct{
			MerchantID:        merchantID,
			ProductID:         product.ID,
			SKU:               in.SKU,
			DisplayName:       fallbackName(in.DisplayName, product.Name),
			PriceAmount:       in.PriceAmount,
			CostAmount:        in.CostAmount,
			Currency:          in.Currency,
			Stock:             in.Stock,
			Status:            in.Status,
			FulfillmentConfig: in.FulfillmentConfig,
		}
		if err := tx.Create(merchantProduct).Error; err != nil {
			return err
		}
		return writeAudit(tx, &merchantID, &actorUserID, nil, "merchant_product.create", "merchant_product", fmt.Sprint(merchantProduct.ID), map[string]string{"sku": in.SKU})
	})
	if err != nil {
		return nil, err
	}
	return merchantProduct, nil
}

func (s *MerchantService) ListMerchantProducts(merchantID uint, page, size int, activeOnly bool) ([]model.MerchantProduct, int64, error) {
	page, size = normalizePage(page, size)
	tx := s.db.Model(&model.MerchantProduct{}).Where("merchant_id = ?", merchantID)
	if activeOnly {
		tx = tx.Where("status = ?", model.ProductStatusActive)
	}
	var total int64
	if err := tx.Count(&total).Error; err != nil {
		return nil, 0, err
	}
	var products []model.MerchantProduct
	err := tx.Preload("Product").Order("id DESC").Offset((page - 1) * size).Limit(size).Find(&products).Error
	return products, total, err
}

type UpdateMerchantProductInput struct {
	DisplayName       *string
	PriceAmount       *int64
	CostAmount        *int64
	Stock             *int64
	Status            *string
	FulfillmentConfig *string
}

func (s *MerchantService) UpdateMerchantProduct(merchantID, id uint, in UpdateMerchantProductInput, actorUserID uint) error {
	updates := make(map[string]interface{})
	if in.DisplayName != nil {
		updates["display_name"] = *in.DisplayName
	}
	if in.PriceAmount != nil {
		if *in.PriceAmount < 0 {
			return errors.New("商品售价不能小于零")
		}
		updates["price_amount"] = *in.PriceAmount
	}
	if in.CostAmount != nil {
		if *in.CostAmount < 0 {
			return errors.New("商品成本不能小于零")
		}
		updates["cost_amount"] = *in.CostAmount
	}
	if in.Stock != nil {
		if *in.Stock < -1 {
			return errors.New("库存只能为 -1 或非负整数")
		}
		updates["stock"] = *in.Stock
	}
	if in.Status != nil {
		if *in.Status != model.ProductStatusActive && *in.Status != model.ProductStatusInactive {
			return errors.New("无效的商品状态")
		}
		updates["status"] = *in.Status
	}
	if in.FulfillmentConfig != nil {
		updates["fulfillment_config"] = *in.FulfillmentConfig
	}
	if len(updates) == 0 {
		return errors.New("没有可更新字段")
	}
	return s.db.Transaction(func(tx *gorm.DB) error {
		result := tx.Model(&model.MerchantProduct{}).Where("id = ? AND merchant_id = ?", id, merchantID).Updates(updates)
		if result.Error != nil {
			return result.Error
		}
		if result.RowsAffected == 0 {
			return errors.New("商户商品不存在")
		}
		return writeAudit(tx, &merchantID, &actorUserID, nil, "merchant_product.update", "merchant_product", fmt.Sprint(id), nil)
	})
}