package services

import (
	"fmt"
	"platform/pkg/u"
	"platform/web/core"
	m "platform/web/models"
	q "platform/web/queries"
	"time"

	"github.com/shopspring/decimal"
	"gorm.io/gen/field"
)

var Resource = &resourceService{}

type resourceService struct{}

// CreateResourceByBalance 通过余额购买套餐
func (s *resourceService) CreateResourceByBalance(user *m.User, data *CreateResourceData) error {
	now := time.Now()

	// 获取 sku
	detail, err := data.TradeDetail(user)
	if err != nil {
		return core.NewServErr("获取产品支付信息失败", err)
	}

	return q.Q.Transaction(func(q *q.Query) error {

		// 更新用户余额
		if err := User.UpdateBalance(q, user, detail.Actual.Neg(), "余额购买产品", nil); err != nil {
			return core.NewServErr("更新用户余额失败", err)
		}

		// 保存套餐
		resource, err := s.Create(q, user.ID, now, data)
		if err != nil {
			return core.NewServErr("创建套餐失败", err)
		}

		// 生成账单
		err = Bill.CreateForResource(q, user.ID, resource.ID, nil, detail)
		if err != nil {
			return core.NewServErr("生成账单失败", err)
		}

		// 核销优惠券
		if detail.CouponUserId != nil {
			err = Coupon.UseCoupon(q, *detail.CouponUserId)
			if err != nil {
				return core.NewServErr("核销优惠券失败", err)
			}
		}

		return nil
	})
}

func (s *resourceService) Create(q *q.Query, uid int32, now time.Time, data *CreateResourceData) (*m.Resource, error) {
	// 套餐基本信息
	var resource = m.Resource{
		UserID:     uid,
		ResourceNo: u.P(ID.GenReadable("res")),
		Active:     true,
		Type:       data.Type,
		Code:       data.Type.Code(),
	}
	switch data.Type {

	// 短效套餐
	case m.ResourceTypeShort:
		var short = data.Short
		if short == nil {
			return nil, core.NewBizErr("短效套餐数据不能为空")
		}
		resource.Short = &m.ResourceShort{
			Live:  short.Live,
			Type:  short.Mode,
			Quota: short.Quota,
			Code:  data.Code(),
		}
		if short.Mode == m.ResourceModeTime {
			if short.Expire == nil {
				return nil, core.NewBizErr("包时套餐过期时间不能为空")
			}
			var duration = time.Duration(*short.Expire) * 24 * time.Hour
			resource.Short.ExpireAt = u.P(now.Add(duration))
		}

	// 长效套餐
	case m.ResourceTypeLong:
		var long = data.Long
		if long == nil {
			return nil, core.NewBizErr("长效套餐数据不能为空")
		}
		resource.Long = &m.ResourceLong{
			Live:  long.Live,
			Type:  long.Mode,
			Quota: long.Quota,
			Code:  data.Code(),
		}
		if long.Mode == m.ResourceModeTime {
			if long.Expire == nil {
				return nil, core.NewBizErr("包时套餐过期时间不能为空")
			}
			var duration = time.Duration(*long.Expire) * 24 * time.Hour
			resource.Long.ExpireAt = u.P(now.Add(duration))
		}
	default:
		return nil, core.NewBizErr("不支持的套餐类型")
	}

	err := q.Resource.Create(&resource)
	if err != nil {
		return nil, core.NewServErr("创建套餐失败", err)
	}

	return &resource, nil
}

func (s *resourceService) Update(data *UpdateResourceData) error {
	if data.Active == nil {
		return core.NewBizErr("更新套餐失败，active 不能为空")
	}

	do := make([]field.AssignExpr, 0)
	if data.Active != nil {
		do = append(do, q.Resource.Active.Value(*data.Active))
	}

	_, err := q.Resource.
		Where(q.Resource.ID.Eq(data.Id)).
		UpdateSimple(do...)
	if err != nil {
		return core.NewServErr("更新套餐失败", err)
	}

	return nil
}

type UpdateResourceData struct {
	core.IdReq
	Active *bool `json:"active"`
}

func (s *resourceService) CalcPrice(skuCode string, count int32, user *m.User, cuid *int32) (*m.ProductSku, *m.ProductDiscount, *m.CouponUser, decimal.Decimal, decimal.Decimal, error) {

	sku, err := q.ProductSku.
		Joins(q.ProductSku.Discount).
		Where(q.ProductSku.Code.Eq(skuCode), q.ProductSku.Status.Eq(int32(m.SkuStatusEnabled))).
		Take()
	if err != nil {
		return nil, nil, nil, decimal.Zero, decimal.Zero, core.NewServErr("产品不可用", err)
	}

	// 原价
	price := sku.Price
	amount := price.Mul(decimal.NewFromInt32(count))

	// 折扣价
	discount := sku.Discount
	if discount == nil {
		return nil, nil, nil, decimal.Zero, decimal.Zero, core.NewServErr("价格查询失败", err)
	}

	discountRate := discount.Rate()
	if user != nil && user.DiscountID != nil { // 用户特殊优惠
		uDiscount, err := q.ProductDiscount.Where(q.ProductDiscount.ID.Eq(*user.DiscountID)).Take()
		if err != nil {
			return nil, nil, nil, decimal.Zero, decimal.Zero, core.NewServErr("客户特殊价查询失败", err)
		}

		uDiscountRate := uDiscount.Rate()
		if uDiscountRate.Cmp(discountRate) > 0 {
			discountRate = uDiscountRate
			discount = uDiscount
		}
	}
	discounted := amount.Mul(discountRate)

	// 优惠价
	coupon := (*m.CouponUser)(nil)
	couponApplied := discounted.Copy()
	if user != nil && cuid != nil {
		var err error
		coupon, err = Coupon.GetUserCoupon(user.ID, *cuid, discounted)
		if err != nil {
			return nil, nil, nil, decimal.Zero, decimal.Zero, err
		}
		couponApplied = discounted.Sub(coupon.Coupon.Amount)
	}

	// 约束到最低价格
	if discounted.Cmp(sku.PriceMin) < 0 {
		discounted = sku.PriceMin.Copy()
	}
	if couponApplied.Cmp(sku.PriceMin) < 0 {
		couponApplied = sku.PriceMin.Copy()
	}

	return sku, discount, coupon, discounted, couponApplied, nil
}

type CreateResourceData struct {
	Type     m.ResourceType           `json:"type" validate:"required"`
	Short    *CreateShortResourceData `json:"short,omitempty"`
	Long     *CreateLongResourceData  `json:"long,omitempty"`
	CouponId *int32                   `json:"coupon,omitempty"`
}

type CreateShortResourceData struct {
	Live   int32          `json:"live" validate:"required"`
	Mode   m.ResourceMode `json:"mode" validate:"required"`
	Quota  int32          `json:"quota" validate:"required"`
	Expire *int32         `json:"expire"`

	name  string
	price *decimal.Decimal
}

type CreateLongResourceData struct {
	Live   int32          `json:"live" validate:"required"`
	Mode   m.ResourceMode `json:"mode" validate:"required"`
	Quota  int32          `json:"quota" validate:"required"`
	Expire *int32         `json:"expire"`

	name  string
	price *decimal.Decimal
}

func (data *CreateResourceData) Count() int32 {
	switch {
	default:
		return 0
	case data.Type == m.ResourceTypeShort && data.Short != nil:
		return data.Short.Quota
	case data.Type == m.ResourceTypeLong && data.Long != nil:
		return data.Long.Quota
	}
}

func (data *CreateResourceData) Code() string {
	switch {
	default:
		return ""

	case data.Type == m.ResourceTypeShort && data.Short != nil:
		return fmt.Sprintf(
			"mode=%s&live=%d&expire=%d",
			data.Short.Mode.Code(), data.Short.Live, u.Else(data.Short.Expire, 0),
		)

	case data.Type == m.ResourceTypeLong && data.Long != nil:
		return fmt.Sprintf(
			"mode=%s&live=%d&expire=%d",
			data.Long.Mode.Code(), data.Long.Live, u.Else(data.Long.Expire, 0),
		)
	}
}

func (data *CreateResourceData) TradeDetail(user *m.User) (*TradeDetail, error) {
	sku, discount, coupon, amount, actual, err := Resource.CalcPrice(data.Code(), data.Count(), user, data.CouponId)
	if err != nil {
		return nil, err
	}

	var discountId *int32 = nil
	if discount != nil {
		discountId = &discount.ID
	}
	var couponUserId *int32 = nil
	if coupon != nil {
		couponUserId = &coupon.ID
	}
	return &TradeDetail{
		data,
		m.TradeTypePurchase,
		sku.Name,
		amount, actual,
		discountId, couponUserId,
	}, nil
}

// 服务错误
type ResourceServiceErr string

func (e ResourceServiceErr) Error() string {
	return string(e)
}

const (
	ErrBalanceNotEnough = ResourceServiceErr("余额不足")
)