package services

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

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

var Resource = &resourceService{}

type resourceService struct{}

// CreateResourceByBalance 通过余额购买套餐
func (s *resourceService) CreateResourceByBalance(uid int32, now time.Time, data *CreateResourceData) error {

	// 找到用户
	user, err := q.User.
		Where(q.User.ID.Eq(uid)).
		Take()
	if err != nil {
		return err
	}

	// 获取 sku
	sku, err := s.GetSku(data.Code())
	if err != nil {
		return err
	}

	// 检查余额
	coupon, _, amount, actual, err := s.GetPrice(sku, data.Count(), &uid, data.CouponCode)
	if err != nil {
		return err
	}
	couponId := (*int32)(nil)
	if coupon != nil {
		couponId = &coupon.ID
	}

	newBalance := user.Balance.Sub(amount)
	if newBalance.IsNegative() {
		return ErrBalanceNotEnough
	}

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

		// 更新用户余额
		_, err = q.User.
			Where(
				q.User.ID.Eq(uid),
				q.User.Balance.Eq(user.Balance),
			).
			UpdateSimple(q.User.Balance.Value(newBalance))
		if err != nil {
			return core.NewServErr("更新用户余额失败", err)
		}

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

		// 生成账单
		err = Bill.CreateForResourceByBalance(q, uid, resource.ID, couponId, sku.Name, amount, actual)
		if err != nil {
			return core.NewServErr("生成账单失败", err)
		}

		// 核销优惠券
		if coupon != nil {
			err = Coupon.UseCoupon(q, coupon.ID)
			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) GetSku(code string) (*m.ProductSku, error) {
	sku, err := q.ProductSku.
		Joins(q.ProductSku.Discount).
		Where(q.ProductSku.Code.Eq(code)).
		Take()
	if err != nil {
		return nil, core.NewServErr("产品不可用", err)
	}

	if sku.Discount == nil {
		return nil, core.NewServErr("价格查询失败", err)
	}

	return sku, nil
}

func (s *resourceService) GetPrice(sku *m.ProductSku, count int32, uid *int32, couponCode *string) (*m.Coupon, decimal.Decimal, decimal.Decimal, decimal.Decimal, error) {

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

	// 折扣价
	discount := sku.Discount.Decimal()
	if uid != nil { // 用户特殊优惠
		var err error
		uSku, err := q.ProductSkuUser.
			Joins(q.ProductSkuUser.Discount).
			Where(
				q.ProductSkuUser.UserID.Eq(*uid),
				q.ProductSkuUser.ProductSkuID.Eq(sku.ID)).
			Take()
		if err != nil && !errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, decimal.Zero, decimal.Zero, decimal.Zero, core.NewServErr("客户特殊价查询失败", err)
		}
		if uSku.Discount == nil {
			return nil, decimal.Zero, decimal.Zero, decimal.Zero, core.NewServErr("价格获取失败")
		}
		uDiscount := uSku.Discount.Decimal()
		if uDiscount.Cmp(discount) > 0 {
			discount = uDiscount
		}
	}
	discounted := amount.Mul(discount)

	// 优惠价
	coupon := (*m.Coupon)(nil)
	couponApplied := discounted.Copy()
	if couponCode != nil {
		var err error
		coupon, err = Coupon.GetCouponAvailableByCode(*couponCode, discounted, uid)
		if err != nil {
			return nil, decimal.Zero, decimal.Zero, decimal.Zero, err
		}
		couponApplied = discounted.Sub(coupon.Amount)
	}

	return coupon, amount, discounted, couponApplied, nil
}

type CreateResourceData struct {
	Type       m.ResourceType           `json:"type" validate:"required"`
	Short      *CreateShortResourceData `json:"short,omitempty"`
	Long       *CreateLongResourceData  `json:"long,omitempty"`
	CouponCode *string                  `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 (c *CreateResourceData) Count() int32 {
	switch {
	default:
		return 0
	case c.Type == m.ResourceTypeShort && c.Short != nil:
		return c.Short.Quota
	case c.Type == m.ResourceTypeLong && c.Long != nil:
		return c.Long.Quota
	}
}

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

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

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

func (c *CreateResourceData) TradeDetail() (*TradeDetail, error) {
	sku, err := Resource.GetSku(c.Code())
	if err != nil {
		return nil, err
	}

	coupon, _, amount, actual, err := Resource.GetPrice(sku, c.Count(), nil, c.CouponCode)
	if err != nil {
		return nil, err
	}

	return &TradeDetail{
		m.TradeTypePurchase,
		sku.Name,
		amount, actual,
		&coupon.ID, c,
	}, nil
}

// 服务错误
type ResourceServiceErr string

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

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