package services

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

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

var Resource = &resourceService{}

type resourceService struct{}

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)
	if err != nil {
		return err
	}

	// 检查余额
	_, amount, err := s.GetPrice(sku, data.Count(), &uid)
	if err != nil {
		return err
	}
	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 := createResource(q, uid, now, data)
		if err != nil {
			return core.NewServErr("创建套餐失败", err)
		}

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

		return nil
	})
}

func (s *resourceService) CreateResourceByTrade(uid int32, now time.Time, data *CreateResourceByTradeData, trade *m.Trade) error { // 检查交易
	if trade == nil {
		return core.NewBizErr("交易数据不能为空")
	}
	if trade.Status != m.TradeStatusSuccess {
		return core.NewBizErr("交易状态不正确")
	}

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

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

		// 生成账单
		err = q.Bill.Create(newForConsume(uid, Bill.GenNo(), data.GetSubject(), data.GetAmount(), resource, trade))
		if err != nil {
			return core.NewServErr("生成账单失败", err)
		}

		return nil
	})
}

func createResource(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,
	}
	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,
		}
		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,
		}
		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) GetSku(data *CreateResourceData) (*m.ProductSku, error) {
	sku, err := q.ProductSku.Where(q.ProductSku.Code.Eq(data.Code())).Take()
	if err != nil {
		return nil, core.NewServErr("产品不可用", err)
	}

	return sku, nil
}

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

	// 根据用户 id 查询特殊优惠
	var uSku *m.ProductSkuUser
	if uid != nil {
		var err error
		uSku, err = q.ProductSkuUser.Where(
			q.ProductSkuUser.UserID.Eq(*uid),
			q.ProductSkuUser.ProductSkuID.Eq(sku.ID),
		).Take()
		if err != nil && !errors.Is(err, gorm.ErrRecordNotFound) {
			return decimal.Zero, decimal.Zero, core.NewServErr("客户特殊价查询失败", err)
		}
	}

	// 返回计算价格
	price := sku.Price
	if uSku != nil && uSku.Price != nil {
		price = *uSku.Price
	}

	discount := sku.Discount
	if uSku != nil && uSku.Discount != nil {
		discount = *uSku.Discount
	}

	before := price.Mul(decimal.NewFromInt32(count))
	after := before.Mul(decimal.NewFromFloat32(discount))
	return before, after, nil
}

type CreateResourceData struct {
	Type  m.ResourceType           `json:"type" validate:"required"`
	Short *CreateShortResourceData `json:"short,omitempty"`
	Long  *CreateLongResourceData  `json:"long,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) Serialize() (string, error) {
	bytes, err := json.Marshal(c)
	return string(bytes), err
}

func (c *CreateResourceData) Deserialize(str string) error {
	return json.Unmarshal([]byte(str), c)
}

// 交易后创建套餐
type ResourceOnTradeComplete struct{}

func (r ResourceOnTradeComplete) Check(t m.TradeType) (ProductInfo, bool) {
	if t == m.TradeTypePurchase {
		return &CreateResourceByTradeData{}, true
	}
	return nil, false
}

func (r ResourceOnTradeComplete) OnTradeComplete(info ProductInfo, trade *m.Trade) error {
	return Resource.CreateResourceByTrade(trade.UserID, time.Time(*trade.CompletedAt), info.(*CreateResourceByTradeData), trade)
}

type CreateResourceByTradeData struct {
	Subject string              `json:"subject"`
	Amount  decimal.Decimal     `json:"amount"`
	Req     *CreateResourceData `json:"data"`
}

func (e CreateResourceByTradeData) GetType() m.TradeType {
	return m.TradeTypePurchase
}

func (e CreateResourceByTradeData) GetSubject() string {
	return e.Subject
}

func (e CreateResourceByTradeData) GetAmount() decimal.Decimal {
	return e.Amount
}

func (e CreateResourceByTradeData) Serialize() (string, error) {
	bytes, err := json.Marshal(e)
	return string(bytes), err
}

func (e *CreateResourceByTradeData) Deserialize(str string) error {
	return json.Unmarshal([]byte(str), e)
}

func NewCreateResourceByTradeData(req *CreateResourceData) (*CreateResourceByTradeData, error) {
	sku, err := Resource.GetSku(req)
	if err != nil {
		return nil, err
	}

	_, amount, err := Resource.GetPrice(sku, req.Count(), nil)
	if err != nil {
		return nil, err
	}

	return &CreateResourceByTradeData{
		Subject: sku.Name,
		Amount:  amount,
		Req:     req,
	}, nil
}

// 服务错误
type ResourceServiceErr string

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

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