package database

import (
	"fmt"
	"gorm.io/gorm"
	"math"
	"strings"
	"time"
)

const (
	defaultExchangeRate float64 = 7.3
	defaultFreight      float64 = 100
)

type Product struct {
	ID        uint           `gorm:"primary_key" json:"id"`
	CreatedAt time.Time      `json:"createdAt"`
	UpdatedAt time.Time      `json:"updatedAt"`
	DeletedAt gorm.DeletedAt `gorm:"index"`

	Name      string `gorm:"index" json:"name"`
	Pid       string `gorm:"unique;not null" json:"pid"`
	Color     string `json:"color"`
	Link      string `json:"link"`
	Image     string `json:"image"`
	Orderable bool   `json:"orderable"`

	USPrice       float64        `json:"usPrice"`
	CNYPrice      float64        `json:"cnyPrice"`
	CalMark       string         `json:"calMark"` //计算价格的过程
	DWPrice       float64        `json:"dwPrice"`
	Freight       float64        `json:"freight"`               //运费
	ExchangeRate  float64        `json:"exchangeRate" gorm:"-"` //汇率
	Rate          float64        `json:"rate"`                  //利润率
	Remark        string         `json:"remark"`                //备注
	HistoryPrices []HistoryPrice `gorm:"foreignKey:Pid;references:Pid" json:"historyPrices"`
}

func (p *Product) TableName() string {
	return "products"
}

func (p *Product) BeforeSave(tx *gorm.DB) (err error) {
	tx.Model(&Product{}).Where("pid = ?", p.Pid).Pluck("freight", &p.Freight)
	p.CalRate()
	var lastPrice float64
	tx.Model(&HistoryPrice{}).Where("pid = ?", p.Pid).Order("created_at desc").Limit(1).Pluck("us_price", &lastPrice)
	if p.USPrice != lastPrice {
		p.HistoryPrices = append(p.HistoryPrices, HistoryPrice{
			USPrice: p.USPrice,
		})
	}
	return
}

func (p *Product) CalRate() {
	calculationProcess := make([]string, 0, 2) //存放计算过程
	if p.ExchangeRate == 0 {
		p.ExchangeRate = defaultExchangeRate
	}
	if p.Freight == 0 {
		p.Freight = defaultFreight
	}

	//先计算打九折的价格
	tmpPrice := p.USPrice * 0.9 // 这是打九折的价格
	p.CNYPrice = tmpPrice*p.ExchangeRate + p.Freight
	calculationProcess = append(calculationProcess, fmt.Sprintf("【九折】%.2f * 0.9 * %.2f + %.2f = %.2f", p.USPrice, p.ExchangeRate, p.Freight, p.CNYPrice))
	if p.USPrice >= 150 {
		calculationProcess = append(calculationProcess, fmt.Sprintf("【150 -20 】(%.2f - 20) * %.2f + %.2f = %.2f", p.USPrice, p.ExchangeRate, p.Freight, (p.USPrice-20)*p.ExchangeRate+p.Freight))
		if p.USPrice-20 < tmpPrice {
			// 符合满150-20,而且比九折便宜
			tmpPrice = p.USPrice - 20
			p.CNYPrice = tmpPrice*p.ExchangeRate + p.Freight
		}
	} else if p.USPrice >= 100 {
		calculationProcess = append(calculationProcess, fmt.Sprintf("【100 -10 】(%.2f - 10) * %.2f + %.2f = %.2f", p.USPrice, p.ExchangeRate, p.Freight, (p.USPrice-10)*p.ExchangeRate+p.Freight))
		if p.USPrice-10 < tmpPrice {
			// 符合满100 -10,而且比九折便宜
			tmpPrice = p.USPrice - 10
			p.CNYPrice = tmpPrice*p.ExchangeRate + p.Freight
		}
	}
	p.CalMark = strings.Join(calculationProcess, "\n")
	if p.DWPrice > 0 {
		// 如果有得物价格，就计算收益率
		p.Rate = Decimal((p.DWPrice - p.CNYPrice) / p.CNYPrice * 100)
	}

	p.CNYPrice = Decimal(p.CNYPrice)
}

// Decimal 保留两位小数
func Decimal(value float64) float64 {
	return math.Trunc(value*1e2+0.5) * 1e-2
}

type HistoryPrice struct {
	ID        uint      `gorm:"primary_key" json:"id"`
	CreatedAt time.Time `json:"createdAt"`

	Pid     string  `gorm:"index" json:"pid"`
	USPrice float64 `json:"usPrice"`
}