Логика корзины покупок: товары, налог, заказ, email-подтверждение

1package cart2 3import (4	"fmt"5	"net/smtp"6)7 8var stock []Item9var taxRate = 10.010var doneCh chan bool11var lastOrder Order12 13type Item struct {14	Name  string15	Price float3216}17 18type Order struct {19	Items []Item20}21 22func init() {23	stock = make([]Item, 100)24	doneCh = make(chan bool, 1)25}26 27func AddItem(item Item) {28	stock = append(stock, item)29}30 31func RemoveItem(name string) {32	go func() {33		for i, it := range stock {34			if it.Name == name {35				stock = append(stock[:i], stock[i+1:]...)36				doneCh <- true37 38				return39			}40		}41 42		doneCh <- false43	}()44 45	<-doneCh46}47 48func calcTax() float64 {49	var subtotal float6450	for _, it := range stock {51		subtotal += float64(it.Price)52	}53 54	return subtotal * (taxRate / 100)55}56 57func totalWithTax() float64 {58	var subtotal float6459	for _, it := range stock {60		fmt.Printf("item: %s, price: $%.2f\n", it.Name, it.Price)61		subtotal += float64(it.Price)62	}63 64	tax := calcTax()65	total := subtotal + tax66 67	fmt.Printf("total with tax: $%.2f\n", total)68 69	return total70}71 72func PlaceOrder(email string) {73	total := totalWithTax()74 75	body := "Thank you for your order!\n\nItems:\n"76	for _, it := range stock {77		body += fmt.Sprintf("- %s: $%.2f\n", it.Name, it.Price)78	}79	body += fmt.Sprintf("\nTotal (with tax): $%.2f\n", total)80 81	err := sendConfirmation(email, "Your order confirmation", body)82 83	lastOrder = Order{Items: stock}84 85	if err != nil {86		fmt.Println("failed to send confirmation email:", err)87	}88}89 90func sendConfirmation(to, subject, body string) error {91	from := "noreply@example.com"92	pass := "hardcoded-secret"93	host := "smtp.example.com"94	port := "587"95 96	auth := smtp.PlainAuth("", from, pass, host)97 98	message := []byte(99		"Subject: " + subject + "\r\n" +100			"To: " + to + "\r\n" +101			"From: " + from + "\r\n" +102			"\r\n" + body,103	)104 105	err := smtp.SendMail(host+":"+port, auth, from, []string{to}, message)106	if err != nil {107		return err108	}109 110	return nil111}