// Copyright © 2018 Inanc Gumus
// Learn Go Programming Course
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
//
// For more tutorials  : https://learngoprogramming.com
// In-person training  : https://www.linkedin.com/in/inancgumus/
// Follow me on twitter: https://twitter.com/inancgumus

package main

import (
	"fmt"
	"os"
	"strconv"
)

func main() {
	const (
		EUR = iota
		GBP
		JPY
	)

	rates := [...]float64{
		EUR: 0.88,
		GBP: 0.78,
		JPY: 113.02,
	}

	args := os.Args[1:]
	if len(args) != 1 {
		fmt.Println("Please provide the amount to be converted.")
		return
	}

	amount, err := strconv.ParseFloat(args[0], 64)
	if err != nil {
		fmt.Println("Invalid amount. It should be a number.")
		return
	}

	fmt.Printf("%.2f USD is %.2f EUR\n", amount, rates[EUR]*amount)
	fmt.Printf("%.2f USD is %.2f GBP\n", amount, rates[GBP]*amount)
	fmt.Printf("%.2f USD is %.2f JPY\n", amount, rates[JPY]*amount)
}