package main

import (
	"encoding/json"
	"fmt"
	"log"
	"os"
	"strconv"

	"git.0cd.xyz/michael/toolbox/req"
)

const url = "https://cdn.jsdelivr.net/gh/fawazahmed0/currency-api@1/latest/currencies/"

func main() {
	from, to, value := ui()
	body, _, err := req.Get(url+from+"/"+to+".json", nil)
	if err != nil {
		log.Fatal(err)
	}
	var result map[string]interface{}
	if err := json.Unmarshal(body, &result); err != nil {
		log.Fatal(err)
	}
	v, ok := result[to].(float64)
	if !ok {
		log.Fatal("invalid conversion")
	}
	fmt.Printf("%.2f %s\n", v*value, to)
}

func ui() (from, to string, value float64) {
	if len(os.Args) < 4 {
		os.Exit(1)
	}
	val, err := strconv.ParseFloat(os.Args[3], 64)
	if err != nil {
		log.Fatal(err)
	}
	return os.Args[1], os.Args[2], val
}