package main

import "fmt"
import (
	"os/exec"
	"strings"
	"strconv"
	"errors"
	"flag"
)

func getPing(address string) (delay float64, err error) {
	out, err := exec.Command("ping", address, "-c 1").Output()
	if err != nil {
		return -1, err
	}

	lines := strings.Split(strings.ReplaceAll(string(out), "\r\n", "\n"), "\n")
	for i:=0;i<len(lines);i++ {
		if strings.Contains(lines[i], "bytes from") {
			position := strings.Index(lines[i], "time=")

			before, _, success := strings.Cut(lines[i][position:], " ")
			if ! success {
				return -1, errors.New("Line does not match pattern!")
			}
			_, after, success := strings.Cut(before, "=")
			if ! success {
				return -1, errors.New("Line does not match pattern!")
			}

			delay, _ := strconv.ParseFloat(after, 64)
			return delay, nil
		}
	}
	return -1, errors.New("could not resolve host: " + address)
}

func main() {
	flag.Parse()
	hosts := flag.Args()

	if len(hosts) == 0 {
		fmt.Println("Must specify hosts!")
		return
	}

	for i:=0;i<len(hosts);i++ {
		ping, _ := getPing(hosts[i])
		fmt.Printf("%s:\t%f\n", hosts[i], ping)
	}

	return
}