package main

import (
	"fmt"
	"net"
	"time"
)

var protocolsToTest = []string{"tcp", "tcp4", "tcp6"}

func listenOn(firstProtocol, secondProtocol, port string) {
	fmt.Println("\nTesting dual stack listeners...\n First listener:", firstProtocol, "\nSecond listener:", secondProtocol)
	secondListener, e := net.Listen(secondProtocol, port)

	if e != nil {
		fmt.Println("FAILURE:", e.Error())
		return
	} else {
		fmt.Println("SUCCESS: Listening on", secondListener.Addr())
		time.Sleep(5 * time.Second)
		secondListener.Close()
	}
}

func dualStack(firstProtocol string) {
	for _, secondProcotol := range protocolsToTest {
		listenOn(firstProtocol, secondProcotol, ":http")
	}
}

func main() {
	for i, firstProcotolBeingTested := range protocolsToTest {
		fmt.Println("\n========================== RUNNING TEST #", i, "\n")
		firstListener, e := net.Listen(firstProcotolBeingTested, ":http")
		if e != nil {
			fmt.Println(e.Error())
			return
		} else {
			fmt.Println("Successfully bound to free port. Now listening on", firstProcotolBeingTested)
			fmt.Println("Will run dualStack() tests shortly")
			time.Sleep(5 * time.Second) // delay to observe that first listener is actually listening!
			go dualStack(firstProcotolBeingTested)
			time.Sleep(15 * time.Second) // ARBITRARY SLEEP
			firstListener.Close()
		}
	}
}