// Package utils is a library of commonly used utility functions.
package utils

import (
	"fmt"
	"net"
	"os"
)

// GetHostname get hostname
func GetHostname() string {
	name, err := os.Hostname()
	if err != nil {
		name = "unknown"
	}
	return name
}

// GetLocalHTTPAddrPairs get available http server and request address
func GetLocalHTTPAddrPairs() (serverAddr string, requestAddr string) {
	port, err := GetAvailablePort()
	if err != nil {
		fmt.Printf("GetAvailablePort error: %v\n", err)
		return "", ""
	}
	serverAddr = fmt.Sprintf(":%d", port)
	requestAddr = fmt.Sprintf("http://127.0.0.1:%d", port)
	return serverAddr, requestAddr
}

// GetAvailablePort get available port
func GetAvailablePort() (int, error) {
	address, err := net.ResolveTCPAddr("tcp", fmt.Sprintf("%s:0", "0.0.0.0"))
	if err != nil {
		return 0, err
	}

	listener, err := net.ListenTCP("tcp", address)
	if err != nil {
		return 0, err
	}

	port := listener.Addr().(*net.TCPAddr).Port
	err = listener.Close()

	return port, err
}