helper.go

package helper

/*
 * Copyright 2020 Aldelo, LP
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import (
	"fmt"
	"github.com/google/uuid"
	"net"
	"os"
	"strings"
	"time"
)

// GetNetListener triggers the specified port to listen via tcp
func GetNetListener(port uint) (net.Listener, error) {
	if l, e := net.Listen("tcp", fmt.Sprintf(":%d", port)); e != nil {
		return nil, fmt.Errorf("Listen Tcp on Port %d Failed: %v", port, e)
	} else {
		return l, nil
	}
}

// GetLocalIP returns the first non loopback ip
func GetLocalIP() string {
	if addrs, err := net.InterfaceAddrs(); err != nil {
		return ""
	} else {
		for _, a := range addrs {
			if ip, ok := a.(*net.IPNet); ok && !ip.IP.IsLoopback() && !ip.IP.IsInterfaceLocalMulticast() && !ip.IP.IsLinkLocalMulticast() && !ip.IP.IsLinkLocalUnicast() && !ip.IP.IsMulticast() && !ip.IP.IsUnspecified() {
				if ip.IP.To4() != nil {
					return ip.IP.String()
				}
			}
		}

		return ""
	}
}

// LenTrim returns length of space trimmed string s
func LenTrim(s string) int {
	return len(strings.TrimSpace(s))
}

// IntPtr casts int to int pointer
func IntPtr(i int) *int {
	return &i
}

// DurationPtr casts Duration to Duration pointer
func DurationPtr(d time.Duration) *time.Duration {
	return &d
}

// GenerateUUIDv4 will generate a UUID Version 4 (Random) to represent a globally unique identifier (extremely rare chance of collision)
func GenerateUUIDv4() (string, error) {
	id, err := uuid.NewRandom()

	if err != nil {
		// error
		return "", err
	} else {
		// has id
		return id.String(), nil
	}
}

// NewUUID will generate a UUID Version 4 (Random) and ignore error if any
func NewUUID() string {
	id, _ := GenerateUUIDv4()
	return id
}

// FileExists checks if input file in path exists
func FileExists(path string) bool {
	if _, err := os.Stat(path); err == nil {
		return true
	} else {
		return false
	}
}