gex/utils/utils.go

package utils

import (
	"crypto/hmac"
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"log"
	"math/rand"
	"os"
	"runtime"
	"strconv"
	"strings"
	"time"
)

func Cwd(i int) string {
	_, fp, _, _ := runtime.Caller(i)
	slice := strings.Split(fp, "/")
	slice = slice[:len(slice)-1]
	path := strings.Join(slice, "/")
	return path
}

func Err(err error) {
	_, fp, line, _ := runtime.Caller(1)

	errStr := fmt.Sprintf("Error at %s:%d: %s\n", fp, line, err)
	fmt.Printf("%s", errStr)

	log, _ := os.OpenFile("error.log", os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0655)
	defer log.Close()
	errLogStr := fmt.Sprintf("%s %s", time.Now(), errStr)
	log.WriteString(errLogStr)

}

func Hash(key string, data string) string {
	bKey := []byte(key)
	bData := []byte(data)
	h := hmac.New(sha256.New, bKey)
	h.Write(bData)
	return hex.EncodeToString(h.Sum(nil))
}

func Salt(length int) string {
	const charset = "1234567890-=!@#$%^&*()_+abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
	b := make([]byte, length)
	for i := range b {
		b[i] = charset[rand.Intn(len(charset))]
	}
	return string(b)
}

func CheckArgs() {
	if len(os.Args) < 2 {
		log.Fatalf("ERROR: port number required: eg ./bin 3000")
		os.Exit(1)
	}

	_, err := strconv.Atoi(os.Args[1])
	if err != nil {
		log.Fatalf("ERROR: port must be a number")
		os.Exit(1)
	}
}