package common

import (
	"encoding/hex"
	"fmt"
	"strings"
)

// Like fmt.Sprintf, but skips formatting if args are empty.
var Fmt = func(format string, a ...interface{}) string {
	if len(a) == 0 {
		return format
	} else {
		return fmt.Sprintf(format, a...)
	}
}

// IsHex returns true for non-empty hex-string prefixed with "0x"
func IsHex(s string) bool {
	if len(s) > 2 && strings.EqualFold(s[:2], "0x") {
		_, err := hex.DecodeString(s[2:])
		return err == nil
	}
	return false
}

// StripHex returns hex string without leading "0x"
func StripHex(s string) string {
	if IsHex(s) {
		return s[2:]
	}
	return s
}

// StringInSlice returns true if a is found the list.
func StringInSlice(a string, list []string) bool {
	for _, b := range list {
		if b == a {
			return true
		}
	}
	return false
}