Correct sorting of strings containing numbers without leading zeros (#357)

Co-authored-by: Konstantin Kayukin <t_kkayukin@admarketplace.com>

server/utils/strings.go

@@ -3,6 +3,8 @@ package utils
 import (
 	"fmt"
 	"strconv"
+	"strings"
+	"unicode"
 )
 
 const (
@@ -46,3 +48,52 @@ func Format(b float64) string {
 
 	return fmt.Sprintf("%.2f%s", value, multiple)
 }
+
+func CommonPrefix(first, second string) string {
+	var result strings.Builder
+
+	minLength := len(first)
+	if len(second) < minLength {
+		minLength = len(second)
+	}
+
+	for i := 0; i < minLength; i++ {
+		if first[i] != second[i] {
+			break
+		}
+		result.WriteByte(first[i])
+	}
+
+	return result.String()
+}
+
+func NumberPrefix(str string) (int, error) {
+	var result strings.Builder
+
+	for i := 0; i < len(str); i++ {
+		if !unicode.IsDigit(rune(str[i])) {
+			break
+		}
+		result.WriteByte(str[i])
+	}
+
+	return strconv.Atoi(result.String())
+}
+
+func CompareStrings(first, second string) bool {
+	commonPrefix := CommonPrefix(first, second)
+	resultStr1 := strings.TrimPrefix(first, commonPrefix)
+	resultStr2 := strings.TrimPrefix(second, commonPrefix)
+	num1, err1 := NumberPrefix(resultStr1)
+	num2, err2 := NumberPrefix(resultStr2)
+
+	if err1 == nil && err2 == nil {
+		return num1 < num2
+	}
+	if err1 == nil {
+		return true
+	} else if err2 == nil {
+		return false
+	}
+	return resultStr1 < resultStr2
+}