Add utility functions

.github/workflows/build.yml

@@ -16,4 +16,5 @@ jobs:
         run: |
           cd file && go test . && cd ..
           cd email && go test . && cd ..
-          cd jwtAuth && go test . && cd ..
+          cd jwtAuth && go test . && cd ..
+          cd util && go test . && cd ..

examples/go.mod

@@ -2,10 +2,6 @@ module examples
 
 go 1.20
 
-replace email => ../email
-
-replace file => ../file
-
 require (
 	github.com/canopas/go-reusables/email v0.0.0-20230801123715-3957df64671f
 	github.com/canopas/go-reusables/file v0.0.0-20230801123715-3957df64671f

examples/util.go

@@ -0,0 +1,10 @@
+package examples
+
+import "github.com/canopas/go-reusables/util"
+
+
+func ExamplesUtils(){
+	util.GenerateOTP(4)
+	util.LCM([]int{20, 45, 68})
+	util.GCD(124, 674)
+}

go.mod

@@ -1,3 +1,7 @@
 module github.com/canopas/go-reusables
 
 go 1.20
+
+require github.com/sirupsen/logrus v1.9.3
+
+require golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 // indirect

go.sum

@@ -0,0 +1,11 @@
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/sirupsen/logrus v1.9.3 h1:dueUQJ1C2q9oE3F7wvmSGAaVtTmUizReu6fjN8uqzbQ=
+github.com/sirupsen/logrus v1.9.3/go.mod h1:naHLuLoDiP4jHNo9R0sCBMtWGeIprob74mVsIT4qYEQ=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 h1:0A+M6Uqn+Eje4kHMK80dtF3JCXC4ykBgQG4Fe06QRhQ=
+golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

util/README.md

@@ -0,0 +1,13 @@
+# Utils
+
+This module contains utility examples for golang
+
+## Utilities
+
+- Generate OTP for any length
+- Get LCM of given numbers array
+- Get GCD of given numbers
+
+## Example
+
+Find a working example of Utils-reusable at [Example](https://github.com/canopas/go-reusables/blob/main/examples/util.go).

util/go.mod

@@ -0,0 +1,11 @@
+module github.com/canopas/go-reusables/util
+
+go 1.20
+
+require github.com/stretchr/testify v1.8.4
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)

util/go.sum

@@ -0,0 +1,10 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
+github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

util/util.go

@@ -0,0 +1,54 @@
+package util
+
+import (
+	random "crypto/rand"
+	"errors"
+	"io"
+)
+
+// generate OTP of given length with numbers only
+var table = [...]byte{'1', '2', '3', '4', '5', '6', '7', '8', '9', '0'}
+
+func GenerateOTP(length int) (string, error) {
+
+	if length <= 0{
+		return "", errors.New("Enter valid length for OTP")
+	}
+
+	randomNumberBuf := make([]byte, length)
+
+	_, err := io.ReadAtLeast(random.Reader, randomNumberBuf, length)
+	if err != nil {
+		return "", err
+	}
+
+	for i := 0; i < len(randomNumberBuf); i++ {
+		randomNumberBuf[i] = table[int(randomNumberBuf[i])%len(table)]
+	}
+
+	return string(randomNumberBuf), nil
+}
+
+// Find GCD(greatest common divisor) of given numbers
+func GCD(a, b int) int {
+	for b != 0 {
+		t := b
+		b = a % b
+		a = t
+	}
+	return a
+}
+
+// Find LCM(Least Common Multiple) of the list
+func LCM(list []int) int {
+	if len(list) > 0 {
+		if len(list) == 1 {
+			return list[0]
+		}
+		if len(list) == 2 {
+			return list[0] * list[1] / GCD(list[0], list[1])
+		}
+		return LCM([]int{list[0], LCM(list[1:])})
+	}
+	return 0
+}

util/util_test.go

@@ -0,0 +1,30 @@
+package util
+
+import (
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestGenerateOTPError(t *testing.T) {
+	asserts := assert.New(t)
+	temp, err := GenerateOTP(0)
+	asserts.Error(err)
+	asserts.Empty(temp)
+}
+
+func TestGenerateOTPSuccess(t *testing.T) {
+	asserts := assert.New(t)
+	temp, err := GenerateOTP(4)
+	asserts.NoError(err)
+	asserts.NotEmpty(temp)
+}
+
+func TestLCM(t *testing.T) {
+	asserts := assert.New(t)
+	asserts.Equal(40, LCM([]int{4, 8, 20}))
+}
+
+func TestGCD(t *testing.T) {
+	asserts := assert.New(t)
+	asserts.Equal(6, GCD(36, 30))
+}