From 77e12367f3371afd52112d362ee91fdcfdae31dc Mon Sep 17 00:00:00 2001
From: Jordon Bedwell <jordon@envygeeks.io>
Date: Fri, 23 Nov 2018 10:45:18 -0600
Subject: [PATCH] Add {{ randomPassword }}

---
 README.md                        |  8 +++++++
 template/helpers/helpers.go      | 40 ++++++++++++++++++++++++++++++++
 template/helpers/helpers_test.go |  7 ++++++
 3 files changed, 55 insertions(+)

diff --git a/README.md b/README.md
index 2759fe3..81f38df 100644
--- a/README.md
+++ b/README.md
@@ -248,6 +248,14 @@ hello {
 {{ env [key] }}
 ```
 
+### randomPassword
+
+*Generate an alphanumeric password using cryptographically derived random numbers.*
+
+```
+{{ randomPassword [length] }}
+```
+
 ## An Example
 
 Given you did
diff --git a/template/helpers/helpers.go b/template/helpers/helpers.go
index c035b3a..2b559db 100644
--- a/template/helpers/helpers.go
+++ b/template/helpers/helpers.go
@@ -5,7 +5,11 @@
 package helpers
 
 import (
+	"crypto/rand"
 	"fmt"
+	"io"
+	"log"
+	"math/big"
 	"os"
 	"regexp"
 	"strconv"
@@ -159,6 +163,41 @@ func (h *Helpers) TemplateExists(s string) bool {
 	return false
 }
 
+var (
+	letters = []rune(
+		"01234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ",
+	)
+)
+
+func rngCheck() {
+	buf := make([]byte, 1)
+	_, err := io.ReadFull(rand.Reader, buf)
+	if err != nil {
+		log.Fatalln(err)
+	}
+}
+
+// RandPass generates a password using
+// cryptographically derived random numbers
+func (h *Helpers) RandomPassword(n uint) string {
+	rngCheck()
+
+	l, b := int64(len(letters)), make([]rune, n)
+	for i := range b {
+		n, err := rand.Int(rand.Reader, big.NewInt(l))
+		if err != nil {
+			log.Fatalln(err)
+		}
+
+		nn := n.Int64()
+		ll := letters[nn]
+		b[i] = ll
+	}
+
+	return string(b)
+}
+
+// New creates a new Funcs, and registers them
 func New(t *template.Template) *Helpers {
 	return (&Helpers{
 		template: t,
@@ -173,6 +212,7 @@ func (h *Helpers) RegisterFuncs() *Helpers {
 		"chomp":               strings.Trim,
 		"indent":              h.Indent,
 		"addSpace":            h.AddSpace,
+		"randomPassword":      h.RandomPassword,
 		"templateString":      h.TemplateString,
 		"strippedTemplate":    h.StrippedTemplate,
 		"fixIndentedTemplate": h.FixIndentedTemplate,
diff --git a/template/helpers/helpers_test.go b/template/helpers/helpers_test.go
index 68260bf..866a49b 100644
--- a/template/helpers/helpers_test.go
+++ b/template/helpers/helpers_test.go
@@ -327,3 +327,10 @@ func TestTemplateExists(t *testing.T) {
 			ts.description)
 	}
 }
+
+func TestRandomPassword(t *testing.T) {
+	h := New(template.New("envp"))
+	actual := h.RandomPassword(12)
+	assert.Equal(t, 12, len(actual))
+	assert.NotNil(t, actual)
+}