From db41472efc3fd1d053c4a58606017e17a520aea8 Mon Sep 17 00:00:00 2001
From: Naveen Mahalingam <jedib0t@outlook.com>
Date: Sat, 20 Apr 2024 10:31:05 -0700
Subject: [PATCH] passphrase: ahead of time capitalization

---
 README.md               |  2 +-
 passphrase/errors.go    |  3 ++-
 passphrase/generator.go | 35 +++++++++++++++++++++--------------
 3 files changed, 24 insertions(+), 16 deletions(-)

diff --git a/README.md b/README.md
index 7e96792..670e7c9 100644
--- a/README.md
+++ b/README.md
@@ -170,7 +170,7 @@ goos: linux
 goarch: amd64
 pkg: github.com/jedib0t/go-passwords/passphrase
 cpu: AMD Ryzen 9 5900X 12-Core Processor            
-BenchmarkGenerator_Generate-12    	 3015926	       392.7 ns/op	     167 B/op	       8 allocs/op
+BenchmarkGenerator_Generate-12    	 4030634	       292.0 ns/op	     144 B/op	       5 allocs/op
 PASS
 ok  	github.com/jedib0t/go-passwords/passphrase	1.603s
 
diff --git a/passphrase/errors.go b/passphrase/errors.go
index a018777..036a035 100644
--- a/passphrase/errors.go
+++ b/passphrase/errors.go
@@ -7,6 +7,7 @@ import (
 
 var (
 	ErrDictionaryTooSmall = errors.New(fmt.Sprintf("dictionary cannot have less than %d words after word-length restrictions are applied", MinWordsInDictionary))
-	ErrNumWordsInvalid    = errors.New(fmt.Sprintf("number of words cannot be less than %d", MinNumWords))
+	ErrNumWordsTooSmall   = errors.New(fmt.Sprintf("number of words cannot be less than %d", NumWordsMin))
+	ErrNumWordsTooLarge   = errors.New(fmt.Sprintf("number of words cannot be more than %d", NumWordsMax))
 	ErrWordLengthInvalid  = errors.New("word-length rule invalid")
 )
diff --git a/passphrase/generator.go b/passphrase/generator.go
index ab1cf5f..e83d106 100644
--- a/passphrase/generator.go
+++ b/passphrase/generator.go
@@ -11,8 +11,9 @@ import (
 )
 
 const (
-	MinNumWords          = 2
 	MinWordsInDictionary = 256
+	NumWordsMin          = 2
+	NumWordsMax          = 32
 )
 
 type Generator interface {
@@ -48,7 +49,7 @@ func NewGenerator(rules ...Rule) (Generator, error) {
 func (g *generator) Generate() string {
 	var words []string
 
-	// generate words
+	// select words
 	for idx := 0; idx < g.numWords; idx++ {
 		var word string
 		for word == "" || slices.Contains(words, word) {
@@ -56,15 +57,6 @@ func (g *generator) Generate() string {
 		}
 		words = append(words, word)
 	}
-	// capitalize all words
-	if g.capitalize {
-		for idx := range words {
-			r, size := utf8.DecodeRuneInString(words[idx])
-			if r != utf8.RuneError {
-				words[idx] = string(unicode.ToUpper(r)) + words[idx][size:]
-			}
-		}
-	}
 	// inject a random number after one of the words
 	if g.withNumber {
 		idx := g.rng.IntN(len(words))
@@ -83,15 +75,30 @@ func (g *generator) sanitize() (Generator, error) {
 	if g.wordLenMin < 1 || g.wordLenMin > g.wordLenMax {
 		return nil, ErrWordLengthInvalid
 	}
-	// filter the dictionary and remove too-short or too-long words
+
+	// remove words that are too-short & too-long
 	slices.DeleteFunc(g.dictionary, func(word string) bool {
 		return len(word) < g.wordLenMin || len(word) > g.wordLenMax
 	})
 	if len(g.dictionary) < MinWordsInDictionary {
 		return nil, ErrDictionaryTooSmall
 	}
-	if g.numWords < MinNumWords {
-		return nil, ErrNumWordsInvalid
+
+	// capitalize all words in the dictionary ahead of time
+	if g.capitalize {
+		for idx := range g.dictionary {
+			r, size := utf8.DecodeRuneInString(g.dictionary[idx])
+			if r != utf8.RuneError {
+				g.dictionary[idx] = string(unicode.ToUpper(r)) + g.dictionary[idx][size:]
+			}
+		}
+	}
+
+	if g.numWords < NumWordsMin {
+		return nil, ErrNumWordsTooSmall
+	}
+	if g.numWords > NumWordsMax {
+		return nil, ErrNumWordsTooLarge
 	}
 	return g, nil
 }