Add phonetic spelling functionality to password generator

The update introduces a new 'SpellPassword' setting in the configuration that, when enabled, spells out the generated passwords in the phonetic alphabet. The accompanied changes include the addition of 'spelling.go' and 'spelling_test.go' files containing the spelling logic and corresponding tests. The domain-specific error handling is also enhanced for unsupported characters.

config.go

@@ -41,6 +41,8 @@ type Config struct {
 	// NumberPass sets the number of passwords that are generated
 	// and returned by the generator
 	NumberPass int64
+	// SpellPassword if set will spell the generated passwords in the phonetic alphabet
+	SpellPassword bool
 }
 
 // Option is a function that can override default Config settings

spelling.go

@@ -0,0 +1,113 @@
+package apg
+
+import (
+	"fmt"
+	"strings"
+)
+
+var (
+	symbNumNames = map[byte]string{
+		'1': "ONE",
+		'2': "TWO",
+		'3': "THREE",
+		'4': "FOUR",
+		'5': "FIVE",
+		'6': "SIX",
+		'7': "SEVEN",
+		'8': "EIGHT",
+		'9': "NINE",
+		'0': "ZERO",
+		33:  "EXCLAMATION_POINT",
+		34:  "QUOTATION_MARK",
+		35:  "CROSSHATCH",
+		36:  "DOLLAR_SIGN",
+		37:  "PERCENT_SIGN",
+		38:  "AMPERSAND",
+		39:  "APOSTROPHE",
+		40:  "LEFT_PARENTHESIS",
+		41:  "RIGHT_PARENTHESIS",
+		42:  "ASTERISK",
+		43:  "PLUS_SIGN",
+		44:  "COMMA",
+		45:  "HYPHEN",
+		46:  "PERIOD",
+		47:  "SLASH",
+		58:  "COLON",
+		59:  "SEMICOLON",
+		60:  "LESS_THAN",
+		61:  "EQUAL_SIGN",
+		62:  "GREATER_THAN",
+		63:  "QUESTION_MARK",
+		64:  "AT_SIGN",
+		91:  "LEFT_BRACKET",
+		92:  "BACKSLASH",
+		93:  "RIGHT_BRACKET",
+		94:  "CIRCUMFLEX",
+		95:  "UNDERSCORE",
+		96:  "GRAVE",
+		123: "LEFT_BRACE",
+		124: "VERTICAL_BAR",
+		125: "RIGHT_BRACE",
+		126: "TILDE",
+	}
+	alphabetNames = map[byte]string{
+		'A': "Alfa",
+		'B': "Bravo",
+		'C': "Charlie",
+		'D': "Delta",
+		'E': "Echo",
+		'F': "Foxtrot",
+		'G': "Golf",
+		'H': "Hotel",
+		'I': "India",
+		'J': "Juliett",
+		'K': "Kilo",
+		'L': "Lima",
+		'M': "Mike",
+		'N': "November",
+		'O': "Oscar",
+		'P': "Papa",
+		'Q': "Quebec",
+		'R': "Romeo",
+		'S': "Sierra",
+		'T': "Tango",
+		'U': "Uniform",
+		'V': "Victor",
+		'W': "Whiskey",
+		'X': "X_ray",
+		'Y': "Yankee",
+		'Z': "Zulu",
+	}
+)
+
+// Spell returns a given string as spelled english phonetic alphabet string
+func Spell(input string) (string, error) {
+	var returnString []string
+	for _, curChar := range input {
+		curSpellString, err := ConvertByteToWord(byte(curChar))
+		if err != nil {
+			return "", err
+		}
+		returnString = append(returnString, curSpellString)
+	}
+	return strings.Join(returnString, "/"), nil
+}
+
+// ConvertByteToWord converts a given ASCII byte into the corresponding spelled version
+// of the english phonetic alphabet
+func ConvertByteToWord(charByte byte) (string, error) {
+	var returnString string
+	switch {
+	case charByte > 64 && charByte < 91:
+		returnString = alphabetNames[charByte]
+	case charByte > 96 && charByte < 123:
+		returnString = strings.ToLower(alphabetNames[charByte-32])
+	default:
+		returnString = symbNumNames[charByte]
+	}
+
+	if returnString == "" {
+		return "", fmt.Errorf("failed to convert given byte to word: %s is unsupported", string(charByte))
+	}
+	return returnString, nil
+}

spelling_test.go

@@ -0,0 +1,53 @@
+package apg
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestConvertByteToWord(t *testing.T) {
+	tests := []struct {
+		name    string
+		char    byte
+		want    string
+		wantErr bool
+	}{
+		{
+			name:    "UpperCaseChar",
+			char:    'A',
+			want:    alphabetNames['A'],
+			wantErr: false,
+		},
+		{
+			name:    "LowerCaseChar",
+			char:    'a',
+			want:    strings.ToLower(alphabetNames['A']),
+			wantErr: false,
+		},
+		{
+			name:    "NonAlphaChar",
+			char:    '(',
+			want:    symbNumNames['('],
+			wantErr: false,
+		},
+		{
+			name:    "UnsupportedChar",
+			char:    'ü',
+			want:    "",
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := ConvertByteToWord(tt.char)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("ConvertByteToWord() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if got != tt.want {
+				t.Errorf("ConvertByteToWord() got = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}