add auth lib

credentials/validation.go

@@ -0,0 +1,42 @@
+package credentials
+
+import (
+	"regexp"
+	"strings"
+)
+
+var emailRegex = regexp.MustCompile(`^[A-Za-z0-9._%+\-]+@[A-Za-z0-9.\-]+\.[A-Za-z]{2,}$`)
+var usernameAllowedRegex = regexp.MustCompile(`^[A-Za-z0-9._-]{3,20}$`)
+
+const bcryptMaxPasswordBytes = 72
+
+// At least one letter.
+var passwordLetterRegex = regexp.MustCompile(`[A-Za-z]`)
+
+// At least one number or special symbol (non-letter).
+var passwordNonLetterRegex = regexp.MustCompile(`[^A-Za-z]`)
+
+func IsValidEmail(email string) bool {
+	return emailRegex.MatchString(email)
+}
+
+func IsValidUsername(username string) bool {
+	if !usernameAllowedRegex.MatchString(username) {
+		return false
+	}
+
+	return !strings.Contains(username, "..") &&
+		!strings.Contains(username, "--") &&
+		!strings.Contains(username, "__")
+}
+
+func IsValidPassword(password string) bool {
+	return len(password) >= 12 &&
+		IsPasswordWithinBcryptLimit(password) &&
+		passwordLetterRegex.MatchString(password) &&
+		passwordNonLetterRegex.MatchString(password)
+}
+
+func IsPasswordWithinBcryptLimit(password string) bool {
+	return len([]byte(password)) <= bcryptMaxPasswordBytes
+}

credentials/validation_test.go

@@ -0,0 +1,71 @@
+package credentials
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestIsValidEmail(t *testing.T) {
+	tests := []struct {
+		email string
+		want  bool
+	}{
+		{email: "a@example.com", want: true},
+		{email: "user.name+tag@example.co.uk", want: true},
+		{email: "", want: false},
+		{email: "plainaddress", want: false},
+		{email: "user@localhost", want: false},
+		{email: "user@example", want: false},
+	}
+
+	for _, tc := range tests {
+		if got := IsValidEmail(tc.email); got != tc.want {
+			t.Fatalf("IsValidEmail(%q) = %v, want %v", tc.email, got, tc.want)
+		}
+	}
+}
+
+func TestIsValidUsername(t *testing.T) {
+	tests := []struct {
+		username string
+		want     bool
+	}{
+		{username: "abc", want: true},
+		{username: "user_name-1", want: true},
+		{username: "ab", want: false},
+		{username: "this_username_is_way_too_long_for_rules", want: false},
+		{username: "user..name", want: false},
+		{username: "user__name", want: false},
+		{username: "user--name", want: false},
+		{username: "user name", want: false},
+	}
+
+	for _, tc := range tests {
+		if got := IsValidUsername(tc.username); got != tc.want {
+			t.Fatalf("IsValidUsername(%q) = %v, want %v", tc.username, got, tc.want)
+		}
+	}
+}
+
+func TestIsValidPassword(t *testing.T) {
+	longerThan72 := "A1" + strings.Repeat("x", 71)
+	exactly72 := "A1" + strings.Repeat("x", 70)
+	tests := []struct {
+		password string
+		want     bool
+	}{
+		{password: "LongPassword1", want: true},
+		{password: "abcdefghijk1", want: true},
+		{password: exactly72, want: true},
+		{password: longerThan72, want: false},
+		{password: "123456789012", want: false},
+		{password: "OnlyLettersAB", want: false},
+		{password: "short1A", want: false},
+	}
+
+	for _, tc := range tests {
+		if got := IsValidPassword(tc.password); got != tc.want {
+			t.Fatalf("IsValidPassword(%q) = %v, want %v", tc.password, got, tc.want)
+		}
+	}
+}