feat: Implement Two-Factor Authentication (2FA) functionality

- Added support for Two-Factor Authentication, including setup, verification, and disabling features.
- Introduced new components for 2FA setup and verification, enhancing user security.
- Updated user model to include fields for 2FA secret, status, and backup codes.
- Created migration to add necessary database fields for 2FA.
- Enhanced authentication handlers to manage 2FA processes during login and profile updates.
- Updated routes to include 2FA-related endpoints for setup and verification.

internal/auth/totp.go

@@ -0,0 +1,158 @@
+package auth
+
+import (
+	"bytes"
+	"crypto/rand"
+	"encoding/base32"
+	"encoding/base64"
+	"fmt"
+	"image/png"
+	"strings"
+
+	// "github.com/pquerna/otp/base32"
+	"github.com/pquerna/otp/totp"
+)
+
+const (
+	// IssuerName is the name of the issuer that appears in authenticator apps
+	IssuerName = "GoMFT"
+	// SecretSize is the size of the TOTP secret in bytes
+	SecretSize = 20
+	// BackupCodeCount is the number of backup codes to generate
+	BackupCodeCount = 8
+	// BackupCodeLength is the length of each backup code
+	BackupCodeLength = 8
+)
+
+// GenerateTOTPSecret generates a new TOTP secret for a user
+func GenerateTOTPSecret(email string) (string, string, error) {
+	// Generate TOTP key using the library
+	key, err := totp.Generate(totp.GenerateOpts{
+		Issuer:      IssuerName,
+		AccountName: email,
+	})
+	if err != nil {
+		return "", "", fmt.Errorf("failed to generate TOTP key: %v", err)
+	}
+
+	// Generate QR code image
+	var buf bytes.Buffer
+	img, err := key.Image(256, 256)
+	if err != nil {
+		return "", "", fmt.Errorf("failed to generate QR code image: %v", err)
+	}
+
+	// Encode image as PNG and convert to base64
+	err = png.Encode(&buf, img)
+	if err != nil {
+		return "", "", fmt.Errorf("failed to encode QR code image: %v", err)
+	}
+
+	// Create data URL
+	dataURL := fmt.Sprintf("data:image/png;base64,%s", base64.StdEncoding.EncodeToString(buf.Bytes()))
+
+	return key.Secret(), dataURL, nil
+}
+
+// ValidateTOTPCode validates a TOTP code against a secret
+func ValidateTOTPCode(secret string, code string) bool {
+	// Remove any spaces from the code
+	code = strings.ReplaceAll(code, " ", "")
+
+	// Use the library's Validate function
+	return totp.Validate(code, secret)
+}
+
+// GenerateBackupCodes generates a set of backup codes
+func GenerateBackupCodes() ([]string, error) {
+	codes := make([]string, BackupCodeCount)
+	for i := 0; i < BackupCodeCount; i++ {
+		// Generate random bytes
+		bytes := make([]byte, BackupCodeLength/2)
+		_, err := rand.Read(bytes)
+		if err != nil {
+			return nil, fmt.Errorf("failed to generate backup code: %v", err)
+		}
+
+		// Convert to hex string
+		codes[i] = fmt.Sprintf("%x", bytes)
+	}
+	return codes, nil
+}
+
+// ValidateBackupCode validates a backup code against a list of codes
+func ValidateBackupCode(providedCode string, storedCodes string) bool {
+	if storedCodes == "" {
+		return false
+	}
+
+	// Remove any spaces and convert to lowercase
+	providedCode = strings.ToLower(strings.ReplaceAll(providedCode, " ", ""))
+
+	// Split stored codes
+	codes := strings.Split(storedCodes, ",")
+
+	// Check if the provided code matches any stored code
+	for _, code := range codes {
+		if code == providedCode {
+			return true
+		}
+	}
+
+	return false
+}
+
+// RemoveBackupCode removes a used backup code from the list
+func RemoveBackupCode(usedCode string, storedCodes string) string {
+	if storedCodes == "" {
+		return ""
+	}
+
+	usedCode = strings.ToLower(strings.ReplaceAll(usedCode, " ", ""))
+	codes := strings.Split(storedCodes, ",")
+
+	var newCodes []string
+	for _, code := range codes {
+		if code != usedCode {
+			newCodes = append(newCodes, code)
+		}
+	}
+
+	return strings.Join(newCodes, ",")
+}
+
+// GenerateQRCodeURL generates a QR code URL for an existing secret
+func GenerateQRCodeURL(secret string, email string) (string, error) {
+	// Decode the base32 secret
+	secretBytes, err := base32.StdEncoding.DecodeString(secret)
+	if err != nil {
+		return "", fmt.Errorf("failed to decode secret: %v", err)
+	}
+
+	key, err := totp.Generate(totp.GenerateOpts{
+		Issuer:      IssuerName,
+		AccountName: email,
+		Secret:      secretBytes,
+	})
+	if err != nil {
+		return "", fmt.Errorf("failed to generate TOTP key: %v", err)
+	}
+
+	// Generate QR code image
+	var buf bytes.Buffer
+	img, err := key.Image(256, 256)
+	if err != nil {
+		return "", fmt.Errorf("failed to generate QR code image: %v", err)
+	}
+
+	// Encode image as PNG and convert to base64
+	err = png.Encode(&buf, img)
+	if err != nil {
+		return "", fmt.Errorf("failed to encode QR code image: %v", err)
+	}
+
+	// Create data URL
+	dataURL := fmt.Sprintf("data:image/png;base64,%s", base64.StdEncoding.EncodeToString(buf.Bytes()))
+
+	return dataURL, nil
+}