feat: Add slider verification code

pkg/captcha/service.go

@@ -11,6 +11,7 @@ type CaptchaType string
 const (
 	CaptchaTypeLocal     CaptchaType = "local"
 	CaptchaTypeTurnstile CaptchaType = "turnstile"
+	CaptchaTypeSlider    CaptchaType = "slider"
 )
 
 // Service defines the captcha service interface
@@ -18,21 +19,34 @@ type Service interface {
 	// Generate generates a new captcha
 	// For local captcha: returns id and base64 image
 	// For turnstile: returns empty strings
+	// For slider: returns id, background image, and block image (in image field as JSON)
 	Generate(ctx context.Context) (id string, image string, err error)
 
 	// Verify verifies the captcha
 	// For local captcha: token is captcha id, code is user input
 	// For turnstile: token is cf-turnstile-response, code is ignored
+	// For slider: use VerifySlider instead
 	Verify(ctx context.Context, token string, code string, ip string) (bool, error)
 
 	// GetType returns the captcha type
 	GetType() CaptchaType
 }
 
+// SliderService extends Service with slider-specific verification
+type SliderService interface {
+	Service
+	// VerifySlider verifies slider position and trail, returns a one-time token on success
+	VerifySlider(ctx context.Context, id string, x, y int, trail string) (token string, err error)
+	// VerifySliderToken verifies the one-time token issued after slider verification
+	VerifySliderToken(ctx context.Context, token string) (bool, error)
+	// GenerateSlider returns id, background image base64, block image base64
+	GenerateSlider(ctx context.Context) (id string, bgImage string, blockImage string, err error)
+}
+
 // Config holds the configuration for captcha service
 type Config struct {
-	Type         CaptchaType
-	RedisClient  *redis.Client
+	Type            CaptchaType
+	RedisClient     *redis.Client
 	TurnstileSecret string
 }
 
@@ -41,9 +55,16 @@ func NewService(config Config) Service {
 	switch config.Type {
 	case CaptchaTypeTurnstile:
 		return newTurnstileService(config.TurnstileSecret)
+	case CaptchaTypeSlider:
+		return newSliderService(config.RedisClient)
 	case CaptchaTypeLocal:
 		fallthrough
 	default:
 		return newLocalService(config.RedisClient)
 	}
 }
+
+// NewSliderService creates a slider captcha service
+func NewSliderService(redisClient *redis.Client) SliderService {
+	return newSliderService(redisClient)
+}