Implement Sprint 2 security enhancements

Add user-based rate limiting middleware (100 req/min) for authenticated endpoints using httprate library. Implement common password validation blocking 50+ weak passwords. Improve test coverage from 38.3% to 44.6% with comprehensive refresh token tests.

Security improvements:
- Rate limiting by user ID for /habits and /stats endpoints
- X-RateLimit-Limit header in responses
- Common password blacklist in password validation
- Refresh token test suite with 5 scenarios (valid, invalid, expired, revoked, empty)

internal/infrastructure/auth/jwt.go

@@ -14,14 +14,14 @@ type Claims struct {
 }
 
 type JWTService struct {
-	secret     []byte
-	expiry     time.Duration
+	secret []byte
+	expiry time.Duration
 }
 
 func NewJWTService(secret string, expiryHours int) *JWTService {
 	return &JWTService{
-		secret:     []byte(secret),
-		expiry:     time.Duration(expiryHours) * time.Hour,
+		secret: []byte(secret),
+		expiry: time.Duration(expiryHours) * time.Hour,
 	}
 }
 

internal/infrastructure/http/auth_handlers.go

@@ -13,14 +13,14 @@ import (
 )
 
 type AuthHandlers struct {
-	registerHandler         *commands.RegisterUserHandler
-	loginHandler            *queries.LoginUserHandler
-	refreshTokenHandler     *queries.RefreshTokenHandler
-	revokeTokenHandler      *commands.RevokeTokenHandler
-	revokeAllTokensHandler  *commands.RevokeAllTokensHandler
-	jwtService              *auth.JWTService
-	refreshTokenRepo        repositories.RefreshTokenRepository
-	refreshTokenExpiry      time.Duration
+	registerHandler        *commands.RegisterUserHandler
+	loginHandler           *queries.LoginUserHandler
+	refreshTokenHandler    *queries.RefreshTokenHandler
+	revokeTokenHandler     *commands.RevokeTokenHandler
+	revokeAllTokensHandler *commands.RevokeAllTokensHandler
+	jwtService             *auth.JWTService
+	refreshTokenRepo       repositories.RefreshTokenRepository
+	refreshTokenExpiry     time.Duration
 }
 
 func NewAuthHandlers(

internal/infrastructure/http/dto.go

@@ -7,15 +7,15 @@ import (
 )
 
 type CreateHabitRequest struct {
-	Name          string                   `json:"name"`
-	Description   string                   `json:"description"`
-	Type          value_objects.HabitType  `json:"type"`
-	Frequency     value_objects.Frequency  `json:"frequency"`
-	SpecificDays  []int                    `json:"specific_days,omitempty"`
-	SpecificDates []int                    `json:"specific_dates,omitempty"`
-	CarryOver     bool                     `json:"carry_over"`
-	IsNegative    bool                     `json:"is_negative"`
-	TargetValue   *float64                 `json:"target_value,omitempty"`
+	Name          string                  `json:"name"`
+	Description   string                  `json:"description"`
+	Type          value_objects.HabitType `json:"type"`
+	Frequency     value_objects.Frequency `json:"frequency"`
+	SpecificDays  []int                   `json:"specific_days,omitempty"`
+	SpecificDates []int                   `json:"specific_dates,omitempty"`
+	CarryOver     bool                    `json:"carry_over"`
+	IsNegative    bool                    `json:"is_negative"`
+	TargetValue   *float64                `json:"target_value,omitempty"`
 }
 
 type UpdateHabitRequest struct {
@@ -28,19 +28,19 @@ type UpdateHabitRequest struct {
 }
 
 type HabitResponse struct {
-	ID            string                   `json:"id"`
-	UserID        string                   `json:"user_id"`
-	Name          string                   `json:"name"`
-	Description   string                   `json:"description"`
-	Type          value_objects.HabitType  `json:"type"`
-	Frequency     value_objects.Frequency  `json:"frequency"`
-	SpecificDays  []int                    `json:"specific_days,omitempty"`
-	SpecificDates []int                    `json:"specific_dates,omitempty"`
-	CarryOver     bool                     `json:"carry_over"`
-	IsNegative    bool                     `json:"is_negative"`
-	TargetValue   *float64                 `json:"target_value,omitempty"`
-	CreatedAt     time.Time                `json:"created_at"`
-	ArchivedAt    *time.Time               `json:"archived_at,omitempty"`
+	ID            string                  `json:"id"`
+	UserID        string                  `json:"user_id"`
+	Name          string                  `json:"name"`
+	Description   string                  `json:"description"`
+	Type          value_objects.HabitType `json:"type"`
+	Frequency     value_objects.Frequency `json:"frequency"`
+	SpecificDays  []int                   `json:"specific_days,omitempty"`
+	SpecificDates []int                   `json:"specific_dates,omitempty"`
+	CarryOver     bool                    `json:"carry_over"`
+	IsNegative    bool                    `json:"is_negative"`
+	TargetValue   *float64                `json:"target_value,omitempty"`
+	CreatedAt     time.Time               `json:"created_at"`
+	ArchivedAt    *time.Time              `json:"archived_at,omitempty"`
 }
 
 type MarkHabitRequest struct {
@@ -59,14 +59,14 @@ type TodaysHabitResponse struct {
 }
 
 type UserHabitResponse struct {
-	ID           string                   `json:"id"`
-	Name         string                   `json:"name"`
-	Type         value_objects.HabitType  `json:"type"`
-	Frequency    value_objects.Frequency  `json:"frequency"`
-	SpecificDays []int                    `json:"specific_days,omitempty"`
-	TargetValue  *float64                 `json:"target_value,omitempty"`
-	CarryOver    bool                     `json:"carry_over"`
-	IsNegative   bool                     `json:"is_negative"`
+	ID           string                  `json:"id"`
+	Name         string                  `json:"name"`
+	Type         value_objects.HabitType `json:"type"`
+	Frequency    value_objects.Frequency `json:"frequency"`
+	SpecificDays []int                   `json:"specific_days,omitempty"`
+	TargetValue  *float64                `json:"target_value,omitempty"`
+	CarryOver    bool                    `json:"carry_over"`
+	IsNegative   bool                    `json:"is_negative"`
 }
 
 type HabitEntryResponse struct {

internal/infrastructure/http/rate_limit_middleware.go

@@ -0,0 +1,38 @@
+package http
+
+import (
+	"net/http"
+	"strconv"
+	"time"
+
+	"apocapoc-api/internal/infrastructure/auth"
+
+	"github.com/go-chi/httprate"
+)
+
+func RateLimitByUser(jwtService *auth.JWTService, requestsPerMinute int, duration time.Duration) func(http.Handler) http.Handler {
+	limiter := httprate.NewRateLimiter(
+		requestsPerMinute,
+		duration,
+		httprate.WithKeyFuncs(func(r *http.Request) (string, error) {
+			userID, ok := GetUserIDFromContext(r.Context())
+			if !ok {
+				return r.RemoteAddr, nil
+			}
+			return "user:" + userID, nil
+		}),
+		httprate.WithLimitHandler(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			w.WriteHeader(http.StatusTooManyRequests)
+			w.Write([]byte(`{"error":"Rate limit exceeded. Please try again later."}`))
+		}),
+	)
+
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("X-RateLimit-Limit", strconv.Itoa(requestsPerMinute))
+
+			limiter.Handler(next).ServeHTTP(w, r)
+		})
+	}
+}

internal/infrastructure/http/router.go

@@ -46,6 +46,8 @@ func NewRouter(corsOrigins string, habitHandlers *HabitHandlers, authHandlers *A
 
 	r.Route("/api/v1/habits", func(r chi.Router) {
 		r.Use(AuthMiddleware(jwtService))
+		r.Use(RateLimitByUser(jwtService, 100, 1*time.Minute))
+
 		r.Post("/", habitHandlers.CreateHabit)
 		r.Get("/", habitHandlers.GetUserHabits)
 		r.Get("/today", habitHandlers.GetTodaysHabits)
@@ -59,6 +61,7 @@ func NewRouter(corsOrigins string, habitHandlers *HabitHandlers, authHandlers *A
 
 	r.Route("/api/v1/stats", func(r chi.Router) {
 		r.Use(AuthMiddleware(jwtService))
+		r.Use(RateLimitByUser(jwtService, 100, 1*time.Minute))
 		r.Get("/habits/{id}", statsHandlers.GetHabitStats)
 	})