[BE-API-006] be-api: Implement chat stats endpoint

- Added GetStats method to ChatService with database access
- Returns active_users (distinct users who sent messages in last 24h)
- Returns total_messages (non-deleted messages count)
- Returns rooms_active (rooms with messages in last 24h)
- Added GetStats handler and GET /chat/stats route
- Updated ChatService to use NewChatServiceWithDB for database access

Phase: PHASE-2
Priority: P1
Progress: 15/267 (5.6%)

VEZA_COMPLETE_MVP_TODOLIST.json

@@ -1378,7 +1378,19 @@
       "description": "GET /api/v1/chat/stats returns active_users, total_messages, rooms_active",
       "owner": "backend",
       "estimated_hours": 2,
-      "status": "todo",
+      "status": "completed",
+      "completion": {
+        "completed_at": "2025-12-23T00:51:44Z",
+        "actual_hours": 0.5,
+        "commits": [],
+        "files_changed": [
+          "veza-backend-api/internal/services/chat_service.go",
+          "veza-backend-api/internal/handlers/chat_handler.go",
+          "veza-backend-api/internal/api/router.go"
+        ],
+        "notes": "Added GetStats method to ChatService with database access. Returns active_users (distinct users who sent messages in last 24h), total_messages (non-deleted messages), and rooms_active (rooms with messages in last 24h). Added GetStats handler and GET /chat/stats route. Updated ChatService to use NewChatServiceWithDB for database access.",
+        "issues_encountered": []
+      },
       "files_involved": [],
       "implementation_steps": [
         {

veza-backend-api/internal/api/router.go

@@ -500,7 +500,8 @@ func (r *APIRouter) setupTrackRoutes(router *gin.RouterGroup) {
 
 // setupChatRoutes configure les routes de chat
 func (r *APIRouter) setupChatRoutes(router *gin.RouterGroup) {
-	chatService := services.NewChatService(r.config.ChatJWTSecret, r.logger)
+	// BE-API-006: Use NewChatServiceWithDB to enable stats functionality
+	chatService := services.NewChatServiceWithDB(r.config.ChatJWTSecret, r.db.GormDB, r.logger)
 	userRepo := repositories.NewGormUserRepository(r.db.GormDB)
 	userService := services.NewUserServiceWithDB(userRepo, r.db.GormDB)
 
@@ -511,6 +512,7 @@ func (r *APIRouter) setupChatRoutes(router *gin.RouterGroup) {
 		if r.config.AuthMiddleware != nil {
 			chat.Use(r.config.AuthMiddleware.RequireAuth())
 			chat.POST("/token", chatHandler.GetToken)
+			chat.GET("/stats", chatHandler.GetStats) // BE-API-006: Chat stats endpoint
 		}
 	}
 }

veza-backend-api/internal/handlers/chat_handler.go

@@ -7,6 +7,7 @@ import (
 
 	"github.com/gin-gonic/gin"
 	"go.uber.org/zap"
+	apperrors "veza-backend-api/internal/errors"
 	"veza-backend-api/internal/services"
 )
 
@@ -66,3 +67,16 @@ func (h *ChatHandler) GetToken(c *gin.Context) {
 
 	RespondSuccess(c, http.StatusOK, token)
 }
+
+// GetStats returns chat statistics
+// BE-API-006: Implement chat stats endpoint
+func (h *ChatHandler) GetStats(c *gin.Context) {
+	stats, err := h.chatService.GetStats(c.Request.Context())
+	if err != nil {
+		h.logger.Error("Failed to get chat stats", zap.Error(err))
+		RespondWithAppError(c, apperrors.Wrap(apperrors.ErrCodeInternal, "Failed to get chat stats", err))
+		return
+	}
+
+	RespondSuccess(c, http.StatusOK, stats)
+}

veza-backend-api/internal/services/chat_service.go

@@ -1,6 +1,7 @@
 package services
 
 import (
+	"context"
 	"errors"
 	"fmt"
 	"github.com/google/uuid"
@@ -8,11 +9,14 @@ import (
 
 	"github.com/golang-jwt/jwt/v5"
 	"go.uber.org/zap"
+	"gorm.io/gorm"
+	"veza-backend-api/internal/models"
 )
 
 type ChatService struct {
 	jwtSecret string
 	logger    *zap.Logger
+	db        *gorm.DB
 }
 
 func NewChatService(jwtSecret string, logger *zap.Logger) *ChatService {
@@ -25,6 +29,18 @@ func NewChatService(jwtSecret string, logger *zap.Logger) *ChatService {
 	}
 }
 
+// NewChatServiceWithDB crée un nouveau ChatService avec accès à la base de données
+func NewChatServiceWithDB(jwtSecret string, db *gorm.DB, logger *zap.Logger) *ChatService {
+	if logger == nil {
+		logger = zap.NewNop()
+	}
+	return &ChatService{
+		jwtSecret: jwtSecret,
+		logger:    logger,
+		db:        db,
+	}
+}
+
 type ChatTokenResponse struct {
 	Token     string `json:"token"`
 	ExpiresIn int64  `json:"expires_in"`
@@ -61,3 +77,50 @@ func (s *ChatService) GenerateToken(userID uuid.UUID, username string) (*ChatTok
 		WSUrl:     "/ws", // Relative path, frontend appends base URL
 	}, nil
 }
+
+// ChatStats représente les statistiques du chat
+type ChatStats struct {
+	ActiveUsers   int64 `json:"active_users"`
+	TotalMessages int64 `json:"total_messages"`
+	RoomsActive   int64 `json:"rooms_active"`
+}
+
+// GetStats récupère les statistiques du chat
+// BE-API-006: Implement chat stats endpoint
+func (s *ChatService) GetStats(ctx context.Context) (*ChatStats, error) {
+	if s.db == nil {
+		return nil, errors.New("database connection not available")
+	}
+
+	stats := &ChatStats{}
+
+	// Total messages (non supprimés)
+	if err := s.db.WithContext(ctx).Model(&models.Message{}).
+		Where("is_deleted = ?", false).
+		Count(&stats.TotalMessages).Error; err != nil {
+		return nil, fmt.Errorf("failed to count total messages: %w", err)
+	}
+
+	// Active users: utilisateurs distincts qui ont envoyé des messages dans les dernières 24h
+	activeSince := time.Now().Add(-24 * time.Hour)
+	var activeUsersCount int64
+	if err := s.db.WithContext(ctx).Model(&models.Message{}).
+		Where("is_deleted = ? AND created_at >= ?", false, activeSince).
+		Distinct("user_id").
+		Count(&activeUsersCount).Error; err != nil {
+		return nil, fmt.Errorf("failed to count active users: %w", err)
+	}
+	stats.ActiveUsers = activeUsersCount
+
+	// Rooms actives: rooms qui ont eu des messages dans les dernières 24h
+	var roomsActiveCount int64
+	if err := s.db.WithContext(ctx).Model(&models.Message{}).
+		Where("is_deleted = ? AND created_at >= ?", false, activeSince).
+		Distinct("room_id").
+		Count(&roomsActiveCount).Error; err != nil {
+		return nil, fmt.Errorf("failed to count active rooms: %w", err)
+	}
+	stats.RoomsActive = roomsActiveCount
+
+	return stats, nil
+}