add purchasing in analytics endpoint

internal/service/analytics_service.go

@@ -13,6 +13,7 @@ import (
 type AnalyticsService interface {
 	GetPaymentMethodAnalytics(ctx context.Context, req *models.PaymentMethodAnalyticsRequest) (*models.PaymentMethodAnalyticsResponse, error)
 	GetSalesAnalytics(ctx context.Context, req *models.SalesAnalyticsRequest) (*models.SalesAnalyticsResponse, error)
+	GetPurchasingAnalytics(ctx context.Context, req *models.PurchasingAnalyticsRequest) (*models.PurchasingAnalyticsResponse, error)
 	GetProductAnalytics(ctx context.Context, req *models.ProductAnalyticsRequest) (*models.ProductAnalyticsResponse, error)
 	GetProductAnalyticsPerCategory(ctx context.Context, req *models.ProductAnalyticsPerCategoryRequest) (*models.ProductAnalyticsPerCategoryResponse, error)
 	GetDashboardAnalytics(ctx context.Context, req *models.DashboardAnalyticsRequest) (*models.DashboardAnalyticsResponse, error)
@@ -57,6 +58,19 @@ func (s *AnalyticsServiceImpl) GetSalesAnalytics(ctx context.Context, req *model
 	return response, nil
 }
 
+func (s *AnalyticsServiceImpl) GetPurchasingAnalytics(ctx context.Context, req *models.PurchasingAnalyticsRequest) (*models.PurchasingAnalyticsResponse, error) {
+	if err := s.validatePurchasingAnalyticsRequest(req); err != nil {
+		return nil, fmt.Errorf("validation error: %w", err)
+	}
+
+	response, err := s.analyticsProcessor.GetPurchasingAnalytics(ctx, req)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get purchasing analytics: %w", err)
+	}
+
+	return response, nil
+}
+
 func (s *AnalyticsServiceImpl) GetProductAnalytics(ctx context.Context, req *models.ProductAnalyticsRequest) (*models.ProductAnalyticsResponse, error) {
 	// Validate request
 	if err := s.validateProductAnalyticsRequest(req); err != nil {
@@ -168,6 +182,42 @@ func (s *AnalyticsServiceImpl) validateSalesAnalyticsRequest(req *models.SalesAn
 	return nil
 }
 
+func (s *AnalyticsServiceImpl) validatePurchasingAnalyticsRequest(req *models.PurchasingAnalyticsRequest) error {
+	if req == nil {
+		return fmt.Errorf("request cannot be nil")
+	}
+
+	if req.OrganizationID == uuid.Nil {
+		return fmt.Errorf("organization ID is required")
+	}
+
+	if req.DateFrom.IsZero() {
+		return fmt.Errorf("date_from is required")
+	}
+
+	if req.DateTo.IsZero() {
+		return fmt.Errorf("date_to is required")
+	}
+
+	if req.DateFrom.After(req.DateTo) {
+		return fmt.Errorf("date_from cannot be after date_to")
+	}
+
+	if req.GroupBy != "" {
+		validGroupBy := map[string]bool{
+			"day":   true,
+			"hour":  true,
+			"week":  true,
+			"month": true,
+		}
+		if !validGroupBy[req.GroupBy] {
+			return fmt.Errorf("invalid group_by value: %s", req.GroupBy)
+		}
+	}
+
+	return nil
+}
+
 func (s *AnalyticsServiceImpl) validateProductAnalyticsRequest(req *models.ProductAnalyticsRequest) error {
 	if req.OrganizationID == uuid.Nil {
 		return fmt.Errorf("organization ID is required")