add purchasing in analytics endpoint

internal/transformer/analytics_transformer.go

@@ -138,6 +138,91 @@ func SalesAnalyticsModelToContract(resp *models.SalesAnalyticsResponse) *contrac
 	}
 }
 
+// PurchasingAnalyticsContractToModel converts contract request to model
+func PurchasingAnalyticsContractToModel(req *contract.PurchasingAnalyticsRequest) *models.PurchasingAnalyticsRequest {
+	var dateFrom, dateTo time.Time
+
+	if fromTime, toTime, err := util.ParseDateRangeToJakartaTime(req.DateFrom, req.DateTo); err == nil {
+		if fromTime != nil {
+			dateFrom = *fromTime
+		}
+		if toTime != nil {
+			dateTo = *toTime
+		}
+	}
+
+	return &models.PurchasingAnalyticsRequest{
+		OrganizationID: req.OrganizationID,
+		OutletID:       parseOutletID(req.OutletID),
+		DateFrom:       dateFrom,
+		DateTo:         dateTo,
+		GroupBy:        req.GroupBy,
+	}
+}
+
+// PurchasingAnalyticsModelToContract converts model response to contract
+func PurchasingAnalyticsModelToContract(resp *models.PurchasingAnalyticsResponse) *contract.PurchasingAnalyticsResponse {
+	if resp == nil {
+		return nil
+	}
+
+	data := make([]contract.PurchasingAnalyticsData, len(resp.Data))
+	for i, item := range resp.Data {
+		data[i] = contract.PurchasingAnalyticsData{
+			Date:           item.Date,
+			Purchases:      item.Purchases,
+			PurchaseOrders: item.PurchaseOrders,
+			Quantity:       item.Quantity,
+			Ingredients:    item.Ingredients,
+			Vendors:        item.Vendors,
+		}
+	}
+
+	ingredientData := make([]contract.PurchasingIngredientData, len(resp.IngredientData))
+	for i, item := range resp.IngredientData {
+		ingredientData[i] = contract.PurchasingIngredientData{
+			IngredientID:       item.IngredientID,
+			IngredientName:     item.IngredientName,
+			Quantity:           item.Quantity,
+			TotalCost:          item.TotalCost,
+			AverageUnitCost:    item.AverageUnitCost,
+			PurchaseOrderCount: item.PurchaseOrderCount,
+		}
+	}
+
+	vendorData := make([]contract.PurchasingVendorData, len(resp.VendorData))
+	for i, item := range resp.VendorData {
+		vendorData[i] = contract.PurchasingVendorData{
+			VendorID:           item.VendorID,
+			VendorName:         item.VendorName,
+			TotalCost:          item.TotalCost,
+			PurchaseOrderCount: item.PurchaseOrderCount,
+			IngredientCount:    item.IngredientCount,
+			Quantity:           item.Quantity,
+		}
+	}
+
+	return &contract.PurchasingAnalyticsResponse{
+		OrganizationID: resp.OrganizationID,
+		OutletID:       resp.OutletID,
+		OutletName:     resp.OutletName,
+		DateFrom:       resp.DateFrom,
+		DateTo:         resp.DateTo,
+		GroupBy:        resp.GroupBy,
+		Summary: contract.PurchasingSummary{
+			TotalPurchases:            resp.Summary.TotalPurchases,
+			TotalPurchaseOrders:       resp.Summary.TotalPurchaseOrders,
+			TotalQuantity:             resp.Summary.TotalQuantity,
+			AveragePurchaseOrderValue: resp.Summary.AveragePurchaseOrderValue,
+			TotalIngredients:          resp.Summary.TotalIngredients,
+			TotalVendors:              resp.Summary.TotalVendors,
+		},
+		Data:           data,
+		IngredientData: ingredientData,
+		VendorData:     vendorData,
+	}
+}
+
 // ProductAnalyticsContractToModel converts contract request to model
 func ProductAnalyticsContractToModel(req *contract.ProductAnalyticsRequest) *models.ProductAnalyticsRequest {
 	var dateFrom, dateTo time.Time