Send status message to browser to indicate query is done (#1020)

* Send status message to browser to indicate query is done

* Changed so only "finished" status message is emitted per @marpaia

server/service/service_campaigns.go

@@ -70,6 +70,17 @@ type targetTotals struct {
 	MissingInAction uint `json:"missing_in_action"`
 }
 
+const (
+	campaignStatusPending  = "pending"
+	campaignStatusFinished = "finished"
+)
+
+type campaignStatus struct {
+	ExpectedResults uint   `json:"expected_results"`
+	ActualResults   uint   `json:"actual_results"`
+	Status          string `json:"status"`
+}
+
 func (svc service) StreamCampaignResults(ctx context.Context, conn *websocket.Conn, campaignID uint) {
 	// Find the campaign and ensure it is active
 	campaign, err := svc.ds.DistributedQueryCampaign(campaignID)
@@ -107,6 +118,12 @@ func (svc service) StreamCampaignResults(ctx context.Context, conn *websocket.Co
 		return
 	}
 
+	status := campaignStatus{
+		Status: campaignStatusPending,
+	}
+
+	lastStatus := status.Status
+
 	// Loop, pushing updates to results and expected totals
 	for {
 		select {
@@ -118,6 +135,7 @@ func (svc service) StreamCampaignResults(ctx context.Context, conn *websocket.Co
 				if err != nil {
 					fmt.Println("error writing to channel")
 				}
+				status.ActualResults++
 			}
 
 		case <-time.After(1 * time.Second):
@@ -142,10 +160,22 @@ func (svc service) StreamCampaignResults(ctx context.Context, conn *websocket.Co
 				Offline:         metrics.OfflineHosts,
 				MissingInAction: metrics.MissingInActionHosts,
 			}
-
 			if err = conn.WriteJSONMessage("totals", totals); err != nil {
 				return
 			}
+
+			status.ExpectedResults = totals.Online
+			if status.ActualResults >= status.ExpectedResults {
+				status.Status = campaignStatusFinished
+			}
+			// only write status message if status has changed
+			if lastStatus != status.Status {
+				lastStatus = status.Status
+				if err = conn.WriteJSONMessage("status", status); err != nil {
+					return
+				}
+			}
+
 		}
 	}