Jaeger: Run dependency graph queries through backend behind the feature toggle (#103768)

* Start with dependency graph

* Update and add tests

* Fix lint and ordering in test

pkg/tsdb/jaeger/querydata.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"sort"
 
 	"github.com/grafana/grafana-plugin-sdk-go/backend"
 	"github.com/grafana/grafana-plugin-sdk-go/data"
@@ -45,6 +46,23 @@ func queryData(ctx context.Context, dsInfo *datasourceInfo, req *backend.QueryDa
 				Frames: []*data.Frame{frame},
 			}
 		}
+
+		if query.QueryType == "dependencyGraph" {
+			dependencies, err := dsInfo.JaegerClient.Dependencies(ctx, q.TimeRange.From.UnixMilli(), q.TimeRange.To.UnixMilli())
+			if err != nil {
+				response.Responses[q.RefID] = backend.ErrorResponseWithErrorSource(err)
+				continue
+			}
+
+			if len(dependencies.Errors) > 0 {
+				response.Responses[q.RefID] = backend.ErrorResponseWithErrorSource(backend.DownstreamError(fmt.Errorf("error while fetching dependencies, code: %v, message: %v", dependencies.Errors[0].Code, dependencies.Errors[0].Msg)))
+				continue
+			}
+			frames := transformDependenciesResponse(dependencies, q.RefID)
+			response.Responses[q.RefID] = backend.DataResponse{
+				Frames: frames,
+			}
+		}
 	}
 
 	return response, nil
@@ -215,3 +233,70 @@ type TracesResponse struct {
 	Offset int             `json:"offset"`
 	Total  int             `json:"total"`
 }
+
+func transformDependenciesResponse(dependencies DependenciesResponse, refID string) []*data.Frame {
+	// Create nodes frame
+	nodesFrame := data.NewFrame(refID+"_nodes",
+		data.NewField("id", nil, []string{}),
+		data.NewField("title", nil, []string{}),
+	)
+	nodesFrame.Meta = &data.FrameMeta{
+		PreferredVisualization: "nodeGraph",
+	}
+
+	// Create edges frame
+	mainStatField := data.NewField("mainstat", nil, []int64{})
+	mainStatField.Config = &data.FieldConfig{
+		DisplayName: "Call count",
+	}
+	edgesFrame := data.NewFrame(refID+"_edges",
+		data.NewField("id", nil, []string{}),
+		data.NewField("source", nil, []string{}),
+		data.NewField("target", nil, []string{}),
+		mainStatField,
+	)
+
+	edgesFrame.Meta = &data.FrameMeta{
+		PreferredVisualization: "nodeGraph",
+	}
+
+	// Return early if there are no dependencies
+	if len(dependencies.Data) == 0 {
+		return []*data.Frame{nodesFrame, edgesFrame}
+	}
+
+	// Create a map to store unique service nodes
+	servicesByName := make(map[string]bool)
+
+	// Process each dependency
+	for _, dependency := range dependencies.Data {
+		// Add services to the map to track unique services
+		servicesByName[dependency.Parent] = true
+		servicesByName[dependency.Child] = true
+
+		// Add edge data
+		edgesFrame.AppendRow(
+			dependency.Parent+"--"+dependency.Child,
+			dependency.Parent,
+			dependency.Child,
+			int64(dependency.CallCount),
+		)
+	}
+
+	// Convert map keys to slice and sort them - this is to ensure the returned nodes are in a consistent order
+	services := make([]string, 0, len(servicesByName))
+	for service := range servicesByName {
+		services = append(services, service)
+	}
+	sort.Strings(services)
+
+	// Add node data in sorted order
+	for _, service := range services {
+		nodesFrame.AppendRow(
+			service,
+			service,
+		)
+	}
+
+	return []*data.Frame{nodesFrame, edgesFrame}
+}