grafana/pkg/registry/apis/datasource/sub_query.go

package datasource

import (
	"context"
	"encoding/json"
	"io"
	"net/http"
	"time"

	"github.com/grafana/grafana-plugin-sdk-go/backend"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apiserver/pkg/registry/rest"
)

type subQueryREST struct {
	builder *DataSourceAPIBuilder
}

var _ = rest.Connecter(&subQueryREST{})

func (r *subQueryREST) New() runtime.Object {
	return &metav1.Status{}
}

func (r *subQueryREST) Destroy() {
}

func (r *subQueryREST) ConnectMethods() []string {
	return []string{"POST", "GET"}
}

func (r *subQueryREST) NewConnectOptions() (runtime.Object, bool, string) {
	return nil, false, ""
}

func (r *subQueryREST) readQueries(req *http.Request) ([]backend.DataQuery, error) {
	// Simple URL to JSON mapping
	if req.Method == http.MethodGet {
		body := make(map[string]any, 0)
		for k, v := range req.URL.Query() {
			switch len(v) {
			case 0:
				body[k] = true
			case 1:
				body[k] = v[0] // TODO, convert numbers
			default:
				body[k] = v // TODO, convert numbers
			}
		}

		var err error
		dq := backend.DataQuery{
			RefID: "A",
			TimeRange: backend.TimeRange{
				From: time.Now().Add(-1 * time.Hour), // last hour
				To:   time.Now(),
			},
			MaxDataPoints: 1000,
			Interval:      time.Second * 10,
		}
		dq.JSON, err = json.Marshal(body)
		return []backend.DataQuery{dq}, err
	}

	body, err := io.ReadAll(req.Body)
	if err != nil {
		return nil, err
	}
	return readQueries(body)
}

func (r *subQueryREST) Connect(ctx context.Context, name string, opts runtime.Object, responder rest.Responder) (http.Handler, error) {
	pluginCtx, err := r.builder.getPluginContext(ctx, name)
	if err != nil {
		return nil, err
	}

	return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
		queries, err := r.readQueries(req)
		if err != nil {
			responder.Error(err)
			return
		}

		queryResponse, err := r.builder.client.QueryData(ctx, &backend.QueryDataRequest{
			PluginContext: pluginCtx,
			Queries:       queries,
			//  Headers: // from context
		})
		if err != nil {
			return
		}

		jsonRsp, err := json.Marshal(queryResponse)
		if err != nil {
			responder.Error(err)
			return
		}
		w.WriteHeader(200)
		_, _ = w.Write(jsonRsp)
	}), nil
}