refactor promethueus package into sub packages (#43634)

pkg/tsdb/prometheus/middleware/custom_query_params.go

@@ -0,0 +1,56 @@
+package middleware
+
+import (
+	"net/http"
+	"net/url"
+
+	sdkhttpclient "github.com/grafana/grafana-plugin-sdk-go/backend/httpclient"
+	"github.com/grafana/grafana/pkg/infra/log"
+)
+
+const (
+	customQueryParametersMiddlewareName = "prom-custom-query-parameters"
+	customQueryParametersKey            = "customQueryParameters"
+	grafanaDataKey                      = "grafanaData"
+)
+
+func CustomQueryParameters(logger log.Logger) sdkhttpclient.Middleware {
+	return sdkhttpclient.NamedMiddlewareFunc(customQueryParametersMiddlewareName, func(opts sdkhttpclient.Options, next http.RoundTripper) http.RoundTripper {
+		grafanaData, exists := opts.CustomOptions[grafanaDataKey]
+		if !exists {
+			return next
+		}
+
+		data, ok := grafanaData.(map[string]interface{})
+		if !ok {
+			return next
+		}
+		customQueryParamsVal, exists := data[customQueryParametersKey]
+		if !exists {
+			return next
+		}
+
+		customQueryParams, ok := customQueryParamsVal.(string)
+		if !ok || customQueryParams == "" {
+			return next
+		}
+
+		values, err := url.ParseQuery(customQueryParams)
+		if err != nil {
+			logger.Error("Failed to parse custom query parameters, skipping middleware", "error", err)
+			return next
+		}
+
+		return sdkhttpclient.RoundTripperFunc(func(req *http.Request) (*http.Response, error) {
+			q := req.URL.Query()
+			for k, keyValues := range values {
+				for _, value := range keyValues {
+					q.Add(k, value)
+				}
+			}
+			req.URL.RawQuery = q.Encode()
+
+			return next.RoundTrip(req)
+		})
+	})
+}