refactor the rest package introducing middleware concept and the usage of an http router

Signed-off-by: Augustin Husson <husson.augustin@gmail.com>

Author: Nexucis

cmd/promql-langserver/promql-langserver.go

@@ -25,6 +25,7 @@ import (
 	kitlog "github.com/go-kit/kit/log"
 	"github.com/prometheus-community/promql-langserver/config"
 	promClient "github.com/prometheus-community/promql-langserver/prometheus"
+	"github.com/prometheus/common/route"
 
 	"github.com/prometheus-community/promql-langserver/langserver"
 	"github.com/prometheus-community/promql-langserver/rest"
@@ -59,13 +60,17 @@ func main() {
 		}
 
 		logger = kitlog.NewSyncLogger(logger)
-
-		handler, err := rest.CreateInstHandler(context.Background(), prometheusClient, logger)
+		// create the http router
+		router := route.New()
+		// create the api
+		api, err := rest.NewLangServerAPI(context.Background(), prometheusClient, logger, true)
 		if err != nil {
 			log.Fatal(err)
 		}
-
-		err = http.ListenAndServe(fmt.Sprint(":", conf.RESTAPIPort), handler)
+		// register the different route
+		api.Register(router, "")
+		// start the http server
+		err = http.ListenAndServe(fmt.Sprint(":", conf.RESTAPIPort), router)
 		if err != nil {
 			log.Fatal(err)
 		}

go.mod

@@ -5,6 +5,7 @@ go 1.13
 require (
 	github.com/blang/semver v3.5.1+incompatible
 	github.com/go-kit/kit v0.10.0
+	github.com/google/uuid v1.1.1
 	github.com/kelseyhightower/envconfig v1.4.0
 	github.com/pkg/errors v0.9.1
 	github.com/prometheus/client_golang v1.7.1

go.sum

@@ -438,6 +438,7 @@ github.com/jsternberg/zap-logfmt v1.0.0/go.mod h1:uvPs/4X51zdkcm5jXl5SYoN+4RK21K
 github.com/jtolds/gls v4.20.0+incompatible/go.mod h1:QJZ7F/aHp+rZTRtaJ1ow/lLfFfVYBRgL+9YlvaHOwJU=
 github.com/julienschmidt/httprouter v1.2.0 h1:TDTW5Yz1mjftljbcKqRcrYhd4XeOoI98t+9HbQbYf7g=
 github.com/julienschmidt/httprouter v1.2.0/go.mod h1:SYymIcj16QtmaHHD7aYtjjsJG7VTCxuUUipMqKk8s4w=
+github.com/julienschmidt/httprouter v1.3.0 h1:U0609e9tgbseu3rBINet9P48AI/D3oJs4dN7jwJOQ1U=
 github.com/julienschmidt/httprouter v1.3.0/go.mod h1:JR6WtHb+2LUe8TCKY3cZOxFyyO8IZAc4RVcycCCAKdM=
 github.com/jung-kurt/gofpdf v1.0.3-0.20190309125859-24315acbbda5/go.mod h1:7Id9E/uU8ce6rXgefFLlgrJj/GYY22cpxn+r32jIOes=
 github.com/jwilder/encoding v0.0.0-20170811194829-b4e1701a28ef/go.mod h1:Ct9fl0F6iIOGgxJ5npU/IUOhOhqlVrGjyIZc8/MagT0=

rest/api.go

@@ -0,0 +1,217 @@
+// Copyright 2020 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.  // You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package rest
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+
+	"github.com/go-kit/kit/log"
+	"github.com/pkg/errors"
+	"github.com/prometheus-community/promql-langserver/internal/vendored/go-tools/lsp/protocol"
+	"github.com/prometheus-community/promql-langserver/langserver"
+	promClient "github.com/prometheus-community/promql-langserver/prometheus"
+	"github.com/prometheus/common/route"
+)
+
+func returnJSON(w http.ResponseWriter, content interface{}) {
+	encoder := json.NewEncoder(w)
+
+	err := encoder.Encode(content)
+	if err != nil {
+		http.Error(w, errors.Wrapf(err, "failed to write response").Error(), 500)
+	}
+}
+
+type lspData struct {
+	// Expr is the promQL expression and is required for all endpoint available.
+	Expr string `json:"expr"`
+	// Limit is the number max of result returned to the client. It will be used for the autocompletion and the diagnostics.
+	Limit *uint64 `json:"limit,omitempty"`
+	// PositionLine is the number of the line for which the metadata is queried.
+	PositionLine *float64 `json:"positionLine,omitempty"`
+	// PositionChar for which the metadata is queried. Characters are counted as UTF16 Codepoints.
+	PositionChar *float64 `json:"positionChar,omitempty"`
+}
+
+func (d *lspData) UnmarshalJSON(data []byte) error {
+	var tmp lspData
+	type plain lspData
+	if err := json.Unmarshal(data, (*plain)(&tmp)); err != nil {
+		return err
+	}
+	if len(tmp.Expr) == 0 {
+		return fmt.Errorf("promQL expression is not specified")
+	}
+	*d = tmp
+	return nil
+}
+
+func (d *lspData) returnPosition() (protocol.Position, error) {
+	if d.PositionLine == nil {
+		return protocol.Position{}, errors.New("positionLine is not specified")
+	}
+	if d.PositionChar == nil {
+		return protocol.Position{}, errors.New("positionChar is not specified")
+	}
+	return protocol.Position{
+		Line:      *d.PositionLine,
+		Character: *d.PositionChar,
+	}, nil
+}
+
+type API struct {
+	langServer    langserver.HeadlessServer
+	enableMetrics bool
+}
+
+func NewLangServerAPI(ctx context.Context, metadataService promClient.MetadataService, logger log.Logger, enableMetrics bool) (*API, error) {
+	lgs, err := langserver.CreateHeadlessServer(ctx, metadataService, logger)
+	if err != nil {
+		return nil, err
+	}
+	return &API{
+		langServer:    lgs,
+		enableMetrics: enableMetrics,
+	}, nil
+}
+
+// Register the API's endpoints in the given router.
+func (a *API) Register(r *route.Router, prefix string) {
+	r.Post(prefix+"/diagnostics", a.handle(a.diagnostics))
+	r.Post(prefix+"/completion", a.handle(a.completion))
+	r.Post(prefix+"/hover", a.handle(a.hover))
+	r.Post(prefix+"/signatureHelp", a.handle(a.signature))
+}
+
+func (a *API) handle(h http.HandlerFunc) http.HandlerFunc {
+	endpoint := manageDocumentMiddleware(a.langServer)(h)
+	return endpoint
+}
+
+func (a *API) diagnostics(w http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+	requestID, requestData, err := getRequestDataAndID(ctx)
+	if err != nil {
+		http.Error(w, err.Error(), 500)
+		return
+	}
+
+	diagnostics, err := a.langServer.GetDiagnostics(requestID)
+	if err != nil {
+		http.Error(w, errors.Wrapf(err, "failed to get diagnostics").Error(), 500)
+		return
+	}
+
+	items := diagnostics.Diagnostics
+	limit := requestData.Limit
+	if limit != nil && uint64(len(items)) > *limit {
+		items = items[:*limit]
+	}
+
+	returnJSON(w, items)
+}
+
+func (a *API) hover(w http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+	requestID, requestData, err := getRequestDataAndID(ctx)
+	if err != nil {
+		http.Error(w, err.Error(), 500)
+		return
+	}
+	position, err := requestData.returnPosition()
+	if err != nil {
+		http.Error(w, err.Error(), 400)
+		return
+	}
+
+	hover, err := a.langServer.Hover(r.Context(), &protocol.HoverParams{
+		TextDocumentPositionParams: protocol.TextDocumentPositionParams{
+			TextDocument: protocol.TextDocumentIdentifier{
+				URI: requestID,
+			},
+			Position: position,
+		},
+	})
+	if err != nil {
+		http.Error(w, errors.Wrapf(err, "failed to get hover info").Error(), 500)
+		return
+	}
+
+	returnJSON(w, hover)
+}
+
+func (a *API) completion(w http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+	requestID, requestData, err := getRequestDataAndID(ctx)
+	if err != nil {
+		http.Error(w, err.Error(), 500)
+		return
+	}
+	position, err := requestData.returnPosition()
+	if err != nil {
+		http.Error(w, err.Error(), 400)
+		return
+	}
+
+	completion, err := a.langServer.Completion(r.Context(), &protocol.CompletionParams{
+		TextDocumentPositionParams: protocol.TextDocumentPositionParams{
+			TextDocument: protocol.TextDocumentIdentifier{
+				URI: requestID,
+			},
+			Position: position,
+		},
+	})
+	if err != nil {
+		http.Error(w, errors.Wrapf(err, "failed to get completion info").Error(), 500)
+		return
+	}
+
+	items := completion.Items
+	limit := requestData.Limit
+	if limit != nil && uint64(len(items)) > *limit {
+		items = items[:*limit]
+	}
+
+	returnJSON(w, items)
+}
+
+func (a *API) signature(w http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+	requestID, requestData, err := getRequestDataAndID(ctx)
+	if err != nil {
+		http.Error(w, err.Error(), 500)
+		return
+	}
+	position, err := requestData.returnPosition()
+	if err != nil {
+		http.Error(w, err.Error(), 400)
+		return
+	}
+
+	signature, err := a.langServer.SignatureHelp(r.Context(), &protocol.SignatureHelpParams{
+		TextDocumentPositionParams: protocol.TextDocumentPositionParams{
+			TextDocument: protocol.TextDocumentIdentifier{
+				URI: requestID,
+			},
+			Position: position,
+		},
+	})
+	if err != nil {
+		http.Error(w, errors.Wrapf(err, "failed to get hover info").Error(), 500)
+		return
+	}
+
+	returnJSON(w, signature)
+}