Make HTTP middleware easier to use

server/auth/info/info.go

 // Copyright 2015 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 // Package info exposes /auth/api/v1/server/info URL and allows to query it.
 //
 // This endpoint is used by luci services to advertise service account names
 // they use (among other things).
 package info
 
 import (
         "encoding/json"
         "net/http"
         "time"
 
-        "github.com/julienschmidt/httprouter"
         "golang.org/x/net/context"
 
         "github.com/luci/luci-go/server/auth/internal"
-        "github.com/luci/luci-go/server/middleware"
         "github.com/luci/luci-go/server/proccache"
+        "github.com/luci/luci-go/server/router"
 )
 
 // ServiceInfo describes JSON format of /auth/api/v1/server/info response.
 type ServiceInfo struct {
         AppID              string `json:"app_id,omitempty"`
         AppRuntime         string `json:"app_runtime,omitempty"`
         AppRuntimeVersion  string `json:"app_runtime_version,omitempty"`
         AppVersion         string `json:"app_version,omitempty"`
         ServiceAccountName string `json:"service_account_name,omitempty"`
 }
@@ skipping 17 matching lines @@
         if err != nil {
                 return nil, err
         }
         return info.(*ServiceInfo), nil
 }
 
 // ServiceInfoCallback is called by /auth/api/v1/server/info handler.
 type ServiceInfoCallback func(context.Context) (ServiceInfo, error)
 
 // InstallHandlers installs handler that serves info provided by the callback.
-func InstallHandlers(r *httprouter.Router, base middleware.Base, cb ServiceInfoCallback) {
-        handler := func(c context.Context, w http.ResponseWriter, r *http.Request, p httprouter.Params) {
+func InstallHandlers(r *router.Router, base router.MiddlewareChain, cb ServiceInfoCallback) {
+        handler := func(c *router.Context) {
                 var response struct {
                         ServiceInfo
                         Error string `json:"error,omitempty"`
                 }
-                info, err := cb(c)
-                w.Header().Set("Content-Type", "application/json; charset=utf-8")
+                info, err := cb(c.Context)
+                c.Writer.Header().Set("Content-Type", "application/json; charset=utf-8")
                 if err != nil {
-                        w.WriteHeader(http.StatusInternalServerError)
+                        c.Writer.WriteHeader(http.StatusInternalServerError)
                         response.Error = err.Error()
                 } else {
-                        w.WriteHeader(http.StatusOK)
+                        c.Writer.WriteHeader(http.StatusOK)
                         response.ServiceInfo = info
                 }
-                json.NewEncoder(w).Encode(response)
+                json.NewEncoder(c.Writer).Encode(response)
         }
-        r.GET("/auth/api/v1/server/info", base(handler))
+        r.GET("/auth/api/v1/server/info", base, handler)
 }