Improve binapi generator

[govpp.git] / binapigen / gen_rest.go

diff --git a/binapigen/gen_rest.go b/binapigen/gen_rest.go
new file mode 100644 (file)
index 0000000..6ddb57a
--- /dev/null
+++ b/binapigen/gen_rest.go
@@ -0,0 +1,103 @@
+//  Copyright (c) 2020 Cisco and/or its affiliates.
+//
+//  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 binapigen
+
+import (
+       "path"
+       "strconv"
+)
+
+func init() {
+       RegisterPlugin("rest", GenerateREST)
+}
+
+// library dependencies
+const (
+       httpPkg   = GoImportPath("net/http")
+       ioutilPkg = GoImportPath("io/ioutil")
+       jsonPkg   = GoImportPath("encoding/json")
+)
+
+func GenerateREST(gen *Generator, file *File) *GenFile {
+       if file.Service == nil {
+               return nil
+       }
+
+       logf("----------------------------")
+       logf(" Generate REST - %s", file.Desc.Name)
+       logf("----------------------------")
+
+       filename := path.Join(file.FilenamePrefix, file.Desc.Name+"_rest.ba.go")
+       g := gen.NewGenFile(filename, file.GoImportPath)
+       g.file = file
+
+       // generate file header
+       g.P("// Code generated by GoVPP's binapi-generator. DO NOT EDIT.")
+       g.P()
+       g.P("package ", file.PackageName)
+       g.P()
+
+       // generate RPC service
+       if len(file.Service.RPCs) > 0 {
+               genRESTHandler(g, file.Service)
+       }
+
+       return g
+}
+
+func genRESTHandler(g *GenFile, svc *Service) {
+       // generate handler constructor
+       g.P("func RESTHandler(rpc ", serviceApiName, ") ", httpPkg.Ident("Handler"), " {")
+       g.P("   mux := ", httpPkg.Ident("NewServeMux"), "()")
+
+       // generate http handlers for rpc
+       for _, rpc := range svc.RPCs {
+               if rpc.MsgReply == nil {
+                       continue
+               }
+               if rpc.VPP.Stream {
+                       continue // TODO: implement handler for streaming messages
+               }
+               g.P("mux.HandleFunc(", strconv.Quote("/"+rpc.VPP.Request), ", func(w ", httpPkg.Ident("ResponseWriter"), ", req *", httpPkg.Ident("Request"), ") {")
+               g.P("var request = new(", rpc.MsgRequest.GoName, ")")
+               if len(rpc.MsgRequest.Fields) > 0 {
+                       g.P("b, err := ", ioutilPkg.Ident("ReadAll"), "(req.Body)")
+                       g.P("if err != nil {")
+                       g.P("   ", httpPkg.Ident("Error"), "(w, \"read body failed\", ", httpPkg.Ident("StatusBadRequest"), ")")
+                       g.P("   return")
+                       g.P("}")
+                       g.P("if err := ", jsonPkg.Ident("Unmarshal"), "(b, request); err != nil {")
+                       g.P("   ", httpPkg.Ident("Error"), "(w, \"unmarshal data failed\", ", httpPkg.Ident("StatusBadRequest"), ")")
+                       g.P("   return")
+                       g.P("}")
+               }
+               g.P("reply, err := rpc.", rpc.GoName, "(req.Context(), request)")
+               g.P("if err != nil {")
+               g.P("   ", httpPkg.Ident("Error"), "(w, \"request failed: \"+err.Error(), ", httpPkg.Ident("StatusInternalServerError"), ")")
+               g.P("   return")
+               g.P("}")
+               g.P("rep, err := ", jsonPkg.Ident("MarshalIndent"), "(reply, \"\", \"  \")")
+               g.P("if err != nil {")
+               g.P("   ", httpPkg.Ident("Error"), "(w, \"marshal failed: \"+err.Error(), ", httpPkg.Ident("StatusInternalServerError"), ")")
+               g.P("   return")
+               g.P("}")
+               g.P("w.Write(rep)")
+               g.P("})")
+       }
+
+       g.P("return ", httpPkg.Ident("HandlerFunc"), "(mux.ServeHTTP)")
+       g.P("}")
+       g.P()
+}