allow to expose some method via http.HandlerFunc

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

handler.go

@@ -60,6 +60,279 @@ func (h *httpHandler) Options() server.HandlerOptions {
 	return h.opts
 }
 
+func (h *httpServer) HTTPHandlerFunc(handler interface{}) (http.HandlerFunc, error) {
+	if handler == nil {
+		return nil, fmt.Errorf("invalid handler specified: %v", handler)
+	}
+
+	rtype := reflect.TypeOf(handler)
+	if rtype.NumIn() != 3 {
+		return nil, fmt.Errorf("invalid handler, NumIn != 3: %v", rtype.NumIn())
+	}
+
+	argType := rtype.In(1)
+	replyType := rtype.In(2)
+
+	// First arg need not be a pointer.
+	if !isExportedOrBuiltinType(argType) {
+		return nil, fmt.Errorf("invalid handler, argument type not exported: %v", argType)
+	}
+
+	if replyType.Kind() != reflect.Ptr {
+		return nil, fmt.Errorf("invalid handler, reply type not a pointer: %v", replyType)
+	}
+
+	// Reply type must be exported.
+	if !isExportedOrBuiltinType(replyType) {
+		return nil, fmt.Errorf("invalid handler, reply type not exported: %v", replyType)
+	}
+
+	if rtype.NumOut() != 1 {
+		return nil, fmt.Errorf("invalid handler, has wrong number of outs: %v", rtype.NumOut())
+	}
+
+	// The return type of the method must be error.
+	if returnType := rtype.Out(0); returnType != typeOfError {
+		return nil, fmt.Errorf("invalid handler, returns %v not error", returnType.String())
+	}
+
+	return func(w http.ResponseWriter, r *http.Request) {
+		ct := DefaultContentType
+		if htype := r.Header.Get(metadata.HeaderContentType); htype != "" {
+			ct = htype
+		}
+
+		ctx := context.WithValue(r.Context(), rspCodeKey{}, &rspCodeVal{})
+		ctx = context.WithValue(ctx, rspHeaderKey{}, &rspHeaderVal{})
+		md, ok := metadata.FromIncomingContext(ctx)
+		if !ok {
+			md = metadata.New(len(r.Header) + 8)
+		}
+		for k, v := range r.Header {
+			md[k] = strings.Join(v, ", ")
+		}
+		md["RemoteAddr"] = r.RemoteAddr
+		md["Method"] = r.Method
+		md["URL"] = r.URL.String()
+		md["Proto"] = r.Proto
+		md["ContentLength"] = fmt.Sprintf("%d", r.ContentLength)
+		md["TransferEncoding"] = strings.Join(r.TransferEncoding, ",")
+		md["Host"] = r.Host
+		md["RequestURI"] = r.RequestURI
+		ctx = metadata.NewIncomingContext(ctx, md)
+
+		path := r.URL.Path
+
+		if r.Body != nil {
+			defer r.Body.Close()
+		}
+
+		matches := make(map[string]interface{})
+		var match bool
+		var hldr *patHandler
+		var handler *httpHandler
+
+		for _, shdlr := range h.handlers {
+			hdlr := shdlr.(*httpHandler)
+			fh, mp, err := hdlr.handlers.Search(r.Method, path)
+			if err == nil {
+				match = true
+				for k, v := range mp {
+					matches[k] = v
+				}
+				hldr = fh.(*patHandler)
+				handler = hdlr
+				break
+			} else if err == rhttp.ErrMethodNotAllowed && !h.registerRPC {
+				w.WriteHeader(http.StatusMethodNotAllowed)
+				_, _ = w.Write([]byte("not matching route found"))
+				return
+			}
+		}
+
+		if !match && h.registerRPC {
+			microMethod, mok := md.Get(metadata.HeaderEndpoint)
+			if mok {
+				serviceMethod := strings.Split(microMethod, ".")
+				if len(serviceMethod) == 2 {
+					if shdlr, ok := h.handlers[serviceMethod[0]]; ok {
+						hdlr := shdlr.(*httpHandler)
+						fh, mp, err := hdlr.handlers.Search(http.MethodPost, "/"+microMethod)
+						if err == nil {
+							match = true
+							for k, v := range mp {
+								matches[k] = v
+							}
+							hldr = fh.(*patHandler)
+							handler = hdlr
+						}
+					}
+				}
+			}
+		}
+
+		// get fields from url values
+		if len(r.URL.RawQuery) > 0 {
+			umd, cerr := rflutil.URLMap(r.URL.RawQuery)
+			if cerr != nil {
+				w.WriteHeader(http.StatusInternalServerError)
+				_, _ = w.Write([]byte(cerr.Error()))
+				return
+			}
+			for k, v := range umd {
+				matches[k] = v
+			}
+		}
+
+		cf, err := h.newCodec(ct)
+		if err != nil {
+			w.WriteHeader(http.StatusBadRequest)
+			_, _ = w.Write([]byte(err.Error()))
+			return
+		}
+
+		var argv, replyv reflect.Value
+
+		// Decode the argument value.
+		argIsValue := false // if true, need to indirect before calling.
+		if hldr.mtype.ArgType.Kind() == reflect.Ptr {
+			argv = reflect.New(hldr.mtype.ArgType.Elem())
+		} else {
+			argv = reflect.New(hldr.mtype.ArgType)
+			argIsValue = true
+		}
+
+		if argIsValue {
+			argv = argv.Elem()
+		}
+
+		// reply value
+		replyv = reflect.New(hldr.mtype.ReplyType.Elem())
+
+		function := hldr.mtype.method.Func
+		var returnValues []reflect.Value
+
+		if r.Body != nil {
+			var buf []byte
+			buf, err = io.ReadAll(r.Body)
+			if err != nil && err != io.EOF {
+				h.errorHandler(ctx, handler, w, r, err, http.StatusInternalServerError)
+				return
+			}
+
+			if err = cf.Unmarshal(buf, argv.Interface()); err != nil {
+				h.errorHandler(ctx, handler, w, r, err, http.StatusBadRequest)
+				return
+			}
+		}
+
+		matches = rflutil.FlattenMap(matches)
+		if err = rflutil.Merge(argv.Interface(), matches, rflutil.SliceAppend(true), rflutil.Tags([]string{"protobuf", "json"})); err != nil {
+			h.errorHandler(ctx, handler, w, r, err, http.StatusBadRequest)
+			return
+		}
+
+		hr := &rpcRequest{
+			codec:       cf,
+			service:     handler.sopts.Name,
+			contentType: ct,
+			method:      fmt.Sprintf("%s.%s", hldr.name, hldr.mtype.method.Name),
+			endpoint:    fmt.Sprintf("%s.%s", hldr.name, hldr.mtype.method.Name),
+			payload:     argv.Interface(),
+			header:      md,
+		}
+
+		// define the handler func
+		fn := func(fctx context.Context, req server.Request, rsp interface{}) (err error) {
+			returnValues = function.Call([]reflect.Value{hldr.rcvr, hldr.mtype.prepareContext(fctx), argv, reflect.ValueOf(rsp)})
+
+			// The return value for the method is an error.
+			if rerr := returnValues[0].Interface(); rerr != nil {
+				err = rerr.(error)
+			}
+
+			md, ok := metadata.FromOutgoingContext(ctx)
+			if !ok {
+				md = metadata.New(0)
+			}
+			if nmd, ok := metadata.FromOutgoingContext(fctx); ok {
+				for k, v := range nmd {
+					md.Set(k, v)
+				}
+			}
+			metadata.SetOutgoingContext(ctx, md)
+
+			return err
+		}
+
+		// wrap the handler func
+		for i := len(handler.sopts.HdlrWrappers); i > 0; i-- {
+			fn = handler.sopts.HdlrWrappers[i-1](fn)
+		}
+
+		if ct == "application/x-www-form-urlencoded" {
+			cf, err = h.newCodec(DefaultContentType)
+			if err != nil {
+				h.errorHandler(ctx, handler, w, r, err, http.StatusInternalServerError)
+				return
+			}
+			ct = DefaultContentType
+		}
+
+		scode := int(200)
+		appErr := fn(ctx, hr, replyv.Interface())
+
+		w.Header().Set(metadata.HeaderContentType, ct)
+		if md, ok := metadata.FromOutgoingContext(ctx); ok {
+			for k, v := range md {
+				w.Header().Set(k, v)
+			}
+		}
+		if md := getRspHeader(ctx); md != nil {
+			for k, v := range md {
+				for _, vv := range v {
+					w.Header().Add(k, vv)
+				}
+			}
+		}
+		if nct := w.Header().Get(metadata.HeaderContentType); nct != ct {
+			if cf, err = h.newCodec(nct); err != nil {
+				h.errorHandler(ctx, nil, w, r, err, http.StatusBadRequest)
+				return
+			}
+		}
+
+		var buf []byte
+		if appErr != nil {
+			switch verr := appErr.(type) {
+			case *errors.Error:
+				scode = int(verr.Code)
+				buf, err = cf.Marshal(verr)
+			case *Error:
+				buf, err = cf.Marshal(verr.err)
+			default:
+				buf, err = cf.Marshal(appErr)
+			}
+		} else {
+			buf, err = cf.Marshal(replyv.Interface())
+		}
+
+		if err != nil && handler.sopts.Logger.V(logger.ErrorLevel) {
+			handler.sopts.Logger.Errorf(handler.sopts.Context, "handler err: %v", err)
+			return
+		}
+
+		if nscode := GetRspCode(ctx); nscode != 0 {
+			scode = nscode
+		}
+		w.WriteHeader(scode)
+
+		if _, cerr := w.Write(buf); cerr != nil {
+			handler.sopts.Logger.Errorf(ctx, "write failed: %v", cerr)
+		}
+	}, nil
+}
+
 func (h *httpServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	// check for http.HandlerFunc handlers
 	if ph, _, err := h.pathHandlers.Search(r.Method, r.URL.Path); err == nil {
@@ -91,7 +364,9 @@ func (h *httpServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	md["RequestURI"] = r.RequestURI
 	ctx = metadata.NewIncomingContext(ctx, md)
 
-	defer r.Body.Close()
+	if r.Body != nil {
+		defer r.Body.Close()
+	}
 
 	path := r.URL.Path
 	if !strings.HasPrefix(path, "/") {
@@ -192,15 +467,18 @@ func (h *httpServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	function := hldr.mtype.method.Func
 	var returnValues []reflect.Value
 
-	buf, err := io.ReadAll(r.Body)
-	if err != nil && err != io.EOF {
-		h.errorHandler(ctx, handler, w, r, err, http.StatusInternalServerError)
-		return
-	}
+	if r.Body != nil {
+		var buf []byte
+		buf, err = io.ReadAll(r.Body)
+		if err != nil && err != io.EOF {
+			h.errorHandler(ctx, handler, w, r, err, http.StatusInternalServerError)
+			return
+		}
 
-	if err = cf.Unmarshal(buf, argv.Interface()); err != nil {
-		h.errorHandler(ctx, handler, w, r, err, http.StatusBadRequest)
-		return
+		if err = cf.Unmarshal(buf, argv.Interface()); err != nil {
+			h.errorHandler(ctx, handler, w, r, err, http.StatusBadRequest)
+			return
+		}
 	}
 
 	matches = rflutil.FlattenMap(matches)
@@ -279,6 +557,7 @@ func (h *httpServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
+	var buf []byte
 	if appErr != nil {
 		switch verr := appErr.(type) {
 		case *errors.Error: