Small refactoring

4 files changed, 214 insertions, 0 deletions

diff --git a/rpc/errors.go b/rpc/errors.go
new file mode 100644
index 0000000..1af84ee
--- /dev/null
+++ b/rpc/errors.go
@@ -0,0 +1,42 @@
+package rpc
+
+import "fmt"
+
+const (
+	ErrCodeParseError     = -32700
+	ErrCodeInvalidRequest = -32600
+	ErrCodeMethodNotFound = -32601
+	ErrCodeInvalidParams  = -32602
+	ErrCodeInternalError  = -32603
+	ErrUser               = -32000
+)
+
+var errorMap = map[int]string{
+	-32700: "Parse error",      // Invalid JSON was received by the server. An error occurred on the server while parsing the JSON text.
+	-32600: "Invalid Request",  // The JSON sent is not a valid Request object.
+	-32601: "Method not found", // The method does not exist / is not available.
+	-32602: "Invalid params",   // Invalid method parameter(s).
+	-32603: "Internal error",   // Internal JSON-RPC error.
+	-32000: "Other error",
+}
+
+//-32000 to -32099 	RpcServer error 	Reserved for implementation-defined server-errors.
+
+type Error struct {
+	Code    int    `json:"code"`
+	Message string `json:"message"`
+}
+
+func (e Error) Error() string {
+	return fmt.Sprintf("jsonrpc2 error: code: %d message: %s", e.Code, e.Message)
+}
+
+func NewError(code int) Error {
+	if _, ok := errorMap[code]; ok {
+		return Error{
+			Code:    code,
+			Message: errorMap[code],
+		}
+	}
+	return Error{Code: code}
+}
diff --git a/rpc/logger.go b/rpc/logger.go
new file mode 100644
index 0000000..25fe2d6
--- /dev/null
+++ b/rpc/logger.go
@@ -0,0 +1,20 @@
+package rpc
+
+import "log"
+
+type Logger interface {
+	Logf(format string, args ...interface{})
+}
+
+type nopLogger struct{}
+
+func (n nopLogger) Logf(format string, args ...interface{}) {
+}
+
+type stdLogger struct{}
+
+func (n stdLogger) Logf(format string, args ...interface{}) {
+	log.Printf(format, args...)
+}
+
+var StdLogger = stdLogger{}
diff --git a/rpc/server.go b/rpc/server.go
new file mode 100644
index 0000000..12f07e8
--- /dev/null
+++ b/rpc/server.go
@@ -0,0 +1,127 @@
+package rpc
+
+import (
+	"context"
+	"encoding/json"
+	"io"
+	"sync"
+)
+
+const version = "2.0"
+
+type RpcServer struct {
+	Logger              Logger
+	IgnoreNotifications bool
+	handlers            map[string]Handler
+	mu                  sync.RWMutex
+}
+
+func New() *RpcServer {
+	return &RpcServer{
+		Logger:              nopLogger{},
+		IgnoreNotifications: true,
+		handlers:            map[string]Handler{},
+		mu:                  sync.RWMutex{},
+	}
+}
+
+func (r *RpcServer) Register(method string, handler Handler) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	r.handlers[method] = handler
+}
+
+func (r *RpcServer) SingleRequest(ctx context.Context, reader io.Reader, writer io.Writer) {
+	req := new(rpcRequest)
+	if err := json.NewDecoder(reader).Decode(req); err != nil {
+		r.Logger.Logf("Can't read body: %v", err)
+		WriteError(ErrCodeParseError, writer)
+		return
+	}
+	resp := r.callMethod(ctx, req)
+	if req.Id == nil && r.IgnoreNotifications {
+		// notification request
+		return
+	}
+	if err := json.NewEncoder(writer).Encode(resp); err != nil {
+		r.Logger.Logf("Can't write response: %v", err)
+		WriteError(ErrCodeInternalError, writer)
+		return
+	}
+}
+
+func (r *RpcServer) BatchRequest(ctx context.Context, reader io.Reader, writer io.Writer) {
+	var req []rpcRequest
+	if err := json.NewDecoder(reader).Decode(&req); err != nil {
+		r.Logger.Logf("Can't read body: %v", err)
+		WriteError(ErrCodeParseError, writer)
+		return
+	}
+	var responses []*rpcResponse
+	wg := sync.WaitGroup{}
+	wg.Add(len(req))
+	for _, j := range req {
+		go func(req rpcRequest) {
+			defer wg.Done()
+			resp := r.callMethod(ctx, &req)
+			if req.Id == nil && r.IgnoreNotifications {
+				// notification request
+				return
+			}
+			responses = append(responses, resp)
+		}(j)
+	}
+	wg.Wait()
+	if err := json.NewEncoder(writer).Encode(responses); err != nil {
+		r.Logger.Logf("Can't write response: %v", err)
+		WriteError(ErrCodeInternalError, writer)
+	}
+}
+
+func (r *RpcServer) callMethod(ctx context.Context, req *rpcRequest) *rpcResponse {
+	r.mu.RLock()
+	h, ok := r.handlers[req.Method]
+	r.mu.RUnlock()
+	if !ok {
+		return &rpcResponse{
+			Jsonrpc: version,
+			Error:   NewError(ErrCodeMethodNotFound),
+			Id:      req.Id,
+		}
+	}
+	resp, err := h(ctx, req.Params)
+	if err != nil {
+		r.Logger.Logf("User error %v", err)
+		return &rpcResponse{
+			Jsonrpc: version,
+			Error:   err,
+			Id:      req.Id,
+		}
+	}
+	return &rpcResponse{
+		Jsonrpc: version,
+		Result:  resp,
+		Id:      req.Id,
+	}
+}
+
+func WriteError(code int, w io.Writer) {
+	_ = json.NewEncoder(w).Encode(rpcResponse{
+		Jsonrpc: version,
+		Error:   NewError(code),
+	})
+}
+
+type rpcRequest struct {
+	Jsonrpc string          `json:"jsonrpc"`
+	Method  string          `json:"method"`
+	Params  json.RawMessage `json:"params"`
+	Id      any             `json:"id"`
+}
+
+type rpcResponse struct {
+	Jsonrpc string          `json:"jsonrpc"`
+	Result  json.RawMessage `json:"result,omitempty"`
+	Error   error           `json:"error,omitempty"`
+	Id      any             `json:"id,omitempty"`
+}
diff --git a/rpc/wrapper.go b/rpc/wrapper.go
new file mode 100644
index 0000000..0bc0a5c
--- /dev/null
+++ b/rpc/wrapper.go
@@ -0,0 +1,25 @@
+package rpc
+
+import (
+	"context"
+	"encoding/json"
+)
+
+func Wrap[RQ any, RS any](handler func(context.Context, *RQ) (RS, error)) Handler {
+	return func(ctx context.Context, in json.RawMessage) (json.RawMessage, error) {
+		req := new(RQ)
+		if err := json.Unmarshal(in, req); err != nil {
+			return nil, NewError(ErrCodeParseError)
+		}
+		resp, err := handler(ctx, req)
+		if err != nil {
+			return nil, Error{
+				Code:    ErrUser,
+				Message: err.Error(),
+			}
+		}
+		return json.Marshal(resp)
+	}
+}
+
+type Handler func(context.Context, json.RawMessage) (json.RawMessage, error)