init

pkg/util/rpc/rpc.go

@@ -0,0 +1,97 @@
+// Copyright (C) 2025 wangyusong
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+package rpc
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"net/http"
+)
+
+type Handler[Request any, Response any] func(ctx context.Context, req *Request) (*Response, error)
+
+var (
+	ErrBadRequest = func(err error) Error { return newError(http.StatusBadRequest, err) }
+	ErrNotFound   = func(err error) Error { return newError(http.StatusNotFound, err) }
+	ErrInternal   = func(err error) Error { return newError(http.StatusInternalServerError, err) }
+)
+
+type Error struct {
+	Code    int    `json:"code"`
+	Message string `json:"message"`
+}
+
+func (e Error) Error() string {
+	return e.Message
+}
+
+func newError(code int, err error) Error {
+	return Error{
+		Code:    code,
+		Message: err.Error(),
+	}
+}
+
+func API[Request any, Response any](handler Handler[Request, Response]) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		allowCORS(w)
+
+		if r.Method == "OPTIONS" {
+			return
+		}
+
+		var req Request
+		if r.Body != http.NoBody {
+			if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+				http.Error(w, err.Error(), http.StatusBadRequest)
+
+				return
+			}
+		}
+
+		resp, err := handler(r.Context(), &req)
+		if err != nil {
+			var rpcErr Error
+			if errors.As(err, &rpcErr) {
+				w.Header().Set("Content-Type", "application/json")
+				w.WriteHeader(rpcErr.Code)
+				_ = json.NewEncoder(w).Encode(rpcErr)
+
+				return
+			}
+
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+
+			return
+		}
+
+		w.Header().Set("Content-Type", "application/json")
+		if err := json.NewEncoder(w).Encode(resp); err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+
+			return
+		}
+	})
+}
+
+func allowCORS(w http.ResponseWriter) {
+	w.Header().Set("Access-Control-Allow-Origin", "*")
+	w.Header().Set("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE")
+	w.Header().Set("Access-Control-Allow-Headers",
+		"Accept, Content-Type, Content-Length, Accept-Encoding, X-CSRF-Token, Authorization",
+	)
+}