initial commit

magic/json.go

@@ -0,0 +1,63 @@
+package magic
+
+import (
+	"encoding/json"
+	"io"
+	"net/http"
+)
+
+type JsonDecodeError struct {
+	inner error
+}
+
+func (err JsonDecodeError) Error() string {
+	return "failed to decode json: " + err.inner.Error()
+}
+
+func (err JsonDecodeError) WriteResponse(rw http.ResponseWriter) {
+	rw.WriteHeader(http.StatusBadRequest)
+}
+
+type Json[T any] struct {
+	Data T
+}
+
+func NewJson[T any](data T) Json[T] {
+	return Json[T]{
+		Data: data,
+	}
+}
+
+func (data *Json[T]) FromRequest(request *http.Request) error {
+	bodyReader := request.Body
+	defer bodyReader.Close()
+
+	request.Body = http.NoBody
+
+	if err := json.NewDecoder(bodyReader).Decode(&data.Data); err != nil {
+		return JsonDecodeError{inner: err}
+	}
+
+	return nil
+}
+
+type counter struct {
+	counter int64
+}
+
+func (c *counter) Write(b []byte) (int, error) {
+	n := len(b)
+	c.counter += int64(n)
+
+	return n, nil
+}
+
+func (container Json[T]) Write(w io.Writer) (int64, error) {
+	counter := &counter{}
+	err := json.NewEncoder(io.MultiWriter(counter, w)).Encode(container.Data)
+	return counter.counter, err
+}
+
+func (json Json[T]) WriteResponse(w http.ResponseWriter) {
+	json.Write(w)
+}