Move internal packages to an internal folder

For reference: https://go.dev/doc/go1.4#internalpackages

internal/http/response/json/json.go

@@ -0,0 +1,120 @@
+// SPDX-FileCopyrightText: Copyright The Miniflux Authors. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package json // import "miniflux.app/v2/internal/http/response/json"
+
+import (
+	"encoding/json"
+	"errors"
+	"net/http"
+
+	"miniflux.app/v2/internal/http/response"
+	"miniflux.app/v2/internal/logger"
+)
+
+const contentTypeHeader = `application/json`
+
+// OK creates a new JSON response with a 200 status code.
+func OK(w http.ResponseWriter, r *http.Request, body interface{}) {
+	builder := response.New(w, r)
+	builder.WithHeader("Content-Type", contentTypeHeader)
+	builder.WithBody(toJSON(body))
+	builder.Write()
+}
+
+// Created sends a created response to the client.
+func Created(w http.ResponseWriter, r *http.Request, body interface{}) {
+	builder := response.New(w, r)
+	builder.WithStatus(http.StatusCreated)
+	builder.WithHeader("Content-Type", contentTypeHeader)
+	builder.WithBody(toJSON(body))
+	builder.Write()
+}
+
+// NoContent sends a no content response to the client.
+func NoContent(w http.ResponseWriter, r *http.Request) {
+	builder := response.New(w, r)
+	builder.WithStatus(http.StatusNoContent)
+	builder.WithHeader("Content-Type", contentTypeHeader)
+	builder.Write()
+}
+
+func Accepted(w http.ResponseWriter, r *http.Request) {
+	builder := response.New(w, r)
+	builder.WithStatus(http.StatusAccepted)
+	builder.WithHeader("Content-Type", contentTypeHeader)
+	builder.Write()
+}
+
+// ServerError sends an internal error to the client.
+func ServerError(w http.ResponseWriter, r *http.Request, err error) {
+	logger.Error("[HTTP:Internal Server Error] %s => %v", r.URL, err)
+
+	builder := response.New(w, r)
+	builder.WithStatus(http.StatusInternalServerError)
+	builder.WithHeader("Content-Type", contentTypeHeader)
+	builder.WithBody(toJSONError(err))
+	builder.Write()
+}
+
+// BadRequest sends a bad request error to the client.
+func BadRequest(w http.ResponseWriter, r *http.Request, err error) {
+	logger.Error("[HTTP:Bad Request] %s => %v", r.URL, err)
+
+	builder := response.New(w, r)
+	builder.WithStatus(http.StatusBadRequest)
+	builder.WithHeader("Content-Type", contentTypeHeader)
+	builder.WithBody(toJSONError(err))
+	builder.Write()
+}
+
+// Unauthorized sends a not authorized error to the client.
+func Unauthorized(w http.ResponseWriter, r *http.Request) {
+	logger.Error("[HTTP:Unauthorized] %s", r.URL)
+
+	builder := response.New(w, r)
+	builder.WithStatus(http.StatusUnauthorized)
+	builder.WithHeader("Content-Type", contentTypeHeader)
+	builder.WithBody(toJSONError(errors.New("access unauthorized")))
+	builder.Write()
+}
+
+// Forbidden sends a forbidden error to the client.
+func Forbidden(w http.ResponseWriter, r *http.Request) {
+	logger.Error("[HTTP:Forbidden] %s", r.URL)
+
+	builder := response.New(w, r)
+	builder.WithStatus(http.StatusForbidden)
+	builder.WithHeader("Content-Type", contentTypeHeader)
+	builder.WithBody(toJSONError(errors.New("access forbidden")))
+	builder.Write()
+}
+
+// NotFound sends a page not found error to the client.
+func NotFound(w http.ResponseWriter, r *http.Request) {
+	logger.Error("[HTTP:Not Found] %s", r.URL)
+
+	builder := response.New(w, r)
+	builder.WithStatus(http.StatusNotFound)
+	builder.WithHeader("Content-Type", contentTypeHeader)
+	builder.WithBody(toJSONError(errors.New("resource not found")))
+	builder.Write()
+}
+
+func toJSONError(err error) []byte {
+	type errorMsg struct {
+		ErrorMessage string `json:"error_message"`
+	}
+
+	return toJSON(errorMsg{ErrorMessage: err.Error()})
+}
+
+func toJSON(v interface{}) []byte {
+	b, err := json.Marshal(v)
+	if err != nil {
+		logger.Error("[HTTP:JSON] %v", err)
+		return []byte("")
+	}
+
+	return b
+}