feat: backend service

backend/internal/server/httperr/httperr.go

@@ -0,0 +1,52 @@
+// Package httperr defines the standard JSON error envelope shared by every
+// backend HTTP middleware and handler.
+//
+// The envelope shape is fixed by `backend/openapi.yaml` (`ErrorResponse`) and
+// must remain identical across the public, user, admin, and internal route
+// groups so that callers can parse failures uniformly.
+package httperr
+
+import (
+	"github.com/gin-gonic/gin"
+)
+
+// Error code values that appear in the JSON envelope `error.code` field. They
+// are documented in `backend/openapi.yaml` and form the closed set of stable
+// machine-readable failure markers.
+const (
+	CodeNotImplemented     = "not_implemented"
+	CodeInvalidRequest     = "invalid_request"
+	CodeUnauthorized       = "unauthorized"
+	CodeForbidden          = "forbidden"
+	CodeNotFound           = "not_found"
+	CodeConflict           = "conflict"
+	CodeMethodNotAllowed   = "method_not_allowed"
+	CodeInternalError      = "internal_error"
+	CodeServiceUnavailable = "service_unavailable"
+)
+
+// Body stores the inner `error` object of the standard envelope.
+type Body struct {
+	// Code is the stable machine-readable failure marker.
+	Code string `json:"code"`
+
+	// Message is the human-readable client-safe failure description.
+	Message string `json:"message"`
+}
+
+// Response wraps Body in the documented `{"error":{...}}` shape.
+type Response struct {
+	Error Body `json:"error"`
+}
+
+// Abort writes the standard JSON error envelope with statusCode and aborts the
+// gin handler chain. It is the single helper every middleware and handler must
+// use to emit a failure response.
+func Abort(c *gin.Context, statusCode int, code, message string) {
+	c.AbortWithStatusJSON(statusCode, Response{
+		Error: Body{
+			Code:    code,
+			Message: message,
+		},
+	})
+}