refactor(backend): switch to DDD

backend/internal/domain/errors.go

@@ -0,0 +1,46 @@
+package domain
+
+type ErrorCode string
+
+const (
+	// File errors
+	ErrFileNotFound     ErrorCode = "FILE_NOT_FOUND"
+	ErrMIMENotSupported ErrorCode = "MIME_NOT_SUPPORTEDF"
+
+	// Tag errors
+	ErrTagNotFound ErrorCode = "TAG_NOT_FOUND"
+
+	// General errors
+	ErrValidation ErrorCode = "VALIDATION_ERROR"
+	ErrInternal   ErrorCode = "INTERNAL_SERVER_ERROR"
+)
+
+type DomainError struct {
+	Err     error     `json:"-"`
+	Code    ErrorCode `json:"code"`
+	Message string    `json:"message"`
+	Details []any     `json:"-"`
+}
+
+func (e *DomainError) Error() string {
+	if e.Err != nil {
+		return e.Message + ": " + e.Err.Error()
+	}
+	return e.Message
+}
+
+func NewDomainError(err error, code ErrorCode, details ...any) *DomainError {
+	return &DomainError{
+		Err:     err,
+		Code:    code,
+		Details: details,
+	}
+}
+
+func NewUnexpectedError(err error) *DomainError {
+	return &DomainError{
+		Err:     err,
+		Code:    ErrInternal,
+		Message: "An unexpected error occured",
+	}
+}