coreapi: Global options for api constructor

License: MIT
Signed-off-by: Łukasz Magiera <magik6k@gmail.com>

options/global.go

+package options
+
+type ApiSettings struct {
+	Offline bool
+}
+
+type ApiOption func(*ApiSettings) error
+
+func ApiOptions(opts ...ApiOption) (*ApiSettings, error) {
+	options := &ApiSettings{
+		Offline: false,
+	}
+
+	for _, opt := range opts {
+		err := opt(options)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return options, nil
+}
+
+type apiOpts struct{}
+
+var Api dagOpts
+
+func (dagOpts) Offline(offline bool) ApiOption {
+	return func(settings *ApiSettings) error {
+		settings.Offline = offline
+		return nil
+	}
+}