fsm: improve and convert to interface

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

fsm/options.go

@@ -0,0 +1,52 @@
+package fsm
+
+// Options struct holding fsm options
+type Options struct {
+	// Initial state
+	Initial string
+	// Wrappers runs before state
+	Wrappers []StateWrapper
+	// DryRun mode
+	DryRun bool
+}
+
+// Option func signature
+type Option func(*Options)
+
+// StateOptions holds state options
+type StateOptions struct {
+	DryRun bool
+}
+
+// StateDryRun says that state executes in dry run mode
+func StateDryRun(b bool) StateOption {
+	return func(o *StateOptions) {
+		o.DryRun = b
+	}
+}
+
+// StateOption func signature
+type StateOption func(*StateOptions)
+
+// InitialState sets init state for state machine
+func InitialState(initial string) Option {
+	return func(o *Options) {
+		o.Initial = initial
+	}
+}
+
+// WrapState adds a state Wrapper to a list of options passed into the fsm
+func WrapState(w StateWrapper) Option {
+	return func(o *Options) {
+		o.Wrappers = append(o.Wrappers, w)
+	}
+}
+
+// NewOptions returns new Options struct filled by passed Option
+func NewOptions(opts ...Option) Options {
+	options := Options{}
+	for _, o := range opts {
+		o(&options)
+	}
+	return options
+}