wip: experimental branch with finite-state machine processor (doesn't work yet)

internal/handler/fsmwizard/base.go

@@ -82,3 +82,7 @@ func (s State) LogError(err error) {
 func (s State) Move(mc fsm.MachineControls[Wizard], stateID fsm.StateID, pl *Wizard) {
 	s.LogError(mc.Move(stateID, pl))
 }
+
+func (s State) MoveForHandle(mc fsm.MachineControls[Wizard], stateID fsm.StateID, pl *Wizard) {
+	s.LogError(mc.MoveForHandle(stateID, pl))
+}

internal/handler/fsmwizard/waiting_for_member_webhook_state.go

@@ -24,12 +24,12 @@ func (s *WaitingForMemberWebhookState) Enter(pl *Wizard, mc fsm.MachineControls[
 	}
 	if !cm.OldChatMember.MemberIsMember() && cm.OldChatMember.MemberUser().ID == s.App.TGProfile().ID &&
 		cm.NewChatMember.MemberIsMember() && cm.NewChatMember.MemberUser().ID == s.App.TGProfile().ID {
-		s.Move(mc, AddChatMemberStateID, pl)
+		s.MoveForHandle(mc, AddChatMemberStateID, pl)
 		return nil
 	}
 	if cm.OldChatMember.MemberIsMember() && cm.OldChatMember.MemberUser().ID == s.App.TGProfile().ID &&
 		!cm.NewChatMember.MemberIsMember() && cm.NewChatMember.MemberUser().ID == s.App.TGProfile().ID {
-		s.Move(mc, RemoveChatMemberStateID, pl)
+		s.MoveForHandle(mc, RemoveChatMemberStateID, pl)
 		return nil
 	}
 

pkg/fsm/machine.go

@@ -43,6 +43,7 @@ type Machine[T any] struct {
 	initialState StateID
 	states       *types.Map[StateID, IState[T]]
 	errHandler   ErrorState[T]
+	handleNow    bool
 }
 
 // New machine.
@@ -89,6 +90,11 @@ func (m *Machine[T]) Move(id StateID, payload *T) error {
 	return nil
 }
 
+func (m *Machine[T]) MoveForHandle(id StateID, payload *T) error {
+	m.handleNow = true
+	return m.Move(id, payload)
+}
+
 // Handle the input.
 func (m *Machine[T]) Handle(provider MachineStateProvider[T]) error {
 	if provider != nil {
@@ -101,8 +107,14 @@ func (m *Machine[T]) Handle(provider MachineStateProvider[T]) error {
 	if st == nil || err != nil {
 		return err
 	}
-	st.Handle(m.payload, m)
-	return nil
+	for {
+		st.Handle(m.payload, m)
+		if m.handleNow { // MoveForHandle was called, trying to handle again.
+			m.handleNow = false
+			continue
+		}
+		return nil
+	}
 }
 
 // State of the Machine.

pkg/fsm/state.go

@@ -10,6 +10,8 @@ const NilStateID = StateID("")
 // It may fail with an error which should be handled by the IState implementation.
 type MachineControls[T any] interface {
 	Move(StateID, *T) error
+	// MoveForHandle is the same as Move but it also triggers Handle immediately for the next state.
+	MoveForHandle(StateID, *T) error
 	Reset()
 }