action_client.go

package goroslib

import (
	"context"
	"fmt"
	"reflect"
	"strconv"
	"sync"
	"time"

	"github.com/bluenviron/goroslib/v2/pkg/actionproc"
	"github.com/bluenviron/goroslib/v2/pkg/msgs/actionlib_msgs"
	"github.com/bluenviron/goroslib/v2/pkg/msgs/std_msgs"
)

// ActionClientCommState is the communication state of the goal of an action client.
type ActionClientCommState int

// standard goal communication states.
const (
	ActionClientCommStateWaitingForGoalAck ActionClientCommState = iota
	ActionClientCommStatePending
	ActionClientCommStateActive
	ActionClientCommStateWaitingForResult
	ActionClientCommStateWaitingForCancelAck
	ActionClientCommStateRecalling
	ActionClientCommStatePreempting
	ActionClientCommStateDone
	ActionClientCommStateLost
)

var actionClientLabels = map[ActionClientCommState]string{
	ActionClientCommStateWaitingForGoalAck:   "waitingForGoalAck",
	ActionClientCommStatePending:             "pending",
	ActionClientCommStateActive:              "active",
	ActionClientCommStateWaitingForResult:    "waitingForResult",
	ActionClientCommStateWaitingForCancelAck: "waitingForCancelAck",
	ActionClientCommStateRecalling:           "recalling",
	ActionClientCommStatePreempting:          "preempting",
	ActionClientCommStateDone:                "done",
	ActionClientCommStateLost:                "lost",
}

// String implements fmt.Stringer.
func (s ActionClientCommState) String() string {
	if l, ok := actionClientLabels[s]; ok {
		return l
	}
	return "unknown"
}

// ActionClientTerminalState is the terminal state of the goal of an action client.
type ActionClientTerminalState int

// standard goal terminal states.
const (
	ActionClientTerminalStateRecalled ActionClientTerminalState = ActionClientTerminalState(
		actionlib_msgs.GoalStatus_RECALLED)
	ActionClientTerminalStateRejected ActionClientTerminalState = ActionClientTerminalState(
		actionlib_msgs.GoalStatus_REJECTED)
	ActionClientTerminalStatePreempted ActionClientTerminalState = ActionClientTerminalState(
		actionlib_msgs.GoalStatus_PREEMPTED)
	ActionClientTerminalStateAborted ActionClientTerminalState = ActionClientTerminalState(
		actionlib_msgs.GoalStatus_ABORTED)
	ActionClientTerminalStateSucceeded ActionClientTerminalState = ActionClientTerminalState(
		actionlib_msgs.GoalStatus_SUCCEEDED)
	ActionClientTerminalStateLost ActionClientTerminalState = ActionClientTerminalState(
		actionlib_msgs.GoalStatus_LOST)
)

var actionClientTerminalStateLabels = map[ActionClientTerminalState]string{
	ActionClientTerminalStateRecalled:  "recalled",
	ActionClientTerminalStateRejected:  "rejected",
	ActionClientTerminalStatePreempted: "preempted",
	ActionClientTerminalStateAborted:   "aborted",
	ActionClientTerminalStateSucceeded: "succeeded",
	ActionClientTerminalStateLost:      "lost",
}

// String implements fmt.Stringer.
func (s ActionClientTerminalState) String() string {
	if l, ok := actionClientTerminalStateLabels[s]; ok {
		return l
	}
	return "unknown"
}

// ActionClientGoalConf is the configuration of SendGoal().
type ActionClientGoalConf struct {
	// the goal to send.
	Goal interface{}

	// (optional) function in the form func(*ActionClientGoalHandler, *ActionResult)
	// that will be called when a status transition happens.
	OnTransition interface{}

	// (optional) function in the form func(*ActionFeedback) that will be called
	// when a feedback is received.
	OnFeedback interface{}
}

// ActionClientGoalHandler is a goal handler of an ActionClient.
type ActionClientGoalHandler struct {
	ac            *ActionClient
	conf          ActionClientGoalConf
	id            string
	commState     ActionClientCommState
	terminalState ActionClientTerminalState
	result        interface{}
}

// CommState returns the communication state of the goal handler.
func (gh *ActionClientGoalHandler) CommState() ActionClientCommState {
	return gh.commState
}

// TerminalState returns the terminal state of the goal handler.
func (gh *ActionClientGoalHandler) TerminalState() (ActionClientTerminalState, error) {
	if gh.commState != ActionClientCommStateDone {
		return 0, fmt.Errorf("unable to get terminal state when communication state is not Done")
	}

	return gh.terminalState, nil
}

// Cancel cancels the goal.
func (gh *ActionClientGoalHandler) Cancel() {
	gh.ac.mutex.Lock()
	defer gh.ac.mutex.Unlock()

	switch gh.commState {
	case ActionClientCommStateWaitingForCancelAck:
	case ActionClientCommStateDone:
	default:
		gh.ac.cancelPub.Write(&actionlib_msgs.GoalID{
			Id: gh.id,
		})
		gh.transitionTo(ActionClientCommStateWaitingForCancelAck)
	}
}

func findStatusByID(statusList []actionlib_msgs.GoalStatus, id string) (uint8, bool) {
	for _, sta := range statusList {
		if sta.GoalId.Id == id {
			return sta.Status, true
		}
	}
	return 0, false
}

func (gh *ActionClientGoalHandler) onStatus(status uint8) {
	switch gh.commState {
	case ActionClientCommStateWaitingForGoalAck:
		switch status {
		case actionlib_msgs.GoalStatus_PENDING:
			gh.transitionTo(ActionClientCommStatePending)
		case actionlib_msgs.GoalStatus_ACTIVE:
			gh.transitionTo(ActionClientCommStateActive)
		case actionlib_msgs.GoalStatus_REJECTED:
			gh.transitionTo(ActionClientCommStatePending)
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_RECALLING:
			gh.transitionTo(ActionClientCommStatePending)
			gh.transitionTo(ActionClientCommStateRecalling)
		case actionlib_msgs.GoalStatus_RECALLED:
			gh.transitionTo(ActionClientCommStatePending)
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_PREEMPTED:
			gh.transitionTo(ActionClientCommStateActive)
			gh.transitionTo(ActionClientCommStatePreempting)
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_SUCCEEDED:
			gh.transitionTo(ActionClientCommStateActive)
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_ABORTED:
			gh.transitionTo(ActionClientCommStateActive)
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_PREEMPTING:
			gh.transitionTo(ActionClientCommStateActive)
			gh.transitionTo(ActionClientCommStatePreempting)
		}

	case ActionClientCommStatePending:
		switch status {
		case actionlib_msgs.GoalStatus_PENDING:
		case actionlib_msgs.GoalStatus_ACTIVE:
			gh.transitionTo(ActionClientCommStateActive)
		case actionlib_msgs.GoalStatus_REJECTED:
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_RECALLING:
			gh.transitionTo(ActionClientCommStateRecalling)
		case actionlib_msgs.GoalStatus_RECALLED:
			gh.transitionTo(ActionClientCommStateRecalling)
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_PREEMPTED:
			gh.transitionTo(ActionClientCommStateActive)
			gh.transitionTo(ActionClientCommStatePreempting)
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_SUCCEEDED:
			gh.transitionTo(ActionClientCommStateActive)
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_ABORTED:
			gh.transitionTo(ActionClientCommStateActive)
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_PREEMPTING:
			gh.transitionTo(ActionClientCommStateActive)
			gh.transitionTo(ActionClientCommStatePreempting)
		}

	case ActionClientCommStateActive:
		switch status {
		case actionlib_msgs.GoalStatus_PENDING:
		case actionlib_msgs.GoalStatus_ACTIVE:
		case actionlib_msgs.GoalStatus_REJECTED:
		case actionlib_msgs.GoalStatus_RECALLING:
		case actionlib_msgs.GoalStatus_RECALLED:
		case actionlib_msgs.GoalStatus_PREEMPTED:
			gh.transitionTo(ActionClientCommStatePreempting)
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_SUCCEEDED:
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_ABORTED:
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_PREEMPTING:
			gh.transitionTo(ActionClientCommStatePreempting)
		}

	case ActionClientCommStateWaitingForResult:
		switch status {
		case actionlib_msgs.GoalStatus_PENDING:
		case actionlib_msgs.GoalStatus_ACTIVE:
		case actionlib_msgs.GoalStatus_REJECTED:
		case actionlib_msgs.GoalStatus_RECALLING:
		case actionlib_msgs.GoalStatus_RECALLED:
		case actionlib_msgs.GoalStatus_PREEMPTED:
		case actionlib_msgs.GoalStatus_SUCCEEDED:
		case actionlib_msgs.GoalStatus_ABORTED:
		case actionlib_msgs.GoalStatus_PREEMPTING:
		}

	case ActionClientCommStateWaitingForCancelAck:
		switch status {
		case actionlib_msgs.GoalStatus_PENDING:
		case actionlib_msgs.GoalStatus_ACTIVE:
		case actionlib_msgs.GoalStatus_REJECTED:
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_RECALLING:
			gh.transitionTo(ActionClientCommStateRecalling)
		case actionlib_msgs.GoalStatus_RECALLED:
			gh.transitionTo(ActionClientCommStateRecalling)
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_PREEMPTED:
			gh.transitionTo(ActionClientCommStatePreempting)
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_SUCCEEDED:
			gh.transitionTo(ActionClientCommStatePreempting)
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_ABORTED:
			gh.transitionTo(ActionClientCommStatePreempting)
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_PREEMPTING:
			gh.transitionTo(ActionClientCommStatePreempting)
		}

	case ActionClientCommStateRecalling:
		switch status {
		case actionlib_msgs.GoalStatus_PENDING:
		case actionlib_msgs.GoalStatus_ACTIVE:
		case actionlib_msgs.GoalStatus_REJECTED:
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_RECALLING:
		case actionlib_msgs.GoalStatus_RECALLED:
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_PREEMPTED:
			gh.transitionTo(ActionClientCommStatePreempting)
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_SUCCEEDED:
			gh.transitionTo(ActionClientCommStatePreempting)
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_ABORTED:
			gh.transitionTo(ActionClientCommStatePreempting)
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_PREEMPTING:
			gh.transitionTo(ActionClientCommStatePreempting)
		}

	case ActionClientCommStatePreempting:
		switch status {
		case actionlib_msgs.GoalStatus_PENDING:
		case actionlib_msgs.GoalStatus_ACTIVE:
		case actionlib_msgs.GoalStatus_REJECTED:
		case actionlib_msgs.GoalStatus_RECALLING:
		case actionlib_msgs.GoalStatus_RECALLED:
		case actionlib_msgs.GoalStatus_PREEMPTED:
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_SUCCEEDED:
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_ABORTED:
			gh.transitionTo(ActionClientCommStateWaitingForResult)
		case actionlib_msgs.GoalStatus_PREEMPTING:
		}
	}
}

func (gh *ActionClientGoalHandler) onFeedback(fbAction reflect.Value) {
	if gh.conf.OnFeedback != nil {
		reflect.ValueOf(gh.conf.OnFeedback).Call([]reflect.Value{
			fbAction.Elem().FieldByName("Feedback").Addr(),
		})
	}
}

func (gh *ActionClientGoalHandler) onResult(resAction reflect.Value) bool {
	switch gh.commState {
	case ActionClientCommStateWaitingForGoalAck,
		ActionClientCommStateWaitingForCancelAck,
		ActionClientCommStatePending,
		ActionClientCommStateActive,
		ActionClientCommStateWaitingForResult,
		ActionClientCommStateRecalling,
		ActionClientCommStatePreempting:

		gh.result = resAction.Elem().FieldByName("Result").Addr().Interface()
		gh.terminalState = ActionClientTerminalState(
			resAction.Elem().FieldByName("Status").FieldByName("Status").Interface().(uint8))
		gh.transitionTo(ActionClientCommStateDone)
		return false
	}
	return true
}

func (gh *ActionClientGoalHandler) transitionTo(newCommState ActionClientCommState) {
	gh.commState = newCommState

	if gh.conf.OnTransition != nil {
		dres := gh.result
		if dres == nil {
			dres = reflect.New(gh.ac.resType).Interface()
		}

		reflect.ValueOf(gh.conf.OnTransition).Call([]reflect.Value{
			reflect.ValueOf(gh),
			reflect.ValueOf(dres),
		})
	}
}

// ActionClientConf is the configuration of an ActionClient.
type ActionClientConf struct {
	// parent node.
	Node *Node

	// name of the action.
	Name string

	// an instance of the action type.
	Action interface{}
}

// ActionClient is a ROS action client, an entity that can call actions.
type ActionClient struct {
	conf ActionClientConf

	ctx            context.Context
	ctxCancel      func()
	goalType       reflect.Type
	resType        reflect.Type
	fbType         reflect.Type
	goalActionType reflect.Type
	resActionType  reflect.Type
	fbActionType   reflect.Type
	statusSub      *Subscriber
	feedbackSub    *Subscriber
	resultSub      *Subscriber
	goalPub        *Publisher
	cancelPub      *Publisher
	goalCount      int
	goals          map[string]*ActionClientGoalHandler
	mutex          sync.Mutex

	// out
	statusSubOk   chan struct{}
	feedbackSubOk chan struct{}
	resultSubOk   chan struct{}
	goalPubOk     chan struct{}
	cancelPubOk   chan struct{}
}

// NewActionClient allocates an ActionClient. See ActionClientConf for the options.
func NewActionClient(conf ActionClientConf) (*ActionClient, error) {
	if conf.Node == nil {
		return nil, fmt.Errorf("Node is empty")
	}

	if conf.Name == "" {
		return nil, fmt.Errorf("Name is empty")
	}

	if conf.Action == nil {
		return nil, fmt.Errorf("Action is empty")
	}

	if reflect.TypeOf(conf.Action).Kind() != reflect.Ptr {
		return nil, fmt.Errorf("Action is not a pointer")
	}

	actionElem := reflect.ValueOf(conf.Action).Elem().Interface()

	goal, res, fb, err := actionproc.GoalResultFeedback(actionElem)
	if err != nil {
		return nil, err
	}

	// Messages can't fail if GoalResultFeedback didn't fail
	goalAction, resAction, fbAction, _ := actionproc.Messages(actionElem)

	conf.Name = conf.Node.applyCliRemapping(conf.Name)

	ctx, ctxCancel := context.WithCancel(context.Background())

	ac := &ActionClient{
		conf:           conf,
		ctx:            ctx,
		ctxCancel:      ctxCancel,
		goalType:       reflect.TypeOf(goal),
		resType:        reflect.TypeOf(res),
		fbType:         reflect.TypeOf(fb),
		goalActionType: reflect.TypeOf(goalAction),
		resActionType:  reflect.TypeOf(resAction),
		fbActionType:   reflect.TypeOf(fbAction),
		goals:          make(map[string]*ActionClientGoalHandler),
		statusSubOk:    make(chan struct{}),
		feedbackSubOk:  make(chan struct{}),
		resultSubOk:    make(chan struct{}),
		goalPubOk:      make(chan struct{}),
		cancelPubOk:    make(chan struct{}),
	}

	ac.conf.Node.Log(LogLevelDebug, "action client '%s' created",
		ac.conf.Node.absoluteTopicName(ac.conf.Name))

	ac.statusSub, err = NewSubscriber(SubscriberConf{
		Node:     conf.Node,
		Topic:    conf.Name + "/status",
		Callback: ac.onStatus,
		onPublisher: func() {
			select {
			case <-ac.statusSubOk:
				return
			default:
			}
			close(ac.statusSubOk)
		},
	})
	if err != nil {
		return nil, err
	}

	ac.feedbackSub, err = NewSubscriber(SubscriberConf{
		Node:  conf.Node,
		Topic: conf.Name + "/feedback",
		Callback: reflect.MakeFunc(
			reflect.FuncOf([]reflect.Type{reflect.PointerTo(ac.fbActionType)}, []reflect.Type{}, false),
			ac.onFeedback,
		).Interface(),
		onPublisher: func() {
			select {
			case <-ac.feedbackSubOk:
				return
			default:
			}
			close(ac.feedbackSubOk)
		},
	})
	if err != nil {
		ac.statusSub.Close()
		return nil, err
	}

	ac.resultSub, err = NewSubscriber(SubscriberConf{
		Node:  conf.Node,
		Topic: conf.Name + "/result",
		Callback: reflect.MakeFunc(
			reflect.FuncOf([]reflect.Type{reflect.PointerTo(ac.resActionType)}, []reflect.Type{}, false),
			ac.onResult,
		).Interface(),
		onPublisher: func() {
			select {
			case <-ac.resultSubOk:
				return
			default:
			}
			close(ac.resultSubOk)
		},
	})
	if err != nil {
		ac.feedbackSub.Close()
		ac.statusSub.Close()
		return nil, err
	}

	ac.goalPub, err = NewPublisher(PublisherConf{
		Node:  conf.Node,
		Topic: conf.Name + "/goal",
		Msg:   reflect.New(ac.goalActionType).Interface(),
		onSubscriber: func() {
			select {
			case <-ac.goalPubOk:
				return
			default:
			}
			close(ac.goalPubOk)
		},
	})
	if err != nil {
		ac.resultSub.Close()
		ac.feedbackSub.Close()
		ac.statusSub.Close()
		return nil, err
	}

	ac.cancelPub, err = NewPublisher(PublisherConf{
		Node:  conf.Node,
		Topic: conf.Name + "/cancel",
		Msg:   &actionlib_msgs.GoalID{},
		onSubscriber: func() {
			select {
			case <-ac.cancelPubOk:
				return
			default:
			}
			close(ac.cancelPubOk)
		},
	})
	if err != nil {
		ac.goalPub.Close()
		ac.resultSub.Close()
		ac.feedbackSub.Close()
		ac.statusSub.Close()
		return nil, err
	}

	return ac, nil
}

// Close closes an ActionClient and shuts down all its operations.
func (ac *ActionClient) Close() {
	ac.ctxCancel()
	ac.cancelPub.Close()
	ac.goalPub.Close()
	ac.resultSub.Close()
	ac.feedbackSub.Close()
	ac.statusSub.Close()

	ac.conf.Node.Log(LogLevelDebug, "action client '%s' destroyed",
		ac.conf.Node.absoluteTopicName(ac.conf.Name))
}

// WaitForServer waits for the action server to start.
func (ac *ActionClient) WaitForServer() {
	select {
	case <-ac.statusSubOk:
	case <-ac.ctx.Done():
	}

	select {
	case <-ac.feedbackSubOk:
	case <-ac.ctx.Done():
	}

	select {
	case <-ac.resultSubOk:
	case <-ac.ctx.Done():
	}

	select {
	case <-ac.goalPubOk:
	case <-ac.ctx.Done():
	}

	select {
	case <-ac.cancelPubOk:
	case <-ac.ctx.Done():
	}
}

// SendGoal sends a goal.
func (ac *ActionClient) SendGoal(conf ActionClientGoalConf) (*ActionClientGoalHandler, error) {
	if conf.Goal == nil {
		return nil, fmt.Errorf("Goal is empty")
	}
	if reflect.TypeOf(conf.Goal) != reflect.PointerTo(ac.goalType) {
		return nil, fmt.Errorf("Goal must be %s, while is %v",
			reflect.PointerTo(ac.goalType), reflect.TypeOf(conf.Goal))
	}

	if conf.OnTransition != nil {
		cbt := reflect.TypeOf(conf.OnTransition)
		if cbt.Kind() != reflect.Func {
			return nil, fmt.Errorf("OnTransition is not a function")
		}

		if cbt.NumIn() != 2 {
			return nil, fmt.Errorf("OnTransition must accept 2 arguments")
		}
		if cbt.In(0) != reflect.TypeOf(&ActionClientGoalHandler{}) {
			return nil, fmt.Errorf("OnTransition 1st argument must be %s, while is %v",
				reflect.TypeOf(&ActionClientGoalHandler{}), cbt.In(0))
		}

		if cbt.NumOut() != 0 {
			return nil, fmt.Errorf("OnTransition must not return any value")
		}
		if cbt.In(1) != reflect.PointerTo(ac.resType) {
			return nil, fmt.Errorf("OnTransition 2nd argument must be %s, while is %v",
				reflect.PointerTo(ac.resType), cbt.In(1))
		}
	}

	if conf.OnFeedback != nil {
		cbt := reflect.TypeOf(conf.OnFeedback)
		if cbt.Kind() != reflect.Func {
			return nil, fmt.Errorf("OnFeedback is not a function")
		}
		if cbt.NumIn() != 1 {
			return nil, fmt.Errorf("OnFeedback must accept a single argument")
		}
		if cbt.NumOut() != 0 {
			return nil, fmt.Errorf("OnFeedback must not return any value")
		}
		if cbt.In(0) != reflect.PointerTo(ac.fbType) {
			return nil, fmt.Errorf("OnFeedback 1st argument must must be %s, while is %v",
				reflect.PointerTo(ac.fbType), cbt.In(1))
		}
	}

	goalAction := reflect.New(ac.goalActionType)

	now := time.Now()

	header := std_msgs.Header{
		Stamp: now,
	}
	goalAction.Elem().FieldByName("Header").Set(reflect.ValueOf(header))

	goalID := actionlib_msgs.GoalID{
		Stamp: now,
		Id: func() string {
			// https://github.com/ros/actionlib/blob/c3b2bd84f07ff54c36033c92861d3b63b7420590
			// /actionlib/src/actionlib/goal_id_generator.py#L62
			ss := ac.conf.Node.absoluteName() + "-"
			ac.goalCount++
			ss += strconv.FormatInt(int64(ac.goalCount), 10) + "-"
			nowSecs := float64(now.UnixNano()) / 1000000000
			ss += strconv.FormatFloat(nowSecs, 'f', -1, 64)
			return ss
		}(),
	}
	goalAction.Elem().FieldByName("GoalId").Set(reflect.ValueOf(goalID))

	goalAction.Elem().FieldByName("Goal").Set(reflect.ValueOf(conf.Goal).Elem())

	gh := &ActionClientGoalHandler{
		ac:   ac,
		conf: conf,
		id:   goalID.Id,
	}

	func() {
		ac.mutex.Lock()
		defer ac.mutex.Unlock()
		ac.goals[goalID.Id] = gh
	}()

	ac.goalPub.Write(goalAction.Interface())

	return gh, nil
}

// CancelAllGoals cancels all goals running on the server.
func (ac *ActionClient) CancelAllGoals() {
	ac.cancelPub.Write(&actionlib_msgs.GoalID{
		Id: "",
	})
}

func (ac *ActionClient) onStatus(msg *actionlib_msgs.GoalStatusArray) {
	ac.mutex.Lock()
	defer ac.mutex.Unlock()

	// ref
	// https://github.com/ros/actionlib/blob/noetic-devel/actionlib/src/actionlib/action_client.py#L332

	for id, gh := range ac.goals {
		// delete goals in "done" state
		if gh.commState == ActionClientCommStateDone {
			delete(ac.goals, id)
			continue
		}

		status, ok := findStatusByID(msg.StatusList, id)

		// goal not found inside status list
		if !ok {
			switch gh.commState {
			// goal is still waiting to be created on the server
			case ActionClientCommStateWaitingForGoalAck,
				ActionClientCommStateWaitingForResult:
				continue

			// goal doesn't exist on the server, delete it
			default:
				gh.terminalState = ActionClientTerminalStateLost
				gh.transitionTo(ActionClientCommStateDone)
				delete(ac.goals, id)
				continue
			}
		}

		gh.onStatus(status)
	}
}

func (ac *ActionClient) onFeedback(in []reflect.Value) []reflect.Value {
	fbAction := in[0]

	goalStatus := fbAction.Elem().FieldByName("Status").
		Interface().(actionlib_msgs.GoalStatus)

	ac.mutex.Lock()
	defer ac.mutex.Unlock()

	gh, ok := ac.goals[goalStatus.GoalId.Id]
	if !ok {
		return nil
	}

	gh.onStatus(goalStatus.Status)

	gh.onFeedback(fbAction)

	return nil
}

func (ac *ActionClient) onResult(in []reflect.Value) []reflect.Value {
	resAction := in[0]

	goalStatus := resAction.Elem().FieldByName("Status").
		Interface().(actionlib_msgs.GoalStatus)

	ac.mutex.Lock()
	defer ac.mutex.Unlock()

	gh, ok := ac.goals[goalStatus.GoalId.Id]
	if !ok {
		return nil
	}

	gh.onStatus(goalStatus.Status)

	ok = gh.onResult(resAction)
	if !ok {
		delete(ac.goals, goalStatus.GoalId.Id)
	}

	return nil
}