events.go

package spine

import (
	"sync"

	"github.com/enbility/eebus-go/spine/model"
)

var Events events

type ElementChangeType uint16

const (
	ElementChangeAdd ElementChangeType = iota
	ElementChangeUpdate
	ElementChangeRemove
)

type EventType uint16

const (
	EventTypeDeviceChange       EventType = iota // Sent after successful response of NodeManagementDetailedDiscovery
	EventTypeEntityChange                        // Sent after successful response of NodeManagementDetailedDiscovery
	EventTypeSubscriptionChange                  // Sent after successful subscription request from remote
	EventTypeBindingChange                       // Sent after successful binding request from remote
	EventTypeDataChange                          // Sent after remote provided new data items for a function
)

type EventPayload struct {
	Ski           string            // required
	EventType     EventType         // required
	ChangeType    ElementChangeType // required
	Device        *DeviceRemoteImpl // required for DetailedDiscovery Call
	Entity        *EntityRemoteImpl // required for DetailedDiscovery Call and Notify
	Feature       *FeatureRemoteImpl
	CmdClassifier *model.CmdClassifierType // optional, used together with EventType EventTypeDataChange
	Data          any
}

type EventHandler interface {
	HandleEvent(EventPayload)
}

type events struct {
	mu       sync.Mutex
	handlers []EventHandler
}

func (r *events) Subscribe(handler EventHandler) {
	r.mu.Lock()
	defer r.mu.Unlock()

	exists := false
	for _, item := range r.handlers {
		if item == handler {
			exists = true
			break
		}
	}

	if !exists {
		r.handlers = append(r.handlers, handler)
	}
}

func (r *events) Unsubscribe(handler EventHandler) {
	r.mu.Lock()
	defer r.mu.Unlock()

	var newHandlers []EventHandler
	for _, item := range r.handlers {
		if item != handler {
			newHandlers = append(newHandlers, item)
		}
	}
	r.handlers = newHandlers
}

func (r *events) Publish(payload EventPayload) {
	r.mu.Lock()
	defer r.mu.Unlock()
	for _, handler := range r.handlers {
		go handler.HandleEvent(payload)
	}
}