initial commit

events.go

@@ -0,0 +1,80 @@
+package sati
+
+import (
+	"fmt"
+	"sync"
+
+	"github.com/mitchellh/mapstructure"
+)
+
+type EventBus struct {
+	mu         *sync.Mutex
+	idCounter  uint32
+	handlers   map[string]map[uint32]func(data any)
+	eventTypes map[string]any
+}
+
+type EventHandler struct {
+	id    uint32
+	type_ string
+	bus   *EventBus
+}
+
+func (e *EventHandler) Off() {
+	e.bus.mu.Lock()
+	defer e.bus.mu.Unlock()
+
+	delete(e.bus.handlers[e.type_], e.id)
+}
+
+func (e *EventBus) On(event string, handler func(data any)) (*EventHandler, error) {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+
+	if _, ok := e.eventTypes[event]; !ok {
+		return nil, fmt.Errorf("bad event type")
+	}
+
+	e.idCounter++
+	e.handlers[event][e.idCounter] = handler
+	return &EventHandler{
+		id:    e.idCounter,
+		type_: event,
+		bus:   e,
+	}, nil
+}
+
+func (e *EventBus) dispatch(event string, data any) error {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+
+	formattedData, ok := e.eventTypes[event]
+	if !ok {
+		return fmt.Errorf("bad event type")
+	}
+
+	if err := mapstructure.Decode(data, &formattedData); err != nil {
+		return err
+	}
+
+	for _, handler := range e.handlers[event] {
+		handler(formattedData)
+	}
+
+	return nil
+}
+
+// eventTypes values must be structs, not pointers
+func newEventBus(eventTypes map[string]any) *EventBus {
+	e := &EventBus{
+		mu:         &sync.Mutex{},
+		handlers:   make(map[string]map[uint32]func(data any)),
+		eventTypes: eventTypes,
+	}
+
+	for event := range eventTypes {
+		e.handlers[event] = make(map[uint32]func(data any))
+	}
+
+	return e
+}