mc root source folder cleanup

2026-06-27 13:54:54 +02:00
parent b2784574bd
commit 666f250b3e
480 changed files with 325 additions and 325 deletions
@@ -0,0 +1,250 @@
+// Package event is the event handler
+package event
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"log/slog"
+	"reflect"
+)
+
+type Loop struct {
+	HandlerFunctions map[reflect.Type][]reflect.Value
+
+	Ctx          context.Context
+	Cancel       context.CancelFunc
+	eventSources []reflect.SelectCase
+}
+
+type Unhandled struct {
+	Val any
+}
+
+type Anything struct {
+	Val any
+}
+
+// Close is fired when the loop shuts down.
+type Close struct {
+	Reason error
+}
+
+// HandlerDoneErr will stop the event loop and return the error if provided.
+type HandlerDoneErr struct {
+	Return error
+}
+
+// CallFunc is a special value that when fired with Loop.Fire it calls a function on the main loop
+// Its usefull for event event sources to call functions on the main loop
+// because event sources dont run on the main loop
+type CallFunc struct {
+	F    reflect.Value
+	Args []reflect.Value
+}
+
+func (e HandlerDoneErr) Error() string {
+	return "HandlerDoneErr"
+}
+
+func (e HandlerDoneErr) Unwrap() error {
+	return e.Return
+}
+
+// MainHandlerErr is a special error used to tell the event loop that the main loop has exited
+type MainHandlerErr struct {
+	Return error
+}
+
+func (e MainHandlerErr) Error() string {
+	return "MainHandlerErr"
+}
+
+func (e MainHandlerErr) Unwrap() error {
+	return e.Return
+}
+
+// DontForwardErr will stop the event from being forwarded to other handlers, including anything handlers.
+var DontForwardErr = errors.New("dont forward")
+var WhileClosingErr = errors.New("error while closing")
+var ContextDoneErr = errors.New("context done")
+var RecvNotOkErr = errors.New("recv not ok")
+
+func ValidateHandler(h any) (eventType reflect.Type, hv reflect.Value) {
+	hv = reflect.ValueOf(h)
+	if hv.Kind() != reflect.Func {
+		panic("expected method")
+	}
+	if hv.Type().NumIn() != 1 {
+		panic("expected method with one argument")
+	}
+	if hv.Type().NumOut() != 1 || hv.Type().Out(0) != reflect.TypeFor[error]() {
+		panic("expected method that returns an error")
+	}
+	eventType = hv.Type().In(0)
+	return
+}
+
+// RegisterEventSource registers an event source an event source is a channel this channel along with all other event sources will be reflect.Select 'ed until the loop closes
+// here is an example of an event source function
+//
+//	func() (chSending <-chan any) {
+//			ch := make(chan any)
+//			go func() {
+//				ctx := conn.Ctx
+//				for {
+//					select {
+//					case <-ctx.Done():
+//						return
+//					case eventt := <-otherSource:
+//						err = c.DoCommand(eventt)
+//					}
+//				}
+//			}()
+//			chSending = ch
+//			return
+//		}
+func (l *Loop) RegisterEventSource(ch <-chan any) {
+	l.eventSources = append(l.eventSources, reflect.SelectCase{Dir: reflect.SelectRecv, Chan: reflect.ValueOf(ch)})
+}
+
+// Register registers a handler that will not close the loop if it returns an error.
+// Instead, it will log it to slog.Error
+// Warning: If a bad handler is passed in the program will panic.
+func (l *Loop) Register(h any) {
+	eventType, hv := ValidateHandler(h)
+	l.RegisterLow(eventType, hv, false)
+}
+
+// RegisterLow registers a handler that will not close the loop if it returns an error.
+// Instead, it will log it to slog.Error
+// This does not hold true for signaling errors like HandlerDoneErr or DontForwardErr
+// Warning: If a bad handler is passed in the program will panic.
+func (l *Loop) RegisterLow(eventType reflect.Type, hv reflect.Value, critical bool) {
+	handleFunc := hv
+	if !critical {
+		handleFunc = reflect.ValueOf(func(packet any) error {
+			v := hv.Call([]reflect.Value{reflect.ValueOf(packet)})[0]
+			if !v.IsNil() {
+				err := v.Interface().(error)
+				if errors.As(err, &HandlerDoneErr{}) || errors.Is(err, DontForwardErr) {
+					return err
+				}
+				slog.Error("handler failed", "err", err)
+			}
+			return nil
+		})
+	}
+	l.HandlerFunctions[eventType] = append(l.HandlerFunctions[eventType], handleFunc)
+}
+
+// RegisterCritical registers a handler that will close the loop if it returns an error.
+// Warning: If a bad handler is passed in the program will panic.
+func (l *Loop) RegisterCritical(h any) {
+	eventType, hv := ValidateHandler(h)
+	l.HandlerFunctions[eventType] = append(l.HandlerFunctions[eventType], hv)
+}
+
+// FireFound triggers all handlers registered for the specified event type and returns if handlers were found or an error occurred.
+func (l *Loop) FireFound(event any) (found bool, err error) {
+	var handlers []reflect.Value
+	if handlers, found = l.HandlerFunctions[reflect.TypeOf(event)]; found {
+		for _, handler := range handlers {
+			errV := handler.Call([]reflect.Value{reflect.ValueOf(event)})[0]
+			if !errV.IsNil() {
+				err = errV.Interface().(error)
+				err = errors.Join(fmt.Errorf("event handler failed at: %T", event), err)
+				return
+			}
+		}
+	}
+	return
+}
+
+// Fire dispatches the provided event to all appropriate handlers and invokes fallback handlers if the event is unhandled.
+func (l *Loop) Fire(event any) (err error) {
+	err, isErr := event.(error)
+	if isErr {
+		return
+	}
+	err = nil
+
+	f, isCallFunc := event.(CallFunc)
+	if isCallFunc {
+		errV := f.F.Call(f.Args)[0].Interface()
+		if errV != nil {
+			err = errV.(error)
+		}
+		return
+	}
+
+	found, err := l.FireFound(event)
+	if err != nil {
+		if errors.Is(err, DontForwardErr) {
+			err = nil
+		}
+		return
+	}
+	if !found {
+		found, err = l.FireFound(Unhandled{event})
+		if err != nil {
+			return
+		}
+	}
+	found, err = l.FireFound(Anything{event})
+	return
+}
+
+func (l *Loop) ContextDoneListener() (chSending <-chan any) {
+	ch := make(chan any)
+	go func() {
+		<-l.Ctx.Done()
+		ch <- ContextDoneErr
+	}()
+	return ch
+}
+
+func (l *Loop) IsTypeRegistered(t reflect.Type) bool {
+	_, ok := l.HandlerFunctions[t]
+	return ok
+}
+
+func (l *Loop) StartLoop() (err error) {
+	_ = *l // exit early on nil loop
+	l.RegisterEventSource(l.ContextDoneListener())
+	for {
+		_, v, ok := reflect.Select(l.eventSources)
+		if !ok {
+			err = RecvNotOkErr
+			break
+		}
+		err = l.Fire(v.Interface())
+		if err != nil {
+			break
+		}
+	}
+	var contextDoneErr HandlerDoneErr
+	if errors.As(err, &contextDoneErr) {
+		err = contextDoneErr.Return
+	}
+	closeErr := l.Fire(Close{err})
+	if closeErr != nil {
+		err = errors.Join(err, errors.Join(WhileClosingErr, closeErr))
+	}
+	l.Cancel()
+	return
+}
+
+func NewLoop() (l *Loop) {
+	return NewLoopCtx(context.Background())
+}
+
+func NewLoopCtx(ctx context.Context) (l *Loop) {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	l = &Loop{}
+	l.Ctx, l.Cancel = context.WithCancel(ctx)
+	l.HandlerFunctions = make(map[reflect.Type][]reflect.Value)
+	return
+}