move lower level logic into engine

internal/xair/engine.go

@@ -0,0 +1,97 @@
+package xair
+
+import (
+	"fmt"
+	"net"
+	"time"
+
+	"github.com/charmbracelet/log"
+	"github.com/hypebeast/go-osc/osc"
+)
+
+type engine struct {
+	Kind      MixerKind
+	conn      *net.UDPConn
+	mixerAddr *net.UDPAddr
+
+	parser     parser
+	addressMap map[string]string
+
+	done     chan bool
+	respChan chan *osc.Message
+}
+
+// receiveLoop handles incoming OSC messages
+func (e *engine) receiveLoop() {
+	buffer := make([]byte, 4096)
+
+	for {
+		select {
+		case <-e.done:
+			return
+		default:
+			// Set read timeout to avoid blocking forever
+			e.conn.SetReadDeadline(time.Now().Add(100 * time.Millisecond))
+			n, _, err := e.conn.ReadFromUDP(buffer)
+			if err != nil {
+				if netErr, ok := err.(net.Error); ok && netErr.Timeout() {
+					// Timeout is expected, continue loop
+					continue
+				}
+				// Check if we're shutting down to avoid logging expected errors
+				select {
+				case <-e.done:
+					return
+				default:
+					log.Errorf("Read error: %v", err)
+					return
+				}
+			}
+
+			msg, err := e.parseOSCMessage(buffer[:n])
+			if err != nil {
+				log.Errorf("Failed to parse OSC message: %v", err)
+				continue
+			}
+			e.respChan <- msg
+		}
+	}
+}
+
+// parseOSCMessage parses raw bytes into an OSC message with improved error handling
+func (e *engine) parseOSCMessage(data []byte) (*osc.Message, error) {
+	msg, err := e.parser.Parse(data)
+	if err != nil {
+		return nil, err
+	}
+
+	return msg, nil
+}
+
+// sendToAddress sends an OSC message to a specific address (enables replying to different ports)
+func (e *engine) sendToAddress(addr *net.UDPAddr, oscAddress string, args ...any) error {
+	msg := osc.NewMessage(oscAddress)
+	for _, arg := range args {
+		msg.Append(arg)
+	}
+
+	log.Debugf("Sending to %v: %s", addr, msg.String())
+	if len(args) > 0 {
+		log.Debug(" - Arguments: ")
+		for i, arg := range args {
+			if i > 0 {
+				log.Debug(", ")
+			}
+			log.Debugf("%v", arg)
+		}
+	}
+	log.Debug("")
+
+	data, err := msg.MarshalBinary()
+	if err != nil {
+		return fmt.Errorf("failed to marshal message: %v", err)
+	}
+
+	_, err = e.conn.WriteToUDP(data, addr)
+	return err
+}