Refactor and enhance handling of payloads and data structures

Added support for handling various payload types, including GPS and alarms, with new structures and constants. Introduced helper methods for JSON marshalling/unmarshalling of GPS data and modularized the handling of certificates, configurations, and alarms. Implemented foundational server code for testing and expanded several package functionalities.

io.go

@@ -2,10 +2,12 @@ package n9m
 
 import (
 	"bytes"
+	"encoding/binary"
 	"encoding/json"
-	"log"
-
+	"fmt"
 	"github.com/icza/bitio"
+	"log"
+	"time"
 )
 
 // Read package
@@ -20,7 +22,7 @@ func (e *Package) ReadPackage() bool {
 	e.CompressFlag = r.TryReadBool()
 	e.CSRCCount = uint8(r.TryReadBits(4))
 	e.PayloadType = PayloadType(r.TryReadBits(8))
-	e.SSRC = uint16(r.TryReadBits(16))
+	e.SSRC = SpecialPayloadType((r.TryReadBits(8) | (r.TryReadBits(8) << 8)))
 
 	if e.EncryptionFlag && e.CompressFlag {
 		// TODO: get snippet, that use this code
@@ -60,11 +62,34 @@ func (e *Package) ReadPackage() bool {
 
 	e.Accum = e.Accum[12+e.payloadLen:]
 
-	if e.PayloadType == PayloadTypeData {
+	switch e.PayloadType {
+	case PayloadTypeData:
 		if err := json.Unmarshal(e.RawPayload, &e.Payload); err != nil {
 			log.Printf("Error parsing JSON payload: %v", err)
 			return false
 		}
+	case PayloadTypeSpecial:
+		switch e.SSRC {
+		case SpecialPayloadTypeGPS:
+			e.GPS.GPSStatus = e.RawPayload[0]
+			e.GPS.Expand = e.RawPayload[1]
+			e.GPS.Real = e.RawPayload[2]
+
+			e.GPS.Longitude = float64(binary.BigEndian.Uint32(e.RawPayload[4:8])) / 1e6
+			e.GPS.Latitude = float64(binary.BigEndian.Uint32(e.RawPayload[8:12])) / 1e6
+			e.GPS.Speed = float64(binary.BigEndian.Uint32(e.RawPayload[12:16])) / 100
+			e.GPS.Direction = float64(binary.BigEndian.Uint32(e.RawPayload[16:20])) / 100
+			e.GPS.Altitude = int32(binary.BigEndian.Uint32(e.RawPayload[20:24]))
+
+			var err error
+			if e.GPS.Time, err = time.Parse("20060102150405", string(e.RawPayload[24:38])); err != nil {
+				log.Printf("Error parsing time: %v", err)
+			}
+		default:
+			fmt.Println("N9M parser warning: unknown special payload type", e.SSRC)
+		}
+	default:
+		fmt.Println("N9M parser warning: unknown payload type", e.PayloadType)
 	}
 
 	if r.TryError != nil {
@@ -141,3 +166,23 @@ func (e *Package) GetParametersAs(parameters any) error {
 
 	return json.Unmarshal(marshal, parameters)
 }
+
+func (e *Package) SetParameters(parameters any) {
+	e.Payload.Response = struct{}{}
+	e.Payload.Parameter = parameters
+}
+
+func (e *Package) GetResponseAs(response any) error {
+	marshal, err := json.Marshal(e.Payload.Response)
+
+	if err != nil {
+		return err
+	}
+
+	return json.Unmarshal(marshal, response)
+}
+
+func (e *Package) SetResponse(response any) {
+	e.Payload.Parameter = struct{}{}
+	e.Payload.Response = response
+}