Initial commit

go.mod

@@ -0,0 +1,5 @@
+module github.com/acaloiaro/roam-location
+
+go 1.14
+
+require github.com/adrianmo/go-nmea v1.2.0

go.sum

@@ -0,0 +1,9 @@
+github.com/adrianmo/go-nmea v1.2.0 h1:igwvOtEOv4Hg6bpqOcsKFIir3JXYz54FPXQkiWO4EkU=
+github.com/adrianmo/go-nmea v1.2.0/go.mod h1:u8bPnpKt/D/5rll/5l9f6iDfeq5WZW0+/SXdkwix6Tg=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.5.1/go.mod h1:5W2xD1RspED5o8YsWQXVCued0rvSQ+mT+I5cxcmMvtA=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

receiver/nmea_receiver.go

@@ -0,0 +1,66 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net"
+	"os"
+	"strings"
+
+	"github.com/adrianmo/go-nmea"
+)
+
+func main() {
+	listen()
+}
+
+func listen() {
+	addr, _ := net.ResolveUDPAddr("udp", ":22335")
+	sock, _ := net.ListenUDP("udp", addr)
+
+	for {
+		buf := make([]byte, 2048)
+		rlen, _, err := sock.ReadFromUDP(buf)
+		if err != nil {
+			fmt.Println(err)
+		}
+
+		go handlePacket(buf, rlen)
+	}
+}
+
+func handlePacket(buf []byte, rlen int) {
+	sentences := fmt.Sprintln(string(buf[0:rlen]))
+	sentence := strings.Split(sentences, "\n")[0] // We're not concerned with the second sentence, yet
+	s, err := nmea.Parse(sentence)
+	if err != nil {
+		// ignoring bad nmea sentence
+		log.Println("Ignoring bad NMEA sentence:", sentence)
+		return
+	}
+
+	if s.DataType() == nmea.TypeGGA {
+		m := s.(nmea.GGA)
+		fmt.Printf("Raw sentence: %v\n", m)
+		fmt.Printf("Time: %s\n", m.Time)
+		fmt.Printf("Latitude GPS: %f\n", m.Latitude)
+		fmt.Printf("Longitude GPS: %f\n", m.Longitude)
+
+		appendLog(m.Latitude, m.Longitude, sentence)
+	}
+}
+
+func appendLog(lat, lon float64, nmeaSentence string) {
+	dbPath := os.Getenv("ROAM_LOCATION_DB_PATH")
+
+	f, err := os.OpenFile(dbPath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	if err != nil {
+		log.Println(err)
+	}
+	defer f.Close()
+
+	row := fmt.Sprintf("%f,%f,%s\n", lat, lon, nmeaSentence)
+	if _, err := f.WriteString(row); err != nil {
+		log.Println(err)
+	}
+}

service/current_location.go

@@ -0,0 +1,76 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"log"
+	"net/http"
+	"os"
+	"strconv"
+	"strings"
+)
+
+type Location struct {
+	Lat float64 `json:"lat"`
+	Lon float64 `json:"lon"`
+}
+
+func handler(w http.ResponseWriter, r *http.Request) {
+	location := currentLocation()
+	byteArray, err := json.MarshalIndent(location, "", "  ")
+	if err != nil {
+		log.Fatalf("error providing current location: %v", err)
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	fmt.Fprintf(w, string(byteArray))
+}
+
+func currentLocation() (location Location) {
+	dbPath := os.Getenv("ROAM_LOCATION_DB_PATH")
+
+	fileHandle, err := os.Open(dbPath)
+
+	if err != nil {
+		panic("Cannot open file")
+	}
+	defer fileHandle.Close()
+
+	line := ""
+	stat, _ := fileHandle.Stat()
+	fs := stat.Size()
+	var cursor int64 = fs - 1 // start before the newline
+	for {
+		cursor--
+
+		char := make([]byte, 1)
+		fileHandle.ReadAt(char, cursor)
+
+		if cursor != -1 && (char[0] == '\n') { // stop if we find a line
+			break
+		}
+
+		line = fmt.Sprintf("%s%s", string(char), line) // there is more efficient way
+
+		if cursor == -fs { // stop if we are at the begining
+			break
+		}
+	}
+
+	fields := strings.Split(line, ",")
+
+	if f, err := strconv.ParseFloat(fields[0], 64); err == nil {
+		location.Lat = f
+	}
+
+	if f, err := strconv.ParseFloat(fields[1], 64); err == nil {
+		location.Lon = f
+	}
+
+	return
+}
+
+func main() {
+	http.HandleFunc("/current_location", handler)
+	log.Fatal(http.ListenAndServe(":22495", nil))
+}