initial commit

cmd/main.go

@@ -0,0 +1,132 @@
+package main
+
+import (
+	"encoding/csv"
+	"io"
+	"log"
+	"net/http"
+	"os"
+	"slices"
+
+	pb "github.com/cjdenio/uta-trax-api/proto"
+	"google.golang.org/protobuf/proto"
+)
+
+func getVehicles() ([]*pb.VehiclePosition, error) {
+	resp, err := http.Get("https://apps.rideuta.com/tms/gtfs/Vehicle")
+	if err != nil {
+		return nil, err
+	}
+
+	bytes, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	feed := pb.FeedMessage{}
+	err = proto.Unmarshal(bytes, &feed)
+	if err != nil {
+		return nil, err
+	}
+
+	vehicles := make([]*pb.VehiclePosition, 0, len(feed.Entity))
+	for _, v := range feed.Entity {
+		if v.Vehicle != nil {
+			vehicles = append(vehicles, v.Vehicle)
+		}
+	}
+
+	return vehicles, nil
+}
+
+type TripInfo struct {
+	Line      pb.VehicleFeed_Line
+	Direction int
+}
+
+var trips = make(map[string]*TripInfo)
+
+func loadTrips() error {
+	f, err := os.Open("gtfs/trips.txt")
+	if err != nil {
+		return err
+	}
+
+	r := csv.NewReader(f)
+
+	header, err := r.Read()
+	if err != nil {
+		return err
+	}
+
+	route_id := slices.Index(header, "route_id")
+	trip_id := slices.Index(header, "trip_id")
+	// direction_id := slices.Index(header, "direction_id")
+
+	for {
+		if record, err := r.Read(); err == nil {
+			trip_info := new(TripInfo)
+
+			switch record[route_id] {
+			case "8246":
+				trip_info.Line = pb.VehicleFeed_RED
+				trips[record[trip_id]] = trip_info
+			case "39020":
+				trip_info.Line = pb.VehicleFeed_GREEN
+				trips[record[trip_id]] = trip_info
+			case "5907":
+				trip_info.Line = pb.VehicleFeed_BLUE
+				trips[record[trip_id]] = trip_info
+			case "45389":
+				trip_info.Line = pb.VehicleFeed_STREETCAR
+				trips[record[trip_id]] = trip_info
+			}
+		} else {
+			break
+		}
+	}
+
+	return nil
+}
+
+func feedifyVehicles(vehicles []*pb.VehiclePosition) pb.VehicleFeed {
+
+	vehicle_feed := make([]*pb.VehicleFeed_Vehicle, 0, len(vehicles))
+
+	for _, vehicle := range vehicles {
+		trip, ok := trips[*vehicle.Trip.TripId]
+		if !ok {
+			continue
+		}
+
+		vehicle_feed = append(vehicle_feed, &pb.VehicleFeed_Vehicle{
+			Lat:  *vehicle.Position.Latitude,
+			Lon:  *vehicle.Position.Longitude,
+			Line: trip.Line,
+		})
+	}
+
+	return pb.VehicleFeed{
+		Vehicles: vehicle_feed,
+	}
+}
+
+func main() {
+	if err := loadTrips(); err != nil {
+		log.Fatalln(err)
+	}
+
+	http.DefaultServeMux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		vehicles, err := getVehicles()
+		if err != nil {
+			log.Fatalln(err)
+		}
+
+		feed := feedifyVehicles(vehicles)
+		b, _ := proto.Marshal(&feed)
+		w.Header().Add("Content-Type", "application/protobuf")
+		w.Write(b)
+	})
+
+	http.ListenAndServe(":3000", nil)
+}