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gtfs.go
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gtfs.go
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package main
import (
"archive/zip"
"fmt"
"io"
"log"
"os"
"path/filepath"
"strings"
"github.com/artonge/go-gtfs"
)
// The live websocket data does not provide a trip ID, which is needed to generate the real-time feed.
// Here, we parse just enough static GTFS to enable mapping the current time and service ID from the feed to a trip ID.
var g *gtfs.GTFS = nil
// See https://stackoverflow.com/questions/20357223/easy-way-to-unzip-file
// Modfified to unzip to a temporary directory and return path to it
func unzip(src string) (string, error) {
r, err := zip.OpenReader(src)
if err != nil {
return "", err
}
defer func() {
if err := r.Close(); err != nil {
panic(err)
}
}()
dir, err := os.MkdirTemp("", "vivi-gtfs")
if err != nil {
return "", err
}
// Closure to address file descriptors issue with all the deferred .Close() methods
extractAndWriteFile := func(f *zip.File) error {
rc, err := f.Open()
if err != nil {
return err
}
defer func() {
if err := rc.Close(); err != nil {
panic(err)
}
}()
path := filepath.Join(dir, f.Name)
// Check for ZipSlip (Directory traversal)
if !strings.HasPrefix(path, filepath.Clean(dir)+string(os.PathSeparator)) {
return fmt.Errorf("illegal file path: %s", path)
}
if f.FileInfo().IsDir() {
os.MkdirAll(path, f.Mode())
} else {
os.MkdirAll(filepath.Dir(path), f.Mode())
f, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, f.Mode())
if err != nil {
return err
}
defer func() {
if err := f.Close(); err != nil {
panic(err)
}
}()
_, err = io.Copy(f, rc)
if err != nil {
return err
}
}
return nil
}
for _, f := range r.File {
err := extractAndWriteFile(f)
if err != nil {
return "", err
}
}
return dir, nil
}
func initGtfs(dataPath string) {
// Extract GTFS zip file, library only supports loading from directory
dir, err := unzip(dataPath)
if err != nil {
log.Fatalf("Failed to extract GTFS data for mapping trip IDs: %s\n", err)
}
defer os.RemoveAll(dir)
gt, err := gtfs.Load(dir, nil)
if err != nil {
log.Fatalf("Failed to load GTFS data for mapping trip IDs: %s\n", err)
}
g = gt
}
func lookupTripId(serviceId string) string {
for _, trip := range g.Trips {
/*
* Service IDs usually contain the train number, but sometimes in strange forms with other junk appended.
* Try to work around this by counting substring matches as sufficient.
*/
if strings.Contains(trip.ServiceID, serviceId) {
// FIXME: A service does not have a unique trip ID, need to look it up based on current time somehow
return trip.ID
}
}
return ""
}
func lookupGtfsStopIdFromName(name string) string {
// Some stop names differ between GTFS feed and realtime data
stopNameFixups := map[string]string{
"Tukums 1": "Tukums I",
"Tukums 2": "Tukums II",
"BA Turība": "Biznesa Augstskola Turība",
"Rēzekne 2": "Rēzekne II",
}
if fixedName, ok := stopNameFixups[name]; ok {
name = fixedName
}
for _, stop := range g.Stops {
if strings.ToLower(stop.Name) == strings.ToLower(name) {
return stop.ID
}
}
return ""
}