71 lines
1.7 KiB
Go
71 lines
1.7 KiB
Go
package cafes
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import (
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"encoding/xml"
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"fmt"
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"io"
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"log"
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"net/http"
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"github.com/dhconnelly/rtreego"
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"github.com/fofanov/go-osgb"
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)
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const ctcCamWaypointsUrl = "https://ctccambridge.org.uk/ctccambridge-waypoints.gpx"
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type Waypoint struct {
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Lat float64 `xml:"lat,attr"`
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Lon float64 `xml:"lon,attr"`
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Name string `xml:"name"`
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Url string `xml:"url"`
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}
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type Waypoints struct {
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Waypoints []Waypoint `xml:"wpt"`
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}
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func BuildCtcCamIndex(r io.Reader) (*rtreego.Rtree, error) {
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dec := xml.NewDecoder(r)
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var wpt Waypoints
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err := dec.Decode(&wpt)
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if err != nil {
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return nil, err
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}
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trans, err := osgb.NewOSTN15Transformer()
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if err != nil {
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return nil, err
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}
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stops := make([]rtreego.Spatial, len(wpt.Waypoints))
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for i, w := range wpt.Waypoints {
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gpsCoord := osgb.NewETRS89Coord(w.Lon, w.Lat, 0)
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ngCoord, err := trans.ToNationalGrid(gpsCoord)
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if err != nil {
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return nil, fmt.Errorf("Error translating coordinates %v: %v", gpsCoord, err)
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}
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stops[i] = &RefreshmentStop{
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Name: w.Name,
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Url: w.Url,
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Easting: ngCoord.Easting,
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Northing: ngCoord.Northing,
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}
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}
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return rtreego.NewTree(2, 25, 50, stops...), nil
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}
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func FetchCtcCamIndex() (*rtreego.Rtree, error) {
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log.Printf("Fetching %s", ctcCamWaypointsUrl)
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res, err := http.Get(ctcCamWaypointsUrl)
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if err != nil {
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return nil, fmt.Errorf("error getting %s: %v", ctcCamWaypointsUrl, err)
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}
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defer res.Body.Close()
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if res.StatusCode != http.StatusOK {
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return nil, fmt.Errorf("unexpected status fetching %s: %s", ctcCamWaypointsUrl, res.Status)
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}
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index, err := BuildCtcCamIndex(res.Body)
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if err != nil {
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return nil, fmt.Errorf("error building CTC Cambridge stops index: %v", err)
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}
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log.Printf("Loaded %d CTC Cambridge stops", index.Size())
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return index, nil
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}
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