Add missing file.

pkg/cafes/cyclingmaps.go

@@ -0,0 +1,70 @@
+package cafes
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"net/http"
+
+	"github.com/dhconnelly/rtreego"
+	"github.com/fofanov/go-osgb"
+)
+
+const cyclingMapsCafesUrl = "https://cafes.cyclingmaps.net/data/cafes.json"
+
+type CyclingMapsCafe struct {
+	Name    string
+	Website string
+	Lat     float64
+	Lng     float64
+}
+
+func BuildCyclingMapsIndex(r io.Reader) (*rtreego.Rtree, error) {
+	var cafes []CyclingMapsCafe
+	data, err := ioutil.ReadAll(r)
+	if err != nil {
+		return nil, err
+	}
+	err = json.Unmarshal(data, &cafes)
+	if err != nil {
+		return nil, err
+	}
+	trans, err := osgb.NewOSTN15Transformer()
+	if err != nil {
+		return nil, err
+	}
+	stops := make([]rtreego.Spatial, 0, len(cafes))
+	for _, c := range cafes {
+		gpsCoord := osgb.NewETRS89Coord(c.Lng, c.Lat, 0)
+		ngCoord, err := trans.ToNationalGrid(gpsCoord)
+		if err != nil {
+			log.Printf("Error translating coordinates %v: %v", gpsCoord, err)
+			continue
+		}
+		stops = append(stops, &RefreshmentStop{
+			Name:     c.Name,
+			Url:      c.Website,
+			Easting:  ngCoord.Easting,
+			Northing: ngCoord.Northing,
+		})
+	}
+	return rtreego.NewTree(2, 25, 50, stops...), nil
+}
+
+func FetchCyclingMapsIndex() (*rtreego.Rtree, error) {
+	res, err := http.Get(cyclingMapsCafesUrl)
+	if err != nil {
+		return nil, fmt.Errorf("error getting %s: %v", cyclingMapsCafesUrl, err)
+	}
+	defer res.Body.Close()
+	if res.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("unexpected status fetching %s: %s", cyclingMapsCafesUrl, res.Status)
+	}
+	index, err := BuildCyclingMapsIndex(res.Body)
+	if err != nil {
+		return nil, fmt.Errorf("error building cyclingmaps.net cafe stops index: %v", err)
+	}
+	return index, nil
+}