// allMarkers returns the URL fragment containing all the markers of the specified GPS records to be appended
// to a static maps URL.
//
// Static maps documentation: // https://developers.google.com/maps/documentation/staticmaps/
func allMarkers(records []*ds.GPS) string {
// Returned string will be around 1 KB, allocated reasonable buffer:
b := bytes.NewBuffer(make([]byte, 0, 1280))
// MARKERS
var prev *ds.GPS
for idx, r := range records {
if !r.Track() {
prev = r
continue
}
// Determine color. Default marker color: blue;
// First records after a Start event: green
// Last records before a Stop event: red
clr := "blue"
if prev != nil && prev.Evt() == ds.EvtStop {
clr = "red"
}
// Check next
if idx < len(records)-1 && records[idx+1].Evt() == ds.EvtStart {
clr = "green"
}
fmt.Fprintf(b, "&markers=color:%s|label:%c|%f,%f", clr, r.Label, r.GeoPoint.Lat, r.GeoPoint.Lng)
prev = r
}
// PATHS
i := 0
for _, r := range records {
if !r.Track() {
i = 0
continue
}
if i == 0 {
b.WriteString("&path=")
} else if i > 0 {
b.WriteString("|")
}
fmt.Fprintf(b, "%f,%f", r.GeoPoint.Lat, r.GeoPoint.Lng)
i++
}
return b.String()
}
