// SearchLocations around latitude/longitude in bounded area (km) for known location points.
func SearchLocations(latitude, longitude, bound float64) []*GeoData {
if !searchReady {
InitSearch()
}
hashSteps := geohashEstimateStepsByRadius(bound * 1000)
debugf("Hash step: %v, for radius: %v km", hashSteps, bound)
var hash C.GeoHashBits
C.geohashEncodeWGS84(C.double(latitude), C.double(longitude), C.uint8_t(hashSteps), &hash)
neighbours := getNeighbours(uint64(hash.bits), uint8(hashSteps))
box := boundingBox(latitude, longitude, bound)
initialSize := 128 // Initial array size to avoid time waste re-sizing array
var locationsFound = make([]*GeoData, initialSize)
locFoundCount := 0
geoStoreKeysLen := len(geoHashStore)
for nIdx := range neighbours {
neighboursUpperLimit := (neighbours[nIdx] + 1) << uint((maxSteps-hashSteps)*2)
neighbours[nIdx] = neighbours[nIdx] << uint((maxSteps-hashSteps)*2)
// debugf("Normalized Neighbours Hash: %v to %v", neighbours[nIdx], neighboursUpperLimit)
searchIdx := sort.Search(geoStoreKeysLen, func(i int) bool { return geoHashStore[i].GeoHash >= neighbours[nIdx] })
if searchIdx < geoStoreKeysLen { // Not found would turn index=N
// debugf("found location?")
// found location
for i := searchIdx; i < geoStoreKeysLen; i++ {
data := geoHashStore[i]
if data.GeoHash < neighboursUpperLimit {
//var data *GeoData
// debugf("filtering by lat/long: %v %v", data.Latitude, data.Longitude)
// debugf("filtering by bounding box: %v %v %v %v", box[0], box[1], box[2], box[3])
// filter by strict bounding box
box0 := box[0]
box1 := box[1]
box2 := box[2]
box3 := box[3]
lat := data.Latitude
lng := data.Longitude
if ((lat >= box0 && lat <= box1) || (lat <= box0 && lat >= box1)) &&
((lng >= box2 && lng <= box3) || (lng <= box2 && lng >= box3)) {
if locFoundCount < initialSize {
locationsFound[locFoundCount] = data
} else {
locationsFound = append(locationsFound, data)
}
locFoundCount++
// debugf("Search found location in geoHashStore: %v", geoHashStore[searchIdx])
}
} else {
break
}
}
}
}
return locationsFound[:locFoundCount]
}
// Encode a geo hash to MAX(26) steps
func geohashEncodeMax(latitude, longitude float64) uint64 {
var hash C.GeoHashBits
C.geohashEncodeWGS84(C.double(latitude), C.double(longitude), C.uint8_t(maxSteps), &hash)
return uint64(hash.bits)
}