frostfs-node/pkg/util/locode/db/continents/geojson/calls.go
Leonard Lyubich 9669afdfc7 [#316] locode: Implement polygons DB based on GeoJSON polygons
Define database of Earth's polygons in GeoJSON format. Implement resolving
of geo point to continent in which it is located through point-in-polygon
calculation.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
2021-02-09 11:05:55 +03:00

90 lines
2.1 KiB
Go

package continentsdb
import (
"io/ioutil"
locodedb "github.com/nspcc-dev/neofs-node/pkg/util/locode/db"
"github.com/paulmach/orb"
"github.com/paulmach/orb/geojson"
"github.com/paulmach/orb/planar"
"github.com/pkg/errors"
)
const continentProperty = "Continent"
// PointContinent goes through all polygons, and returns continent
// in which point is located.
//
// Returns locodedb.ContinentUnknown if no entry matches.
//
// All GeoJSON feature are parsed from file once and stored in memory.
func (db *DB) PointContinent(point *locodedb.Point) (*locodedb.Continent, error) {
var err error
db.once.Do(func() {
err = db.init()
})
if err != nil {
return nil, err
}
planarPoint := orb.Point{point.Longitude(), point.Latitude()}
var continent string
for _, feature := range db.features {
if multiPolygon, ok := feature.Geometry.(orb.MultiPolygon); ok {
if planar.MultiPolygonContains(multiPolygon, planarPoint) {
continent = feature.Properties.MustString(continentProperty)
break
}
} else if polygon, ok := feature.Geometry.(orb.Polygon); ok {
if planar.PolygonContains(polygon, planarPoint) {
continent = feature.Properties.MustString(continentProperty)
break
}
}
}
c := continentFromString(continent)
return &c, nil
}
func (db *DB) init() error {
data, err := ioutil.ReadFile(db.path)
if err != nil {
return errors.Wrap(err, "could not read data file")
}
features, err := geojson.UnmarshalFeatureCollection(data)
if err != nil {
return errors.Wrap(err, "could not unmarshal GeoJSON feature collection")
}
db.features = features.Features
return nil
}
func continentFromString(c string) locodedb.Continent {
switch c {
default:
return locodedb.ContinentUnknown
case "Africa":
return locodedb.ContinentAfrica
case "Asia":
return locodedb.ContinentAsia
case "Europe":
return locodedb.ContinentEurope
case "North America":
return locodedb.ContinentNorthAmerica
case "South America":
return locodedb.ContinentSouthAmerica
case "Antarctica":
return locodedb.ContinentAntarctica
case "Australia", "Oceania":
return locodedb.ContinentOceania
}
}