frostfs-node/pkg/util/locode/db/continents/geojson/calls.go

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package continentsdb
import (
"fmt"
"os"
locodedb "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util/locode/db"
"github.com/paulmach/orb"
"github.com/paulmach/orb/geojson"
"github.com/paulmach/orb/planar"
)
const continentProperty = "Continent"
// PointContinent goes through all polygons and returns the continent
// in which the 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
minDst float64
)
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
}
}
distance := planar.DistanceFrom(feature.Geometry, planarPoint)
if minDst == 0 || minDst > distance {
minDst = distance
continent = feature.Properties.MustString(continentProperty)
}
}
c := continentFromString(continent)
return &c, nil
}
func (db *DB) init() error {
data, err := os.ReadFile(db.path)
if err != nil {
return fmt.Errorf("could not read data file: %w", err)
}
features, err := geojson.UnmarshalFeatureCollection(data)
if err != nil {
return fmt.Errorf("could not unmarshal GeoJSON feature collection: %w", err)
}
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
}
}