99 lines
2.3 KiB
Go
99 lines
2.3 KiB
Go
package continentsdb
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import (
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"fmt"
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"os"
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locodedb "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util/locode/db"
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"github.com/paulmach/orb"
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"github.com/paulmach/orb/geojson"
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"github.com/paulmach/orb/planar"
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)
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const continentProperty = "Continent"
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// PointContinent goes through all polygons and returns the continent
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// in which the point is located.
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//
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// Returns locodedb.ContinentUnknown if no entry matches.
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//
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// All GeoJSON feature are parsed from file once and stored in memory.
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func (db *DB) PointContinent(point *locodedb.Point) (*locodedb.Continent, error) {
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var err error
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db.once.Do(func() {
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err = db.init()
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})
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if err != nil {
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return nil, err
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}
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planarPoint := orb.Point{point.Longitude(), point.Latitude()}
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var (
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continent string
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minDst float64
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)
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for _, feature := range db.features {
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if multiPolygon, ok := feature.Geometry.(orb.MultiPolygon); ok {
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if planar.MultiPolygonContains(multiPolygon, planarPoint) {
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continent = feature.Properties.MustString(continentProperty)
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break
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}
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} else if polygon, ok := feature.Geometry.(orb.Polygon); ok {
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if planar.PolygonContains(polygon, planarPoint) {
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continent = feature.Properties.MustString(continentProperty)
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break
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}
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}
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distance := planar.DistanceFrom(feature.Geometry, planarPoint)
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if minDst == 0 || minDst > distance {
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minDst = distance
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continent = feature.Properties.MustString(continentProperty)
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}
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}
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c := continentFromString(continent)
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return &c, nil
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}
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func (db *DB) init() error {
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data, err := os.ReadFile(db.path)
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if err != nil {
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return fmt.Errorf("could not read data file: %w", err)
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}
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features, err := geojson.UnmarshalFeatureCollection(data)
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if err != nil {
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return fmt.Errorf("could not unmarshal GeoJSON feature collection: %w", err)
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}
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db.features = features.Features
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return nil
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}
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func continentFromString(c string) locodedb.Continent {
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switch c {
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default:
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return locodedb.ContinentUnknown
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case "Africa":
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return locodedb.ContinentAfrica
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case "Asia":
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return locodedb.ContinentAsia
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case "Europe":
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return locodedb.ContinentEurope
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case "North America":
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return locodedb.ContinentNorthAmerica
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case "South America":
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return locodedb.ContinentSouthAmerica
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case "Antarctica":
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return locodedb.ContinentAntarctica
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case "Australia", "Oceania":
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return locodedb.ContinentOceania
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}
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}
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