[#316] locode: Define the API of location database

Define structure of keys and records of the location database. Define the
interfaces of all components necessary for the formation of the database.
Implement the function of filling the database.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

pkg/util/locode/db/point.go

@@ -0,0 +1,75 @@
+package locodedb
+
+import (
+	"strconv"
+	"strings"
+
+	locodecolumn "github.com/nspcc-dev/neofs-node/pkg/util/locode/column"
+)
+
+// Point represents 2D geographic point.
+type Point struct {
+	lat, lng float64
+}
+
+// NewPoint creates, initializes and returns new Point.
+func NewPoint(lat, lng float64) *Point {
+	return &Point{
+		lat: lat,
+		lng: lng,
+	}
+}
+
+// Latitude returns Point's latitude.
+func (p Point) Latitude() float64 {
+	return p.lat
+}
+
+// Longitude returns Point's longitude.
+func (p Point) Longitude() float64 {
+	return p.lng
+}
+
+// PointFromCoordinates converts UN/LOCODE coordinates to Point.
+func PointFromCoordinates(crd *locodecolumn.Coordinates) (*Point, error) {
+	if crd == nil {
+		return nil, nil
+	}
+
+	cLat := crd.Latitude()
+	cLatDeg := cLat.Degrees()
+	cLatMnt := cLat.Minutes()
+
+	lat, err := strconv.ParseFloat(strings.Join([]string{
+		string(cLatDeg[:]),
+		string(cLatMnt[:]),
+	}, "."), 64)
+	if err != nil {
+		return nil, err
+	}
+
+	if !cLat.Hemisphere().North() {
+		lat = -lat
+	}
+
+	cLng := crd.Longitude()
+	cLngDeg := cLng.Degrees()
+	cLngMnt := cLng.Minutes()
+
+	lng, err := strconv.ParseFloat(strings.Join([]string{
+		string(cLngDeg[:]),
+		string(cLngMnt[:]),
+	}, "."), 64)
+	if err != nil {
+		return nil, err
+	}
+
+	if !cLng.Hemisphere().East() {
+		lng = -lng
+	}
+
+	return &Point{
+		lat: lat,
+		lng: lng,
+	}, nil
+}