109 lines
2.5 KiB
Dart
109 lines
2.5 KiB
Dart
import 'dart:math' as math;
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class DistanceCalculator {
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static const double earthRadiusKm = 6371.0;
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static double calculateDistance({
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required double lat1,
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required double lon1,
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required double lat2,
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required double lon2,
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}) {
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final double dLat = _toRadians(lat2 - lat1);
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final double dLon = _toRadians(lon2 - lon1);
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final double a =
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math.sin(dLat / 2) * math.sin(dLat / 2) +
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math.cos(_toRadians(lat1)) *
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math.cos(_toRadians(lat2)) *
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math.sin(dLon / 2) *
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math.sin(dLon / 2);
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final double c = 2 * math.atan2(math.sqrt(a), math.sqrt(1 - a));
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return earthRadiusKm * c;
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}
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static double _toRadians(double degree) {
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return degree * (math.pi / 180);
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}
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static String formatDistance(double distanceInKm) {
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if (distanceInKm < 1) {
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return '${(distanceInKm * 1000).round()}m';
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} else if (distanceInKm < 10) {
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return '${distanceInKm.toStringAsFixed(1)}km';
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} else {
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return '${distanceInKm.round()}km';
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}
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}
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static bool isWithinDistance({
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required double lat1,
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required double lon1,
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required double lat2,
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required double lon2,
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required double maxDistanceKm,
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}) {
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final distance = calculateDistance(
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lat1: lat1,
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lon1: lon1,
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lat2: lat2,
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lon2: lon2,
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);
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return distance <= maxDistanceKm;
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}
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static double? calculateDistanceFromCurrentLocation({
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required double targetLat,
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required double targetLon,
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double? currentLat,
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double? currentLon,
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}) {
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if (currentLat == null || currentLon == null) {
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return null;
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}
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return calculateDistance(
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lat1: currentLat,
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lon1: currentLon,
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lat2: targetLat,
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lon2: targetLon,
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);
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}
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static List<T> sortByDistance<T>({
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required List<T> items,
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required double Function(T) getLat,
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required double Function(T) getLon,
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required double currentLat,
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required double currentLon,
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}) {
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final List<T> sortedItems = List<T>.from(items);
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sortedItems.sort((a, b) {
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final distanceA = calculateDistance(
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lat1: currentLat,
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lon1: currentLon,
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lat2: getLat(a),
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lon2: getLon(a),
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);
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final distanceB = calculateDistance(
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lat1: currentLat,
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lon1: currentLon,
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lat2: getLat(b),
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lon2: getLon(b),
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);
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return distanceA.compareTo(distanceB);
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});
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return sortedItems;
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}
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static Map<String, double> getDefaultLocationForKorea() {
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return {'latitude': 37.5665, 'longitude': 126.9780};
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}
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}
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