package com.dianwoba.rctamap;


import com.amap.api.maps2d.model.LatLng;
import com.amap.api.maps2d.model.LatLngBounds;

public class LatLngBoundsUtils {
    public static boolean BoundsAreDifferent(LatLngBounds a, LatLngBounds b) {
        LatLng centerA = getCenter(a);
        double latA = centerA.latitude;
        double lngA = centerA.longitude;
        double latDeltaA = a.northeast.latitude - a.southwest.latitude;
        double lngDeltaA = a.northeast.longitude - a.southwest.longitude;

        LatLng centerB = getCenter(b);
        double latB = centerB.latitude;
        double lngB = centerB.longitude;
        double latDeltaB = b.northeast.latitude - b.southwest.latitude;
        double lngDeltaB = b.northeast.longitude - b.southwest.longitude;

        double latEps = LatitudeEpsilon(a, b);
        double lngEps = LongitudeEpsilon(a, b);

        return
                different(latA, latB, latEps) ||
                        different(lngA, lngB, lngEps) ||
                        different(latDeltaA, latDeltaB, latEps) ||
                        different(lngDeltaA, lngDeltaB, lngEps);
    }

    public static LatLng getCenter(LatLngBounds bounds) {
        LatLng northeast = bounds.northeast;
        LatLng southwest = bounds.southwest;
        return new LatLng((northeast.latitude + southwest.latitude)/2, (northeast.longitude + southwest.longitude)/2);
    }

    private static boolean different(double a, double b, double epsilon) {
        return Math.abs(a - b) > epsilon;
    }

    private static double LatitudeEpsilon(LatLngBounds a, LatLngBounds b) {
        double sizeA = a.northeast.latitude - a.southwest.latitude; // something mod 180?
        double sizeB = b.northeast.latitude - b.southwest.latitude; // something mod 180?
        double size = Math.min(Math.abs(sizeA), Math.abs(sizeB));
        return size / 2560;
    }

    private static double LongitudeEpsilon(LatLngBounds a, LatLngBounds b) {
        double sizeA = a.northeast.longitude - a.southwest.longitude;
        double sizeB = b.northeast.longitude - b.southwest.longitude;
        double size = Math.min(Math.abs(sizeA), Math.abs(sizeB));
        return size / 2560;
    }
}