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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
"use strict";
const EXPORTED_SYMBOLS = ["LocationHelper"];
function isPublic(ap) {
let mask = "_nomap";
let result = ap.ssid.indexOf(mask, ap.ssid.length - mask.length);
return result == -1;
}
function sort(a, b) {
return b.signal - a.signal;
}
function encode(ap) {
return { macAddress: ap.mac, signalStrength: ap.signal };
}
/**
* Shared utility functions for modules dealing with
* Location Services.
*/
class LocationHelper {
static formatWifiAccessPoints(accessPoints) {
return accessPoints
.filter(isPublic)
.sort(sort)
.map(encode);
}
/**
* Calculate the distance between 2 points using the Haversine formula.
* https://en.wikipedia.org/wiki/Haversine_formula
*/
static distance(p1, p2) {
let rad = x => (x * Math.PI) / 180;
// Radius of the earth.
let R = 6371e3;
let lat = rad(p2.lat - p1.lat);
let lng = rad(p2.lng - p1.lng);
let a =
Math.sin(lat / 2) * Math.sin(lat / 2) +
Math.cos(rad(p1.lat)) *
Math.cos(rad(p2.lat)) *
Math.sin(lng / 2) *
Math.sin(lng / 2);
let c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
return R * c;
}
}
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