[node] multiple contracting fixes and some more refactoring

nodejs/lib/utils.ts

@@ -5,6 +5,11 @@ export type CategorizedCargo = {
 	goods: CargoManifest;
 };
 
+type Point = {
+	x: number;
+	y: number;
+};
+
 // cargo is a ship.cargo object, want is an optional symbol
 export function categorizeCargo(cargo: Cargo, want?: string): CategorizedCargo {
 	const wanted = cargo.inventory.filter(i => i.symbol === want || i.symbol === 'ANTIMATTER');
@@ -20,6 +25,26 @@ export function categorizeCargo(cargo: Cargo, want?: string): CategorizedCargo {
 	return {wanted: wobj, goods: gobj};
 }
 
+export function distance(a: Point, b: Point) {
+	return Math.sqrt((a.x-b.x)**2 + (a.y-b.y)**2);
+}
+
+export function sortByDistanceFrom<T extends Point>(a: Point, points: Array<T>): Array<{data: T, distance: number}>{
+	let result = points.map(function (m) { return {
+		data: m,
+		distance: distance(a, m),
+	}});
+	result.sort(function(a, b) {
+		if (a.distance < b.distance) {
+			return -1;
+		} else if (a.distance > b.distance) {
+			return 1;
+		}
+		return 0;
+	});
+	return result;
+}
+
 export function systemFromWaypoint(waypoint: string): string {
 	return waypoint.split('-').slice(0,2).join('-');
 }