Begin implementing the functions that actually modify the game board

common/src/algorithms/processCard.spec.ts

@@ -0,0 +1,25 @@
+import { tractorBeam } from "./processCard";
+import { expect } from "chai";
+import "mocha";
+
+describe("The tractorBeam function", () => {
+	it("should move the ships closer", () => {
+		let b = [
+			null, "p1", null, null, "p2", null, null, "p3", null
+		];
+		let nb = [...b];
+		tractorBeam(nb, 4, 1);
+
+		expect(nb).to.have.length(9);
+
+		expect(nb[0]).to.be.null;
+		expect(nb[1]).to.be.null;
+		expect(nb[2]).to.equal("p1");
+		expect(nb[3]).to.be.null;
+		expect(nb[4]).to.equal("p2");
+		expect(nb[5]).to.be.null;
+		expect(nb[6]).to.equal("p3");
+		expect(nb[7]).to.be.null;
+		expect(nb[8]).to.be.null;
+	});
+});

common/src/algorithms/processCard.ts

@@ -0,0 +1,52 @@
+import { FuelCard } from "../types/FuelCard";
+import { Board } from "../types/GameBoard";
+
+/** @internal */
+export function tractorBeam(board: Board, origin: number, magnitude: number) {
+	let delta = 0;
+	while (true) {
+		delta++;
+
+		let behind = origin - delta;
+		let ahead = origin + delta;
+
+		/*
+		Check for a ship behind the origin, if there is a ship there then pull
+		it towards the origin (forwards). If it were to collide with another
+		ship, then drift until it no longer collides.
+		*/
+		if (behind >= 0 && board[behind] != null) {
+			let ship = board[behind];
+			let localMagnitude = magnitude;
+			while (board[behind + localMagnitude] != null) {
+				localMagnitude++;
+			};
+			board[behind + localMagnitude] = ship
+			board[behind] = null;
+		};
+
+		/*
+		Check for a ship ahead of the origin, if there is a ship there then
+		pull it towards the origin (backwards). If it were to collide with
+		another ship, then drift until it no longer collides.
+		*/
+		if (ahead < board.length && board[ahead] != null) {
+			let ship = board[ahead];
+			let localMagnitude = magnitude;
+			while (board[ahead - localMagnitude] != null) {
+				localMagnitude++;
+			};
+			board[ahead - localMagnitude] = ship
+			board[ahead] = null;
+		};
+
+		if (behind < 0 && ahead >= board.length) {
+			break;
+		};
+	};
+};
+
+/** @internal */
+export function moveShip(board: Board, shipLocation: number, fuel: FuelCard) {};
+
+export function processCard(board: Board, shipLocation: number, fuel: FuelCard) {};

common/src/index.ts

@@ -2,6 +2,7 @@
 	export { Status } from "./enums/Status";
 
 // Algorithms
+	export * from "./algorithms/processCard";
 	export * from "./algorithms/movementDirection";
 
 // Data