Part 2 doesn't work!

Ahh seems like it should but I'm getting undefined!

Author: romellem

2019/23/network.js

@@ -39,7 +39,7 @@ class Network {
 			});
 	}
 
-	run(break_on_address = 255) {
+	partOne(break_on_address = 255) {
 		while (true) {
 			for (let nic of this.nics) {
 				let outputs = nic.run();
@@ -56,6 +56,53 @@ class Network {
 			}
 		}
 	}
+
+	partTwo(nat_address = 255) {
+		let nat_packet;
+		let last_nat_sent = [];
+
+		const IDLE_REST = 200;
+
+		// Some arbitrary number of loops to test if "idle"
+		let idle = IDLE_REST;
+		while (true) {
+			idle--;
+			for (let nic of this.nics) {
+				let outputs = nic.run();
+				if (outputs.length === 3) {
+					idle = IDLE_REST;
+					let address = outputs.shift();
+					let x = outputs.shift();
+					let y = outputs.shift();
+
+					if (address === nat_address) {
+						nat_packet = [x, y];
+					} else {
+						this.packet_queue[address].push([x, y]);
+					}
+				}
+			}
+
+			if (idle < 0 && this.packetQueueSize() === 0) {
+				// Once the network is idle, the NAT sends only the last packet
+				// it received to address 0.
+				this.packet_queue[0].push(nat_packet);
+
+				// What is the first Y value delivered by the NAT to the computer at address 0 twice in a row?
+				if (last_nat_sent[1] === nat_packet[1]) {
+					return { x: nat_packet[0], y: nat_packet[1] };
+				}
+
+				// @todo Reset NAT packet here?, e.g. `nat_packet = undefined`?
+				last_nat_sent = nat_packet;
+				idle = IDLE_REST;
+			}
+		}
+	}
+
+	packetQueueSize() {
+		return this.packet_queue.reduce((sum, queue) => sum + queue.length, 0);
+	}
 }
 
 module.exports = {

2019/23/part-one.js

@@ -2,5 +2,4 @@ const { input } = require('./input');
 const { Network } = require('./network');
 
 let network = new Network(input);
-let net_packet = network.run();
-console.log(net_packet);
+console.log(network.partOne());

2019/23/part-two.js

@@ -1,2 +1,5 @@
 const { input } = require('./input');
+const { Network } = require('./network');
 
+let network = new Network(input);
+console.log(network.partTwo());