From ac21d58606c2c4d7e4e319bb9487b3b7307f104f Mon Sep 17 00:00:00 2001
From: Dece <shgck@pistache.land>
Date: Mon, 23 Dec 2019 13:07:43 +0100
Subject: [PATCH] Day 23 part 2

---
 2019/day23.py | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/2019/day23.py b/2019/day23.py
index 1a4a3d6..08825e7 100644
--- a/2019/day23.py
+++ b/2019/day23.py
@@ -1,5 +1,6 @@
 from queue import Empty, SimpleQueue
 from threading import Thread
+import time
 
 from intcode import Intcode
 
@@ -7,19 +8,41 @@ from intcode import Intcode
 def main():
     codes = Intcode.parse_file("day23.txt")
     network = Network(50, codes)
+
+    # Part 1
     for nic in network.nics:
         thread = Thread(target=lambda: nic.run(), name=f"NIC {nic.address}")
         thread.start()
+    
+    # Part 2
+    last_nat_y = None
+    while True:
+        time.sleep(0.1)
+        for nic in network.nics:
+            if not nic.inq.empty:
+                break
+        else:
+            if not network.last_nat_packet:
+                continue
+            x, y = network.last_nat_packet
+            if y == last_nat_y:
+                exit(f"Sending another {y} from NAT.")
+            last_nat_y = y
+            print(f"Network is idle, sending NAT packet to 0.")
+            network.nics[0].inq.put(x)
+            network.nics[0].inq.put(y)
 
 
 class Network:
 
     def __init__(self, size, codes):
         self.nics = [NIC(address, self, codes) for address in range(size)]
+        self.last_nat_packet = None
 
     def route(self, sender, dest, x, y):
         if dest == 255:
-            print(f"Packet to 255: {x, y}.")
+            print(f"NAT: {x, y}.")
+            self.last_nat_packet = (x, y)
             return
         print(f"Send {x, y} from {sender} to {dest}")
         self.nics[dest].inq.put(x)