From d5e9170109085c80b30ddb71015bc538d8bbfecc Mon Sep 17 00:00:00 2001
From: Lennart ten Wolde <0p1q9o2w@hotmail.nl>
Date: Wed, 9 Mar 2016 22:16:58 +0100
Subject: [PATCH] Manually perform idle updates. Fixed #160 #99

Manually performs idle updates by keeping track of the player's
movement.
It compensates for the missing idle packets attempting to get a ratio of
20 movement related packets per second.
---
 .../us/myles/ViaVersion/ConnectionInfo.java   | 11 +++++
 .../us/myles/ViaVersion/ViaIdleThread.java    | 42 +++++++++++++++++++
 .../us/myles/ViaVersion/ViaVersionPlugin.java |  1 +
 .../ViaVersion/handlers/ViaDecodeHandler.java |  5 +++
 4 files changed, 59 insertions(+)
 create mode 100644 src/main/java/us/myles/ViaVersion/ViaIdleThread.java

diff --git a/src/main/java/us/myles/ViaVersion/ConnectionInfo.java b/src/main/java/us/myles/ViaVersion/ConnectionInfo.java
index 964fcd3c5..28bd84f85 100644
--- a/src/main/java/us/myles/ViaVersion/ConnectionInfo.java
+++ b/src/main/java/us/myles/ViaVersion/ConnectionInfo.java
@@ -12,6 +12,9 @@ import us.myles.ViaVersion.packets.State;
 @Getter
 @Setter
 public class ConnectionInfo {
+    private static final long IDLE_PACKET_DELAY = 50L; // Update every 50ms (20tps)
+    private static final long IDLE_PACKET_LIMIT = 20; // Max 20 ticks behind
+
     private final SocketChannel channel;
     private Object lastPacket;
     private java.util.UUID UUID;
@@ -22,6 +25,7 @@ public class ConnectionInfo {
     private int entityID;
     private boolean active = true;
     private String username;
+    private long nextIdlePacket = 0L;
 
     public ConnectionInfo(SocketChannel socketChannel) {
         this.channel = socketChannel;
@@ -33,6 +37,7 @@ public class ConnectionInfo {
 
     public void setActive(boolean active) {
         this.active = active;
+        this.nextIdlePacket = System.currentTimeMillis() + IDLE_PACKET_DELAY; // Update every 50 ticks
     }
 
     public void sendRawPacket(final ByteBuf packet, boolean currentThread) {
@@ -56,4 +61,10 @@ public class ConnectionInfo {
     public void closeWindow() {
         this.openWindow = null;
     }
+
+    public void incrementIdlePacket() {
+        // Notify of next update
+        // Allow a maximum lag spike of 1 second (20 ticks/updates)
+        this.nextIdlePacket = Math.max(nextIdlePacket + IDLE_PACKET_DELAY, System.currentTimeMillis() - IDLE_PACKET_DELAY * IDLE_PACKET_LIMIT);
+    }
 }
diff --git a/src/main/java/us/myles/ViaVersion/ViaIdleThread.java b/src/main/java/us/myles/ViaVersion/ViaIdleThread.java
new file mode 100644
index 000000000..31ce146db
--- /dev/null
+++ b/src/main/java/us/myles/ViaVersion/ViaIdleThread.java
@@ -0,0 +1,42 @@
+package us.myles.ViaVersion;
+
+import org.bukkit.scheduler.BukkitRunnable;
+import us.myles.ViaVersion.api.ViaVersion;
+import us.myles.ViaVersion.util.ReflectionUtil;
+
+import java.util.Map;
+import java.util.UUID;
+
+public class ViaIdleThread extends BukkitRunnable {
+    private final Map<UUID, ConnectionInfo> portedPlayers;
+    private final Class<?> idlePacketClass;
+
+    public ViaIdleThread(Map<UUID, ConnectionInfo> portedPlayers) {
+        this.portedPlayers = portedPlayers;
+        try {
+            this.idlePacketClass = ReflectionUtil.nms("PacketPlayInFlying");
+        } catch(ClassNotFoundException e) {
+            throw new RuntimeException("Couldn't find player idle packet, help!", e);
+        }
+    }
+
+    @Override
+    public void run() {
+        for(ConnectionInfo info : portedPlayers.values()) {
+            long nextIdleUpdate = info.getNextIdlePacket();
+            if(nextIdleUpdate <= System.currentTimeMillis()) {
+                try {
+                    Object packet = idlePacketClass.newInstance();
+                    info.getChannel().pipeline().fireChannelRead(packet);
+                } catch(InstantiationException | IllegalAccessException e) {
+                    System.out.println("Failed to create idle packet.");
+                    if(ViaVersion.getInstance().isDebug()) {
+                        e.printStackTrace();
+                    }
+                } finally {
+                    info.incrementIdlePacket();
+                }
+            }
+        }
+    }
+}
diff --git a/src/main/java/us/myles/ViaVersion/ViaVersionPlugin.java b/src/main/java/us/myles/ViaVersion/ViaVersionPlugin.java
index 12625e8b2..fb9347e01 100644
--- a/src/main/java/us/myles/ViaVersion/ViaVersionPlugin.java
+++ b/src/main/java/us/myles/ViaVersion/ViaVersionPlugin.java
@@ -73,6 +73,7 @@ public class ViaVersionPlugin extends JavaPlugin implements ViaVersionAPI {
 
         getLogger().info("ViaVersion " + getDescription().getVersion() + " is now enabled, injecting. (Allows 1.8 to be accessed via 1.9)");
         injectPacketHandler();
+        new ViaIdleThread(portedPlayers).runTaskTimerAsynchronously(this, 1L, 1L); // Updates player's idle status
 
         if (getConfig().getBoolean("checkforupdates"))
             UpdateUtil.sendUpdateMessage(this);
diff --git a/src/main/java/us/myles/ViaVersion/handlers/ViaDecodeHandler.java b/src/main/java/us/myles/ViaVersion/handlers/ViaDecodeHandler.java
index d283e39e1..ef455cd07 100644
--- a/src/main/java/us/myles/ViaVersion/handlers/ViaDecodeHandler.java
+++ b/src/main/java/us/myles/ViaVersion/handlers/ViaDecodeHandler.java
@@ -38,6 +38,11 @@ public class ViaDecodeHandler extends ByteToMessageDecoder {
                     bytebuf.clear();
                     throw e;
                 }
+
+                // Update idle status (player, position, look, positionandlook)
+                if(id == 0x0F || id == 0x0E || id == 0x0D || id == 0x0C) {
+                    info.incrementIdlePacket();
+                }
             }
             // call minecraft decoder
             list.addAll(PacketUtil.callDecode(this.minecraftDecoder, ctx, bytebuf));