From 98557dcecf081fb19d7c5b50b55a065a65945ac2 Mon Sep 17 00:00:00 2001
From: pop4959 <pop4959@gmail.com>
Date: Sat, 22 Aug 2020 09:51:23 -0700
Subject: [PATCH] Add world border checking to teleportation safety (#3536)

Fixes #3499. Please see that issue for discussion about the bug.

Fix demonstration with `/tppos`: https://imgur.com/a/Mo4okQa
---
 .../earth2me/essentials/AsyncTeleport.java    |  9 +++-
 .../essentials/utils/LocationUtil.java        | 41 ++++++++++++++++++-
 2 files changed, 47 insertions(+), 3 deletions(-)

diff --git a/Essentials/src/com/earth2me/essentials/AsyncTeleport.java b/Essentials/src/com/earth2me/essentials/AsyncTeleport.java
index 43cf1dd8d..860e56036 100644
--- a/Essentials/src/com/earth2me/essentials/AsyncTeleport.java
+++ b/Essentials/src/com/earth2me/essentials/AsyncTeleport.java
@@ -179,8 +179,13 @@ public class AsyncTeleport implements IAsyncTeleport {
             }
         }
         teleportee.setLastLocation();
-        PaperLib.getChunkAtAsync(target.getLocation()).thenAccept(chunk -> {
-            Location loc = target.getLocation();
+        final Location targetLoc = target.getLocation();
+        if (ess.getSettings().isTeleportSafetyEnabled() && LocationUtil.isBlockOutsideWorldBorder(targetLoc.getWorld(), targetLoc.getBlockX(), targetLoc.getBlockZ())) {
+            targetLoc.setX(LocationUtil.getXInsideWorldBorder(targetLoc.getWorld(), targetLoc.getBlockX()));
+            targetLoc.setZ(LocationUtil.getZInsideWorldBorder(targetLoc.getWorld(), targetLoc.getBlockZ()));
+        }
+        PaperLib.getChunkAtAsync(targetLoc).thenAccept(chunk -> {
+            Location loc = targetLoc;
             if (LocationUtil.isBlockUnsafeForUser(teleportee, chunk.getWorld(), loc.getBlockX(), loc.getBlockY(), loc.getBlockZ())) {
                 if (ess.getSettings().isTeleportSafetyEnabled()) {
                     if (ess.getSettings().isForceDisableTeleportSafety()) {
diff --git a/Essentials/src/com/earth2me/essentials/utils/LocationUtil.java b/Essentials/src/com/earth2me/essentials/utils/LocationUtil.java
index 307b0ea65..dc04ff991 100644
--- a/Essentials/src/com/earth2me/essentials/utils/LocationUtil.java
+++ b/Essentials/src/com/earth2me/essentials/utils/LocationUtil.java
@@ -92,6 +92,38 @@ public class LocationUtil {
         return y > world.getMaxHeight() || HOLLOW_MATERIALS.contains(world.getBlockAt(x, y - 1, z).getType());
     }
 
+    public static boolean isBlockOutsideWorldBorder(final World world, final int x, final int z) {
+        final Location center = world.getWorldBorder().getCenter();
+        final int radius = (int) world.getWorldBorder().getSize() / 2;
+        final int x1 = center.getBlockX() - radius, x2 = center.getBlockX() + radius;
+        final int z1 = center.getBlockZ() - radius, z2 = center.getBlockZ() + radius;
+        return x < x1 || x > x2 || z < z1 || z > z2;
+    }
+
+    public static int getXInsideWorldBorder(final World world, final int x) {
+        final Location center = world.getWorldBorder().getCenter();
+        final int radius = (int) world.getWorldBorder().getSize() / 2;
+        final int x1 = center.getBlockX() - radius, x2 = center.getBlockX() + radius;
+        if (x < x1) {
+            return x1;
+        } else if (x > x2) {
+            return x2;
+        }
+        return x;
+    }
+
+    public static int getZInsideWorldBorder(final World world, final int z) {
+        final Location center = world.getWorldBorder().getCenter();
+        final int radius = (int) world.getWorldBorder().getSize() / 2;
+        final int z1 = center.getBlockZ() - radius, z2 = center.getBlockZ() + radius;
+        if (z < z1) {
+            return z1;
+        } else if (z > z2) {
+            return z2;
+        }
+        return z;
+    }
+
     public static boolean isBlockUnsafeForUser(final IUser user, final World world, final int x, final int y, final int z) {
         if (user.getBase().isOnline() && world.equals(user.getBase().getWorld()) && (user.getBase().getGameMode() == GameMode.CREATIVE || user.getBase().getGameMode() == GameMode.SPECTATOR || user.isGodModeEnabled()) && user.getBase().getAllowFlight()) {
             return false;
@@ -100,7 +132,10 @@ public class LocationUtil {
         if (isBlockDamaging(world, x, y, z)) {
             return true;
         }
-        return isBlockAboveAir(world, x, y, z);
+        if (isBlockAboveAir(world, x, y, z)) {
+            return true;
+        }
+        return isBlockOutsideWorldBorder(world, x, z);
     }
 
     public static boolean isBlockUnsafe(final World world, final int x, final int y, final int z) {
@@ -175,6 +210,10 @@ public class LocationUtil {
         int x = loc.getBlockX();
         int y = (int) Math.round(loc.getY());
         int z = loc.getBlockZ();
+        if (isBlockOutsideWorldBorder(world, x, z)) {
+            x = getXInsideWorldBorder(world, x);
+            z = getZInsideWorldBorder(world, z);
+        }
         final int origX = x;
         final int origY = y;
         final int origZ = z;