Prevents exiting border at speed.

#51

src/main/java/world/bentobox/border/Border.java

@@ -1,7 +1,15 @@
 package world.bentobox.border;
 
+import java.util.ArrayList;
+import java.util.List;
+
+import org.bukkit.World;
+import org.eclipse.jdt.annotation.NonNull;
+
 import world.bentobox.bentobox.api.addons.Addon;
+import world.bentobox.bentobox.api.addons.GameModeAddon;
 import world.bentobox.bentobox.api.configuration.Config;
+import world.bentobox.bentobox.util.Util;
 import world.bentobox.border.commands.IslandBorderCommand;
 import world.bentobox.border.listeners.PlayerBorder;
 import world.bentobox.border.listeners.PlayerListener;
@@ -16,6 +24,8 @@ public final class Border extends Addon {
 
     private Config<Settings> config = new Config<>(this, Settings.class);
 
+    private @NonNull List<GameModeAddon> gameModes = new ArrayList<>();
+
     @Override
     public void onLoad() {
         // Save default config.yml
@@ -26,13 +36,14 @@ public void onLoad() {
 
     @Override
     public void onEnable() {
+        gameModes.clear();
         // Register commands
         getPlugin().getAddonsManager().getGameModeAddons().forEach(gameModeAddon -> {
 
-            if (!this.settings.getDisabledGameModes().contains(
-                    gameModeAddon.getDescription().getName())) {
+            if (!this.settings.getDisabledGameModes().contains(gameModeAddon.getDescription().getName())) {
 
                 hooked = true;
+                gameModes.add(gameModeAddon);
 
                 log("Border hooking into " + gameModeAddon.getDescription().getName());
                 gameModeAddon.getPlayerCommand().ifPresent(c -> new IslandBorderCommand(this, c, "border"));
@@ -78,4 +89,11 @@ public Settings getSettings() {
         return this.settings;
     }
 
+    /**
+     * @param world
+     * @return true if world is being handled by Border
+     */
+    public boolean inGameWorld(World world) {
+        return gameModes.stream().anyMatch(gm -> gm.inWorld(Util.getWorld(world)));
+    }
 }

src/main/java/world/bentobox/border/listeners/PlayerBorder.java

@@ -88,6 +88,7 @@ public void showBarrier(Player player, Island island) {
         if (!User.getInstance(player).getMetaData(BORDER_STATE_META_DATA).map(MetaDataValue::asBoolean).orElse(addon.getSettings().isShowByDefault())) {
             return;
         }
+
         // Get the locations to show
         Location loc = player.getLocation();
         int xMin = island.getMinProtectedX();
@@ -156,6 +157,8 @@ private void teleportPlayer(Player p) {
             Vector unitVector = i.getCenter().toVector().subtract(p.getLocation().toVector()).normalize()
                     .multiply(new Vector(1,0,1));
             p.setVelocity(new Vector (0,0,0));
+            // Get distance from border
+
             Location to = p.getLocation().toVector().add(unitVector).toLocation(p.getWorld());
             to.setPitch(p.getLocation().getPitch());
             to.setYaw(p.getLocation().getYaw());

src/main/java/world/bentobox/border/listeners/PlayerListener.java

@@ -1,17 +1,24 @@
 package world.bentobox.border.listeners;
 
+import java.util.HashSet;
 import java.util.Optional;
+import java.util.Set;
+import java.util.UUID;
 
 import org.bukkit.Bukkit;
+import org.bukkit.Location;
 import org.bukkit.entity.Player;
 import org.bukkit.event.EventHandler;
 import org.bukkit.event.EventPriority;
 import org.bukkit.event.Listener;
 import org.bukkit.event.player.PlayerJoinEvent;
+import org.bukkit.event.player.PlayerMoveEvent;
 import org.bukkit.event.player.PlayerQuitEvent;
 import org.bukkit.event.player.PlayerRespawnEvent;
 import org.bukkit.event.player.PlayerTeleportEvent;
 import org.bukkit.event.vehicle.VehicleExitEvent;
+import org.bukkit.util.RayTraceResult;
+import org.bukkit.util.Vector;
 
 import world.bentobox.bentobox.api.user.User;
 import world.bentobox.bentobox.database.objects.Island;
@@ -23,10 +30,13 @@
  */
 public class PlayerListener implements Listener {
 
+    private static final Vector XZ = new Vector(1,0,1);
     private final Border addon;
+    private Set<UUID> inTeleport;
 
     public PlayerListener(Border addon) {
         this.addon = addon;
+        inTeleport = new HashSet<>();
     }
 
     @EventHandler(priority = EventPriority.NORMAL)
@@ -35,7 +45,7 @@ public void onPlayerJoin(PlayerJoinEvent e) {
         addon.getIslands().getProtectedIslandAt(e.getPlayer().getLocation()).ifPresent(i ->
         addon.getPlayerBorder().showBarrier(e.getPlayer(), i));
     }
-    
+
     @EventHandler(priority = EventPriority.NORMAL)
     public void onPlayerQuit(PlayerQuitEvent e) {
         addon.getPlayerBorder().clearUser(User.getInstance(e.getPlayer()));
@@ -56,6 +66,52 @@ public void onPlayerTeleport(PlayerTeleportEvent e) {
         addon.getPlayerBorder().showBarrier(e.getPlayer(), i)));
     }
 
+    @EventHandler(priority = EventPriority.NORMAL)
+    public void onPlayerLeaveIsland(PlayerMoveEvent e) {
+        Player p = e.getPlayer();
+        Location from = e.getFrom();
+        if (!outsideCheck(e.getPlayer(), from, e.getTo())) {
+            return;
+        }
+        // Move the player back inside the border
+        if (addon.getIslands().getProtectedIslandAt(from).isPresent()) {
+            e.setCancelled(true);
+            inTeleport.add(p.getUniqueId());
+            Util.teleportAsync(p, from).thenRun(() -> inTeleport.remove(p.getUniqueId()));
+            return;
+        }
+        // Backtrack
+        addon.getIslands().getIslandAt(p.getLocation()).ifPresent(i -> {
+            Vector unitVector = i.getCenter().toVector().subtract(p.getLocation().toVector()).normalize()
+                    .multiply(new Vector(1,0,1));
+            RayTraceResult r = i.getProtectionBoundingBox().rayTrace(p.getLocation().toVector(), unitVector, i.getRange());
+            if (r != null) {
+                inTeleport.add(p.getUniqueId());
+                Util.teleportAsync(p, r.getHitPosition().toLocation(p.getWorld(), p.getLocation().getYaw(), p.getLocation().getPitch()))
+                .thenRun(() -> {
+                    addon.getPlugin().logDebug("Teleport done");
+                    inTeleport.remove(p.getUniqueId());
+                });
+            }
+        });
+
+
+    }
+
+    private boolean outsideCheck(Player player, Location from, Location to) {
+        User user = User.getInstance(player);
+        // Only process if there is a change in X or Z coords
+        if ((from.getWorld() != null && from.getWorld().equals(to.getWorld())
+                && from.toVector().multiply(XZ).equals(to.toVector().multiply(XZ)))
+                || !addon.getSettings().isUseBarrierBlocks()
+                || !addon.inGameWorld(player.getWorld())
+                || !addon.getIslands().getIslandAt(to).filter(i -> addon.getIslands().locationIsOnIsland(player, i.getCenter())).isPresent()
+                || !user.getMetaData(PlayerBorder.BORDER_STATE_META_DATA).map(md -> md.asBoolean()).orElse(addon.getSettings().isShowByDefault())) {
+            return false;
+        }
+        return addon.getIslands().getIslandAt(to).filter(i -> !i.onIsland(to)).isPresent();
+    }
+
     /**
      * Teleports a player back home if they use a vehicle to glitch out of the world border
      * @param event - event