Add PlayerPreTeleportEvent

paper-api/src/main/java/io/papermc/paper/event/player/PlayerPreTeleportEvent.java

@@ -0,0 +1,96 @@
+package io.papermc.paper.event.player;
+
+import io.papermc.paper.entity.TeleportFlag;
+import org.bukkit.Location;
+import org.bukkit.entity.Player;
+import org.bukkit.event.Cancellable;
+import org.bukkit.event.HandlerList;
+import org.bukkit.event.player.PlayerEvent;
+import org.bukkit.event.player.PlayerTeleportEvent;
+import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.NotNull;
+import org.jspecify.annotations.NullMarked;
+import java.util.Set;
+
+/**
+ * Event that is fired before attempting to teleport the player (Allows for pre-teleport handling, such as dismounting passengers if teleporting cross-worlds etc.)
+ * After the handling of this event, the player teleport will either proceed or cancel.
+ */
+@NullMarked
+public class PlayerPreTeleportEvent extends PlayerEvent implements Cancellable {
+
+    private static final HandlerList HANDLER_LIST = new HandlerList();
+
+    private Location to;
+    private PlayerTeleportEvent.TeleportCause cause;
+    private Set<TeleportFlag> allFlags;
+
+    private boolean cancelled;
+
+    @ApiStatus.Internal
+    public PlayerPreTeleportEvent(@NotNull Player player, @NotNull Location to, @NotNull PlayerTeleportEvent.TeleportCause cause, @NotNull Set<TeleportFlag> allFlags) {
+        super(player);
+        this.to = to;
+        this.cause = cause;
+        this.allFlags = allFlags;
+    }
+
+    /**
+     * Updates the destination location of the teleport
+     */
+    public void setTo(Location location) {
+        this.to = location;
+    }
+
+    /**
+     * The current location of the player (pre teleporting)
+     * @return the current location of the player
+     */
+    public Location getFrom() {
+        return getPlayer().getLocation();
+    }
+
+    /**
+     * The location the player will be teleported to (if this event is not cancelled) {@link Location}
+     * @return the destination location the player will be teleported to
+     */
+    public Location getTo() {
+        return this.to;
+    }
+
+    /**
+     * The cause of the teleportation {@link PlayerTeleportEvent.TeleportCause}
+     * @return the cause for the teleportation (What causes this to trigger)
+     */
+    public PlayerTeleportEvent.TeleportCause getCause() {
+        return this.cause;
+    }
+
+    /**
+     * The teleport flags associated with this teleport {@link TeleportFlag}
+     * @return associated teleport flags
+     */
+    public Set<TeleportFlag> getFlags() {
+        return this.allFlags;
+    }
+
+    @Override
+    public boolean isCancelled() {
+        return false;
+    }
+
+    @Override
+    public void setCancelled(final boolean cancel) {
+        this.cancelled = cancel;
+    }
+
+    @Override
+    public @NotNull HandlerList getHandlers() {
+        return HANDLER_LIST;
+    }
+
+    public static HandlerList getHandlerList() {
+        return HANDLER_LIST;
+    }
+
+}

paper-server/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java

@@ -15,6 +15,7 @@
 import io.papermc.paper.entity.LookAnchor;
 import io.papermc.paper.entity.PaperPlayerGiveResult;
 import io.papermc.paper.entity.PlayerGiveResult;
+import io.papermc.paper.event.player.PlayerPreTeleportEvent;
 import io.papermc.paper.math.Position;
 import io.papermc.paper.util.MCUtil;
 import it.unimi.dsi.fastutil.shorts.ShortArraySet;
@@ -1477,6 +1478,21 @@ public boolean teleport(Location location, org.bukkit.event.player.PlayerTelepor
                 allFlags.add(flag);
             }
         }
+
+        // Paper start - Add PlayerPreTeleportEvent
+        // Create & Call the PlayerPreTeleportEvent.
+        PlayerPreTeleportEvent preTeleportEvent = new PlayerPreTeleportEvent(this, location, cause, allFlags); // Paper - PreTeleport API
+        this.server.getPluginManager().callEvent(preTeleportEvent);
+        // Return False to inform the Plugin that the teleport was intercepted and the teleport should not proceed
+        if (preTeleportEvent.isCancelled()) {
+            return false;
+        }
+        // Updates the teleport location if the destination was changed in the PreTeleport event
+        if (!preTeleportEvent.getTo().equals(location)) {
+            location = preTeleportEvent.getTo();
+        }
+        // Paper end - Add PlayerPreTeleportEvent
+
         boolean dismount = !allFlags.contains(io.papermc.paper.entity.TeleportFlag.EntityState.RETAIN_VEHICLE);
         boolean ignorePassengers = allFlags.contains(io.papermc.paper.entity.TeleportFlag.EntityState.RETAIN_PASSENGERS);
         // Paper end - Teleport API