From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Caleb Bassham <caleb.bassham@gmail.com>
Date: Fri, 28 Sep 2018 02:32:19 -0500
Subject: [PATCH] Call player spectator target events and improve
 implementation

Use a proper teleport for teleporting to entities in different
worlds.

Implementation improvements authored by Spottedleaf <Spottedleaf@users.noreply.github.com>
Validate that the target entity is valid and deny spectate
requests from frozen players.

Also, make sure the entity is spawned to the client before
sending the camera packet. If the entity isn't spawned clientside
when it receives the camera packet, then the client will not
spectate the target entity.

Co-authored-by: Spottedleaf <Spottedleaf@users.noreply.github.com>

diff --git a/src/main/java/net/minecraft/server/level/ServerPlayer.java b/src/main/java/net/minecraft/server/level/ServerPlayer.java
index ba938eb9844157cccedb5f673a44720538912bc5..be56cbfc2a7d966a8c5fc9c89f99f73c94e23ab6 100644
--- a/src/main/java/net/minecraft/server/level/ServerPlayer.java
+++ b/src/main/java/net/minecraft/server/level/ServerPlayer.java
@@ -1983,6 +1983,19 @@ public class ServerPlayer extends Player {
 
         this.camera = (Entity) (entity == null ? this : entity);
         if (entity1 != this.camera) {
+            // Paper start - Add PlayerStartSpectatingEntityEvent and PlayerStopSpectatingEntity Event
+            if (this.camera == this) {
+                com.destroystokyo.paper.event.player.PlayerStopSpectatingEntityEvent playerStopSpectatingEntityEvent = new com.destroystokyo.paper.event.player.PlayerStopSpectatingEntityEvent(this.getBukkitEntity(), entity1.getBukkitEntity());
+                if (!playerStopSpectatingEntityEvent.callEvent()) {
+                    return;
+                }
+            } else {
+                com.destroystokyo.paper.event.player.PlayerStartSpectatingEntityEvent playerStartSpectatingEntityEvent = new com.destroystokyo.paper.event.player.PlayerStartSpectatingEntityEvent(this.getBukkitEntity(), entity1.getBukkitEntity(), entity.getBukkitEntity());
+                if (!playerStartSpectatingEntityEvent.callEvent()) {
+                    return;
+                }
+            }
+            // Paper end
             Level world = this.camera.level();
 
             if (world instanceof ServerLevel) {
@@ -1998,7 +2011,6 @@ public class ServerPlayer extends Player {
             this.connection.send(new ClientboundSetCameraPacket(this.camera));
             this.connection.resetPosition();
         }
-
     }
 
     @Override