From a47bb93d24109141ce92e58eeb55252c79d37bd3 Mon Sep 17 00:00:00 2001
From: Lixfel <agga-games@gmx.de>
Date: Mon, 4 Oct 2021 13:09:28 +0200
Subject: [PATCH] Displayable

---
 src/de/steamwar/lobby/Displayable.java | 91 ++++++++++++++++++++++++++
 1 file changed, 91 insertions(+)
 create mode 100644 src/de/steamwar/lobby/Displayable.java

diff --git a/src/de/steamwar/lobby/Displayable.java b/src/de/steamwar/lobby/Displayable.java
new file mode 100644
index 0000000..7fd21c5
--- /dev/null
+++ b/src/de/steamwar/lobby/Displayable.java
@@ -0,0 +1,91 @@
+/*
+ * This file is a part of the SteamWar software.
+ *
+ * Copyright (C) 2021  SteamWar.de-Serverteam
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package de.steamwar.lobby;
+
+import de.steamwar.lobby.listener.BasicListener;
+import org.bukkit.Location;
+import org.bukkit.entity.Player;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.HandlerList;
+import org.bukkit.event.player.PlayerJoinEvent;
+import org.bukkit.event.player.PlayerMoveEvent;
+import org.bukkit.event.player.PlayerQuitEvent;
+
+import java.util.HashSet;
+import java.util.Set;
+import java.util.function.Consumer;
+
+public class Displayable extends BasicListener {
+
+    private final Set<Player> visible = new HashSet<>();
+
+    private final int chunkX;
+    private final int chunkZ;
+    private final Consumer<Player> show;
+    private final Consumer<Player> hide;
+
+    public Displayable(Location location, Consumer<Player> show, Consumer<Player> hide) {
+        this.chunkX = posToChunk(location.getX());
+        this.chunkZ = posToChunk(location.getZ());
+        this.show = show;
+        this.hide = hide;
+    }
+
+    @EventHandler
+    public void onJoin(PlayerJoinEvent e) {
+        checkLocation(e.getPlayer(), e.getPlayer().getLocation());
+    }
+
+    @EventHandler
+    public void onMove(PlayerMoveEvent e) {
+        checkLocation(e.getPlayer(), e.getTo());
+    }
+
+    private void checkLocation(Player player, Location at) {
+        boolean shown = visible.contains(player);
+        int viewDistance = player.getClientViewDistance();
+        boolean see = Math.abs(chunkX - posToChunk(at.getX())) < viewDistance && Math.abs(chunkZ - posToChunk(at.getZ())) < viewDistance;
+
+        if(!shown && see) {
+            show.accept(player);
+            visible.add(player);
+        }
+
+        if(shown && !see) {
+            hide.accept(player);
+            visible.remove(player);
+        }
+    }
+
+    @EventHandler
+    public void onQuit(PlayerQuitEvent e) {
+        visible.remove(e.getPlayer());
+    }
+
+    public void delete() {
+        visible.forEach(hide);
+        visible.clear();
+        HandlerList.unregisterAll(this);
+    }
+
+    private int posToChunk(double coord) {
+        return (int)(coord / 16) - (coord < 0 ? 1 : 0);
+    }
+}