Mansion only totem drops (#56)

* Mansion only totem drops (#49)

* fix eventhandler annotations

* minor style fixes

* don't use concurrent hashmap

src/main/java/org/purpurmc/purpurextras/modules/RaidTotemDropsModule.java

@@ -0,0 +1,70 @@
+package org.purpurmc.purpurextras.modules;
+
+import org.bukkit.Bukkit;
+import org.bukkit.Material;
+import org.bukkit.entity.Entity;
+import org.bukkit.entity.EntityType;
+import org.bukkit.entity.Raider;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.EventPriority;
+import org.bukkit.event.Listener;
+import org.bukkit.event.entity.EntityDeathEvent;
+import org.bukkit.event.raid.RaidSpawnWaveEvent;
+import org.bukkit.event.raid.RaidStopEvent;
+import org.bukkit.inventory.ItemStack;
+import org.purpurmc.purpurextras.PurpurExtras;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.SplittableRandom;
+import java.util.UUID;
+
+/**
+ * Modifies the drop rate of totems from Evokers spawned in a raid
+ */
+public class RaidTotemDropsModule implements PurpurExtrasModule, Listener {
+
+    private final SplittableRandom random;
+    private final int dropChance;
+    private final Map<UUID, Raider> raiders = new HashMap<>();
+
+    protected RaidTotemDropsModule() {
+        dropChance = PurpurExtras.getPurpurConfig().getInt("settings.raid-totem-drops.chance", 0);
+        random = new SplittableRandom();
+    }
+
+    @EventHandler(ignoreCancelled = true, priority = EventPriority.NORMAL)
+    public void onRaidSpawn(RaidSpawnWaveEvent event) {
+        event.getRaiders().forEach(r -> raiders.put(r.getUniqueId(), r));
+    }
+
+    @EventHandler(ignoreCancelled = true, priority = EventPriority.NORMAL)
+    public void onRaidDeath(EntityDeathEvent event) {
+        if (raiders.get(event.getEntity().getUniqueId()) == null) return;
+        raiders.remove(event.getEntity().getUniqueId());
+        if (event.getEntityType() != EntityType.EVOKER) return;
+        boolean totem = dropChance >= 100 || random.nextInt(1, 101) <= dropChance;
+        event.getDrops().stream().filter(i -> i.getType() == Material.TOTEM_OF_UNDYING).findFirst().ifPresentOrElse(i -> {
+            if (!totem)
+                event.getDrops().remove(i);
+        }, () -> {
+            if (totem)
+                event.getDrops().add(new ItemStack(Material.TOTEM_OF_UNDYING));
+        });
+    }
+
+    @EventHandler(ignoreCancelled = true, priority = EventPriority.NORMAL)
+    public void onRaidEnd(RaidStopEvent event) {
+        event.getRaid().getRaiders().stream().map(Entity::getUniqueId).forEach(raiders::remove);
+    }
+
+    @Override
+    public void enable() {
+        Bukkit.getServer().getPluginManager().registerEvents(this, PurpurExtras.getInstance());
+    }
+
+    @Override
+    public boolean shouldEnable() {
+        return PurpurExtras.getPurpurConfig().getBoolean("settings.raid-totem-drops.enabled", false);
+    }
+}