#642: Add a DragonBattle API to manipulate respawn phases etc

By: Parker Hawke <hawkeboyz2@hotmail.com>

paper-server/src/main/java/org/bukkit/craftbukkit/boss/CraftDragonBattle.java

@@ -0,0 +1,85 @@
+package org.bukkit.craftbukkit.boss;
+
+import com.google.common.base.Preconditions;
+import net.minecraft.server.EnderDragonBattle;
+import net.minecraft.server.Entity;
+import net.minecraft.server.EnumDragonRespawn;
+import org.bukkit.Location;
+import org.bukkit.boss.BossBar;
+import org.bukkit.boss.DragonBattle;
+import org.bukkit.entity.EnderDragon;
+
+public class CraftDragonBattle implements DragonBattle {
+
+    private final EnderDragonBattle handle;
+
+    public CraftDragonBattle(EnderDragonBattle handle) {
+        this.handle = handle;
+    }
+
+    @Override
+    public EnderDragon getEnderDragon() {
+        Entity entity = handle.d.getEntity(handle.m);
+        return (entity != null) ? (EnderDragon) entity.getBukkitEntity() : null;
+    }
+
+    @Override
+    public BossBar getBossBar() {
+        return new CraftBossBar(handle.bossBattle);
+    }
+
+    @Override
+    public Location getEndPortalLocation() {
+        return new Location(handle.d.getWorld(), handle.o.getX(), handle.o.getY(), handle.o.getZ());
+    }
+
+    @Override
+    public boolean hasBeenPreviouslyKilled() {
+        return handle.d(); // PAIL rename hasBeenPreviouslyKilled
+    }
+
+    @Override
+    public void initiateRespawn() {
+        this.handle.e(); // PAIL rename initiateRespawn
+    }
+
+    @Override
+    public RespawnPhase getRespawnPhase() {
+        return toBukkitRespawnPhase(handle.p);
+    }
+
+    @Override
+    public boolean setRespawnPhase(RespawnPhase phase) {
+        Preconditions.checkArgument(phase != null && phase != RespawnPhase.NONE, "Invalid respawn phase provided: %s", phase);
+
+        if (handle.p == null) {
+            return false;
+        }
+
+        this.handle.a(toNMSRespawnPhase(phase));
+        return true;
+    }
+
+    @Override
+    public void resetCrystals() {
+        this.handle.f(); // PAIL rename resetCrystals
+    }
+
+    @Override
+    public int hashCode() {
+        return handle.hashCode();
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        return obj instanceof CraftDragonBattle && ((CraftDragonBattle) obj).handle == this.handle;
+    }
+
+    private RespawnPhase toBukkitRespawnPhase(EnumDragonRespawn phase) {
+        return (phase != null) ? RespawnPhase.values()[phase.ordinal()] : RespawnPhase.NONE;
+    }
+
+    private EnumDragonRespawn toNMSRespawnPhase(RespawnPhase phase) {
+        return (phase != RespawnPhase.NONE) ? EnumDragonRespawn.values()[phase.ordinal()] : null;
+    }
+}