Fix mob always dropping xp when killed (#823)

src/main/java/net/glowstone/block/blocktype/BlockTnt.java

@@ -15,20 +15,33 @@
 public class BlockTnt extends BlockType {
 
     /**
-     * Convert a TNT block into a primed TNT entity.
+     * Convert a TNT block into a primed TNT entity with the player who ignited the TNT.
      *
      * @param tntBlock The block to ignite.
      * @param ignitedByExplosion True if another explosion caused this ignition.
+     * @param player The player who ignited the TNT.
      */
-    public static void igniteBlock(Block tntBlock, boolean ignitedByExplosion) {
+    public static void igniteBlock(
+        Block tntBlock, boolean ignitedByExplosion, GlowPlayer player) {
         tntBlock.setType(Material.AIR);
         World world = tntBlock.getWorld();
         GlowTntPrimed tnt = (GlowTntPrimed) world
             .spawnEntity(tntBlock.getLocation().add(0.5, 0, 0.5), EntityType.PRIMED_TNT);
+        tnt.setSource(player);
         tnt.setIgnitedByExplosion(ignitedByExplosion);
         world.playSound(tntBlock.getLocation(), Sound.ENTITY_TNT_PRIMED, 1, 1);
     }
 
+    /**
+     * Convert a TNT block into a primed TNT entity.
+     *
+     * @param tntBlock The block to ignite.
+     * @param ignitedByExplosion True if another explosion caused this ignition.
+     */
+    public static void igniteBlock(Block tntBlock, boolean ignitedByExplosion) {
+        igniteBlock(tntBlock, ignitedByExplosion, null);
+    }
+
     @Override
     public void afterPlace(GlowPlayer player, GlowBlock block, ItemStack holding,
         GlowBlockState oldState) {
@@ -44,7 +57,7 @@ public void onNearBlockChanged(GlowBlock block, BlockFace face, GlowBlock change
     @Override
     public void updatePhysics(GlowBlock me) {
         if (me.isBlockIndirectlyPowered()) {
-            igniteBlock(me, false);
+            igniteBlock(me, false, null);
         }
     }
 

src/main/java/net/glowstone/block/itemtype/ItemFlintAndSteel.java

@@ -27,7 +27,7 @@ public boolean onToolRightClick(GlowPlayer player, GlowBlock target, BlockFace f
             return true;
         }
         if (target.getType() == Material.TNT) {
-            fireTnt(target);
+            fireTnt(target, player);
             return true;
         }
         if (target.isFlammable() || target.getType().isOccluding()) {
@@ -49,8 +49,8 @@ private void fireNetherPortal(GlowBlock target, BlockFace face) {
         }
     }
 
-    private void fireTnt(GlowBlock tnt) {
-        BlockTnt.igniteBlock(tnt, false);
+    private void fireTnt(GlowBlock tnt,GlowPlayer player) {
+        BlockTnt.igniteBlock(tnt, false, player);
     }
 
     private boolean setBlockOnFire(GlowPlayer player, GlowBlock clicked, BlockFace face,

src/main/java/net/glowstone/entity/GlowLivingEntity.java

@@ -31,6 +31,7 @@
 import net.glowstone.entity.meta.MetadataIndex;
 import net.glowstone.entity.objects.GlowExperienceOrb;
 import net.glowstone.entity.objects.GlowLeashHitch;
+import net.glowstone.entity.passive.GlowWolf;
 import net.glowstone.entity.projectile.GlowProjectile;
 import net.glowstone.inventory.EquipmentMonitor;
 import net.glowstone.net.GlowSession;
@@ -97,6 +98,15 @@ public abstract class GlowLivingEntity extends GlowEntity implements LivingEntit
     @Getter
     @Setter
     private Player killer;
+
+    /**
+     * The tick that the entity got hit by a player.
+     * The default value was set to -101 rather than 0.
+     */
+    @Getter
+    @Setter
+    private int playerDamageTick = -101;
+
     /**
      * Whether entities can collide with this entity.
      */
@@ -815,7 +825,8 @@ public void setHealth(double health) {
                 if (world.getGameRuleMap().getBoolean("doMobLoot")) {
                     LootData data = LootingManager.generate(this);
                     deathEvent.getDrops().addAll(data.getItems());
-                    if (data.getExperience() > 0) {
+                    // Only drop experience when hit by a player within 5 seconds (100 game ticks)
+                    if (ticksLived - playerDamageTick <= 100 && data.getExperience() > 0) {
                         // split experience
                         Integer[] values = ExperienceSplitter.cut(data.getExperience());
                         for (Integer exp : values) {
@@ -891,6 +902,14 @@ public void damage(double amount, Entity source, DamageCause cause) {
         // apply damage
         amount = event.getFinalDamage();
         lastDamage = amount;
+
+        if (isPlayerHit(source)) {
+            playerDamageTick = ticksLived;
+            if (health - amount <= 0) {
+                killer = determinePlayer(source);
+            }
+        }
+
         setHealth(health - amount);
         playEffect(EntityEffect.HURT);
 
@@ -915,6 +934,62 @@ public void damage(double amount, Entity source, DamageCause cause) {
         setLastDamager(source);
     }
 
+    /**
+     * Checks if the source of damage was caused by a player.
+     *
+     * @param source The source of damage
+     * @return true if the source of damage was caused by a player, false otherwise.
+     */
+    private boolean isPlayerHit(Entity source) {
+        // If directly damaged by a player
+        if (source instanceof GlowPlayer) {
+            return true;
+        }
+
+        // If damaged by a TNT ignited by a player
+        if (source instanceof GlowTntPrimed) {
+            GlowPlayer player = (GlowPlayer)((GlowTntPrimed) source).getSource();
+            return
+                player != null
+                && (player.getGameMode() == GameMode.SURVIVAL
+                || player.getGameMode() == GameMode.ADVENTURE);
+        }
+
+        // If damaged by a tamed wolf
+        if (source instanceof GlowWolf) {
+            return ((GlowWolf) source).isTamed();
+        }
+
+        // All other cases
+        return false;
+    }
+
+    /**
+     * Determines the player who did the damage from source of damage.
+     *
+     * @param source The incoming source of damage
+     * @return Player object if the source of damage was caused by a player, null otherwise.
+     */
+    private Player determinePlayer(Entity source) {
+        // If been killed by an ignited tnt
+        if (source instanceof GlowTntPrimed) {
+            return (Player)((GlowTntPrimed) source).getSource();
+        }
+
+        // If been killed by a player
+        if (source instanceof GlowPlayer) {
+            return (Player) source;
+        }
+
+        // If been killed by a tamed wolf
+        if (source instanceof GlowWolf) {
+            return (Player)((GlowWolf) source).getOwner();
+        }
+
+        // All other cases
+        return null;
+    }
+
     @Override
     public double getMaxHealth() {
         return attributeManager.getPropertyValue(Key.KEY_MAX_HEALTH);

src/main/java/net/glowstone/entity/GlowTntPrimed.java

@@ -22,8 +22,19 @@ public class GlowTntPrimed extends GlowExplosive implements TNTPrimed {
     @Getter
     @Setter
     private int fuseTicks;
+    @Setter
     private Entity source;
 
+    /**
+     * Get the player that ignited the TNT.
+     *
+     * @return Player that ignited the TNT
+     */
+    public GlowPlayer getPlayer() {
+        Entity source = getSource();
+        return (source instanceof GlowPlayer) ? (GlowPlayer) source : null;
+    }
+
     /**
      * Creates a primed TNT block.
      *
@@ -98,7 +109,7 @@ public List<Message> createSpawnMessage() {
 
     @Override
     public final Entity getSource() {
-        return source.isValid() ? source : null;
+        return (source != null && source.isValid()) ? source : null;
     }
 
     @Override

src/main/java/net/glowstone/entity/projectile/GlowArrow.java

@@ -2,6 +2,7 @@
 
 import lombok.Getter;
 import lombok.Setter;
+import net.glowstone.block.GlowBlock;
 import net.glowstone.block.blocktype.BlockTnt;
 import net.glowstone.entity.meta.MetadataIndex;
 import net.glowstone.net.message.play.entity.SpawnObjectMessage;
@@ -81,7 +82,7 @@ public void collide(Block block) {
         setFireTicks(0); // Arrows stop burning when they land, and ignite only TNT
         switch (block.getType()) {
             case TNT:
-                BlockTnt.igniteBlock(block, false);
+                BlockTnt.igniteBlock((GlowBlock) block, false);
                 break;
             case WOOD_BUTTON:
             case STONE_BUTTON: