Chat messages when player dies and cleaner damage types

src/main/java/net/minestom/server/entity/Player.java

@@ -1,5 +1,6 @@
 package net.minestom.server.entity;
 
+import club.thectm.minecraft.text.TextBuilder;
 import club.thectm.minecraft.text.TextObject;
 import com.google.gson.JsonObject;
 import net.minestom.server.MinecraftServer;
@@ -76,6 +77,11 @@ public class Player extends LivingEntity {
     private Team team;
     private BelowNameScoreboard belowNameScoreboard;
 
+    /**
+     * Last damage source to hit this player, used to display the death message.
+     */
+    private DamageType lastDamageSource;
+
     // Abilities
     private boolean invulnerable;
     private boolean flying;
@@ -109,6 +115,14 @@ public class Player extends LivingEntity {
         setCanPickupItem(true); // By default
     }
 
+    @Override
+    public void damage(DamageType type, float value) {
+        if(!isImmune(type)) {
+            lastDamageSource = type;
+        }
+        super.damage(type, value);
+    }
+
     @Override
     public void update() {
 
@@ -229,6 +243,33 @@ public class Player extends LivingEntity {
 
     }
 
+    @Override
+    public void kill() {
+        if(!isDead()) {
+            // send death message to player
+            TextObject deathMessage;
+            if(lastDamageSource != null) {
+                deathMessage = lastDamageSource.buildDeathMessage();
+            } else { // may happen if killed by the server without applying damage
+                deathMessage = TextBuilder.of("Killed by poor programming.").build();
+            }
+            CombatEventPacket deathPacket = CombatEventPacket.death(this, Optional.empty(), deathMessage);
+            playerConnection.sendPacket(deathPacket);
+
+            // send death message to chat
+            TextObject chatMessage;
+            if(lastDamageSource != null) {
+                chatMessage = lastDamageSource.buildChatMessage(this);
+            } else { // may happen if killed by the server without applying damage
+                chatMessage = TextBuilder.of(getUsername()+" was killed by poor programming.").build();
+            }
+            MinecraftServer.getConnectionManager().getOnlinePlayers().forEach(player -> {
+                player.sendMessage(chatMessage);
+            });
+        }
+        super.kill();
+    }
+
     @Override
     public void spawn() {
 

src/main/java/net/minestom/server/entity/damage/DamageType.java

@@ -1,5 +1,8 @@
 package net.minestom.server.entity.damage;
 
+import club.thectm.minecraft.text.TextBuilder;
+import club.thectm.minecraft.text.TextObject;
+import net.minestom.server.entity.Entity;
 import net.minestom.server.entity.Player;
 
 /**
@@ -7,13 +10,31 @@ import net.minestom.server.entity.Player;
  */
 public class DamageType {
 
-    // TODO
+    public static final DamageType VOID = new DamageType("void");
+    public static final DamageType GRAVITY = new DamageType("gravity");
+    private final String identifier;
 
-    public static final DamageType VOID = new DamageType();
-    public static final DamageType PLAYER = new DamageType();
+    public DamageType(String identifier) {
+        this.identifier = identifier;
+    }
+
+    public String getIdentifier() {
+        return identifier;
+    }
+
+    public TextObject buildChatMessage(Player killed) {
+        return TextBuilder.of(killed.getUsername()+" was killed by damage of type "+identifier).build();
+    }
+
+    public TextObject buildDeathMessage() {
+        return TextBuilder.of("Killed by damage of type "+identifier).build();
+    }
 
     public static DamageType fromPlayer(Player player) {
-        // TODO
-        return PLAYER;
+        return new EntityDamage(player);
+    }
+
+    public static DamageType fromProjectile(Entity shooter, Entity projectile) {
+        return new EntityProjectileDamage(shooter,  projectile);
     }
 }

src/main/java/net/minestom/server/entity/damage/EntityDamage.java

@@ -0,0 +1,20 @@
+package net.minestom.server.entity.damage;
+
+import net.minestom.server.entity.Entity;
+
+/**
+ * Represents damage inflicted by an entity
+ */
+public class EntityDamage extends DamageType {
+
+    private final Entity source;
+
+    public EntityDamage(Entity source) {
+        super("entity_source");
+        this.source = source;
+    }
+
+    public Entity getSource() {
+        return source;
+    }
+}

src/main/java/net/minestom/server/entity/damage/EntityProjectileDamage.java

@@ -0,0 +1,26 @@
+package net.minestom.server.entity.damage;
+
+import net.minestom.server.entity.Entity;
+
+/**
+ * Represents damage inflicted by an entity, via a projectile
+ */
+public class EntityProjectileDamage extends DamageType {
+
+    private Entity shooter;
+    private final Entity projectile;
+
+    public EntityProjectileDamage(Entity shooter, Entity projectile) {
+        super("projectile_source");
+        this.shooter = shooter;
+        this.projectile = projectile;
+    }
+
+    public Entity getProjectile() {
+        return projectile;
+    }
+
+    public Entity getShooter() {
+        return shooter;
+    }
+}

src/main/java/net/minestom/server/network/packet/server/ServerPacketIdentifier.java

@@ -53,7 +53,7 @@ public class ServerPacketIdentifier {
     public static final int OPEN_SIGN_EDITOR = 0x30;
     public static final int CRAFT_RECIPE_RESPONSE = 0x31;
     public static final int PLAYER_ABILITIES = 0x32;
-    public static final int COMBAT_EVENT = 0x33; // Do not seem to be used by the client
+    public static final int COMBAT_EVENT = 0x33;
     public static final int PLAYER_INFO = 0x34;
     public static final int FACE_PLAYER = 0x35;
     public static final int PLAYER_POSITION_AND_LOOK = 0x36;

src/main/java/net/minestom/server/network/packet/server/play/CombatEventPacket.java

@@ -0,0 +1,80 @@
+package net.minestom.server.network.packet.server.play;
+
+import club.thectm.minecraft.text.TextObject;
+import net.minestom.server.chat.Chat;
+import net.minestom.server.entity.Entity;
+import net.minestom.server.entity.Player;
+import net.minestom.server.network.packet.PacketWriter;
+import net.minestom.server.network.packet.server.ServerPacket;
+import net.minestom.server.network.packet.server.ServerPacketIdentifier;
+
+import java.util.Optional;
+
+/**
+ * Packet sent during combat to a player.
+ * Only death is supported for the moment (other events are ignored anyway as of 1.15.2)
+ */
+public class CombatEventPacket implements ServerPacket {
+
+    private EventType type;
+    private int duration;
+    private int opponent;
+    private int playerID;
+    private TextObject deathMessage;
+
+    private CombatEventPacket() {}
+
+    public static CombatEventPacket enter() {
+        CombatEventPacket packet = new CombatEventPacket();
+        packet.type = EventType.ENTER_COMBAT;
+        return packet;
+    }
+
+    public static CombatEventPacket end(int durationInTicks, Optional<Entity> opponent) {
+        CombatEventPacket packet = new CombatEventPacket();
+        packet.type = EventType.END_COMBAT;
+        packet.duration = durationInTicks;
+        packet.opponent = opponent.map(Entity::getEntityId).orElse(-1);
+        return packet;
+    }
+
+    public static CombatEventPacket death(Player player, Optional<Entity> killer, TextObject message) {
+        CombatEventPacket packet = new CombatEventPacket();
+        packet.type = EventType.DEATH;
+        packet.playerID = player.getEntityId();
+        packet.opponent = killer.map(Entity::getEntityId).orElse(-1);
+        packet.deathMessage = message;
+        return packet;
+    }
+
+    @Override
+    public void write(PacketWriter writer) {
+        writer.writeVarInt(type.ordinal());
+        switch (type) {
+            case ENTER_COMBAT:
+                // nothing to add
+                break;
+
+            case END_COMBAT:
+                writer.writeVarInt(duration);
+                writer.writeInt(opponent);
+                break;
+
+            case DEATH:
+                writer.writeVarInt(playerID);
+                writer.writeInt(opponent);
+                writer.writeSizedString(deathMessage.toJson().toString());
+                break;
+        }
+    }
+
+    @Override
+    public int getId() {
+        return ServerPacketIdentifier.COMBAT_EVENT;
+    }
+
+    public enum EventType {
+        ENTER_COMBAT, END_COMBAT, // both ignored by Notchian client
+        DEATH,
+    }
+}