Scoreboard Support and API

src/main/java/org/cloudburstmc/server/player/Player.java

@@ -93,8 +93,11 @@
 import org.cloudburstmc.server.registry.CommandRegistry;
 import org.cloudburstmc.server.registry.EntityRegistry;
 import org.cloudburstmc.server.registry.ItemRegistry;
+import org.cloudburstmc.server.scoreboard.Scoreboard;
+import org.cloudburstmc.server.scoreboard.impl.CloudScoreboard;
 import org.cloudburstmc.server.utils.*;
 
+import javax.annotation.Nullable;
 import java.io.File;
 import java.net.InetSocketAddress;
 import java.util.*;
@@ -221,6 +224,8 @@ public class Player extends Human implements CommandSender, InventoryHolder, Chu
 
     private final PlayerChunkManager chunkManager = new PlayerChunkManager(this);
 
+    private Scoreboard scoreboard;
+
     public int packetsRecieved;
 
     public long lastSkinChange;
@@ -2008,6 +2013,10 @@ public void close(TextContainer message, String reason, boolean notify) {
                 if (this.fishing != null) {
                     this.stopFishing(false);
                 }
+                if (this.scoreboard != null) {
+                    ((CloudScoreboard) this.scoreboard).getPlayers().remove(this);
+                    this.scoreboard = null;
+                }
             }
 
             for (Player player : new ArrayList<>(this.server.getOnlinePlayers().values())) {
@@ -3343,6 +3352,33 @@ public boolean pickupEntity(Entity entity, boolean near) {
         return false;
     }
 
+    /**
+     * Gets the current {@link Scoreboard} of
+     * the player
+     *
+     * @return the current scoreboard of the player
+     */
+    @Nullable
+    public Scoreboard getScoreboard() {
+        return this.scoreboard;
+    }
+
+    /**
+     * Sets the player's {@link Scoreboard} to the
+     * specified scoreboard
+     *
+     * @param scoreboard the scoreboard to set
+     */
+    public void setScoreboard(@Nullable Scoreboard scoreboard) {
+        if (this.scoreboard != null) {
+            ((CloudScoreboard) this.scoreboard).hide(this);
+        }
+        if (scoreboard != null) {
+            ((CloudScoreboard) scoreboard).show(this);
+        }
+        this.scoreboard = scoreboard;
+    }
+
     @Override
     public String toString() {
         return "Player(name=" + getName() + ")";

src/main/java/org/cloudburstmc/server/scoreboard/DisplayMode.java

@@ -0,0 +1,26 @@
+package org.cloudburstmc.server.scoreboard;
+
+/**
+ * Represents where a {@link ScoreboardObjective} should be displayed
+ * on a {@link Scoreboard}.
+ */
+public enum DisplayMode {
+
+    /**
+     * Display mode that shows the objective
+     * in the player list.
+     */
+    LIST,
+
+    /**
+     * Display mode that shows the objective
+     * ion the sidebar.
+     */
+    SIDEBAR,
+
+    /**
+     * Display mode that shows the objective
+     * below the player's name.
+     */
+    BELOWNAME
+}

src/main/java/org/cloudburstmc/server/scoreboard/Score.java

@@ -0,0 +1,81 @@
+package org.cloudburstmc.server.scoreboard;
+
+import org.cloudburstmc.server.scoreboard.impl.CloudScore;
+
+/**
+ * Represents a score for a {@link ScoreboardObjective}.
+ */
+public interface Score<T> {
+
+    /**
+     * Gets the {@link ScoreboardObjective} of
+     * this score
+     *
+     * @return the scoreboard objective of this score
+     */
+    ScoreboardObjective getObjective();
+
+    /**
+     * Gets the amount
+     *
+     * @return the amount
+     */
+    int getAmount();
+
+    /**
+     * Sets the amount
+     *
+     * @param value the amount
+     */
+    void setAmount(int value);
+
+    /**
+     * Gets the name of this score
+     *
+     * @return the name of this score
+     */
+    String getName();
+
+    /**
+     * Gets the type of score this is
+     *
+     * @return the type of score this is
+     */
+    ScoreType<T> getScoreType();
+
+    /**
+     * Gets the value of this score
+     *
+     * @return the value of this score
+     */
+    T getValue();
+
+    /**
+     * Sets the value of the score
+     *
+     * @param value the value of the score
+     */
+    void setValue(T value);
+
+    /**
+     * Creates a new instance of a {@link ScoreBuilder}
+     *
+     * @param scoreType the score type
+     * @param <U> the value
+     * @return a new instance of a score builder
+     */
+    static <U> ScoreBuilder<U> builder(ScoreType<U> scoreType) {
+        return CloudScore.providedBuilder(scoreType);
+    }
+
+    interface ScoreBuilder<T> {
+
+        ScoreBuilder<T> amount(int amount);
+
+        ScoreBuilder<T> name(String name);
+
+        ScoreBuilder<T> value(T value);
+
+        Score<T> build();
+    }
+}

src/main/java/org/cloudburstmc/server/scoreboard/ScoreType.java

@@ -0,0 +1,50 @@
+package org.cloudburstmc.server.scoreboard;
+
+import lombok.AccessLevel;
+import lombok.AllArgsConstructor;
+import org.cloudburstmc.server.entity.Entity;
+import org.cloudburstmc.server.player.Player;
+
+/**
+ * Represents the score type for the
+ * {@link Score} in a {@link Scoreboard}.
+ */
+@AllArgsConstructor(access = AccessLevel.PRIVATE)
+public class ScoreType<T> {
+
+    /**
+     * A score type where the value is
+     * that of a player.
+     */
+    public static final ScoreType<Player> PLAYER = new ScoreType<>("player", Player.class);
+
+    /**
+     * A score type where the value is
+     * that of an entity.
+     */
+    public static final ScoreType<Entity> ENTITY = new ScoreType<>("entity", Entity.class);
+
+    /**
+     * A fake score type that does not
+     * require an entity or player.
+     */
+    public static final ScoreType<String> FAKE = new ScoreType<>("fake", String.class);
+
+    private String name;
+    private Class<T> supportedType;
+
+    /**
+     * Gets the supported value type for
+     * this score type
+     *
+     * @return the supported value for this score type
+     */
+    public Class<T> getSupportedType() {
+        return supportedType;
+    }
+
+    @Override
+    public String toString() {
+        return name;
+    }
+}

src/main/java/org/cloudburstmc/server/scoreboard/Scoreboard.java

@@ -0,0 +1,61 @@
+package org.cloudburstmc.server.scoreboard;
+
+import org.cloudburstmc.server.player.Player;
+import org.cloudburstmc.server.scoreboard.impl.CloudScoreboard;
+
+import javax.annotation.Nullable;
+import java.util.Collection;
+import java.util.Set;
+
+/**
+ * Represents a scoreboard in the game, which can contain
+ * various information and be used to display data for players.
+ */
+public interface Scoreboard {
+
+    /**
+     * Gets the {@link ScoreboardObjective} with the specified name
+     *
+     * @param objectiveName the name of the objective
+     * @return the objective with the specified name
+     */
+    @Nullable
+    ScoreboardObjective getObjective(String objectiveName);
+
+    Set<ScoreboardObjective> getObjectives();
+
+    /**
+     * Registers a new {@link ScoreboardObjective} to the scoreboard
+     * @param objective the objective
+     */
+    void registerObjective(ScoreboardObjective objective);
+
+    /**
+     * Deregisters a {@link ScoreboardObjective} from the scoreboard.
+     *
+     * @param name the name of the objective
+     */
+    void deregisterObjective(String name);
+
+    /**
+     * Creates a new instance of a {@link ScoreboardBuilder}
+     *
+     * @return a new instance of a scoreboard builder
+     */
+    static ScoreboardBuilder builder() {
+        return CloudScoreboard.providedBuilder();
+    }
+
+    interface ScoreboardBuilder {
+
+        ScoreboardBuilder objectives(ScoreboardObjective... objectives);
+
+        ScoreboardBuilder players(Player... players);
+
+        default ScoreboardBuilder players(Collection<Player> players) {
+            return this.players(players.toArray(new Player[0]));
+        }
+
+        Scoreboard build();
+    }
+}

src/main/java/org/cloudburstmc/server/scoreboard/ScoreboardCriteria.java

@@ -0,0 +1,12 @@
+package org.cloudburstmc.server.scoreboard;
+
+/**
+ * The criterion for a {@link ScoreboardObjective}.
+ */
+public enum ScoreboardCriteria {
+
+    /**
+     * Dummy scoreboard criterion.
+     */
+    DUMMY
+}