Pretty much finished

src/main/java/mc/unraveled/reforged/data/DataManager.java

@@ -0,0 +1,101 @@
+package mc.unraveled.reforged.data;
+
+import lombok.SneakyThrows;
+import mc.unraveled.reforged.api.Baker;
+import mc.unraveled.reforged.api.Locker;
+import mc.unraveled.reforged.plugin.Traverse;
+import mc.unraveled.reforged.storage.DBUser;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.HashSet;
+import java.util.Set;
+import java.util.UUID;
+import java.util.stream.Collectors;
+
+public final class DataManager implements Baker, Locker {
+    private final Traverse plugin;
+    private Set<PlayerData> playerDataCache = new HashSet<>(); // Should only be set by the baker.
+    private boolean baked = false; // Should only be set by the baker.
+
+    public DataManager(Traverse plugin) {
+        this.plugin = plugin;
+        DBUser user = new DBUser(plugin.getSQLManager().establish());
+        user.createTable();
+        playerDataCache.addAll(user.all());
+        user.close();
+        bake();
+    }
+
+    @Nullable
+    public PlayerData getPlayerData(String playerName) {
+        return playerDataCache.stream()
+                .filter(data -> data.getUserName().equals(playerName))
+                .findFirst()
+                .orElse(null);
+    }
+
+    @Nullable
+    public PlayerData getPlayerData(UUID uuid) {
+        return playerDataCache.stream()
+                .filter(data -> data.getUuid().equals(uuid))
+                .findFirst()
+                .orElse(null);
+    }
+
+    public void addPlayerData(PlayerData data) {
+        if (baked) throw new IllegalStateException("Cannot add player data while the data manager is baked.");
+
+        playerDataCache.add(data);
+    }
+
+    public void removePlayerData(PlayerData data) {
+        if (baked) throw new IllegalStateException("Cannot remove player data while the data manager is baked.");
+
+        playerDataCache.remove(data);
+    }
+
+    public void removePlayerData(UUID uuid) {
+        if (baked) throw new IllegalStateException("Cannot remove player data while the data manager is baked.");
+
+        playerDataCache.removeIf(data -> data.getUuid().equals(uuid));
+    }
+
+    public void removePlayerData(String playerName) {
+        if (baked) throw new IllegalStateException("Cannot remove player data while the data manager is baked.");
+
+        playerDataCache.removeIf(data -> data.getUserName().equals(playerName));
+    }
+
+    public void saveData(PlayerData data) {
+        DBUser user = new DBUser(plugin.getSQLManager().establish());
+        user.insert(data);
+    }
+
+    @SneakyThrows
+    @Override
+    public void bake() {
+        if (baked) return;
+
+        synchronized (lock()) {
+            this.playerDataCache = playerDataCache.stream().collect(Collectors.toUnmodifiableSet());
+            lock().wait(1000);
+        }
+
+        this.baked = true;
+        lock().notify();
+    }
+
+    @SneakyThrows
+    @Override
+    public void unbake() {
+        if (!baked) return;
+
+        synchronized (lock()) {
+            this.playerDataCache = new HashSet<>(playerDataCache);
+            lock().wait(1000);
+        }
+
+        this.baked = false;
+        lock().notify();
+    }
+}