Add a custom currency API

src/main/java/dev/zontreck/libzontreck/currency/Account.java

@@ -0,0 +1,85 @@
+package dev.zontreck.libzontreck.currency;
+
+import dev.zontreck.ariaslib.events.EventBus;
+import dev.zontreck.libzontreck.currency.events.TransactionHistoryFlushEvent;
+import net.minecraft.core.UUIDUtil;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.ListTag;
+import net.minecraft.nbt.NbtUtils;
+import net.minecraft.nbt.Tag;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.UUID;
+
+public class Account
+{
+	public UUID player_id;
+	public List<Transaction> history;
+	public int balance;
+
+	public AccountReference getRef()
+	{
+		return new AccountReference(player_id);
+	}
+
+	protected Account(UUID ID)
+	{
+		player_id=ID;
+		history=new ArrayList<>();
+		balance=0;
+	}
+
+	public CompoundTag save()
+	{
+		CompoundTag tag = new CompoundTag();
+		tag.put("id", NbtUtils.createUUID(player_id));
+		tag.putInt("balance", balance);
+		ListTag txs = new ListTag();
+		for(Transaction tx : history)
+		{
+			txs.add(tx.save());
+		}
+
+		tag.put("history", txs);
+
+		return tag;
+	}
+
+	public Account(CompoundTag tag)
+	{
+		player_id = NbtUtils.loadUUID(tag.get("id"));
+		balance = tag.getInt("balance");
+		history=new ArrayList<>();
+		ListTag lst = tag.getList("history", Tag.TAG_COMPOUND);
+		for(Tag t : lst){
+			CompoundTag lTag = (CompoundTag) t;
+			history.add(new Transaction(lTag));
+		}
+	}
+
+	/**
+	 * Internal function for use only by the garbage collector to reduce memory footprint. Maximum of 20 transactions will be retained in the memory
+	 *
+	 * When the TX history grows beyond 20, the history should clear and it should get transferred to the long-term tx history storage. That file is not retained in memory, and only gets loaded when clearing to merge the lists. It is immediately saved and unloaded
+	 * @see LongTermTransactionHistoryRecord
+	 */
+	public void flushTxHistory()
+	{
+		LongTermTransactionHistoryRecord rec = LongTermTransactionHistoryRecord.of(player_id);
+		rec.addHistory(history);
+		rec.commit();
+		EventBus.BUS.post(new TransactionHistoryFlushEvent(this, rec, history));
+		rec = null;
+		history = new ArrayList<>();
+	}
+
+	/**
+	 * Checks if the account is a player or system account
+	 * @return True if the player has a valid UUID
+	 */
+	public boolean isValidPlayer()
+	{
+		return !player_id.equals(new UUID(0,0));
+	}
+}