strangedb/src/main/java/it/cavallium/strangedb/lists/StrandeDbList.java

package it.cavallium.strangedb.lists;

import it.unimi.dsi.fastutil.longs.LongArrayList;
import it.cavallium.strangedb.EnhancedObject;
import it.cavallium.strangedb.database.IDatabaseTools;

import java.io.IOException;
import java.util.StringJoiner;

public abstract class StrandeDbList<T> extends EnhancedObject {

	private final Object indicesAccessLock = new Object();

	protected abstract LongArrayList getIndices();

	public StrandeDbList() {

	}

	public StrandeDbList(IDatabaseTools databaseTools) throws IOException {
		super(databaseTools);
	}

	public T get(int index) throws IOException {
		synchronized (indicesAccessLock) {
			long uid = getIndices().getLong(index);
			return loadItem(uid);
		}
	}

	public void add(T value) throws IOException {
		long uid = databaseTools.getObjectsIO().newNullObject();
		synchronized (indicesAccessLock) {
			getIndices().add(uid);
			writeItemToDisk(uid, value);
		}
	}

	public void update(int index, T value) throws IOException {
		synchronized (indicesAccessLock) {
			long uid = getIndices().getLong(index);
			writeItemToDisk(uid, value);
		}
	}

	public void set(int index, T value) throws IOException {
		long uid = databaseTools.getObjectsIO().newNullObject();
		synchronized (indicesAccessLock) {
			getIndices().set(index, uid);
			writeItemToDisk(uid, value);
		}
	}

	public void add(int index, T value) throws IOException {
		long uid = databaseTools.getObjectsIO().newNullObject();
		synchronized (indicesAccessLock) {
			getIndices().add(index, uid);
			writeItemToDisk(uid, value);
		}
	}

	public T getLast() throws IOException {
		synchronized (indicesAccessLock) {
			if (getIndices().size() > 0) {
				return get(getIndices().size() - 1);
			} else {
				return null;
			}
		}
	}

	public boolean isEmpty() {
		synchronized (indicesAccessLock) {
			return getIndices().size() <= 0;
		}
	}

	public int size() {
		synchronized (indicesAccessLock) {
			return getIndices().size();
		}
	}

	protected abstract T loadItem(long uid) throws IOException;

	protected abstract void writeItemToDisk(long uid, T item) throws IOException;

	@Override
	public String toString() {
		return new StringJoiner(", ", StrandeDbList.class.getSimpleName() + "[", "]")
						.add(getIndices().size() + " items")
						.toString();
	}
}