java-org.hwo.ui/src/org/hwo/models/History.java

package org.hwo.models;

import java.util.Arrays;
import java.util.LinkedList;

public class History<E> {
	private LinkedList<HistoryListener<E>> historyListeners = new LinkedList<>();
	private LinkedList<E> items = new LinkedList<>();
	private int historySize = 10;
	
	public History(){
	}
	
	public History(int historySize) {
		this.historySize = historySize;
	}
	
	public void addHistoryListener(HistoryListener<E> listener) {
		historyListeners.add(listener);
	}
	public void removeHistoryListener(HistoryListener<E> listener) {
		historyListeners.remove(listener);
	}
	
	protected void fireHistoryChanged() {
		for (HistoryListener<E> historyListener : historyListeners) {
			historyListener.HistoryChanged(this);
		}
	}
	protected void fireHistoryItemAdded(E item) {
		for (HistoryListener<E> historyListener : historyListeners) {
			historyListener.HistoryItemAdded(this,item);
		}
	}
	protected void fireHistoryItemRemoved(E item) {
		for (HistoryListener<E> historyListener : historyListeners) {
			historyListener.HistoryItemRemoved(this, item);
		}
	}
	
	public void clear() {
		items.clear();
		fireHistoryChanged();
	}
	
	public boolean contains(E item) {
		return items.contains(item);
	}
	
	public int size() {
		return this.items.size();
	}
	
	public E get(int index) {
		return this.items.get(index);
	}
	
	public Object[] getItems(){
		return items.toArray();
	}
	
	public E[] getItems(E[] at) {
		return items.toArray(at);
	}
	
	public void setItems(E[] items) {
		this.items.clear();
		this.items.addAll(Arrays.asList(items));
		fireHistoryChanged();
		
		clampHistory();
	}
	
	public void add(E item) {
		if (this.items.contains(item)) {
			if (this.items.indexOf(item) > 0) {
				this.items.remove(item);
				this.items.add(0,item);
				fireHistoryChanged();
				clampHistory();
				return;
			}
		} else {
			this.items.add(0,item);
			fireHistoryItemAdded(item);
			clampHistory();
		}
	}
	
	public void remove(E item) {
		this.items.remove(item);
		fireHistoryItemRemoved(item);
	}

	private void clampHistory() {
		if (items.size() > historySize) {
			while (items.size() > historySize) {
				fireHistoryItemRemoved(items.removeLast());
			}
		}
	}
	
	
	
	public int getHistorySize() {
		return historySize;
	}

	public void setHistorySize(int historySize) {
		this.historySize = historySize;
	}



	public static interface HistoryListener<T> {
		void HistoryChanged(History<T> history);
		void HistoryItemAdded(History<T> history,T item);
		void HistoryItemRemoved(History<T> history,T item);
	}
}