java-recipe-manager/src/main/lombok/org/leumasjaffe/recipe/view/AutoGrowPanel.java

package org.leumasjaffe.recipe.view;

import java.awt.Component;
import java.util.ArrayList;
import java.util.List;
import java.util.function.Function;
import java.util.function.IntFunction;
import java.util.function.Supplier;

import javax.swing.JPanel;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;

import org.jdesktop.swingx.VerticalLayout;
import org.leumasjaffe.event.AnyActionDocumentListener;

import lombok.AllArgsConstructor;

@SuppressWarnings("serial")
public class AutoGrowPanel extends JPanel {
	public static interface DocumentListenable {
		void addDocumentListener(DocumentListener dl);
		void removeDocumentListener(DocumentListener dl);
		default void setListPosition(int zeroIndex) {}
	}
	
	@AllArgsConstructor
	private class DeleteOnEmpty implements AnyActionDocumentListener {
		DocumentListenable content;
		@Override public void update(DocumentEvent e) {
			if (e.getDocument().getLength() == 0) {
				content.removeDocumentListener(this);
				int index = members.indexOf(content);
				members.remove(index);
				for (final int size = members.size(); index < size; ++index) {
					members.get(index).setListPosition(index);
				}
				remove((Component) content);
				getParent().getParent().validate();
			}
		}
	}
	
	IntFunction<DocumentListenable> prod;
	AnyActionDocumentListener grow;
	List<DocumentListenable> members = new ArrayList<>();
	
	/**
	 * @wbp.parser.constructor
	 */
	public AutoGrowPanel(Supplier<DocumentListenable> prod) {
		this(i -> prod.get(), 1);
	}
	
	public AutoGrowPanel(IntFunction<DocumentListenable> prod, int create) {
		this.prod = prod;
		
		this.grow = new AnyActionDocumentListener() {
			@Override public void update(DocumentEvent e) {
				getBack().removeDocumentListener(this);
				getBack().addDocumentListener(new DeleteOnEmpty(getBack()));
				extend();
				getParent().getParent().validate();
			}
		};

		setLayout(new VerticalLayout(5));
		while (create-- > 0) {
			extend();
		}
	}

	public <T> AutoGrowPanel(Function<T, DocumentListenable> function, List<T> ingredients) {
		this(i -> function.apply(ingredients.get(i)), ingredients.size());
		
	}

	private void extend() {
		members.add(prod.apply(members.size()));
		add((Component) getBack());
		getBack().addDocumentListener(grow);
	}

	private DocumentListenable getBack() {
		return members.get(members.size() - 1);
	}
	
}