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.Consumer;
import java.util.function.Function;
import java.util.function.IntConsumer;
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);
				onDelete.accept(index);
				for (final int size = members.size(); index < size; ++index) {
					members.get(index).setListPosition(index);
				}
				remove((Component) content);
				validateNthParent(4);
			}
		}		
	}
	
	@AllArgsConstructor
	private class ExtendAction<T, C extends Component & DocumentListenable> implements AnyActionDocumentListener {
		final Function<T, C> factory;
		final Consumer<? super T> previous;
		final Supplier<? extends T> next;
		T current = null;

		@Override
		public void update(DocumentEvent e) {
			previous.accept(current);
			
			final C object = factory.apply(current = next.get());
			final DocumentListenable back = getBack();
			
			back.removeDocumentListener(this);
			back.addDocumentListener(new DeleteOnEmpty(back));			
			object.addDocumentListener(this);
			
			members.add(object);
			add(object);

			validateNthParent(4);
		}
		
	}
	
	IntFunction<DocumentListenable> prod;
	AnyActionDocumentListener grow;
	IntConsumer onDelete;
	List<DocumentListenable> members = new ArrayList<>();
	
	@SafeVarargs
	public <T, C extends Component & DocumentListenable> AutoGrowPanel(Function<T, C> function,
			Supplier<T> newItem, Consumer<? super T> onData, IntConsumer onDelete, T...ts) {
		setLayout(new VerticalLayout(5));
		
		T next = newItem.get();
		this.onDelete = onDelete;
		this.grow = new ExtendAction<T, C>(function, onData, newItem, next);
		
		for (T value : ts) {
			C listen = function.apply(value);
			members.add(listen);
			add(listen);
			listen.addDocumentListener(new DeleteOnEmpty(listen));
		}
		
		C empty = function.apply(next);
		members.add(empty);
		add(empty);
		empty.addDocumentListener(this.grow);
	}

	private DocumentListenable getBack() {
		return members.get(members.size() - 1);
	}
	
	private void validateNthParent(int i) {
		Component current = getParent();
		Component next = current;
		while (i --> 0 && next != null) {
			current = next;
			next = current.getParent();
		}
		current.validate();
	}
	
}