package dev.kske.undoredo;

import java.util.*;

/**
 * @param <C> the change type to store in this change manager
 * @author Maximilian K&auml;fer
 * @author Kai S. K. Engelbart
 * @since 0.0.1
 */
public final class UnlimitedChangeManager<C extends Change> implements ChangeManager<C> {

	private final List<C> changes = new LinkedList<>();

	private int	index		= -1;
	private int	markedIndex	= -1;

	@Override
	public void addChange(C change) {
		change.apply();
		changes.add(change);
		++index;
	}

	@Override
	public boolean undo() {
		if (isUndoAvailable()) {
			changes.get(index).invert().apply();
			--index;
			return true;
		}
		return false;
	}

	@Override
	public boolean redo() {
		if (isRedoAvailable()) {
			changes.get(index + 1).apply();
			++index;
			return true;
		}
		return false;
	}

	@Override
	public void mark() {
		markedIndex = index;
	}

	@Override
	public boolean isAtMarkedIndex() {
		return markedIndex == index;
	}

	@Override
	public boolean isUndoAvailable() {
		return index > -1;
	}

	@Override
	public boolean isRedoAvailable() {
		return index < changes.size() - 1;
	}

	@Override
	public List<C> getChanges() {
		return Collections.unmodifiableList(changes);
	}
}