/* 
 * esodata - data structures and other things, of varying utility
 * Copyright 2022, Ben Culkin
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *   
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
package bjc.esodata;

import java.util.AbstractList;
import java.util.ArrayList;
import java.util.List;

/**
 * A list that has a default value that out-of-bounds accesses return.
 *
 * @author Ben Culkin
 * @param <ValueType>
 *                    The type of the values contained in the list.
 */
public class DefaultList<ValueType> extends AbstractList<ValueType> {
	/*
	 * @NOTE 9/17/18
	 *
	 * A possible feature to add would be the ability to set a 'default index', so
	 * that the default value is 'whatever is at that list index'
	 *
	 * Of course, this would cause an exception if that index was out of bounds, but
	 * what are you going to do?
	 */

	private ValueType defVal;

	private List<ValueType> backing;

	/**
	 * Create a new DefaultList.
	 */
	public DefaultList() {
		this(new ArrayList<>(), null);
	}

	/**
	 * Create a new DefaultList, with a set default value.
	 *
	 * @param defVal
	 *               The default value for the list.
	 */
	public DefaultList(ValueType defVal) {
		this(new ArrayList<>(), defVal);
	}

	/**
	 * Create a new DefaultList, with a specific backing list.
	 *
	 * @param backer
	 *               The backing list to use.
	 *
	 */
	public DefaultList(List<ValueType> backer) {
		this(backer, null);
	}

	/**
	 * Create a new DefaultList, with a set default value.
	 *
	 * @param backer
	 *               The backing list to use.
	 *
	 * @param defVal
	 *               The default value for the list.
	 */
	public DefaultList(List<ValueType> backer, ValueType defVal) {
		this.defVal = defVal;

		this.backing = backer;
	}

	/**
	 * Get the default value.
	 *
	 * @return The default value.
	 */
	public ValueType getDefault() {
		return defVal;
	}

	/**
	 * Set the default value.
	 *
	 * @param defVal
	 *               The default value.
	 */
	public void setDefault(ValueType defVal) {
		this.defVal = defVal;
	}

	@Override
	public ValueType get(int idx) {
		if (idx < 0 || idx >= backing.size()) return defVal;
		else                                  return backing.get(idx);
	}

	@Override
	public int size() {
		return backing.size();
	}

	@Override
	public ValueType set(int idx, ValueType val) {
		return backing.set(idx, val);
	}

	@Override
	public void add(int idx, ValueType val) {
		backing.add(idx, val);
	}

	@Override
	public ValueType remove(int idx) {
		return backing.remove(idx);
	}
}