package net.sourceforge.tuned;


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

import net.sourceforge.tuned.PreferencesMap.Adapter;


public class PreferencesList<T> extends AbstractList<T> {
	
	private final PreferencesMap<T> prefs;
	
	
	public PreferencesList(PreferencesMap<T> preferencesMap) {
		this.prefs = preferencesMap;
	}
	

	@Override
	public T get(int index) {
		return prefs.get(key(index));
	}
	

	private String key(int index) {
		return Integer.toString(index);
	}
	

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

	@Override
	public boolean add(T e) {
		setImpl(size(), e);
		return true;
	}
	

	@Override
	public void add(int index, T element) {
		int size = size();
		
		if (index > size)
			throw new IndexOutOfBoundsException(String.format("Index: %d, Size: %d", index, size));
		
		copy(index, index + 1, size - index);
		
		setImpl(index, element);
	}
	

	private T setImpl(int index, T element) {
		return prefs.put(key(index), element);
	}
	

	/**
	 * @return always null
	 */
	@Override
	public T remove(int index) {
		int lastIndex = size() - 1;
		
		copy(index + 1, index, lastIndex - index);
		prefs.remove(key(lastIndex));
		
		return null;
	}
	

	@Override
	public T set(int index, T element) {
		if (index < 0 || index >= size())
			throw new IndexOutOfBoundsException();
		
		return setImpl(index, element);
	}
	

	private void copy(int startIndex, int newStartIndex, int count) {
		if (count == 0 || startIndex == newStartIndex)
			return;
		
		List<T> copy = new ArrayList<T>(subList(startIndex, startIndex + count));
		
		for (int i = newStartIndex, n = 0; n < count; i++, n++) {
			setImpl(i, copy.get(n));
		}
	}
	

	@Override
	public void clear() {
		prefs.clear();
	}
	

	public static PreferencesList<String> map(Preferences prefs) {
		return new PreferencesList<String>(PreferencesMap.map(prefs));
	}
	

	public static <T> PreferencesList<T> map(Preferences prefs, Adapter<T> adapter) {
		return new PreferencesList<T>(PreferencesMap.map(prefs, adapter));
	}
	
}