import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;

import perlforjava.control.Looper;
import perlforjava.functions.Arrays;
import perlforjava.functions.Mapper;
import perlforjava.lang.Block;

/**
 * The Schwartzian Transform written in Java.
 */
public class TheSchwartz {

	private ArrayList list;

	/**
	 * Comparator to sort by length.
	 */
	public final static Comparator BY_LENGTH;
	
	/**
	 * Comparator to sort alphabetically.
	 */	
	public final static Comparator ALPHABETICALLY;
	
	/**
	 * Static initializer
	 */
	static {
		BY_LENGTH = new Comparator() {
			public int compare(Object a, Object b) {
				return ((Integer) ((List) a).get(1)).compareTo(
					((Integer) ((List) b).get(1)));
			}
		};
		ALPHABETICALLY = new Comparator() {
			public int compare(Object a, Object b) {
				String s1 = a.toString().substring(1);
				String s2 = b.toString().substring(1);
				return s1.compareTo(s2);
			}
		};		
	}

	/**
	 * Simple Constructor. 
	 * 
	 * @param list
	 */
	public TheSchwartz(ArrayList list) {
		this.list = list;
	}

	/**
	 * Workhorse function. Sorting by passed in Comparator
	 * 
	 * @return
	 */
	public ArrayList sort(Comparator sortBy) {
	
		List out = Mapper.map(new Block() {
				// pull the first element from each List and return it
				protected Object process(Object elem) {
					return ((List) elem).get(0);
				}
			}, Arrays.sort(
				// run the comparison of Integer values to determine order
				sortBy,
			// map each string into an ArrayList of string => length
			Mapper.map(new Block() {
				protected Object process(Object elem) {
					ArrayList temp = new ArrayList();
					temp.add(elem);
					temp.add(new Integer(((String) elem).length()));
					return temp;
				}
			}, list)));
		return (ArrayList)out;
	}

	public static void main(String[] args) {

		// Create a new List of values to sort
		ArrayList in = new ArrayList();
		in.add("fu");
		in.add("duhh");
		in.add("birdy");
		in.add("sea");

		/* Sort based upon length of string by mapping each string to
		   a List where the first element is the string and the second is
		   its length. Sort on the latter and return a new List of strings. */

		TheSchwartz merlyn = new TheSchwartz(in);
		List outByLength = merlyn.sort(TheSchwartz.BY_LENGTH);

		System.out.println("By Length:");

		// Loop over the results to view them
		Looper.foreach(outByLength, new Block() {
			protected Object process(Object elem) {
				System.out.println("ELEM " + elem.toString());
				return null;
			}
		});
		
		System.out.println("\nAlphabetically:");
		
		List outAlphabetically = merlyn.sort(TheSchwartz.ALPHABETICALLY);

			// Loop over the results to view them
			Looper.foreach(outAlphabetically, new Block() {
				protected Object process(Object elem) {
					System.out.println("ELEM " + elem.toString());
					return null;
				}
			});		
		
	}
}