// Exercise 2.3.12 (Solution published at http://algs4.cs.princeton.edu/)
package algs23;
import stdlib.*;
import java.awt.Font;
/* ***********************************************************************
 *  Compilation:  javac TraceQuick3way.java
 *  Execution:    java  TraceQuick3way string
 *
 *  Quicksort the sequence of strings specified as the command-line
 *  arguments and show the detailed trace.
 *
 *  % java TraceQuick3way QUICKSORTEXAMPLE
 *
 *************************************************************************/

public class XTraceQuick3way {
	private static int line = 0;


	public static void sort(String[] a) {
		sort(a, 0, a.length - 1);
	}

	private static void sort(String[] a, int lo, int hi) {
		if (hi < lo) return;
		if (hi == lo) {
			draw(a, lo);
			line++;
			return;
		}

		int lt = lo, gt = hi;
		String v = a[lo];
		int i = lo;
		while (i <= gt) {
			int cmp = a[i].compareTo(v);
			if      (cmp < 0) exch(a, lt++, i++);
			else if (cmp > 0) exch(a, i, gt--);
			else              i++;
		}

		// a[lo..lt-1] < v = a[lt..gt] < a[gt+1..hi].
		draw(a, lo, lt, gt, hi);
		line++;

		sort(a, lo, lt-1);
		sort(a, gt+1, hi);
	}



	// exchange a[i] and a[j]
	private static void exch(String[] a, int i, int j) {
		String swap = a[i];
		a[i] = a[j];
		a[j] = swap;
	}

	// is v < w ?
	private static boolean less(String v, String w) {
		return (v.compareTo(w) < 0);
	}

	// draw the contents of the array, with a[lo] in red
	private static void draw(String[] a, int lo) {
		StdDraw.setPenColor(StdDraw.LIGHT_GRAY);
		StdDraw.text(-5.00, line, lo + "");
		StdDraw.text(-1.25, line, lo + "");
		for (int i = 0; i < a.length; i++) {
			if (i == lo)  StdDraw.setPenColor(StdDraw.BOOK_RED);
			else          StdDraw.setPenColor(StdDraw.LIGHT_GRAY);
			StdDraw.text(i, line, a[i]);
		}
	}

	// draw the contents of the array, with a[lo] to a[hi] in black
	private static void draw(String[] a, int lo, int lt, int gt, int hi) {
		StdDraw.setPenColor(StdDraw.BLACK);
		StdDraw.text(-5.00, line, lo + "");
		StdDraw.text(-1.25, line, hi + "");
		StdDraw.setPenColor(StdDraw.BOOK_RED);
		StdDraw.text(-3.75, line, lt + "");
		StdDraw.text(-2.50, line, gt + "");
		for (int i = 0; i < a.length; i++) {
			if (i >= lt && i <= gt)      StdDraw.setPenColor(StdDraw.BOOK_RED);
			else if (i >= lo && i <= hi) StdDraw.setPenColor(StdDraw.BLACK);
			else                         StdDraw.setPenColor(StdDraw.LIGHT_GRAY);
			StdDraw.text(i, line, a[i]);
		}
	}

	// display header
	private static void header(String[] a) {
		int N = a.length;
		StdDraw.setPenColor(StdDraw.BLACK);
		StdDraw.text(N/2.0, -4, "a[ ]");
		for (int i = 0; i < N; i++)
			StdDraw.text(i, -3, i + "");
		StdDraw.text(-5.00, -3, "lo");
		StdDraw.text(-3.75, -3, "lt");
		StdDraw.text(-2.50, -3, "gt");
		StdDraw.text(-1.25, -3, "hi");
		StdDraw.setPenColor(StdDraw.BOOK_RED);
		StdDraw.line(-5.25, -2.65, N-.5, -2.65);
		StdDraw.setPenColor(StdDraw.BLACK);
		for (int i = 0; i < a.length; i++)
			StdDraw.text(i, -2, a[i]);
		StdRandom.shuffle(a);
		for (int i = 0; i < a.length; i++)
			StdDraw.text(i, -1, a[i]);
	}

	// display footer
	private static void footer(String[] a) {
		int N = a.length;
		StdDraw.setPenColor(StdDraw.BLACK);
		for (int i = 0; i < N; i++)
			StdDraw.text(i, line, a[i]);
	}


	// test client
	public static void main(String[] args) {
		args = new String[] { "SORTEXAMPLE" };

		// parse command-line argument as an array of 1-character strings
		String s = args[0];
		int N = s.length();
		String[] a = new String[N];
		for (int i = 0; i < N; i++)
			a[i] = s.substring(i, i+1);

		// set canvas size
		StdDraw.setCanvasSize(30*(N+4), 30*(N+4));
		StdDraw.setXscale(-5, N+1);
		StdDraw.setYscale(N+1, -5);
		StdDraw.setFont(new Font("SansSerif", Font.PLAIN, 13));

		// display the header
		header(a);

		// sort the array and display trace
		sort(a);

		// display the footer
		footer(a);
	}

}