// Exercise 2.2.2 (Solution published at http://algs4.cs.princeton.edu/)
package algs22;
import stdlib.*;
import java.awt.Font;
/* ***********************************************************************
 *  Compilation:  javac TraceMerge.java
 *  Execution:    java  TraceMerge input
 *
 *  Mergesort the sequence of strings specified as the command-line
 *  arguments and show the detailed trace.
 *
 *  % java TraceMerge MERGESORTEXAMPLE
 *
 *************************************************************************/

public class XTraceMerge {
	private static int line = 0;

	private static void merge(String[] a, String[] aux, int lo, int m, int hi) {

		// copy to aux[]
		for (int k = lo; k <= hi; k++) {
			aux[k] = a[k];
		}

		// merge back to a[]
		int i = lo, j = m+1;
		for (int k = lo; k <= hi; k++) {
			if      (i > m)                a[k] = aux[j++];
			else if (j > hi)               a[k] = aux[i++];
			else if (less(aux[j], aux[i])) a[k] = aux[j++];
			else                           a[k] = aux[i++];
		}

	}

	// mergesort a[lo..hi] using auxiliary array aux[lo..hi]
	private static void sort(String[] a, String[] aux, int lo, int hi) {
		if (hi <= lo) return;
		int m = lo + (hi - lo) / 2;
		sort(a, aux, lo, m);
		sort(a, aux, m + 1, hi);
		merge(a, aux, lo, m, hi);
		draw(a, lo, m, hi);
		line++;
	}

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

	// 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] to a[hi] in black
	private static void draw(String[] a, int lo, int m, int hi) {
		StdDraw.setPenColor(StdDraw.BLACK);
		StdDraw.text(-2.50, line, m  + "");
		StdDraw.setPenColor(StdDraw.BOOK_RED);
		StdDraw.text(-3.75, line, lo + "");
		StdDraw.text(-1.25, line, hi + "");
		for (int i = 0; i < a.length; i++) {
			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, -3, "a[ ]");
		for (int i = 0; i < N; i++)
			StdDraw.text(i, -2, i + "");
		StdDraw.text(-3.75, -2, "lo");
		StdDraw.text(-2.50, -2, "m");
		StdDraw.text(-1.25, -2, "hi");
		StdDraw.setPenColor(StdDraw.BOOK_RED);
		StdDraw.line(-4, -1.65, N-.5, -1.65);
		StdDraw.setPenColor(StdDraw.BLACK);
		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 < a.length; i++)
			StdDraw.text(i, N-1, a[i]);
	}


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

		// 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+3), 30*(N+3));
		StdDraw.setXscale(-4, N+1);
		StdDraw.setYscale(N+1, -4);
		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);
	}

}