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/*

 * CS 3114 Project 3

 * Author: Kevin Lee

 * Compiler: Eclipse 3.7.0

 * Operating System: Windows 7 x64

 * Date Completed: 11/1/2011

 * 

 * The following program sorts a specified file on disk using

 * heapsort and a buffer pool. The file size must be a multiple

 * of 4096 and comprised of key-value records of 2 bytes each

 * (4 bytes total per record). The buffer pool uses the least

 * recently used scheme and the number of 4096 byte blocks the

 * buffer stores is specified in the command line for this

 * program. A statistics file is also outputted to show the

 * sorted file, cache hits/misses, and disk reads/writes.

 * 

 * On my honor:

 *

 * - I have not used source code obtained from another student,

 * or any other unauthorized source, either modified or

 * unmodified.

 *

 * - All source code and documentation used in my program is

 * either my original work, or was derived by me from the

 * source code published in the textbook for this course.

 *

 * - I have not discussed coding details about this project with

 * anyone other than my partner (in the case of a joint

 * submission), instructor, ACM/UPE tutors or the TAs assigned

 * to this course. I understand that I may discuss the concepts

 * of this program with other students, and that another student

 * may help me debug my program so long as neither of us writes

 * anything during the discussion or modifies any computer file

 * during the discussion. I have violated neither the spirit nor

 * letter of this restriction.

 */

import java.io.FileNotFoundException;

import java.io.IOException;

import java.io.RandomAccessFile;

import java.nio.ByteBuffer;

public class heapsort {

	public static void main(String[] args) {

		// Check if correct arguments are supplied

		if (args.length != 3) {

			System.out.println("Usage: heapsort <data-file-name> <numb-buffers> <stat-file-name>");

			return;

		}

		// Save file paths and buffer size

		String dataFile = args[0];

		String statFile = args[2];

		int buffSize = Integer.parseInt(args[1]);

		long fileSize = 0;

		RandomAccessFile file = null;

		// Check if specified buffer size is within acceptable range

		if (buffSize < 1 || buffSize > 20) {

			System.out.println("Specified buffer size must be between 1 and 20");

			return;

		}

		// Get the length of the file to sort

		try {

			file = new RandomAccessFile(dataFile, "r");

			fileSize = file.length();

		} catch (FileNotFoundException e) {

			e.printStackTrace();

		} catch (IOException e) {

			e.printStackTrace();

		}

		// Check to make sure file is a multiple of 4096

		if (fileSize % 4 != 0) {

			System.out.println("Input file size must be a multiple of 4096");

			return;

		}

		// Create a new buffer and heap sort class

		LRUBuffer buff = new LRUBuffer(dataFile, statFile, buffSize, 4096, 4);

		MaxHeap heap = new MaxHeap(buff, fileSize/4);

		// Start sort

		long time1 = System.currentTimeMillis();

		heap.buildheap();

		for (int i = 0; i < fileSize/4; i++) {

			heap.removemax();

		}

		buff.flushBuffer();

		long time2 = System.currentTimeMillis();

		// Write sort statistics

		buff.writeStats(time2 - time1);

		// Print the first record from each block in the sorted file

		try {

			int column = 1;

			byte[] data = new byte[4];

			ByteBuffer bbuff;

			short key, value;

			for (long i = 0; i < fileSize; i+=4096) {

				file.seek(i);

				file.read(data);

				bbuff = ByteBuffer.wrap(data);

				key = bbuff.getShort();

				value = bbuff.getShort();

				System.out.printf("%05d %05d ", key, value);

				if (column % 8 == 0) {

					System.out.println();

				}

				column++;

			}

			file.close();

		} catch (IOException e) {

			e.printStackTrace();

		}

	}

}