import java.io.*;
import java.util.*;

/*
 * @author Lyndon Walker and Stephen Cope
 * Department of Statistics, The University of Auckland
 * Copyright (c) 2008
 *
 * This Java class stub provides a way to process a portion of an input file
 * using the Sun Grid Engine. For full documentation refer to:
 * http://www.stat.auckland.ac.nz/~kimihia/sun-grid#qsub-java-partial
 *
 * A typical usage example:
 *  qsub -t 1-50 Simulation.sh input.csv
 *
 * Simulation.sh contains:
 *  #$ -S /bin/sh
 *  java Simulation $@ $SGE_TASK_ID $SGE_TASK_LAST
 *
 */


public class Simulation
{
	static Simulation sim;

	public int getInputFileLines(String filename)
	{
		long fileSize = 0;
		int fileLines = 0;
		try
		{
			// get size of file (so we know where to seek to)
			RandomAccessFile r = new RandomAccessFile(filename, "r");
			fileSize = r.length();
			r.close();

			FileReader i = new FileReader(filename);
			LineNumberReader l = new LineNumberReader(i);
			// now go there
			l.skip(fileSize);
			fileLines = l.getLineNumber();
			// Some may say that we should decrement the above
			// value, however in my experience that is only
			// necessary if you have a blank line at the end of
			// your input data. I'm working with well-formed CSV
			// files here, so this is correct.
			l.close();
			i.close();

		}
		catch (IOException e)
		{
			System.err.println("Problem reading file: "+filename);
			Runtime.getRuntime().exit(1);
		}
		return fileLines;
	}

	public int [] readfile(String filename, int task_start, int task_last)
	{
		int [] counts = new int [2];
		counts[0] = counts[1] = 0;

		// calculate which records to keep
		int record_count_all = getInputFileLines(filename); // how many in the file
		int record_count_subset = (record_count_all/task_last); // split the records equally amongst tasks
		int record_start = record_count_subset * (task_start - 1); // where this process starts reading
		if ( record_start > 0 ) record_start ++;
		int record_count = 0; // how many have been read

		//System.err.println("About to read lines: "+record_start // DEBUG
		//+" and the next "+record_count_subset+" (of "+record_count_all+")"); // DEBUG

		// read in csv file
		try 
		{
			FileReader input = new FileReader(filename);
			BufferedReader bufRead = new BufferedReader(input);

			String line;        // String that holds current file line

			// skip over the first records that we are ignoring
			for ( int skip_count = 1 ; skip_count < record_start ; skip_count++ )
				bufRead.readLine();
				// either use the line above or the line below!!! DEBUG
				//System.err.println(""+skip_count+" discarding: "+bufRead.readLine()); // DEBUG


			// Read first line
			line = bufRead.readLine();
			record_count++;

			// Read through file one line at time. Print line # and line
			// Quit when either:
			// - we reach the end of the file
			// - we have read our subset of records
			while (line != null && record_count <= record_count_subset)
			{
				//System.err.println("parsing line: "+line); // DEBUG

				String[] tokens = line.split(",");
				if (Integer.parseInt(tokens[0]) == 1)
					++counts[0];
				else 
					++counts[1];

				line = bufRead.readLine();
				record_count++;
			}
			bufRead.close();
		}
		catch (IOException e)
		{
			e.printStackTrace();
			System.err.println("Problem reading file: "+filename);
			Runtime.getRuntime().exit(1);
		}

		return counts;
	} /* readfile */

	public static void main(String [] args)
	{
		int sge_task_id = 1;
		int sge_task_last = 1;

		if ( args.length < 1 )
		{
			System.err.println("usage: Simulation filename [SGE_TASK_ID SGE_TASK_LAST]");
			Runtime.getRuntime().exit(1);
		}
		if ( args.length >= 3 )
		{
			try
			{
				sge_task_id   = Integer.parseInt(args[args.length-2]);
				sge_task_last = Integer.parseInt(args[args.length-1]);

				System.err.println("SGE task numbers: "+sge_task_id+" of "+sge_task_last);
			}
			catch (NumberFormatException e) {
				System.err.println("Ignoring unparseable SGE task numbers: "
						+args[args.length-2]+","+args[args.length-1]);

				sge_task_id = 1;
				sge_task_last = 1;
			}
		}

		sim = new Simulation();

		int counts [] = sim.readfile(args[0], sge_task_id, sge_task_last);

		// simulation
		doMagicUpon(counts);

	} /* main */

	public static void doMagicUpon(int [] data)
	{
		// TODO your simulation goes here
	}

} /* class*/