/***************************************************
  Course 01252 Concurrent Systems
  
  Possible solution for point 4. of cplab2
  HHL 09-09-2004 rev. 10-09-2007
****************************************************/

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


class Searcher extends Thread {

    char[] text, pattern;
    int from = 0, to = 0;       // Search the sub-string text[from..(to-1)]
    Vector<Integer> result;     // Local result

    public Searcher(char[] txt, char[] p, int f, int t) {
	text = txt;  pattern = p;  from = f;  to = t;
	result = new Vector<Integer>();
    }

    public Vector<Integer> getResult() {
	return result;
    }

    public void run() {
	final int pl = pattern.length;
	// VERY naive string matching to consume some CPU-cycles
	for (int i = from ; i <= to - pl; i++) {
	    boolean eq = true;
	    for (int j= 0; j < pl; j++) {
		if (text[i+j] != pattern[j]) eq = false;  // We should break here
	    }
	    if (eq) result.add(i);
	} 
    }

}


public class ParSearch {

    static final int max = 10000000;       // Max no. of chars searched

    static char[] text = new char[max];    // (part of) file to be searched
    static int    tl;                      // Length of actual text
    static char[] pattern;                 // Search pattern
    static int    n = 1;                   // No. of threads to use
    static String datafile;                // Name of data file 


    static void getParameters(String[] argv) {
	// Reads parameters into static variables
	// No need to modify
	try {
	    String fname = argv[0];
	    pattern  = argv[1].toCharArray();
	    if (argv.length > 2) {
		n = new Integer(argv[2]).intValue();
	    }
	    if (argv.length > 3) {
		datafile = argv[3];
	    }
      
	    InputStreamReader file = 
		new InputStreamReader(new FileInputStream(fname));

	    tl = file.read(text);

	    if (file.read() >=0) 
		System.out.println("\nWarning: file truncated to "+
				   max+" characters\n");
      
	    if (n <= 0 || pattern.length < 1 || 
		pattern.length > tl/n) throw new Exception();
      
	} catch (Exception e) {
	    System.out.println(
	        "\n"+
		" Usage: java Search file pattern [threads] \n"+
		"   0 < threads \n"+
		"   0 < size(pattern) <= size(file)/threads \n");
	    System.exit(1);
	}
    }
  
    static public boolean check(int pos) {  
	// Check that pattern does occur at pos
	try{
	    for (int j= 0; j < pattern.length; j++) {
		if (text[pos+j] != pattern[j]) return false;
	    }
	    return true;
	} catch (Exception e) {return false;}
    }

    public static void main(String[] argv) {
	try {
	    getParameters(argv);

	    final int pl = pattern.length;

	    Searcher[] s = new Searcher[n];
	    final int sectl = tl/n;
      
	    long start = System.currentTimeMillis();

	    // Create threads with properly overlapping search sections
	    for (int i = 0; i < n-1; i++) {
		s[i] = new Searcher(text,pattern,i*sectl,(i+1)*(sectl)+pl-1);
	    }
	    s[n-1] = new Searcher(text,pattern,(n-1)*sectl,tl);
      
	    // Run threads concurrently and await termination
	    for (int i = 0; i < n; i++) s[i].start();
	    for (int i = 0; i < n; i++) 
		try { s[i].join();} catch (InterruptedException ie){};
    
	    long time = System.currentTimeMillis()-start;

	    int total = 0;
	    for (int i = 0; i < n; i++) {
		total = total + s[i].getResult().size();
	    }	

	    System.out.println("\n" + total         + 
			       " occurrences of Pattern \"" + 
			       new String(pattern) + "\""
			       );
    
	    for (int i = 0; i < n; i++) {
		for (int pos : s[i].getResult()) {
		    // System.out.print(" "+ pos);
		    if (!check(pos)) { 
			System.out.print("\n ERROR: Pattern not found at " + 
					 pos + "!!\n");
		    }
		}
	    }

	    System.out.println("\n\nin "+time+" milliseconds\n");
      
	    if (datafile != null) {
		// Append result to data file
		FileWriter f = new FileWriter(datafile,true);
		PrintWriter data =  new PrintWriter(new BufferedWriter(f));
		data.println(n + " " + time);
		data.close();
	    }

	} catch (Exception e) { System.out.println("Search: "+e);}
    }

}