/* Use, modification, and distribution are subject to the Boost Software 
License, Version 1.0. (See accompanying file LICENSE_1.0.txt or copy at 
www.boost.org/LICENSE_1.0.txt) */

/*
PageRank - new Test version 
Revision 2.4

2/17/04

*/


import java.util.*;
import java.sql.*;
import java.io.*;
import java.text.DecimalFormat;


class PageRankTest
{
    public static int ITER = 50;  // 50 sounds like a good amount

    /* method for resetting all of the ranks back to 1.0 without performing
       another crawl.  Mainly for testing purposes.  As a ranking only
       needs to be run once per crawler, there should be no reason to
       reset the ranks between crawls */
    private static void resetRanks(Connection conn) throws SQLException
    {
	ResultSet rs;
	Statement stmt;

	stmt = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,
				     ResultSet.CONCUR_UPDATABLE);

	rs = stmt.executeQuery("Select urlid, rank From url");

	while(rs.next())
	    {
		rs.updateFloat(2,(float)1.0);
		rs.updateRow();
	    }
    }


    /* the big ranking algorithm.  Rank for a page is calculated through
       a simple formula, that is rather complex to implement.  The formula
       is: rank(x)=  0.15 + 0.85 * The sum of (rank/number of links) for 
       all pages that link to x. For optimization, I perform all SQL 
       database lookups before performing any calculations. */
    private static void pageRank(Connection conn) throws SQLException
    {
	ResultSet rs1, rs2;
	Statement stmt,stmt2;
	float rank, new_rank;
	int count, id;
	float[] ranks =  new float[55000];
	int[] counts = new int[55000];
	int i;
	float j;
	Integer value;
	Iterator it;
	HashSet links[] = new HashSet[55000];
	float [][] changes = new float[55000][50];

	// initializing the HashSet array that will contain all of the
	// pages linked to a page
	for (i = 1; i < 55000; i++)
	    {
		links[i] = new HashSet();
	    }


	stmt = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,
				     ResultSet.CONCUR_UPDATABLE);
	
	stmt2 = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,
				     ResultSet.CONCUR_UPDATABLE);
	
	rs1 = stmt.executeQuery("Select lurl, count(lurl) as num from link Group by lurl");
	
	int temp;
	
	// initializing array counts[] to the number of links on each page
	while(rs1.next())
	    {
		temp = rs1.getInt(1);
		counts[temp] = rs1.getInt(2);
		
	    }

	/* initializing array ranks[] to the rank of each page.  If a
	   page is a dead link or should otherwise be skipped, its rank
	   is set to zero. */
	rs1 = stmt.executeQuery("Select urlid From url_to_text");
	for(i = 0; i < 55000; i++)
	    {
		ranks[i] = 0;
	    }
	while(rs1.next())
	    {
		temp = rs1.getInt(1);
		ranks[temp] = 1;
	    }
	
	/* each HashSet i in links contains the ids of the pages that link
	   to i */
	for(i = 0; i < 55000; i++)
	    {
		j = ranks[i];
		if(j != 0)
		    {
			rs2 = stmt.executeQuery("Select lurl From link where urlid = " + i );
			while(rs2.next())
			    {
				temp = rs2.getInt(1);
				value = new Integer(temp);
				links[i].add(value);
			    }
			System.out.println(i);
		    }	
	    }

	/* actually performing the calculations.  Skips any pages
	   where count is zero to avoid division erros, and skips
	   any pages that have no rank, as they are most likely dead links
	*/
	for(int  k = 1; k <= ITER; k++)
	    {

		for(i = 0; i < 55000; i++)
		    {
			j = ranks[i];
			if(j != 0)
			    {
				new_rank = (float)0.15;
				it = links[i].iterator();
				while(it.hasNext())
				    {
					value = (Integer)it.next();
					id = value.intValue();
					count = counts[id];
					rank = ranks[id];
					if (count != 0)
					    {
						new_rank += 0.85 * (rank / count);
						System.out.println(rank + "\t" + count + "\t" + new_rank);
					    }
				    }
				ranks[i] = new_rank;
				changes[i][k-1] = new_rank;
				System.out.println(i);
			    }
		    }
		System.out.println("End of iteration " + k);
	    }

	// writing out the new ranks to the database
	rs1 = stmt.executeQuery("Select urlid,rank From url");
	rs1.beforeFirst();
	i = 1;
	while(rs1.next())
	    {
		rs1.updateFloat(2,ranks[i]);
		rs1.updateRow();
		i++;
	    }
	// writing out the changes in rank to a flat file for later review
	outputChanges(changes);
    }
    
    /* method that writes out the changes to ranks over time to a text
       file called rankchanges.txt */
    public static void outputChanges(float[][] changes)
    {
	int i,j;
       
	try
	    {
		FileOutputStream out = new FileOutputStream("rankchanges.txt");
		PrintStream p = new PrintStream(out);
		
		for(i = 0; i < 55000; i++)
		    {
			for (j = 0; j < 49; j++)
		{
		    p.print("" + changes[i][j] + " ");
		}
			p.println("" + changes[i][49]);
		    }
		p.close();
	    }
	catch(Exception e)
	    {
		System.err.println("Well, shit!");
	    }
    }

    /* testing method for printing all of the ranks */
    public static void printRanks(Connection conn) throws SQLException
    {
	ResultSet rs;
	Statement stmt;
	

	stmt = conn.createStatement();
	rs = stmt.executeQuery("Select rank From url");
    	
	while(rs.next())
	    {
		System.out.println(rs.getFloat(1));
	    }

    }
    
    public static void main(String args[]) throws SQLException
    {
	boolean commandline = false;
	String database = null;
	String option = null;
	if(args.length == 0) {
	    System.out.println("ERROR: Database name must be supplied as a command-line argument.");
	    System.exit(1);
	}
	else if(args.length == 1) {
	    database = args[0];
	}
	else if(args.length == 2) {
	    option = args[0];
	    database = args[1];
	}
	String answer = "";
	Connection conn;
	
	try
	    {
		Class.forName("com.mysql.jdbc.Driver").newInstance();
	    }
	catch(Exception ex)
	    {
		System.err.println(ex);
		System.exit(1);
	    }
    
	conn = DriverManager.getConnection("jdbc:mysql://violet.mathcs.carleton.edu/" + database,"webcrawler","twlv34-1");
	
	if(option == null) {
	    System.out.println("Calculate (c), reset (r) or display (d)?");
	    InputStreamReader is = new InputStreamReader(System.in);
	    BufferedReader br = new BufferedReader(is);
	    try
		{
		    answer = br.readLine();
		}
	    catch(IOException ex)
		{
		    System.err.println(ex);
		    System.exit(1);
		}
	}
	else {
	    answer = option;
	}
	if (answer.equals("r"))
	    {
		resetRanks(conn);
	    }
	else if (answer.equals("c"))
	    {
		pageRank(conn);
	    }
	else {
	    printRanks(conn);
	}
    }
}