import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;
import java.util.*;
import java.net.*;

/**
 * Performs what is probably the most intersting search, the motif
 * search. The motif search takes a string of words from the user
 * and finds the set of synonyms for all of those words. Then it
 * finds the occurrences of each of these words, and assigns scores
 * to pages in the database which match the words and their synonyms.
 * It also gives additional weight to words which are less common.
 */

public class MotifSearch extends LitsearchBase {

    public String drawPage(HttpServletRequest request,
			   HttpServletResponse response) throws Exception {
	String searchQuery = request.getParameter("query");
	
	//If there is no query, show the search page.
	if (searchQuery == null) {
	    Template t = new Template(TEMPLATE_DIR + "motifsearch.html");
	    return t.toString();
	}

	searchQuery = searchQuery.trim();
	String text = "";
	String[] stripes = new String[2];
	stripes[0] = "<tr bgcolor='#e0e0e0'>";
	stripes[1] = "<tr bgcolor='#ffffff'>";
	int curColor = 0;


	//Parse the query into individual words, the stem those words.
	ArrayList terms = new ArrayList();
	while (true) {
	    int i = searchQuery.indexOf(' ');
	    if (i == -1) {
		terms.add(PorterStemmer.stem(searchQuery));
		break;
	    }
	    terms.add(PorterStemmer.stem(searchQuery.substring(0, i)));
	    searchQuery = searchQuery.substring(i + 1).trim();
	}


	//Call the search algorithm to get a list of results and scores
	Hashtable results = doMotifSearch(terms);

	text += "<table cellpadding='4' cellspacing='1' width='100%'>";
	text += stripes[curColor % 2] + "<td colspan=4>";
	text += "Found " + results.size() + " results for your query: <b>\"" +
	    request.getParameter("query") + "\"</b></td></tr>\n";
	text += stripes[curColor++ %2] + 
	    "<td>Title</td><td>Author</td><td>Page (click to view)</td><td>Score</td></tr>\n";


	if (results.size() == 0) return text + "</td></tr></table>";


	//Look up the full information on each of the search results.
	ConnectionWrapper wrapper = null;
	try {
	    wrapper = DatabaseHook.getConnection();
	    Connection c = wrapper.connection();
	    Statement stmt = c.createStatement();
	    ResultSet rs;	
	    String query;

	    ArrayList finalResults = new ArrayList();
	    Enumeration enum = results.keys();
	    String pageList = "-1";
	    while (enum.hasMoreElements()) {
		String key = (String) enum.nextElement();
		query = "SELECT w.id, w.title, b.name, u.page, u.id AS pageid " +
		    "FROM UniquePage u, Work w, WrittenBy b " +
		    "WHERE u.id =" + key +
		    " AND w.id = u.work AND b.work = w.id";
		rs = stmt.executeQuery(query);
		if (!rs.next()) break;
		int score =  Integer.parseInt((String) results.get(rs.getString(5)));
		ResultStore r = new ResultStore(rs.getInt(1), rs.getString(2), rs.getString(3),
						rs.getString(4), rs.getString(5), score);
		finalResults.add(r);
	    }

	    //Sort the results in order of score
	    Collections.sort(finalResults);
	    int max = 1;
	    ResultStore maxRS = (ResultStore) Collections.max(finalResults);
	    if (maxRS != null) max = maxRS.score;


	    //Display the results in pretty tabular format
	    for (int i = finalResults.size() - 1; i >= 0; i--) {
		ResultStore r = (ResultStore) finalResults.get(i);
		int widthGood = (int) (r.score * 60.0 / max);
		int widthBad = 60 - widthGood;

		text += stripes[curColor++ % 2];
		text += "<td><a href='DescribeWork?work=" + r.id + "'>" + r.title + "</a></td>";
		text += "<td><a href='DescribeAuthor?name=" + URLEncoder.encode(r.name) + 
		    "'>" + r.name + "</a></td>\n";
		text += "<td><b><a href='Reader?work=" + r.id + "&page=" + r.page + 
		    "'>page " + r.page + "</a></td>\n";
		text += "<td><img src='" + IMAGE_DIR + "bar_on.gif' height=12 width=" + widthGood + ">" +
		    "<img src='" + IMAGE_DIR + "bar_off.gif' height=12 width=" + widthBad + "> " +
		    r.score + "</td></tr>\n";
	    }
	    text += stripes[curColor++ % 2];
	    text += "<td colspan=4><a href='MotifSearch'>Search Again</a>\n";
	    text += "</td></tr></table>";

	    wrapper.checkIn();
	    return text;

	} catch (Exception e) {
	    wrapper.checkIn();
	    throw e;
	}
    }


    /** 
     * Performs the motif search. Comments in the code describe the process
     * Note: This function used to make much more use of "interesting"
     * unions and subqueries, but these were rewritten to preserve MySQL
     * compatibility. The query is still pretty "interesting," though.
     */
    public Hashtable doMotifSearch(ArrayList terms) throws Exception {
	int numSynPerWord = 12 / terms.size();
	ConnectionWrapper wrapper = null;
	try {
	    wrapper = DatabaseHook.getConnection();
	    Connection c = wrapper.connection();
	    Statement stmt = c.createStatement();
	    ResultSet rs = null;
	    String query;

	    //Step 1: Find all of the words
	    query = "SELECT id FROM Word WHERE word IN (-1";
	    Iterator itr = terms.iterator();
	    while (itr.hasNext()) {
		query += ", " + formatString((String) itr.next());
	    }
	    query += ")";
	    rs = stmt.executeQuery(query);
	    
	    int[] roots = new int[terms.size()];
	    int[] freqs = new int[terms.size()];

	    int i = 0;
	    while (rs.next()) {
		roots[i++] = rs.getInt(1);
	    }
	    Arrays.sort(roots);   //sort roots inascending order
	    
	    //Step 1.5: Get the frequencies of all of the roots
	    query = "SELECT word, count(*) score FROM PageContainsWord where word IN(-1";
	    for (i = 0; i < roots.length; i++) {
		query += ", " + roots[i];
	    }
	    query += ") GROUP BY word ORDER BY word";
	    rs = stmt.executeQuery(query);
	    i = 0;
	    int maxFreq = 0;
	    while (rs.next()) {
		int f = rs.getInt(1);
		if (f > maxFreq) maxFreq = f;
		freqs[i++] = f;
	    }

	    //Step 2: Get X synonyms from each description.
	    String allSyn = "";
	    for (i = 0; i < terms.size(); i++) {
		if (freqs[i] > 0) {
		    //get the frequency of each word and use to determine the num to accept
		    query = "SELECT child FROM Syn WHERE root = " + roots[i] + 
			" LIMIT " + numSynPerWord * maxFreq / freqs[i];
		    ;
		    rs = stmt.executeQuery(query);
		    while (rs.next()) {
			allSyn += rs.getString(1) + ",";
		    }
		    allSyn += roots[i] + ",";
		}
	    }

	    //Step 3: Do the large query, group the results by the
	    //page they appear on, and assign each page a score
	    //based on these results.
	    allSyn = allSyn.substring(0, allSyn.length() - 1);
	    query = 
		"SELECT page, COUNT(*) AS score " +
		"FROM PageContainsWord WHERE word IN (" + allSyn + ") " +
		"GROUP BY page " +
		"ORDER BY score DESC, page " +
		"LIMIT 40";
	    
	    Hashtable pageKeys = new Hashtable();
	    rs = stmt.executeQuery(query);
	    while(rs.next()) {
		pageKeys.put(rs.getString(1), rs.getString(2));
	    }
	    wrapper.checkIn();	    
	    return pageKeys;

	} catch (Exception e) {
	    wrapper.checkIn();
	    throw e;
        }
    }

    class ResultStore implements Comparable {
	public int id;
	public String title;
	public String name;
	public String page;
	public String pageid;
	public int score;
	public ResultStore(int i, String t, String n, String p, String pi, int s) {
	    id = i; title = t; name = n; page = p; pageid = pi; score = s;
	}

	public int compareTo(Object o) {
	    ResultStore s = (ResultStore) o;
	    if (s.score == score) return 0;
	    if (s.score > score) return -1;
	    return 1;
	}
    }
}