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


/**
 * Servlet which displays a page of a text. It sends a query to the
 * database to get a particular sequence of words, then 
 * formats them in HTML
 */
public class Reader extends LitsearchBase {

    public String drawPage(HttpServletRequest request,
			   HttpServletResponse response) throws Exception {
	int work, page;
	Hashtable highlight = null;
	ConnectionWrapper wrapper = null;

	try {
	    work = Integer.parseInt(request.getParameter("work"));
	    page = Integer.parseInt(request.getParameter("page"));
	    String hi = request.getParameter("highlight");
	    int end, start = 0;

	    if (hi != null) {
		while ((end = hi.indexOf(",", start)) != -1) {
		    if (highlight == null) highlight = new Hashtable();
		    highlight.put(hi.substring(start, end), "");
		    start = end + 1;
		}
		if (start < hi.length() - 1) highlight.put(hi.substring(start), "");
	    }
	} catch (Exception e) {
	    return drawError("Invalid input",
			     "Your request for this particular work and " +
			     "page was not properly formatted.");
	}

	try {
	    wrapper = DatabaseHook.getConnection();
	    Connection c = wrapper.connection();
	    Statement stmt = c.createStatement();
	    StringBuffer text = new StringBuffer();
	    String linkAhead = "";
	    String title = "";

	    ResultSet rs = stmt.executeQuery
		("SELECT Work.title, WrittenBy.name " +
		 "FROM Work, WrittenBy " +
		 "WHERE WrittenBy.work = Work.id AND Work.id = " + work);
	    if (rs.next()) {
		title = "<font size=5>" + rs.getString(1) + 
		    "</font><br><i>by " + rs.getString(2) + "</i><br><br>";
	    }

	    rs = stmt.executeQuery
		("SELECT MAX(page) FROM UniquePage WHERE work=" + work);
	    if (rs.next()) {
		int lastPage = rs.getInt(1);
		linkAhead = "<table bgcolor='#e0e0e0' cellpadding=6><tr><td>";
		linkAhead += "\npage " + page + " of " + lastPage + " | ";
		if (page > 1) 
		    linkAhead += "<a href='Reader?work=" + work +"&page=" +
			(page - 1) + "'>prev. page</a> | ";
		if (page < lastPage) 
		    linkAhead += "<a href='Reader?work=" + work +"&page=" +
			(page + 1) + "'>next page</a>";
		linkAhead += "</td></tr></table>\n";
	    }
			      
	    String query = 
		"SELECT w.context " +
		"FROM WordDetails w, UniquePage u " +
		"WHERE u.work=" + work + " AND u.page=" + page +
		" AND w.gpos >= u.global_start AND w.gpos <= u.global_end " +
		"ORDER BY w.gpos";
	    
	    rs = stmt.executeQuery(query);
	    
	    text.append(title);
	    text.append(linkAhead);
	    text.append("<br><br>\n");
	    while (rs.next()) {
		String token = rs.getString(1).replace('-', '\n');
		Object good = null;
		if (highlight != null) {
		    good = highlight.get(PorterStemmer.stem(token));
		}
		if (good != null) text.append("<B>");
		text.append(token).append(" ");
		if (token.endsWith("\n")) {
		    text.append("<BR>");
		}
		if (good != null) text.append("</B>");
	    }
	    text.append("<br><br>\n").append(linkAhead);

	    wrapper.checkIn();
	    return text.toString();

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