import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.text.*;

/**
 * This is the abstract class that all of the servlets subclass off of.
 * All it does is take care of the repetitive IO stuff, wraps the 
 * entire page in the standard header and footer, and provides some
 * convenience methods for handling errors and formatting strings.
 *
 * All subclasses must implement the drawPage method to draw themselves.
 */

public abstract class LitsearchBase extends HttpServlet {
    public static final String ROOT_DIR      = "/web/concordia/WEB-INF/"; 
    public static final String TEMPLATE_DIR  = ROOT_DIR + "templates/";
    public static final String IMAGE_DIR     = "/litsearch/images/";
    public static final String MAIN_TEMPLATE = TEMPLATE_DIR + "template.html";

    public void doGet(HttpServletRequest request,
		      HttpServletResponse response) {
	doPost(request, response);
    }

    public void doPost(HttpServletRequest request,
		       HttpServletResponse response) {
	PrintWriter out;

	response.setContentType("text/html");
	try {
	    out = response.getWriter();
	} catch (IOException e) { return; }

	try {
	    Template template = new Template(MAIN_TEMPLATE);
	    String content = drawPage(request, response);
	    template.substitute("CONTENT FRAME", content);
	    out.println(template);
	} catch (Exception e) {
	    handleException(e, out);
	}
    }

    public abstract String drawPage(HttpServletRequest request,
				    HttpServletResponse response) throws Exception;


    protected void handleException(Exception e, PrintWriter out) {
	e.printStackTrace(out);
    }

    protected String drawError(String title, String message) {
	return "<FONT SIZE=5><B>" + title + "</B></FONT><BR>\n" +
	    "We're sorry. The following error occurred:<BR>\n" +
	    message;
    }

    protected String formatString(String s) {
	if (s == null) return "null";
	
	StringBuffer buf = new StringBuffer(s);
	for (int i = 0; i < buf.length(); i++) {
	    if (buf.charAt(i) == '\'') {
		buf.insert(i, '\'');
		i++;
	    }
	}
	buf.insert(0, '\'');
	buf.append('\'');
	return buf.toString();
    }
}