package com.jarticles;

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

import javax.servlet.*;
import javax.servlet.http.*;

public class TemplateEngineDemo extends HttpServlet {
  private String documentPath = null;

  public void init(ServletConfig config) throws ServletException {
    super.init(config);
    
    documentPath = getInitParameter("documentPath");
    // if no directory provided for loading the template, throwing the exception
    if (documentPath == null || documentPath.trim().length() == 0) {
      throw new UnavailableException (this, "No directory provided for loading the template.");
    }
  }
  
  private String getDocumentPath() {
    return documentPath;  
  }
    
  public void service(HttpServletRequest req, HttpServletResponse res)
                throws IOException, ServletException {
      long userId = -1;
      String userIdStr = req.getParameter("userId");
      
      if (userIdStr != null) {
        try {
          userId = Long.parseLong(userIdStr);
        } catch (NumberFormatException nfe) { 
          // so userId = -1;
        }
      }
      
      // find a user and load his information into a hashtable
      User user = User.findUserById(userId);
      Hashtable nvPairs = new Hashtable();
      nvPairs.put("firstName", user.getFirstName());
      nvPairs.put("lastName", user.getLastName());
      nvPairs.put("sex", user.getSex());
      nvPairs.put("position", user.getPosition());
      
      // load a template and map the information of user into it
      String template = loadTemplate("userInfo.html");
      String result = StringUtil.replace(template, nvPairs, "<!", ">");
      
      res.setContentType("text/html");
      PrintWriter out = res.getWriter();
      out.println(result);
      out.close();
  }
    
  private final String loadTemplate(String fileName) throws IOException {
    String templatePath = getDocumentPath();
    File tmplFile = new File(templatePath + fileName);
    BufferedReader in = new BufferedReader(new FileReader(tmplFile));
    
    String data = null;
    StringBuffer buf = new StringBuffer();
    while ( (data = in.readLine()) != null ) {
      buf.append(data);  
    }
    return buf.toString();
  }
}