/**A Hit Counter Servlet that logs the number of non unique page hits to disk and
* displays the result in HTML. 
* This is done without mixing code and HTML, i.e. code separation is used. 
* Internet Programming 2 - Course
* @author Martin Carlsson
*/
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import mixer.*;


public class HitCounterHTML extends HttpServlet {
    
    private static int count = 0;
    private static String servletRoot = "/hit-counter-html";
    private static String htmlFile = null;
    private String countFile = "countFile.txt";
    private String htmlFileName ="hit-counts.htm";
    
    public void init()throws ServletException {
        BufferedReader bR = null;
        countFile = getServletContext().getRealPath(servletRoot + "\\" + countFile);   
       
        if(htmlFile == null) {
            htmlFile = Mixer.getContent(new File(getServletContext().getRealPath(servletRoot + "\\" + htmlFileName)));
        }
        try {
            bR = new BufferedReader(new FileReader(countFile));
            String countString = bR.readLine();
            count = Integer.parseInt(countString);
            return;
        }
        catch (FileNotFoundException fNfE){
            System.err.println("Couldn't find file " + countFile);
        }
        catch (IOException iOe){
            System.err.println("Couldn't read file " + countFile);
        }
        catch (NumberFormatException nFe){
            System.err.println("Value not valid in file " + countFile);
        }
        finally{
            try{
                if(bR !=null)
                    bR.close();
            }
            catch(IOException iOe){
                System.err.println("Could not close BufferedReader stream"); 
            }
        }
    }
   
    /*Saves the number of clients requesting this servlet every 10 request.*/
    public void doGet(HttpServletRequest req, HttpServletResponse res) throws IOException, ServletException {
        
        Mixer m = new Mixer(htmlFile);
        //res.setContentType("text/plain");
        PrintWriter out = res.getWriter();
        int localCount;
        synchronized(this){
            localCount = ++count;
            if(localCount % 10 == 0)//sparar till disk var 10:e sidbesök
               saveCount();
        }
        m.add("_m_", "Total number of hits: " + localCount);
        res.setContentType("text/html");
        out.println(m.getMix());
       
    }
    
    /*Is called when the servlet unloads. Calls the 
    destroy() method of the super class, then savestate()*/    
    public void destroy() {
        
        saveCount();
    }
    
    //Saves to disk
    public void saveCount() {
        PrintWriter pW = null;
        try {
            pW = new PrintWriter(new FileWriter(countFile));
            pW.println(count);
            return;
        }
        catch(IOException IoE){ 
            System.err.println("Couln't write to " + countFile);
            }
        finally{
            if(pW != null) {
                pW.close();
            }
        }
    }
} // End class HitCounterHTML