import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.nio.file.FileSystemNotFoundException;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


/*
 * Detta program är en räknare som visar hur många som besökt en sida.
 * Värdet lagras i en fil på serversidan.
 *

 */
/**
 * Servlet implementation class HitCounter
 */
@WebServlet("/HitCounter")
public class HitCounter extends HttpServlet {
	private static final long serialVersionUID = 1L;
	private int count;
	private String fileName = "number_of_hits.txt";
	private File file;
	private String initial;


	  public HitCounter() {
		 super(); // TODO Auto-generated constructor stub }
	 }

	/**
	 * @see HttpServlet#HttpServlet()
	 */
 /*Denna metod hämtar värdet från filen */
	public void init() throws ServletException {
		file = new File(getServletContext().getRealPath("/") + fileName);
		FileReader fileReader = null;
		BufferedReader bufferedReader = null;

		try {
			fileReader = new FileReader(file.getAbsolutePath());
			bufferedReader = new BufferedReader(fileReader);
			initial = bufferedReader.readLine();
			count = Integer.parseInt(initial);
			return;
		} catch (FileNotFoundException fnfe) {
			System.err.println("Problem med att hitta filen");
		} catch (IOException ioe) {
			System.err.println("Problem med att läsa filen");
		} catch (NumberFormatException nfe) {
			System.err.println("Problem med värdet");
		} finally {
			try {
				if (bufferedReader != null) {
					bufferedReader.close();
				}
			} catch (IOException ioe) {
				System.out.println("hej");
			}
		}

		String initial = getInitParameter("initial");
		try {
			count = Integer.parseInt(initial);
			return;
		} catch (NumberFormatException nfe) {
			count = 0;
		}

	}


	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
	 *      response)
	 */

	/*Metoden skriver ut siffran som finns lagrad i filen*/
	protected void doGet(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		response.setContentType("text/plain");
		PrintWriter out = response.getWriter();

		synchronized (this) {
			count++;
			out.println("Since loading, this servlet has been accessed "
					+ count + " times.");
		}
	}

	public void destroy() {
		super.destroy();
		saveState();
	}

	/*Detta sparar värdet på antalet träffar i filen */
	public void saveState() {
		FileWriter fileWriter = null;
		PrintWriter printWriter = null;
		synchronized (this) {
			try {
				fileWriter = new FileWriter(file);
				printWriter = new PrintWriter(fileWriter);
				printWriter.println(count);
				return;
			} catch (IOException ioe) {
				System.out.println("hej");
			}

			finally {
				if (printWriter != null) {
					printWriter.flush();
					printWriter.close();
				}
			}
		}

	}



	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
	 *      response)
	 */
	protected void doPost(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
	}

}