package org.simon.jspwiki.plugin;

import com.ecyrd.jspwiki.plugin.WikiPlugin;
import com.ecyrd.jspwiki.plugin.PluginException;
import com.ecyrd.jspwiki.WikiContext;
import com.ecyrd.jspwiki.WikiEngine;
import com.ecyrd.jspwiki.WikiPage;

import java.util.*;
import java.io.FileInputStream;
import java.io.File;
import java.io.IOException;
import java.io.FileOutputStream;

import org.apache.log4j.Category;


/**
 * User: SimonLei
 * Date: 2004-2-15
 * Time: 10:25:31
 * $Id$
 */
public class PageViewCountPlugin implements WikiPlugin {
    private static Category log = Category.getInstance(PageViewCountPlugin.class);
    private static HashMap counters = null;
    private static Thread counterSaveThread = null;
    public static final String COUNTER_PAGE = "PageCount.txt";
    private static String ROOT = null;

    private synchronized void loadProperties(WikiEngine engine) {
        if (counters != null) return;
        counters = new HashMap();
        ROOT = engine.getServletContext().getRealPath("/");

        Properties stringCounters = new Properties();
        try {
            FileInputStream fis = new FileInputStream(new File(ROOT, COUNTER_PAGE));
            stringCounters.load( fis);
            fis.close();
        } catch (IOException e) {
            log.error("Can't load counter page, will create a new one.", e);
        }
        Enumeration enu = stringCounters.propertyNames();
        while (enu.hasMoreElements()) {
            String str = (String) enu.nextElement();
            counters.put(str, new Counter(stringCounters.getProperty(str)));
        }

        if (counterSaveThread == null) {
            counterSaveThread = new CounterSaveThread();
            counterSaveThread.start();
        }

    }

    public String execute(WikiContext context, Map params) throws PluginException {
        WikiEngine engine = context.getEngine();
        WikiPage page = context.getPage();

        loadProperties(engine);

        if (page == null) return "0";
        String pageName = page.getName();
        synchronized (counters) {
            Counter counter = (Counter) counters.get(pageName);
            if (counter == null) {
                counter = new Counter(0);
                counters.put(pageName, counter);
            }
            counter.increase();
            return counter.toString();
        }
    }

    class Counter {
        private int count;

        public Counter(int _count) {
            count = _count;
        }

        public Counter(String _count) {
            try {
                count = Integer.parseInt(_count);
            } catch (Exception e) {
                count = 0;
            }
        }

        public void increase() {
            count++;
        }

        public String toString() {
            return "" + count;
        }
    }

    class CounterSaveThread extends Thread {
        public void run() {
            try {
                while (true) {
                    synchronized (counters) {
                            Properties stringCounters = new Properties();
                            Iterator iter = counters.keySet().iterator();
                            while (iter.hasNext()) {
                                Object key = iter.next();
                                stringCounters.put(key, counters.get(key).toString());
                            }
                        try {
                            FileOutputStream fos = new FileOutputStream(new File(ROOT, COUNTER_PAGE));
                            stringCounters.store( fos,
                                    "The view counts for pages. Don't modify it.");
                            fos.close ();
                        } catch (IOException e) {
                            log.error("Can't store counters", e);
                        }
                    }
                    Thread.sleep(5 * 1000);
                }
            } catch (InterruptedException e) {
                log.error("The counter store thread interrupted. No more counter saved.");
            }
        }
    }

}