/*******************************************************************************
 *
 * Copyright (c) 2004-2011 Oracle Corporation.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *
 *    Kohsuke Kawaguchi, Winston Prakash
 *
 *
 *******************************************************************************/ 

package hudson.lifecycle;

import hudson.FilePath;
import hudson.Launcher.LocalLauncher;
import hudson.Util;
import hudson.model.Hudson;
import hudson.util.IOUtils;
import hudson.util.StreamTaskListener;
import org.eclipse.hudson.jna.NativeAccessException;
import org.eclipse.hudson.jna.NativeUtils;

import org.apache.commons.io.FileUtils;
import org.apache.commons.io.output.ByteArrayOutputStream;

import java.io.File;
import java.io.IOException;
import java.io.FileWriter;
import java.net.URL;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * {@link Lifecycle} for Hudson installed as Windows service.
 *
 * @author Kohsuke Kawaguchi
 * @see WindowsInstallerLink
 */
public class WindowsServiceLifecycle extends Lifecycle {

    public WindowsServiceLifecycle() {
        updateHudsonExeIfNeeded();
    }

    /**
     * If <tt>hudson.exe</tt> is old compared to our copy, schedule an overwrite
     * (except that since it's currently running, we can only do it when Hudson
     * restarts next time.)
     */
    private void updateHudsonExeIfNeeded() {
        try {
            File rootDir = Hudson.getInstance().getRootDir();

            URL exe = getClass().getResource("/windows-service/hudson.exe");
            String ourCopy = Util.getDigestOf(exe.openStream());
            File currentCopy = new File(rootDir, "hudson.exe");
            if (!currentCopy.exists()) {
                return;
            }
            String curCopy = new FilePath(currentCopy).digest();

            if (ourCopy.equals(curCopy)) {
                return; // identical
            }
            File stage = new File(rootDir, "hudson.exe.new");
            FileUtils.copyURLToFile(exe, stage);

            NativeUtils.getInstance().windowsMoveFile(stage, currentCopy);

            LOGGER.info("Scheduled a replacement of hudson.exe");
        } catch (NativeAccessException exc) {
            LOGGER.log(Level.SEVERE, "Failed to replace hudson.exe", exc);
        } catch (IOException e) {
            LOGGER.log(Level.SEVERE, "Failed to replace hudson.exe", e);
        } catch (InterruptedException e) {
            LOGGER.log(Level.SEVERE, "Failed to replace hudson.exe", e);
        }
    }

    /**
     * On Windows, hudson.war is locked, so we place a new version under a
     * special name, which is picked up by the service wrapper upon restart.
     */
    @Override
    public void rewriteHudsonWar(File by) throws IOException {
        File dest = getHudsonWar();
        // this should be impossible given the canRewriteHudsonWar method,
        // but let's be defensive
        if (dest == null) {
            throw new IOException("hudson.war location is not known.");
        }

        // backing up the old hudson.war before its lost due to upgrading
        // unless we are trying to rewrite hudson.war by a backup itself
        File bak = new File(dest.getPath() + ".bak");
        if (!by.equals(bak)) {
            FileUtils.copyFile(dest, bak);
        }

        File rootDir = Hudson.getInstance().getRootDir();
        File copyFiles = new File(rootDir, "hudson.copies");

        FileWriter w = null;
        try {
            w = new FileWriter(copyFiles, true);
            w.write(by.getAbsolutePath() + '>' + getHudsonWar().getAbsolutePath() + '\n');
        } finally {
            IOUtils.closeQuietly(w);
        }
    }

    @Override
    public void restart() throws IOException, InterruptedException {
        File me = getHudsonWar();
        File home = me.getParentFile();

        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        StreamTaskListener task = new StreamTaskListener(baos);
        task.getLogger().println("Restarting a service");
        int r = new LocalLauncher(task).launch().cmds(new File(home, "hudson.exe"), "restart")
                .stdout(task).pwd(home).join();
        if (r != 0) {
            throw new IOException(baos.toString());
        }
    }
    private static final Logger LOGGER = Logger.getLogger(WindowsServiceLifecycle.class.getName());
}