/**
 * *****************************************************************************
 *
 * Copyright (c) 2012 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:
 *
 * Winston Prakash
 *
 *****************************************************************************
 */
package org.eclipse.hudson.plugins;

import hudson.ProxyConfiguration;
import hudson.Util;
import java.io.*;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import org.apache.commons.io.IOUtils;
import org.apache.commons.io.input.CountingInputStream;
import org.eclipse.hudson.plugins.UpdateSiteManager.AvailablePluginInfo;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Background Job to install or update a Job
 *
 * @author Winston Prakash
 */
public final class PluginInstallationJob implements Runnable {

    private Logger logger = LoggerFactory.getLogger(PluginInstallationJob.class);
    private final AvailablePluginInfo plugin;
    private File pluginsDir;
    private boolean success;
    private String errorMsg;
    private ProxyConfiguration proxyConfig;

    public PluginInstallationJob(AvailablePluginInfo plugin, File dir, ProxyConfiguration proxyConfig) {
        this.plugin = plugin;
        pluginsDir = dir;
        this.proxyConfig = proxyConfig;
    }

    public String getName() {
        return plugin.getDisplayName();
    }

    @Override
    public void run() {
        URL src;
        try {
            logger.info("Installing the plugin " + getName());
            src = getDownloadURL();
            File dst = getDestination();
            File tmp = download(src);
            replace(dst, tmp);
            logger.info(getName() + " installation successful");
        } catch (Exception exc) {
            logger.error(getName() + " installation unsuccessful", exc);
            success = false;
            errorMsg = getStackTrace(exc);
            return;
        } catch (Error err) {
            logger.error(getName() + " installation unsuccessful", err);
            success = false;
            errorMsg = getStackTrace(err);
            return;
        }
        success = true;
    }

    @Override
    public String toString() {
        return super.toString() + "[plugin=" + plugin.getDisplayName() + "]";
    }

    public boolean getStatus() {
        return success;
    }

    public String getErrorMsg() {
        return errorMsg;
    }

    public static String getStackTrace(Throwable throwable) {
        Writer result = new StringWriter();
        PrintWriter printWriter = new PrintWriter(result);
        throwable.printStackTrace(printWriter);
        return result.toString();
    }

    private File download(URL src) throws IOException {
        URLConnection con;
        if ((proxyConfig != null) && (proxyConfig.name != null)) {
            con = proxyConfig.openUrl(src);
        } else {
            con = src.openConnection();
        }
        int total = con.getContentLength();
        CountingInputStream in = new CountingInputStream(con.getInputStream());
        byte[] buf = new byte[8192];
        int len;

        File dst = getDestination();
        File tmp = new File(dst.getPath() + ".tmp");
        OutputStream out = new FileOutputStream(tmp);

        try {
            while ((len = in.read(buf)) >= 0) {
                out.write(buf, 0, len);
                //job.status = job.new Installing(total == -1 ? -1 : in.getCount() * 100 / total);
            }
        } catch (IOException e) {
            throw new IOException("Failed to load " + src + " to " + tmp, e);
        } finally {
            IOUtils.closeQuietly(out);
            IOUtils.closeQuietly(in);
        }

        if (total != -1 && total != tmp.length()) {
            throw new IOException("Inconsistent file length: expected " + total + " but only got " + tmp.length());
        }

        return tmp;
    }

    /**
     * Called when the download is completed to overwrite the old file with the
     * new file.
     */
    private void replace(File dst, File src) throws IOException {
        File bak = Util.changeExtension(dst, ".bak");
        bak.delete();
        dst.renameTo(bak);
        dst.delete(); // any failure up to here is no big deal
        if (!src.renameTo(dst)) {
            throw new IOException("Failed to rename " + src + " to " + dst);
        }
    }

    private URL getDownloadURL() throws MalformedURLException {
        return new URL(plugin.getDownloadUrl());
    }

    private File getDestination() {
        return new File(pluginsDir, plugin.getName() + ".hpi");
    }
}