package hudson.model;

import hudson.CloseProofOutputStream;
import hudson.FilePath;
import hudson.Launcher;
import hudson.Launcher.LocalLauncher;
import hudson.Proc;
import hudson.Proc.RemoteProc;
import hudson.Util;
import hudson.model.Descriptor.FormException;
import hudson.remoting.Callable;
import hudson.remoting.Channel;
import hudson.remoting.Channel.Listener;
import hudson.remoting.RemoteInputStream;
import hudson.remoting.RemoteOutputStream;
import hudson.remoting.VirtualChannel;
import hudson.util.NullStream;
import hudson.util.StreamCopyThread;
import hudson.util.StreamTaskListener;
import org.kohsuke.stapler.StaplerRequest;
import org.kohsuke.stapler.StaplerResponse;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Serializable;
import java.net.URL;
import java.net.URLConnection;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Information about a Hudson slave node.
 *
 * @author Kohsuke Kawaguchi
 */
public final class Slave implements Node, Serializable {
    /**
     * PluginName of this slave node.
     */
    protected final String name;

    /**
     * Description of this node.
     */
    private final String description;

    /**
     * Path to the root of the workspace
     * from the view point of this node, such as "/hudson"
     */
    protected final String remoteFS;

    /**
     * Number of executors of this node.
     */
    private int numExecutors = 2;

    /**
     * Job allocation strategy.
     */
    private Mode mode;

    /**
     * Command line to launch the agent, like
     * "ssh myslave java -jar /path/to/hudson-remoting.jar"
     */
    private String agentCommand;

    /**
     * @stapler-constructor
     */
    public Slave(String name, String description, String command, String remoteFS, int numExecutors, Mode mode) throws FormException {
        this.name = name;
        this.description = description;
        this.numExecutors = numExecutors;
        this.mode = mode;
        this.agentCommand = command;
        this.remoteFS = remoteFS;

        if (name.equals(""))
            throw new FormException("Invalid slave configuration. PluginName is empty", null);

        // this prevents the config from being saved when slaves are offline.
        // on a large deployment with a lot of slaves, some slaves are bound to be offline,
        // so this check is harmful.
        //if (!localFS.exists())
        //    throw new FormException("Invalid slave configuration for " + name + ". No such directory exists: " + localFS, null);
        if (remoteFS.equals(""))
            throw new FormException("Invalid slave configuration for " + name + ". No remote directory given", null);
    }

    public String getCommand() {
        return agentCommand;
    }

    public String getRemoteFS() {
        return remoteFS;
    }

    public String getNodeName() {
        return name;
    }

    public String getNodeDescription() {
        return description;
    }

    public FilePath getFilePath() {
        return new FilePath(getComputer().getChannel(),remoteFS);
    }

    public int getNumExecutors() {
        return numExecutors;
    }

    public Mode getMode() {
        return mode;
    }

    /**
     * Estimates the clock difference with this slave.
     *
     * @return
     *      difference in milli-seconds.
     *      a positive value indicates that the master is ahead of the slave,
     *      and negative value indicates otherwise.
     */
    public long getClockDifference() throws IOException {
        VirtualChannel channel = getComputer().getChannel();
        if(channel==null)   return 0;   // can't check

        try {
            long startTime = System.currentTimeMillis();
            long slaveTime = channel.call(new Callable<Long,RuntimeException>() {
                public Long call() {
                    return System.currentTimeMillis();
                }
            });
            long endTime = System.currentTimeMillis();

            return (startTime+endTime)/2 - slaveTime;
        } catch (InterruptedException e) {
            return 0;   // couldn't check
        }
    }


    /**
     * Gets the clock difference in HTML string.
     */
    public String getClockDifferenceString() {
        try {
            long diff = getClockDifference();
            if(-1000<diff && diff <1000)
                return "In sync";  // clock is in sync

            long abs = Math.abs(diff);

            String s = Util.getTimeSpanString(abs);
            if(diff<0)
                s += " ahead";
            else
                s += " behind";

            if(abs>100*60) // more than a minute difference
                s = "<span class='error'>"+s+"</span>";

            return s;
        } catch (IOException e) {
            return "<span class='error'>Unable to check</span>";
        }
    }

    public Computer createComputer() {
        return new ComputerImpl(this);
    }

    public FilePath getWorkspaceFor(TopLevelItem item) {
        return getWorkspaceRoot().child(item.getName());
    }

    /**
     * Root directory on this slave where all the job workspaces are laid out.
     */
    public FilePath getWorkspaceRoot() {
        return getFilePath().child("workspace");
    }

    public static final class ComputerImpl extends Computer {
        private volatile Channel channel;

        /**
         * This is where the log from the remote agent goes.
         */
        private File getLogFile() {
            return new File(Hudson.getInstance().getRootDir(),"slave-"+nodeName+".log");
        }

        private ComputerImpl(Slave slave) {
            super(slave);
        }

        /**
         * Launches a remote agent.
         */
        private void launch(final Slave slave) {
            closeChannel();

            OutputStream os;
            try {
                os = new FileOutputStream(getLogFile());
            } catch (FileNotFoundException e) {
                logger.log(Level.SEVERE, "Failed to create log file "+getLogFile(),e);
                os = new NullStream();
            }
            final OutputStream launchLog = os;

            // launch the slave agent asynchronously
            threadPoolForRemoting.execute(new Runnable() {
                // TODO: do this only for nodes that are so configured.
                // TODO: support passive connection via JNLP
                public void run() {
                    final StreamTaskListener listener = new StreamTaskListener(launchLog);
                    try {
                        listener.getLogger().println("Launching slave agent");
                        listener.getLogger().println("$ "+slave.agentCommand);
                        final Process proc = Runtime.getRuntime().exec(slave.agentCommand);

                        // capture error information from stderr. this will terminate itself
                        // when the process is killed.
                        new StreamCopyThread("stderr copier for remote agent on "+slave.getNodeName(),
                            proc.getErrorStream(), launchLog).start();

                        setChannel(proc.getInputStream(),proc.getOutputStream(),launchLog,new Listener() {
                            public void onClosed(Channel channel, IOException cause) {
                                if(cause!=null)
                                    cause.printStackTrace(listener.error("slave agent was terminated"));
                                proc.destroy();
                            }
                        });

                        logger.info("slave agent launched for "+slave.getNodeName());

                    } catch (IOException e) {
                        Util.displayIOException(e,listener);

                        String msg = Util.getWin32ErrorMessage(e);
                        if(msg==null)   msg="";
                        else            msg=" : "+msg;
                        msg = "Unable to launch the slave agent for " + slave.getNodeName() + msg;
                        logger.log(Level.SEVERE,msg,e);
                        e.printStackTrace(listener.error(msg));
                    }
                }
            });
        }

        private final Object channelLock = new Object();

        /**
         * Creates a {@link Channel} from the given stream and sets that to this slave.
         */
        public void setChannel(InputStream in, OutputStream out, OutputStream launchLog, Listener listener) throws IOException {
            synchronized(channelLock) {
                if(this.channel!=null)
                    throw new IllegalStateException("Already connected");

                channel = new Channel(nodeName,threadPoolForRemoting,
                    in,out, launchLog);
                channel.addListener(new Listener() {
                    public void onClosed(Channel c,IOException cause) {
                        ComputerImpl.this.channel = null;
                    }
                });
                channel.addListener(listener);
            }
            Hudson.getInstance().getQueue().scheduleMaintenance();
        }

        @Override
        public VirtualChannel getChannel() {
            return channel;
        }

        public void doLaunchSlaveAgent(StaplerRequest req, StaplerResponse rsp) throws IOException, ServletException {
            if(channel!=null) {
                rsp.sendError(HttpServletResponse.SC_NOT_FOUND);
                return;
            }

            launch((Slave) getNode());

            // TODO: would be nice to redirect the user to "launching..." wait page,
            // then spend a few seconds there and poll for the completion periodically.
            rsp.sendRedirect("log");
        }

        /**
         * Gets the string representation of the slave log.
         */
        public String getLog() throws IOException {
            return Util.loadFile(getLogFile());
        }

        /**
         * Handles incremental log.
         */
        public void doProgressiveLog( StaplerRequest req, StaplerResponse rsp) throws IOException {
            new LargeText(getLogFile(),false).doProgressText(req,rsp);
        }

        /**
         * Serves jar files for JNLP slave agents.
         */
        public JnlpJar getJnlpJars(String fileNamePlusJar) {
            return new JnlpJar(fileNamePlusJar.substring(0,fileNamePlusJar.length()-4)); // remove .jar
        }

        @Override
        protected void kill() {
            super.kill();
            closeChannel();
        }

        private void closeChannel() {
            Channel c = channel;
            channel = null;
            if(c!=null)
                try {
                    c.close();
                } catch (IOException e) {
                    logger.log(Level.SEVERE, "Failed to terminate channel to "+getDisplayName(),e);
                }
        }

        @Override
        protected void setNode(Node node) {
            super.setNode(node);
            if(channel==null)
                // maybe the configuration was changed to relaunch the slave, so try it now.
                launch((Slave)node);
        }

        private static final Logger logger = Logger.getLogger(ComputerImpl.class.getName());
    }

    /**
     * Web-bound object used to serve jar files for JNLP.
     */
    public static final class JnlpJar {
        private final String className;

        public JnlpJar(String className) {
            this.className = className;
        }

        public void doIndex( StaplerRequest req, StaplerResponse rsp) throws IOException, ServletException {
            // where is the jar file?
            // we can't use ServletContext.getResourcePaths() because
            // during debugging there's no WEB-INF/lib.
            URL classFile = getClass().getClassLoader().getResource(className.replace('.', '/') + ".class");
            if(classFile==null) {
                rsp.sendError(HttpServletResponse.SC_NOT_FOUND);
                return;
            }

            String loc = classFile.toExternalForm().substring(4);// cut off jar:
            loc = loc.substring(0,loc.lastIndexOf('!'));


            URLConnection con = new URL(loc).openConnection();
            InputStream in = con.getInputStream();
            rsp.serveFile(req, in, con.getLastModified(), con.getContentLength(), "*.jar" );
            in.close();
        }

    }

    public Launcher createLauncher(TaskListener listener) {
        return new Launcher(listener, getComputer().getChannel()) {
            public Proc launch(final String[] cmd, final String[] env, InputStream _in, OutputStream _out, FilePath _workDir) throws IOException {
                printCommandLine(cmd,_workDir);

                final OutputStream out = new RemoteOutputStream(new CloseProofOutputStream(_out));
                final InputStream  in  = _in==null ? null : new RemoteInputStream(_in);
                final String workDir = _workDir==null ? null : _workDir.getRemote();

                return new RemoteProc(getChannel().callAsync(new RemoteLaunchCallable(cmd, env, in, out, workDir)));
            }

            @Override
            public boolean isUnix() {
                // Windows can handle '/' as a path separator but Unix can't,
                // so err on Unix side
                return remoteFS.indexOf("\\")==-1;
            }
        };
    }

    /**
     * Gets th ecorresponding computer object.
     */
    public Computer getComputer() {
        return Hudson.getInstance().getComputer(getNodeName());
    }

    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        final Slave that = (Slave) o;

        return name.equals(that.name);
    }

    public int hashCode() {
        return name.hashCode();
    }

    /**
     * Invoked by XStream when this object is read into memory.
     */
    private Object readResolve() {
        // convert the old format to the new one
        if(command!=null && agentCommand==null) {
            if(command.length()>0)  command += ' ';
            agentCommand = command+"java -jar ~/bin/slave.jar";
        }
        return this;
    }

//
// backwrad compatibility
//
    /**
     * In Hudson < 1.69 this was used to store the local file path
     * to the remote workspace. No longer in use.
     *
     * @deprecated
     *      ... but still in use during the transition.
     */
    private File localFS;

    /**
     * In Hudson < 1.69 this was used to store the command
     * to connect to the remote machine, like "ssh myslave".
     *
     * @deprecated
     */
    private transient String command;

    private static class RemoteLaunchCallable implements Callable<Integer,IOException> {
        private final String[] cmd;
        private final String[] env;
        private final InputStream in;
        private final OutputStream out;
        private final String workDir;

        public RemoteLaunchCallable(String[] cmd, String[] env, InputStream in, OutputStream out, String workDir) {
            this.cmd = cmd;
            this.env = env;
            this.in = in;
            this.out = out;
            this.workDir = workDir;
        }

        public Integer call() throws IOException {
            Proc p = new LocalLauncher(TaskListener.NULL).launch(cmd, env, in, out,
                workDir ==null ? null : new FilePath(new File(workDir)));
            return p.join();
        }

        private static final long serialVersionUID = 1L;
    }
}