// Sleep delays the execution of the remainder of the chain of commands.
//
// Params:
// 	-duration (time.Duration): Time to sleep.
//  -message (string): The message to log when entering sleep.
func Sleep(c cookoo.Context, p *cookoo.Params) (interface{}, cookoo.Interrupt) {
	dur := p.Get("duration", 10*time.Millisecond).(time.Duration)
	msg := p.Get("messages", "Sleeping").(string)
	log.Info(c, msg)
	time.Sleep(dur)
	log.Info(c, "Woke up.")
	return true, nil
}

// handleConn handles an individual client connection.
//
// It manages the connection, but passes channels on to `answer()`.
func (s *server) handleConn(conn net.Conn, conf *ssh.ServerConfig) {
	defer conn.Close()
	log.Info(s.c, "Accepted connection.")
	_, chans, reqs, err := ssh.NewServerConn(conn, conf)
	if err != nil {
		// Handshake failure.
		log.Errf(s.c, "Failed handshake: %s (%v)", err, conn)
		return
	}

	// Discard global requests. We're only concerned with channels.
	safely.GoDo(s.c, func() { ssh.DiscardRequests(reqs) })

	condata := sshConnection(conn)

	// Now we handle the channels.
	for incoming := range chans {
		log.Infof(s.c, "Channel type: %s\n", incoming.ChannelType())
		if incoming.ChannelType() != "session" {
			incoming.Reject(ssh.UnknownChannelType, "Unknown channel type")
		}

		channel, req, err := incoming.Accept()
		if err != nil {
			// Should close request and move on.
			panic(err)
		}
		safely.GoDo(s.c, func() { s.answer(channel, req, condata) })
	}
	conn.Close()
}

// RunOnce runs the equivalent of `confd --onetime`.
//
// This may run the process repeatedly until either we time out (~20 minutes) or
// the templates are successfully built.
//
// Importantly, this blocks until the run is complete.
//
// Params:
// - node (string): The etcd node to use. (Only etcd is currently supported)
//
// Returns:
// - The []bytes from stdout and stderr when running the program.
//
func RunOnce(c cookoo.Context, p *cookoo.Params) (interface{}, cookoo.Interrupt) {
	node := p.Get("node", defaultEtcd).(string)

	dargs := []string{"-onetime", "-node", node, "-log-level", "error"}

	log.Info(c, "Building confd templates. This may take a moment.")

	limit := 1200
	timeout := time.Second * 3
	var lasterr error
	start := time.Now()
	for i := 0; i < limit; i++ {
		out, err := exec.Command("confd", dargs...).CombinedOutput()
		if err == nil {
			log.Infof(c, "Templates generated for %s on run %d", node, i)
			return out, nil
		}
		log.Debugf(c, "Recoverable error: %s", err)
		log.Debugf(c, "Output: %q", out)
		lasterr = err

		time.Sleep(timeout)
		log.Infof(c, "Re-trying template build. (Elapsed time: %d)", time.Now().Sub(start)/time.Second)
	}

	return nil, fmt.Errorf("Could not build confd templates before timeout. Last error: %s", lasterr)
}

// Ping handles a simple test SSH exec.
//
// Returns the string PONG and exit status 0.
//
// Params:
// 	- channel (ssh.Channel): The channel to respond on.
// 	- request (*ssh.Request): The request.
//
func Ping(c cookoo.Context, p *cookoo.Params) (interface{}, cookoo.Interrupt) {
	channel := p.Get("channel", nil).(ssh.Channel)
	req := p.Get("request", nil).(*ssh.Request)
	log.Info(c, "PING\n")
	if _, err := channel.Write([]byte("pong")); err != nil {
		log.Errf(c, "Failed to write to channel: %s", err)
	}
	sendExitStatus(0, channel)
	req.Reply(true, nil)
	return nil, nil
}

// setJoinMode determines what mode to start the etcd server in.
//
// In discovery mode, this will use the discovery URL to join a new cluster.
// In "existing" mode, this will join to an existing cluster directly.
//
// Params:
//	- client (etcd.Getter): initialized etcd client
//	- path (string): path to get. This will go through os.ExpandEnv().
// 	- desiredLen (string): The number of nodes to expect in etcd. This is
// 	usually stored as a string.
//
// Returns:
//  string "existing" or "new"
func setJoinMode(c cookoo.Context, p *cookoo.Params) (interface{}, cookoo.Interrupt) {
	cli := p.Get("client", nil).(client.Client)
	dlen := p.Get("desiredLen", "3").(string)
	path := p.Get("path", "").(string)
	path = os.ExpandEnv(path)

	state := "existing"

	dint, err := strconv.Atoi(dlen)
	if err != nil {
		log.Warnf(c, "Expected integer length, got '%s'. Defaulting to 3", dlen)
		dint = 3
	}

	// Ideally, this should look in the /deis/status directory in the discovery
	// service. That will indicate how many members have been online in the
	// last few hours. This is a good indicator of whether a cluster exists,
	// even if not all the hosts are healthy.
	res, err := etcd.SimpleGet(cli, path, true)
	if err != nil {
		// This means that the discovery server is brand new, and nothing
		// has written to it yet. So we're new.
		if strings.Contains(err.Error(), "Key not found") {
			return "new", nil
		}
		log.Errf(c, "Failed simple get of %s: %s", path, err)
		return state, err
	}

	if !res.Node.Dir {
		//return state, errors.New("Expected a directory node in discovery service")
		log.Info(c, "No status information found in discovery service. Assuming new.")
		state = "new"
	} else if len(res.Node.Nodes) < dint {
		log.Info(c, "Cluster has not reached consensus number. Assuming new.")
		state = "new"
	}

	os.Setenv("ETCD_INITIAL_CLUSTER_STATE", state)
	return state, nil
}

// listen handles accepting and managing connections. However, since closer
// is len(1), it will not block the sender.
func (s *server) listen(l net.Listener, conf *ssh.ServerConfig, closer chan interface{}) error {
	cxt := s.c
	log.Info(cxt, "Accepting new connections.")
	defer l.Close()

	// FIXME: Since Accept blocks, closer may not be checked often enough.
	for {
		log.Info(cxt, "Checking closer.")
		if len(closer) > 0 {
			<-closer
			log.Info(cxt, "Shutting down SSHD listener.")
			return nil
		}
		conn, err := l.Accept()
		if err != nil {
			log.Warnf(cxt, "Error during Accept: %s", err)
			// We shouldn't kill the listener because of an error.
			return err
		}
		safely.GoDo(cxt, func() {
			s.handleConn(conn, conf)
		})
	}
}

// Wait waits for a sync.WaitGroup to finish.
//
// Params:
// 	- wg (Waiter): The thing to wait for.
// 	- msg (string): The message to print when done. If this is empty, nothing is sent.
// 	- waiting (string): String to tell what we're waiting for. If empty, nothing is displayed.
// 	- failures (int): The number of failures that occurred while waiting.
//
// Returns:
//  Nothing.
func Wait(c cookoo.Context, p *cookoo.Params) (interface{}, cookoo.Interrupt) {
	ok, missing := p.RequiresValue("wg")
	if !ok {
		return nil, &cookoo.FatalError{"Missing required fields: " + strings.Join(missing, ", ")}
	}
	wg := p.Get("wg", nil).(Waiter)
	msg := p.Get("msg", "").(string)
	fails := p.Get("failures", 0).(int)
	waitmsg := p.Get("waiting", "").(string)

	if len(waitmsg) > 0 {
		log.Info(c, waitmsg)
	}

	wg.Wait()
	if len(msg) > 0 {
		log.Info(c, msg)
	}

	if fails > 0 {
		return nil, fmt.Errorf("There were %d failures while waiting.", fails)
	}
	return nil, nil
}

// KillOnExit kills PIDs when the program exits.
//
// Otherwise, this blocks until an os.Interrupt or os.Kill is received.
//
// Params:
//  This treats Params as a map of process names (unimportant) to PIDs. It then
// attempts to kill all of the pids that it receives.
func KillOnExit(c cookoo.Context, p *cookoo.Params) (interface{}, cookoo.Interrupt) {
	sigs := make(chan os.Signal, 1)
	signal.Notify(sigs, os.Interrupt, os.Kill)

	safely.GoDo(c, func() {
		log.Info(c, "Builder is running.")

		<-sigs

		c.Log("info", "Builder received signal to stop.")
		pids := p.AsMap()
		killed := 0
		for name, pid := range pids {
			if pid, ok := pid.(int); ok {
				if proc, err := os.FindProcess(pid); err == nil {
					log.Infof(c, "Killing %s (pid=%d)", name, pid)
					proc.Kill()
					killed++
				}
			}
		}
	})
	return nil, nil
}