// Invoke tests whether or not this event script should be invoked
// for the given Serf event.
func (s *EventFilter) Invoke(e serf.Event) bool {
	if s.Event == "*" {
		return true
	}

	if e.EventType().String() != s.Event {
		return false
	}

	if s.Event == "user" && s.Name != "" {
		userE, ok := e.(serf.UserEvent)
		if !ok {
			return false
		}

		if userE.Name != s.Name {
			return false
		}
	}

	if s.Event == "query" && s.Name != "" {
		query, ok := e.(*serf.Query)
		if !ok {
			return false
		}

		if query.Name != s.Name {
			return false
		}
	}

	return true
}

func (c *Cluster) handleSerfEvent(e serf.Event) {
	switch e.EventType() {
	case serf.EventMemberJoin:
		c.logger.Debug("Handling member join event")
		go c.addEventMembers(e)

	case serf.EventMemberLeave:
		c.logger.Debug("Handling graceful member exit event")
		go c.removeEventMembers(e)

	case serf.EventMemberFailed:
		c.logger.Debug("Handling unresponsive member event")
		go c.updateEventMembers(e)

	case serf.EventMemberUpdate:
		c.logger.Debug("Handling member metadata update event")
		go c.updateEventMembers(e)

	case serf.EventMemberReap:
		c.logger.Debug("Handling forced member exit event")
		go c.removeEventMembers(e)

	default:
		c.logger.Warnf("Unhandled Serf event: %#v", e)
	}

	if c.config.SerfEvents != nil {
		c.config.SerfEvents <- e
	}
}

// invokeEventScript will execute the given event script with the given
// event. Depending on the event, the semantics of how data are passed
// are a bit different. For all events, the SERF_EVENT environmental
// variable is the type of the event. For user events, the SERF_USER_EVENT
// environmental variable is also set, containing the name of the user
// event that was fired.
//
// In all events, data is passed in via stdin to faciliate piping. See
// the various stdin functions below for more information.
func invokeEventScript(logger *log.Logger, script string, self serf.Member, event serf.Event) error {
	defer metrics.MeasureSince([]string{"agent", "invoke", script}, time.Now())
	var output bytes.Buffer

	// Determine the shell invocation based on OS
	var shell, flag string
	if runtime.GOOS == windows {
		shell = "cmd"
		flag = "/C"
	} else {
		shell = "/bin/sh"
		flag = "-c"
	}

	cmd := exec.Command(shell, flag, script)
	cmd.Args[0] = "serf-event"
	cmd.Env = append(os.Environ(),
		"SERF_EVENT="+event.EventType().String(),
		"SERF_SELF_NAME="+self.Name,
		"SERF_SELF_ROLE="+self.Tags["role"],
	)
	cmd.Stderr = &output
	cmd.Stdout = &output

	// Add all the tags
	for name, val := range self.Tags {
		tag_env := fmt.Sprintf("SERF_TAG_%s=%s", strings.ToUpper(name), val)
		cmd.Env = append(cmd.Env, tag_env)
	}

	stdin, err := cmd.StdinPipe()
	if err != nil {
		return err
	}

	switch e := event.(type) {
	case serf.MemberEvent:
		go memberEventStdin(logger, stdin, &e)
	case serf.UserEvent:
		cmd.Env = append(cmd.Env, "SERF_USER_EVENT="+e.Name)
		cmd.Env = append(cmd.Env, fmt.Sprintf("SERF_USER_LTIME=%d", e.LTime))
		go userEventStdin(logger, stdin, &e)
	default:
		return fmt.Errorf("Unknown event type: %s", event.EventType().String())
	}

	if err := cmd.Start(); err != nil {
		return err
	}

	err = cmd.Wait()
	logger.Printf("[DEBUG] Event '%s' script output: %s",
		event.EventType().String(), output.String())

	if err != nil {
		return err
	}

	return nil
}

// Invoke tests whether or not this event script should be invoked
// for the given Serf event.
func (s *EventFilter) Invoke(e serf.Event) bool {
	if s.Event == "*" {
		return true
	}

	if e.EventType().String() != s.Event {
		return false
	}

	if s.UserEvent != "" {
		userE, ok := e.(serf.UserEvent)
		if !ok {
			return false
		}

		if userE.Name != s.UserEvent {
			return false
		}
	}

	return true
}

// invokeEventScript will execute the given event script with the given
// event. Depending on the event, the semantics of how data are passed
// are a bit different. For all events, the SERF_EVENT environmental
// variable is the type of the event. For user events, the SERF_USER_EVENT
// environmental variable is also set, containing the name of the user
// event that was fired.
//
// In all events, data is passed in via stdin to faciliate piping. See
// the various stdin functions below for more information.
func invokeEventScript(logger *log.Logger, script string, self serf.Member, event serf.Event) error {
	var output bytes.Buffer

	// Determine the shell invocation based on OS
	var shell, flag string
	if runtime.GOOS == windows {
		shell = "cmd"
		flag = "/C"
	} else {
		shell = "/bin/sh"
		flag = "-c"
	}

	cmd := exec.Command(shell, flag, script)
	cmd.Args[0] = "serf-event"
	cmd.Env = append(cmd.Env,
		"SERF_EVENT="+event.EventType().String(),
		"SERF_SELF_NAME="+self.Name,
		"SERF_SELF_ROLE="+self.Role,
	)
	cmd.Stderr = &output
	cmd.Stdout = &output

	stdin, err := cmd.StdinPipe()
	if err != nil {
		return err
	}

	switch e := event.(type) {
	case serf.MemberEvent:
		go memberEventStdin(logger, stdin, &e)
	case serf.UserEvent:
		cmd.Env = append(cmd.Env, "SERF_USER_EVENT="+e.Name)
		cmd.Env = append(cmd.Env, fmt.Sprintf("SERF_USER_LTIME=%d", e.LTime))
		go userEventStdin(logger, stdin, &e)
	default:
		return fmt.Errorf("Unknown event type: %s", event.EventType().String())
	}

	if err := cmd.Start(); err != nil {
		return err
	}

	err = cmd.Wait()
	logger.Printf("[DEBUG] Event '%s' script output: %s",
		event.EventType().String(), output.String())

	if err != nil {
		return err
	}

	return nil
}

// invokeEventScript will execute the given event script with the given
// event. Depending on the event, the semantics of how data are passed
// are a bit different. For all events, the SERF_EVENT environmental
// variable is the type of the event. For user events, the SERF_USER_EVENT
// environmental variable is also set, containing the name of the user
// event that was fired.
//
// In all events, data is passed in via stdin to faciliate piping. See
// the various stdin functions below for more information.
func invokeEventScript(logger *log.Logger, script string, self serf.Member, event serf.Event) error {
	var output bytes.Buffer
	cmd := exec.Command("/bin/sh", "-c", script)
	cmd.Args[0] = "serf-event"
	cmd.Env = append(cmd.Env,
		"SERF_EVENT="+event.EventType().String(),
		"SERF_SELF_NAME="+self.Name,
		"SERF_SELF_ROLE="+self.Role,
	)
	cmd.Stderr = &output
	cmd.Stdout = &output

	stdin, err := cmd.StdinPipe()
	if err != nil {
		return err
	}

	switch e := event.(type) {
	case serf.MemberEvent:
		go memberEventStdin(logger, stdin, &e)
	case serf.UserEvent:
		cmd.Env = append(cmd.Env, "SERF_USER_EVENT="+e.Name)
		go userEventStdin(logger, stdin, &e)
	default:
		return fmt.Errorf("Unknown event type: %s", event.EventType().String())
	}

	if err := cmd.Start(); err != nil {
		return err
	}

	err = cmd.Wait()
	logger.Printf("[DEBUG] Event '%s' script output: %s",
		event.EventType().String(), output.String())

	if err != nil {
		return err
	}

	return nil
}

// invokeEventScript will execute the given event script with the given
// event. Depending on the event, the semantics of how data are passed
// are a bit different. For all events, the SERF_EVENT environmental
// variable is the type of the event. For user events, the SERF_USER_EVENT
// environmental variable is also set, containing the name of the user
// event that was fired.
//
// In all events, data is passed in via stdin to faciliate piping. See
// the various stdin functions below for more information.
func invokeEventScript(logger *log.Logger, script string, self serf.Member, event serf.Event) error {
	defer metrics.MeasureSince([]string{"agent", "invoke", script}, time.Now())
	var output bytes.Buffer

	// Determine the shell invocation based on OS
	var shell, flag string
	if runtime.GOOS == windows {
		shell = "cmd"
		flag = "/C"
	} else {
		shell = "/bin/sh"
		flag = "-c"
	}

	cmd := exec.Command(shell, flag, script)
	cmd.Env = append(os.Environ(),
		"SERF_EVENT="+event.EventType().String(),
		"SERF_SELF_NAME="+self.Name,
		"SERF_SELF_ROLE="+self.Tags["role"],
	)
	cmd.Stderr = &output
	cmd.Stdout = &output

	// Add all the tags
	for name, val := range self.Tags {
		tag_env := fmt.Sprintf("SERF_TAG_%s=%s", strings.ToUpper(name), val)
		cmd.Env = append(cmd.Env, tag_env)
	}

	stdin, err := cmd.StdinPipe()
	if err != nil {
		return err
	}

	switch e := event.(type) {
	case serf.MemberEvent:
		go memberEventStdin(logger, stdin, &e)
	case serf.UserEvent:
		cmd.Env = append(cmd.Env, "SERF_USER_EVENT="+e.Name)
		cmd.Env = append(cmd.Env, fmt.Sprintf("SERF_USER_LTIME=%d", e.LTime))
		go streamPayload(logger, stdin, e.Payload)
	case *serf.Query:
		cmd.Env = append(cmd.Env, "SERF_QUERY_NAME="+e.Name)
		cmd.Env = append(cmd.Env, fmt.Sprintf("SERF_QUERY_LTIME=%d", e.LTime))
		go streamPayload(logger, stdin, e.Payload)
	default:
		return fmt.Errorf("Unknown event type: %s", event.EventType().String())
	}

	if err := cmd.Start(); err != nil {
		return err
	}

	err = cmd.Wait()
	logger.Printf("[DEBUG] agent: Event '%s' script output: %s",
		event.EventType().String(), output.String())
	if err != nil {
		return err
	}

	// If this is a query and we have output, respond
	if query, ok := event.(*serf.Query); ok && len(output.Bytes()) > 0 {
		if err := query.Respond(output.Bytes()); err != nil {
			logger.Printf("[WARN] agent: Failed to respond to query '%s': %s",
				event.String(), err)
		}
	}

	return nil
}

// invokeEventScript will execute the given event script with the given
// event. Depending on the event, the semantics of how data are passed
// are a bit different. For all events, the SERF_EVENT environmental
// variable is the type of the event. For user events, the SERF_USER_EVENT
// environmental variable is also set, containing the name of the user
// event that was fired.
//
// In all events, data is passed in via stdin to faciliate piping. See
// the various stdin functions below for more information.
func invokeEventScript(logger *log.Logger, script string, self serf.Member, event serf.Event) error {
	defer metrics.MeasureSince([]string{"agent", "invoke", script}, time.Now())
	output, _ := circbuf.NewBuffer(maxBufSize)

	// Determine the shell invocation based on OS
	var shell, flag string
	if runtime.GOOS == windows {
		shell = "cmd"
		flag = "/C"
	} else {
		shell = "/bin/sh"
		flag = "-c"
	}

	cmd := exec.Command(shell, flag, script)
	cmd.Env = append(os.Environ(),
		"SERF_EVENT="+event.EventType().String(),
		"SERF_SELF_NAME="+self.Name,
		"SERF_SELF_IP="+self.Addr.String(),
		"SERF_SELF_PORT="+fmt.Sprintf("%v", self.Port),
		"SERF_SELF_ROLE="+self.Tags["role"],
	)
	cmd.Stderr = output
	cmd.Stdout = output

	// Add all the tags
	for name, val := range self.Tags {
		//http://stackoverflow.com/questions/2821043/allowed-characters-in-linux-environment-variable-names
		//(http://pubs.opengroup.org/onlinepubs/000095399/basedefs/xbd_chap08.html for the long version)
		//says that env var names must be in [A-Z0-9_] and not start with [0-9].
		//we only care about the first part, so convert all chars not in [A-Z0-9_] to _
		sanitizedName := sanitizeTagRegexp.ReplaceAllString(strings.ToUpper(name), "_")
		tag_env := fmt.Sprintf("SERF_TAG_%s=%s", sanitizedName, val)
		cmd.Env = append(cmd.Env, tag_env)
	}

	stdin, err := cmd.StdinPipe()
	if err != nil {
		return err
	}

	switch e := event.(type) {
	case serf.MemberEvent:
		go memberEventStdin(logger, stdin, &e)
	case serf.UserEvent:
		cmd.Env = append(cmd.Env, "SERF_USER_EVENT="+e.Name)
		cmd.Env = append(cmd.Env, fmt.Sprintf("SERF_USER_LTIME=%d", e.LTime))
		go streamPayload(logger, stdin, e.Payload)
	case *serf.Query:
		cmd.Env = append(cmd.Env, "SERF_QUERY_NAME="+e.Name)
		cmd.Env = append(cmd.Env, fmt.Sprintf("SERF_QUERY_LTIME=%d", e.LTime))
		go streamPayload(logger, stdin, e.Payload)
	default:
		return fmt.Errorf("Unknown event type: %s", event.EventType().String())
	}

	// Start a timer to warn about slow handlers
	slowTimer := time.AfterFunc(warnSlow, func() {
		logger.Printf("[WARN] agent: Script '%s' slow, execution exceeding %v",
			script, warnSlow)
	})

	if err := cmd.Start(); err != nil {
		return err
	}

	// Warn if buffer is overritten
	if output.TotalWritten() > output.Size() {
		logger.Printf("[WARN] agent: Script '%s' generated %d bytes of output, truncated to %d",
			script, output.TotalWritten(), output.Size())
	}

	err = cmd.Wait()
	slowTimer.Stop()
	logger.Printf("[DEBUG] agent: Event '%s' script output: %s",
		event.EventType().String(), output.String())
	if err != nil {
		return err
	}

	// If this is a query and we have output, respond
	if query, ok := event.(*serf.Query); ok && output.TotalWritten() > 0 {
		if err := query.Respond(output.Bytes()); err != nil {
			logger.Printf("[WARN] agent: Failed to respond to query '%s': %s",
				event.String(), err)
		}
	}

	return nil
}

// HandleEvent processes a generic Serf event and dispatches it to the appropriate
// destination.
func (s SerfEventHandler) HandleEvent(e serf.Event) {
	if e == nil {
		return
	}

	var reconcile bool
	switch e.EventType() {

	// If the event is a Join event, call NodeJoined and then reconcile event with
	// persistent storage.
	case serf.EventMemberJoin:
		reconcile = s.ReconcileOnJoin
		if s.NodeJoined != nil {
			s.NodeJoined.HandleMemberJoin(e.(serf.MemberEvent))
		}

	// If the event is a Leave event, call NodeLeft and then reconcile event with
	// persistent storage.
	case serf.EventMemberLeave:
		reconcile = s.ReconcileOnLeave
		if s.NodeLeft != nil {
			s.NodeLeft.HandleMemberLeave(e.(serf.MemberEvent))
		}

	// If the event is a Failed event, call NodeFailed and then reconcile event with
	// persistent storage.
	case serf.EventMemberFailed:
		reconcile = s.ReconcileOnFail
		if s.NodeFailed != nil {
			s.NodeFailed.HandleMemberFailure(e.(serf.MemberEvent))
		}

	// If the event is a Reap event, reconcile event with persistent storage.
	case serf.EventMemberReap:
		reconcile = s.ReconcileOnReap
		if s.NodeReaped != nil {
			s.NodeReaped.HandleMemberReap(e.(serf.MemberEvent))
		}

	// If the event is a user event, handle leader elections, user events and unknown events.
	case serf.EventUser:
		s.handleUserEvent(e.(serf.UserEvent))

	// If the event is an Update event, call NodeUpdated
	case serf.EventMemberUpdate:
		reconcile = s.ReconcileOnUpdate
		if s.NodeUpdated != nil {
			s.NodeUpdated.HandleMemberUpdate(e.(serf.MemberEvent))
		}

	// If the event is a query, call Query Handler
	case serf.EventQuery:
		if s.QueryHandler != nil {
			s.QueryHandler.HandleQueryEvent(*e.(*serf.Query))
		}
	default:
		s.Logger.Warn("unhandled Serf Event: %#v", e)
		return
	}

	// Reconcile event with external storage
	if reconcile && s.Reconciler != nil {
		s.reconcile(e.(serf.MemberEvent))
	}
}