main.go

// Craig Hesling
// May 25, 2018
//
// This is a simple OpenChirp service that output the running diff of the data.
package main

import (
	"math"
	"os"
	"os/signal"
	"strconv"
	"strings"
	"syscall"

	"github.com/openchirp/framework/rest"

	"github.com/openchirp/framework"
	"github.com/openchirp/framework/utils"
	log "github.com/sirupsen/logrus"
	"github.com/urfave/cli"
)

const (
	version string = "1.0"
)

const (
	configKeyInputTopics  = "InputTopics"
	configKeyOutputTopics = "OutputTopics"
)

var configParams = []rest.ServiceConfigParameter{
	rest.ServiceConfigParameter{
		Name:        configKeyInputTopics,
		Description: "Comma separated list of input topics to apply the diff to",
		Example:     "frequency, temp",
		Required:    true,
	},
	rest.ServiceConfigParameter{
		Name:        configKeyOutputTopics,
		Description: "Comma separated list of corresponding output topics",
		Example:     "frequency_diff, temp_diff",
		Required:    false,
	},
}

const (
	defaultOutputTopicSuffix = "_diff"
)

const (
	// Set this value to true to have the service publish a service status of
	// "Running" each time it receives a device update event
	runningStatus = true
)

// Device holds the device specific last values and target topics for the difference.
type Device struct {
	outtopics  []string
	lastvalues []float64
}

// NewDevice is called by the framework when a new device has been linked.
func NewDevice() framework.Device {
	d := new(Device)
	return framework.Device(d)
}

// ProcessLink is called once, during the initial setup of a
// device, and is provided the service config for the linking device.
func (d *Device) ProcessLink(ctrl *framework.DeviceControl) string {
	logitem := log.WithField("deviceid", ctrl.Id())
	logitem.Debug("Linking with config:", ctrl.Config())

	// Allows space in comma seperated list
	inputTopicsString := strings.Replace(ctrl.Config()[configKeyInputTopics], " ", "", -1)
	outputTopicsString := strings.Replace(ctrl.Config()[configKeyOutputTopics], " ", "", -1)
	inputTopics := strings.Split(inputTopicsString, ",")
	outputTopics := strings.Split(outputTopicsString, ",")

	d.outtopics = make([]string, len(inputTopics))
	d.lastvalues = make([]float64, len(inputTopics))

	for i, intopic := range inputTopics {
		var outtopic string
		if i < len(outputTopics) && (len(outputTopics[i]) > 0) {
			outtopic = outputTopics[i]
		} else {
			// if no putput topic specified, simply append a _diff to the topic
			outtopic = intopic + defaultOutputTopicSuffix
		}
		d.outtopics[i] = outtopic
		d.lastvalues[i] = math.NaN()
		ctrl.Subscribe(intopic, i)
	}

	logitem.Debug("Finished Linking")

	// This message is sent to the service status for the linking device
	return "Success"
}

// ProcessUnlink is called once, when the service has been unlinked from
// the device.
func (d *Device) ProcessUnlink(ctrl *framework.DeviceControl) {
	logitem := log.WithField("deviceid", ctrl.Id())
	logitem.Debug("Unlinked:")
}

// ProcessConfigChange is ignored in this case.
func (d *Device) ProcessConfigChange(ctrl *framework.DeviceControl, cchanges, coriginal map[string]string) (string, bool) {
	logitem := log.WithField("deviceid", ctrl.Id())

	logitem.Debug("Ignoring Config Change:", cchanges)
	return "", false
}

// ProcessMessage is called upon receiving a pubsub message destined for
// this device.
func (d *Device) ProcessMessage(ctrl *framework.DeviceControl, msg framework.Message) {
	logitem := log.WithField("deviceid", ctrl.Id())
	logitem.Debugf("Processing diff for topic %s", msg.Topic())

	index := msg.Key().(int)
	value, err := strconv.ParseFloat(string(msg.Payload()), 64)
	if err != nil {
		logitem.Warnf("Failed to convert message (\"%v\") to float64", string(msg.Payload()))
		return
	}

	// First value is only stored, so that we don't get spurious spikes
	if math.IsNaN(d.lastvalues[index]) {
		logitem.Debugf("Setting first value | newvalue=%s", utils.FormatFloat64(value))
		d.lastvalues[index] = value
		return
	}

	diff := value - d.lastvalues[index]
	d.lastvalues[index] = value

	logitem.Debugf("lastvalue=%.10f | newvalue=%.10f | diff=%s", d.lastvalues[index], value, utils.FormatFloat64(diff))

	ctrl.Publish(d.outtopics[index], utils.FormatFloat64(diff))
}

// run is the main function that gets called once form main()
func run(ctx *cli.Context) error {
	/* Set logging level (verbosity) */
	log.SetLevel(log.Level(uint32(ctx.Int("log-level"))))

	log.Info("Starting Math Diff Service")

	/* Start framework service client */
	c, err := framework.StartServiceClientManaged(
		ctx.String("framework-server"),
		ctx.String("mqtt-server"),
		ctx.String("service-id"),
		ctx.String("service-token"),
		"Unexpected disconnect!",
		NewDevice)
	if err != nil {
		log.Error("Failed to StartServiceClient: ", err)
		return cli.NewExitError(nil, 1)
	}
	defer c.StopClient()
	log.Info("Started service")

	/* Post service's global status */
	if err := c.SetStatus("Starting"); err != nil {
		log.Error("Failed to publish service status: ", err)
		return cli.NewExitError(nil, 1)
	}
	log.Info("Published Service Status")

	/* Updating device config parameters */
	if err := c.UpdateConfigParameters(configParams); err != nil {
		log.Error("Failed to update service config parameters: ", err)
		return cli.NewExitError(nil, 1)
	}
	log.Info("Updated Service Config Parameters")

	/* Setup signal channel */
	signals := make(chan os.Signal, 1)
	signal.Notify(signals, os.Interrupt, syscall.SIGTERM)

	/* Post service status indicating I started */
	if err := c.SetStatus("Started"); err != nil {
		log.Error("Failed to publish service status: ", err)
		return cli.NewExitError(nil, 1)
	}
	log.Info("Published Service Status")

	/* Wait on a signal */
	sig := <-signals
	log.Info("Received signal ", sig)
	log.Warning("Shutting down")

	/* Post service's global status */
	if err := c.SetStatus("Shutting down"); err != nil {
		log.Error("Failed to publish service status: ", err)
	}
	log.Info("Published service status")

	return nil
}

func main() {
	/* Parse arguments and environmental variable */
	app := cli.NewApp()
	app.Name = "math-diff-service"
	app.Usage = ""
	app.Copyright = "See https://github.com/openchirp/math-diff-service for copyright information"
	app.Version = version
	app.Action = run
	app.Flags = []cli.Flag{
		cli.StringFlag{
			Name:   "framework-server",
			Usage:  "OpenChirp framework server's URI",
			Value:  "http://localhost:7000",
			EnvVar: "FRAMEWORK_SERVER",
		},
		cli.StringFlag{
			Name:   "mqtt-server",
			Usage:  "MQTT server's URI (e.g. scheme://host:port where scheme is tcp or tls)",
			Value:  "tls://localhost:1883",
			EnvVar: "MQTT_SERVER",
		},
		cli.StringFlag{
			Name:   "service-id",
			Usage:  "OpenChirp service id",
			EnvVar: "SERVICE_ID",
		},
		cli.StringFlag{
			Name:   "service-token",
			Usage:  "OpenChirp service token",
			EnvVar: "SERVICE_TOKEN",
		},
		cli.IntFlag{
			Name:   "log-level",
			Value:  4,
			Usage:  "debug=5, info=4, warning=3, error=2, fatal=1, panic=0",
			EnvVar: "LOG_LEVEL",
		},
	}

	/* Launch the application */
	app.Run(os.Args)
}