func NewStore(ttl uint64, registryURL string) *Store {
	s := &Store{
		TTL:         ttl,
		pollCh:      make(chan bool),
		restartChan: make(chan *ConfigChange, 10),
	}

	u, err := url.Parse(registryURL)
	if err != nil {
		log.Fatalf("ERROR: Unable to parse %s", err)
	}

	switch strings.ToLower(u.Scheme) {
	case "redis":
		s.Backend = &RedisBackend{
			RedisHost: u.Host,
		}
		s.Backend.connect()
	case "consul":
		s.Backend = NewConsulBackend()
	default:
		log.Fatalf("ERROR: Unsupported registry backend: %s", u)
	}

	return s
}

func initOrDie() {

	if registryURL == "" {
		log.Fatalf("ERROR: Registry URL not specified. Use '-registry redis://127.0.0.1:6379' or set 'GALAXY_REGISTRY_URL'")
	}

	configStore = config.NewStore(config.DefaultTTL, registryURL)

	serviceRuntime = runtime.NewServiceRuntime(configStore, dns, hostIP)

	apps, err := configStore.ListAssignments(env, pool)
	if err != nil {
		log.Fatalf("ERROR: Could not retrieve service configs for /%s/%s: %s", env, pool, err)
	}

	workerChans = make(map[string]chan string)
	for _, app := range apps {
		appCfg, err := configStore.GetApp(app, env)
		if err != nil {
			log.Fatalf("ERROR: Could not retrieve service config for /%s/%s: %s", env, pool, err)
		}

		workerChans[appCfg.Name()] = make(chan string)
	}

	signalsChan = make(chan os.Signal, 1)
	signal.Notify(signalsChan, os.Interrupt, os.Kill, syscall.SIGTERM)
	go deregisterHost(signalsChan)
}

func NewServiceRuntime(configStore *config.Store, dns, hostIP string) *ServiceRuntime {
	var err error
	var client *docker.Client

	dockerZero, err := dockerBridgeIp()
	if err != nil {
		log.Fatalf("ERROR: Unable to find docker0 bridge: %s", err)
	}

	endpoint := GetEndpoint()

	if certPath := os.Getenv("DOCKER_CERT_PATH"); certPath != "" {
		cert := certPath + "/cert.pem"
		key := certPath + "/key.pem"
		ca := certPath + "/ca.pem"
		client, err = docker.NewTLSClient(endpoint, cert, key, ca)
	} else {
		client, err = docker.NewClient(endpoint)
	}

	if err != nil {
		log.Fatalf("ERROR: Unable to initialize docker client: %s: %s", err, endpoint)
	}

	client.HTTPClient.Timeout = 60 * time.Second

	return &ServiceRuntime{
		dns:          dns,
		configStore:  configStore,
		hostIP:       hostIP,
		dockerIP:     dockerZero,
		dockerClient: client,
	}
}

func ensureEnv() {
	envs, err := configStore.ListEnvs()
	if err != nil {
		log.Fatalf("ERROR: Could not check envs: %s", err)
	}

	if strings.TrimSpace(env) == "" {
		log.Fatalf("ERROR: Need an env.  Use '-env <env>'. Existing envs are: %s.", strings.Join(envs, ","))
	}
}

func ensurePool() {

	pools, err := configStore.ListPools(env)
	if err != nil {
		log.Fatalf("ERROR: Could not check pools: %s", err)
	}

	if strings.TrimSpace(pool) == "" {
		log.Fatalf("ERROR: Need a pool.  Use '-pool <pool>'. Existing pools are: %s", strings.Join(pools, ","))
	}
}

// wait until a stack is in a final state, then delete it
func waitAndDelete(name string) {
	log.Println("Attempting to delete stack:", name)
	// we need to get the StackID in order to lookup DELETE events
	desc, err := stack.DescribeStacks(name)
	if err != nil {
		log.Fatalf("ERROR: %s", err)
	} else if len(desc.Stacks) == 0 {
		log.Fatal("ERROR: could not describe stack:", name)
	}

	stackId := desc.Stacks[0].Id

	err = stack.WaitForComplete(stackId, 5*time.Minute)
	if err != nil {
		log.Fatal(err)
	}

	_, err = stack.Delete(name)
	if err != nil {
		log.Fatal(err)
	}

	// wait
	err = stack.WaitForComplete(stackId, 5*time.Minute)
	if err != nil {
		log.Fatal(err)
	}
	log.Println("Deleted stack:", name)
}

// Print a Cloudformation template to stdout.
func stackTemplate(c *cli.Context) {
	stackName := c.Args().First()
	if c.String("region") != "" {
		stack.Region = c.String("region")
	}

	if stackName == "" {
		os.Stdout.Write(stack.DefaultGalaxyTemplate())
		return
	}

	if c.String("region") != "" {
		stack.Region = c.String("region")
	}

	stackTmpl, err := stack.GetTemplate(stackName)
	if err != nil {
		if err, ok := err.(*aws.Error); ok {
			if err.Code == "ValidationError" && strings.Contains(err.Message, "does not exist") {
				log.Fatalf("ERROR: Stack '%s' does not exist", stackName)
			}
		}
		log.Fatal(err)
	}

	if _, err := os.Stdout.Write(stackTmpl); err != nil {
		log.Fatal(err)
	}
}

func poolCreate(c *cli.Context) {
	ensureEnvArg(c)
	ensurePoolArg(c)
	initStore(c)
	created, err := configStore.CreatePool(utils.GalaxyPool(c), utils.GalaxyEnv(c))
	if err != nil {
		log.Fatalf("ERROR: Could not create pool: %s", err)
		return
	}

	if created {
		log.Printf("Pool %s created\n", utils.GalaxyPool(c))
	} else {
		log.Printf("Pool %s already exists\n", utils.GalaxyPool(c))
	}

	ec2host, err := runtime.EC2PublicHostname()
	if err != nil || ec2host == "" {
		log.Debug("not running from AWS, skipping pool creation")
		return
	}

	// now create the cloudformation stack
	// is this fails, the stack can be created separately with
	// stack:create_pool
	stackCreatePool(c)
}

func appList(c *cli.Context) {
	initStore(c)
	err := commander.AppList(configStore, utils.GalaxyEnv(c))
	if err != nil {
		log.Fatalf("ERROR: %s", err)
	}
}

func appRun(c *cli.Context) {
	ensureEnvArg(c)
	initStore(c)
	initRuntime(c)

	app := ensureAppParam(c, "app:run")

	if len(c.Args()) < 2 {
		log.Fatalf("ERROR: Missing command to run.")
		return
	}

	err := commander.AppRun(configStore, serviceRuntime, app, utils.GalaxyEnv(c), c.Args()[1:])
	if err != nil {
		log.Fatalf("ERROR: %s", err)
	}
}

func poolList(c *cli.Context) {
	initStore(c)

	envs := []string{utils.GalaxyEnv(c)}
	if utils.GalaxyEnv(c) == "" {
		var err error
		envs, err = configStore.ListEnvs()
		if err != nil {
			log.Fatalf("ERROR: %s", err)
		}
	}

	columns := []string{"ENV | POOL | APPS "}

	for _, env := range envs {
		pools, err := configStore.ListPools(env)
		if err != nil {
			log.Fatalf("ERROR: cannot list pools: %s", err)
			return
		}

		if len(pools) == 0 {
			columns = append(columns, strings.Join([]string{
				env,
				"",
				""}, " | "))
			continue
		}

		for _, pool := range pools {

			assigments, err := configStore.ListAssignments(env, pool)
			if err != nil {
				log.Fatalf("ERROR: cannot list pool assignments: %s", err)
			}

			columns = append(columns, strings.Join([]string{
				env,
				pool,
				strings.Join(assigments, ",")}, " | "))
		}

	}
	output := columnize.SimpleFormat(columns)
	log.Println(output)
}

// Backup app config to a file or STDOUT
func appBackup(c *cli.Context) {
	initStore(c)

	env := utils.GalaxyEnv(c)
	if env == "" {
		log.Fatal("ERROR: env is required.  Pass --env or set GALAXY_ENV")
	}

	backup := &backupData{
		Time: time.Now(),
	}

	toBackup := c.Args()

	if len(toBackup) == 0 {
		appList, err := configStore.ListApps(env)
		if err != nil {
			log.Fatalf("ERROR: %s\n", err)
		}

		for _, app := range appList {
			toBackup = append(toBackup, app.Name())
		}
	}

	errCount := 0
	for _, app := range toBackup {
		data, err := getAppBackup(app, env)
		if err != nil {
			// log errors and continue
			log.Errorf("ERROR: %s [%s]", err, app)
			errCount++
			continue
		}
		backup.Apps = append(backup.Apps, data)
	}

	if errCount > 0 {
		fmt.Printf("WARNING: backup completed with %d errors\n", errCount)
		defer os.Exit(errCount)
	}

	j, err := json.MarshalIndent(backup, "", "  ")
	if err != nil {
		log.Fatal(err)
	}

	fileName := c.String("file")
	if fileName != "" {
		if err := ioutil.WriteFile(fileName, j, 0666); err != nil {
			log.Fatal(err)
		}
		return
	}

	os.Stdout.Write(j)
}

func ensureAppParam(c *cli.Context, command string) string {
	app := c.Args().First()
	if app == "" {
		cli.ShowCommandHelp(c, command)
		log.Fatal("ERROR: app name missing")
	}

	exists, err := appExists(app, utils.GalaxyEnv(c))
	if err != nil {
		log.Fatalf("ERROR: can't deteremine if %s exists: %s", app, err)
	}

	if !exists {
		log.Fatalf("ERROR: %s does not exist. Create it first.", app)
	}

	return app
}

// return --base, or try to find a base cloudformation stack
func getBase(c *cli.Context) string {
	errNoBase := fmt.Errorf("could not identify a unique base stack")

	base := c.String("base")
	if base != "" {
		return base
	}

	descResp, err := stack.DescribeStacks("")
	if err != nil {
		log.Fatal(err)
	}

	for _, stack := range descResp.Stacks {
		// first check for galaxy:base tag
		baseTag := false
		for _, t := range stack.Tags {
			if t.Key == "galaxy" && t.Value == "base" {
				baseTag = true
			}
		}
		if baseTag {
			if base != "" {
				err = errNoBase
			}
			base = stack.Name
			continue
		}
		parts := strings.Split(stack.Name, "-")

		// check for "-base" in the name
		if parts[len(parts)-1] == "base" {
			if base != "" {
				err = errNoBase
			}
			base = stack.Name
			continue
		}

		// the best we can do for now is look for a stack with a single word
		if len(parts) == 1 {
			if base != "" {
				err = errNoBase
			}
			base = stack.Name

			log.Printf("Warning: guessing base stack: %s", base)
		}
	}

	if err != nil {
		log.Fatalf("%s: %s", err, "use --base")
	}

	return base
}

func pgPsql(c *cli.Context) {
	ensureEnvArg(c)
	initStore(c)
	app := ensureAppParam(c, "pg:psql")

	appCfg, err := configStore.GetApp(app, utils.GalaxyEnv(c))
	if err != nil {
		log.Fatalf("ERROR: Unable to run command: %s.", err)
		return
	}

	database_url := appCfg.Env()["DATABASE_URL"]
	if database_url == "" {
		log.Printf("No DATABASE_URL configured.  Set one with config:set first.")
		return
	}

	if !strings.HasPrefix(database_url, "postgres://") {
		log.Printf("DATABASE_URL is not a postgres database.")
		return
	}

	cmd := exec.Command("psql", database_url)

	cmd.Stdin = os.Stdin
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr

	// Ignore SIGINT while the process is running
	ch := make(chan os.Signal, 1)
	signal.Notify(ch, os.Interrupt)

	defer func() {
		signal.Stop(ch)
		close(ch)
	}()

	go func() {
		for {
			_, ok := <-ch
			if !ok {
				break
			}
		}
	}()

	err = cmd.Start()
	if err != nil {
		log.Fatal(err)
	}

	err = cmd.Wait()
	if err != nil {
		fmt.Printf("Command finished with error: %v\n", err)
	}
}

func appRestart(c *cli.Context) {
	initStore(c)

	app := ensureAppParam(c, "app:restart")

	err := commander.AppRestart(configStore, app, utils.GalaxyEnv(c))
	if err != nil {
		log.Fatalf("ERROR: %s", err)
	}
}

func appDelete(c *cli.Context) {
	ensureEnvArg(c)
	initStore(c)

	app := ensureAppParam(c, "app:delete")

	err := commander.AppDelete(configStore, app, utils.GalaxyEnv(c))
	if err != nil {
		log.Fatalf("ERROR: %s", err)
	}
}

func configUnset(c *cli.Context) {
	ensureEnvArg(c)
	initStore(c)
	app := ensureAppParam(c, "config:unset")

	err := commander.ConfigUnset(configStore, app, utils.GalaxyEnv(c), c.Args().Tail())
	if err != nil {
		log.Fatalf("ERROR: Unable to unset config: %s.", err)
		return
	}
}

func configList(c *cli.Context) {
	ensureEnvArg(c)
	initStore(c)
	app := ensureAppParam(c, "config")

	err := commander.ConfigList(configStore, app, utils.GalaxyEnv(c))
	if err != nil {
		log.Fatalf("ERROR: Unable to list config: %s.", err)
		return
	}
}

func loadConfig() {
	configFile := filepath.Join(cfgDir(), "galaxy.toml")

	_, err := os.Stat(configFile)
	if err == nil {
		if _, err := toml.DecodeFile(configFile, &config); err != nil {
			log.Fatalf("ERROR: Unable to logout: %s", err)
			return
		}
	}

}