// GetValues queries etcd for keys prefixed by prefix.
func (c *Client) GetValues(keys []string) (map[string]string, error) {
	vars := make(map[string]string)
	for _, key := range keys {
		log.Debug("getting %s from vault", key)
		resp, err := c.client.Logical().Read(key)

		if err != nil {
			log.Debug("there was an error extracting %s", key)
			return nil, err
		}
		if resp == nil || resp.Data == nil {
			continue
		}

		// if the key has only one string value
		// treat it as a string and not a map of values
		if val, ok := isKV(resp.Data); ok {
			vars[key] = val
		} else {
			// save the json encoded response
			// and flatten it to allow usage of gets & getvs
			js, _ := json.Marshal(resp.Data)
			vars[key] = string(js)
			flatten(key, resp.Data, vars)
		}
	}
	return vars, nil
}

// createStageFile stages the src configuration file by processing the src
// template and setting the desired owner, group, and mode. It also sets the
// StageFile for the template resource.
// It returns an error if any.
func (t *TemplateResource) createStageFile() error {
	log.Debug("Using source template " + t.Src)

	if !isFileExist(t.Src) {
		return errors.New("Missing template: " + t.Src)
	}

	log.Debug("Compiling source template " + t.Src)
	tmpl, err := template.New(path.Base(t.Src)).Funcs(t.funcMap).ParseFiles(t.Src)
	if err != nil {
		return fmt.Errorf("Unable to process template %s, %s", t.Src, err)
	}

	// create TempFile in Dest directory to avoid cross-filesystem issues
	temp, err := ioutil.TempFile(filepath.Dir(t.Dest), "."+filepath.Base(t.Dest))
	if err != nil {
		return err
	}

	if err = tmpl.Execute(temp, nil); err != nil {
		temp.Close()
		os.Remove(temp.Name())
		return err
	}
	defer temp.Close()

	// Set the owner, group, and mode on the stage file now to make it easier to
	// compare against the destination configuration file later.
	os.Chmod(temp.Name(), t.FileMode)
	os.Chown(temp.Name(), t.Uid, t.Gid)
	t.StageFile = temp
	return nil
}

// sync compares the staged and dest config files and attempts to sync them
// if they differ. sync will run a config check command if set before
// overwriting the target config file. Finally, sync will run a reload command
// if set to have the application or service pick up the changes.
// It returns an error if any.
func (t *TemplateResource) sync() error {
	staged := t.StageFile.Name()
	defer os.Remove(staged)
	log.Debug("Comparing candidate config to " + t.Dest)
	ok, err := sameConfig(staged, t.Dest)
	if err != nil {
		log.Error(err.Error())
	}
	if config.Noop() {
		log.Warning("Noop mode enabled " + t.Dest + " will not be modified")
		return nil
	}
	if !ok {
		log.Info("Target config " + t.Dest + " out of sync")
		if t.CheckCmd != "" {
			if err := t.check(); err != nil {
				return errors.New("Config check failed: " + err.Error())
			}
		}
		log.Debug("Overwriting target config " + t.Dest)
		if err := os.Rename(staged, t.Dest); err != nil {
			return err
		}
		if t.ReloadCmd != "" {
			if err := t.reload(); err != nil {
				return err
			}
		}
		log.Info("Target config " + t.Dest + " has been updated")
	} else {
		log.Info("Target config " + t.Dest + " in sync")
	}
	return nil
}

func getTemplateResources(config Config) ([]*TemplateResource, error) {
	var lastError error
	templates := make([]*TemplateResource, 0)
	log.Debug("Loading template resources from confdir " + config.ConfDir)
	if !isFileExist(config.ConfDir) {
		log.Warning(fmt.Sprintf("Cannot load template resources: confdir '%s' does not exist", config.ConfDir))
		return nil, nil
	}
	paths, err := recursiveFindFiles(config.ConfigDir, "*toml")
	if err != nil {
		return nil, err
	}

	if len(paths) < 1 {
		log.Warning("Found no templates")
	}

	for _, p := range paths {
		log.Debug(fmt.Sprintf("Found template: %s", p))
		t, err := NewTemplateResource(p, config)
		if err != nil {
			lastError = err
			continue
		}
		templates = append(templates, t)
	}
	return templates, lastError
}

// ProcessTemplateResources is a convenience function that loads all the
// template resources and processes them serially. Called from main.
// It returns a list of errors if any.
func ProcessTemplateResources(c etcdutil.EtcdClient) []error {
	runErrors := make([]error, 0)
	var err error
	if c == nil {
		runErrors = append(runErrors, errors.New("An etcd client is required"))
		return runErrors
	}
	log.Debug("Loading template resources from confdir " + config.ConfDir())
	if !isFileExist(config.ConfDir()) {
		log.Warning(fmt.Sprintf("Cannot load template resources confdir '%s' does not exist", config.ConfDir()))
		return runErrors
	}
	paths, err := filepath.Glob(filepath.Join(config.ConfigDir(), "*toml"))
	if err != nil {
		runErrors = append(runErrors, err)
		return runErrors
	}
	for _, p := range paths {
		log.Debug("Processing template resource " + p)
		t, err := NewTemplateResourceFromPath(p, c)
		if err != nil {
			runErrors = append(runErrors, err)
			log.Error(err.Error())
			continue
		}
		if err := t.process(); err != nil {
			runErrors = append(runErrors, err)
			log.Error(err.Error())
			continue
		}
		log.Debug("Processing of template resource " + p + " complete")
	}
	return runErrors
}

// createStageFile stages the src configuration file by processing the src
// template and setting the desired owner, group, and mode. It also sets the
// StageFile for the template resource.
// It returns an error if any.
func (t *TemplateResource) createStageFile() error {
	t.Src = filepath.Join(config.TemplateDir(), t.Src)
	log.Debug("Using source template " + t.Src)
	if !isFileExist(t.Src) {
		return errors.New("Missing template: " + t.Src)
	}
	// create TempFile in Dest directory to avoid cross-filesystem issues
	temp, err := ioutil.TempFile(filepath.Dir(t.Dest), "."+filepath.Base(t.Dest))
	if err != nil {
		os.Remove(temp.Name())
		return err
	}
	defer temp.Close()
	log.Debug("Compiling source template " + t.Src)
	tplFuncMap := make(template.FuncMap)
	tplFuncMap["Base"] = path.Base

	tplFuncMap["GetDir"] = t.Dirs.Get
	tmpl := template.Must(template.New(path.Base(t.Src)).Funcs(tplFuncMap).ParseFiles(t.Src))
	if err = tmpl.Execute(temp, t.Vars); err != nil {
		return err
	}
	// Set the owner, group, and mode on the stage file now to make it easier to
	// compare against the destination configuration file later.
	os.Chmod(temp.Name(), t.FileMode)
	os.Chown(temp.Name(), t.Uid, t.Gid)
	t.StageFile = temp
	return nil
}

// sync compares the staged and dest config files and attempts to sync them
// if they differ. sync will run a config check command if set before
// overwriting the target config file. Finally, sync will run a reload command
// if set to have the application or service pick up the changes.
// It returns an error if any.
func (t *TemplateResource) sync() error {
	staged := t.StageFile.Name()
	if t.keepStageFile {
		log.Info("Keeping staged file: " + staged)
	} else {
		defer os.Remove(staged)
	}

	log.Debug("Comparing candidate config to " + t.Dest)
	ok, err := sameConfig(staged, t.Dest)
	if err != nil {
		log.Error(err.Error())
	}
	if t.noop {
		log.Warning("Noop mode enabled. " + t.Dest + " will not be modified")
		return nil
	}
	if !ok {
		log.Info("Target config " + t.Dest + " out of sync")
		if t.CheckCmd != "" {
			if err := t.check(); err != nil {
				return errors.New("Config check failed: " + err.Error())
			}
		}
		log.Debug("Overwriting target config " + t.Dest)
		err := os.Rename(staged, t.Dest)
		if err != nil {
			if strings.Contains(err.Error(), "device or resource busy") {
				log.Debug("Rename failed - target is likely a mount. Trying to write instead")
				// try to open the file and write to it
				var contents []byte
				var rerr error
				contents, rerr = ioutil.ReadFile(staged)
				if rerr != nil {
					return rerr
				}
				err := ioutil.WriteFile(t.Dest, contents, t.FileMode)
				// make sure owner and group match the temp file, in case the file was created with WriteFile
				os.Chown(t.Dest, t.Uid, t.Gid)
				if err != nil {
					return err
				}
			} else {
				return err
			}
		}
		if t.ReloadCmd != "" {
			if err := t.reload(); err != nil {
				return err
			}
		}
		log.Info("Target config " + t.Dest + " has been updated")
	} else {
		log.Debug("Target config " + t.Dest + " in sync")
	}
	return nil
}

// setVars sets the Vars for template resource.
func (t *TemplateResource) setVars() error {
	var err error
	log.Debug("Retrieving keys from etcd")
	log.Debug("Key prefix set to " + config.Prefix())
	t.Vars, err = etcdutil.GetValues(t.etcdClient, config.Prefix(), t.Keys)
	if err != nil {
		return err
	}
	return nil
}

// reload executes the reload command.
// It returns nil if the reload command returns 0.
func (t *TemplateResource) reload() error {
	log.Debug("Running " + t.ReloadCmd)
	c := exec.Command("/bin/sh", "-c", t.ReloadCmd)
	output, err := c.CombinedOutput()
	if err != nil {
		return err
	}
	log.Debug(fmt.Sprintf("%q", string(output)))
	return nil
}

// setVars sets the Vars for template resource.
func (t *TemplateResource) setVars() error {
	var err error
	log.Debug("Retrieving keys from store")
	log.Debug("Key prefix set to " + config.Prefix())
	vars, err := t.storeClient.GetValues(appendPrefix(config.Prefix(), t.Keys))
	if err != nil {
		return err
	}
	t.Vars = cleanKeys(vars)
	return nil
}

// setVars sets the Vars for template resource.
func (t *TemplateResource) setVars() error {
	var err error
	log.Debug("Retrieving keys from store")
	log.Debug("Key prefix set to " + t.prefix)
	result, err := t.storeClient.GetValues(appendPrefix(t.prefix, t.Keys))
	if err != nil {
		return err
	}
	t.store.Purge()
	for k, v := range result {
		t.store.Set(filepath.Join("/", strings.TrimPrefix(k, t.prefix)), v)
	}
	return nil
}

// NewDynamoDBClient returns an *dynamodb.Client with a connection to the region
// configured via the AWS_REGION environment variable.
// It returns an error if the connection cannot be made or the table does not exist.
func NewDynamoDBClient(table string) (*Client, error) {
	creds := credentials.NewChainCredentials(
		[]credentials.Provider{
			&credentials.EnvProvider{},
			&credentials.EC2RoleProvider{},
		})
	_, err := creds.Get()
	if err != nil {
		return nil, err
	}
	var c *aws.Config
	if os.Getenv("DYNAMODB_LOCAL") != "" {
		log.Debug("DYNAMODB_LOCAL is set")
		c = &aws.Config{Endpoint: "http://localhost:8000"}
	} else {
		c = nil
	}
	d := dynamodb.New(c)
	// Check if the table exists
	_, err = d.DescribeTable(&dynamodb.DescribeTableInput{TableName: &table})
	if err != nil {
		return nil, err
	}
	return &Client{d, table}, nil
}

// LoadConfig initializes the confd configuration by first setting defaults,
// then overriding setting from the confd config file, and finally overriding
// settings from flags set on the command line.
// It returns an error if any.
func LoadConfig(path string) error {
	setDefaults()
	if path == "" {
		log.Warning("Skipping confd config file.")
	} else {
		log.Debug("Loading " + path)

		configBytes, err := ioutil.ReadFile(path)
		if err != nil {
			return err
		}

		_, err = toml.Decode(string(configBytes), &config)
		if err != nil {
			return err
		}
	}
	processFlags()
	if !isValidateEtcdScheme(config.Confd.EtcdScheme) {
		return errors.New("Invalid etcd scheme: " + config.Confd.EtcdScheme)
	}
	err := setEtcdHosts()
	if err != nil {
		return err
	}
	return nil
}

// Iterate through `machines`, trying to connect to each in turn.
// Returns the first successful connection or the last error encountered.
// Assumes that `machines` is non-empty.
func tryConnect(machines []string, password string) (redis.Conn, error) {
	var err error
	for _, address := range machines {
		var conn redis.Conn
		network := "tcp"
		if _, err = os.Stat(address); err == nil {
			network = "unix"
		}
		log.Debug(fmt.Sprintf("Trying to connect to redis node %s", address))

		dialops := []redis.DialOption{
			redis.DialConnectTimeout(time.Second),
			redis.DialReadTimeout(time.Second),
			redis.DialWriteTimeout(time.Second),
		}

		if password != "" {
			dialops = append(dialops, redis.DialPassword(password))
		}

		conn, err = redis.Dial(network, address, dialops...)

		if err != nil {
			continue
		}
		return conn, nil
	}
	return nil, err
}

// NewDynamoDBClient returns an *dynamodb.Client with a connection to the region
// configured via the AWS_REGION environment variable.
// It returns an error if the connection cannot be made or the table does not exist.
func NewDynamoDBClient(table string) (*Client, error) {
	var c *aws.Config
	if os.Getenv("DYNAMODB_LOCAL") != "" {
		log.Debug("DYNAMODB_LOCAL is set")
		endpoint := "http://localhost:8000"
		c = &aws.Config{
			Endpoint: &endpoint,
		}
	} else {
		c = nil
	}

	session := session.New(c)

	// Fail early, if no credentials can be found
	_, err := session.Config.Credentials.Get()
	if err != nil {
		return nil, err
	}

	d := dynamodb.New(session)

	// Check if the table exists
	_, err = d.DescribeTable(&dynamodb.DescribeTableInput{TableName: &table})
	if err != nil {
		return nil, err
	}
	return &Client{d, table}, nil
}

// NewTemplateResource creates a TemplateResource.
func NewTemplateResource(path string, config Config) (*TemplateResource, error) {
	if config.StoreClient == nil {
		return nil, errors.New("A valid StoreClient is required.")
	}
	var tc *TemplateResourceConfig
	log.Debug("Loading template resource from " + path)
	_, err := toml.DecodeFile(path, &tc)
	if err != nil {
		return nil, fmt.Errorf("Cannot process template resource %s - %s", path, err.Error())
	}
	tr := tc.TemplateResource
	tr.expandEnv()
	tr.keepStageFile = config.KeepStageFile
	tr.noop = config.Noop
	tr.storeClient = config.StoreClient
	tr.funcMap = newFuncMap()
	tr.store = memkv.New()
	addFuncs(tr.funcMap, tr.store.FuncMap)
	tr.prefix = filepath.Join("/", config.Prefix, tr.Prefix)
	if tr.Src == "" {
		return nil, ErrEmptySrc
	}
	tr.Src = filepath.Join(config.TemplateDir, tr.Src)
	return &tr, nil
}

// reload executes the reload command.
// It returns nil if the reload command returns 0.
func (t *TemplateResource) reload() error {
	log.Debug("Running " + t.ReloadCmd)
	c := exec.Command("/bin/sh", "-c", t.ReloadCmd)
	if err := c.Run(); err != nil {
		return err
	}
	return nil
}

func main() {
	// Most flags are defined in the confd/config package which allows us to
	// override configuration settings from the command line. Parse the flags now
	// to make them active.
	flag.Parse()
	if printVersion {
		fmt.Printf("confd %s\n", Version)
		os.Exit(0)
	}
	if configFile == "" {
		if IsFileExist(defaultConfigFile) {
			configFile = defaultConfigFile
		}
	}
	// Initialize the global configuration.
	log.Debug("Loading confd configuration")
	if err := config.LoadConfig(configFile); err != nil {
		log.Fatal(err.Error())
	}
	// Configure logging. While you can enable debug and verbose logging, however
	// if quiet is set to true then debug and verbose messages will not be printed.
	log.SetQuiet(config.Quiet())
	log.SetVerbose(config.Verbose())
	log.SetDebug(config.Debug())
	log.Notice("Starting confd")

	// Create the storage client
	log.Notice("Backend set to " + config.Backend())
	store, err := backends.New(config.Backend())
	if err != nil {
		log.Fatal(err.Error())
	}

	signalChan := make(chan os.Signal, 1)
	signal.Notify(signalChan, syscall.SIGINT, syscall.SIGTERM)
	for {
		runErrors := template.ProcessTemplateResources(store)
		// If the -onetime flag is passed on the command line we immediately exit
		// after processing the template config files.
		if onetime {
			if len(runErrors) > 0 {
				os.Exit(1)
			}
			os.Exit(0)
		}
		select {
		case c := <-signalChan:
			log.Info(fmt.Sprintf("captured %v exiting...", c))
			os.Exit(0)
		case <-time.After(time.Duration(config.Interval()) * time.Second):
			// Continue processing templates.
		}
	}
}

// check executes the check command to validate the staged config file. The
// command is modified so that any references to src template are substituted
// with a string representing the full path of the staged file. This allows the
// check to be run on the staged file before overwriting the destination config
// file.
// It returns nil if the check command returns 0 and there are no other errors.
func (t *TemplateResource) check() error {
	var cmdBuffer bytes.Buffer
	data := make(map[string]string)
	data["src"] = t.StageFile.Name()
	tmpl, err := template.New("checkcmd").Parse(t.CheckCmd)
	if err != nil {
		return err
	}
	if err := tmpl.Execute(&cmdBuffer, data); err != nil {
		return err
	}
	log.Debug("Running " + cmdBuffer.String())
	c := exec.Command("/bin/sh", "-c", cmdBuffer.String())
	output, err := c.CombinedOutput()
	if err != nil {
		return err
	}
	log.Debug(fmt.Sprintf("%q", string(output)))
	return nil
}

func main() {
	flag.Parse()
	if printVersion {
		fmt.Printf("confd %s\n", Version)
		os.Exit(0)
	}
	if err := initConfig(); err != nil {
		log.Fatal(err.Error())
	}

	log.Info("Starting confd")

	storeClient, err := backends.New(backendsConfig)
	if err != nil {
		log.Fatal(err.Error())
	}

	templateConfig.StoreClient = storeClient
	if onetime {
		if err := template.Process(templateConfig); err != nil {
			os.Exit(1)
		}
		os.Exit(0)
	}

	stopChan := make(chan bool)
	doneChan := make(chan bool)
	errChan := make(chan error, 10)

	var processor template.Processor
	switch {
	case config.Watch:
		processor = template.WatchProcessor(templateConfig, stopChan, doneChan, errChan)
	default:
		processor = template.IntervalProcessor(templateConfig, stopChan, doneChan, errChan, config.Interval)
	}

	go processor.Process()

	signalChan := make(chan os.Signal, 1)
	signal.Notify(signalChan, syscall.SIGINT, syscall.SIGTERM)
	for {
		select {
		case err := <-errChan:
			log.Debug(err.Error())
		case s := <-signalChan:
			log.Info(fmt.Sprintf("Captured %v. Exiting...", s))
			close(doneChan)
		case <-doneChan:
			os.Exit(0)
		}
	}
}