// New creates new instance of MetricSet.
func New(base mb.BaseMetricSet) (mb.MetricSet, error) {
	// Additional configuration options
	config := struct {
		ServerStatusPath string `config:"server_status_path"`
		Username         string `config:"username"`
		Password         string `config:"password"`
	}{
		ServerStatusPath: defaultPath,
		Username:         "",
		Password:         "",
	}

	if err := base.Module().UnpackConfig(&config); err != nil {
		return nil, err
	}

	metricSet := &MetricSet{
		BaseMetricSet: base,
		URLs:          make(map[string]string, len(base.Module().Config().Hosts)),
	}

	// Parse the config, create URLs, and check for errors.
	var errs multierror.Errors
	for _, host := range base.Module().Config().Hosts {
		u, err := getURL(config.Username, config.Password, config.ServerStatusPath, host)
		if err != nil {
			errs = append(errs, err)
			continue
		}
		metricSet.URLs[host] = u.String()
		debugf("apache-status URL=%s", redactPassword(*u))
	}

	return metricSet, errs.Err()
}

// Validate validates the Settings data and returns an error describing
// all problems or nil if there are none.
func (s Settings) Validate() error {
	// TODO: winlogbeat should not try to validate top-level beats config

	validKeys := []string{
		"fields", "fields_under_root", "tags",
		"name", "refresh_topology_freq", "ignore_outgoing", "topology_expire", "geoip",
		"queue_size", "bulk_queue_size", "max_procs",
		"processors", "logging", "output", "path", "winlogbeat",
	}
	sort.Strings(validKeys)

	// Check for invalid top-level keys.
	var errs multierror.Errors
	for k := range s.Raw {
		k = strings.ToLower(k)
		i := sort.SearchStrings(validKeys, k)
		if i >= len(validKeys) || validKeys[i] != k {
			errs = append(errs, fmt.Errorf("Invalid top-level key '%s' "+
				"found. Valid keys are %s", k, strings.Join(validKeys, ", ")))
		}
	}

	err := s.Winlogbeat.Validate()
	if err != nil {
		errs = append(errs, err)
	}

	return errs.Err()
}

// uninstallLog unregisters the event logger from the registry and closes the
// log's handle if it is open.
func uninstallLog(provider, source string, log *elog.Log) error {
	var errs multierror.Errors

	if log != nil {
		err := clearEventLog(Handle(log.Handle), "")
		if err != nil {
			errs = append(errs, err)
		}

		err = log.Close()
		if err != nil {
			errs = append(errs, err)
		}
	}

	err := elog.RemoveSource(providerName, sourceName)
	if err != nil {
		errs = append(errs, err)
	}

	err = elog.RemoveProvider(providerName)
	if err != nil {
		errs = append(errs, err)
	}

	return errs.Err()
}

// initLog initializes an event logger. It registers the source name with
// the registry if it does not already exist.
func initLog(provider, source, msgFile string) (*elog.Log, error) {
	// Install entry to registry:
	_, err := elog.Install(providerName, sourceName, msgFile, true, allLevels)
	if err != nil {
		return nil, err
	}

	// Open a new logger for writing events:
	log, err := elog.Open(sourceName)
	if err != nil {
		var errs multierror.Errors
		errs = append(errs, err)
		err := elog.RemoveSource(providerName, sourceName)
		if err != nil {
			errs = append(errs, err)
		}
		err = elog.RemoveProvider(providerName)
		if err != nil {
			errs = append(errs, err)
		}
		return nil, errs.Err()
	}

	return log, nil
}

// Setup the URLs to the mod_status endpoints.
func (m *MetricSeter) Setup(ms *helper.MetricSet) error {
	// Additional configuration options
	config := struct {
		ServerStatusPath string `config:"server_status_path"`
		Username         string `config:"username"`
		Password         string `config:"password"`
	}{
		ServerStatusPath: defaultPath,
		Username:         "",
		Password:         "",
	}

	if err := ms.Module.ProcessConfig(&config); err != nil {
		return err
	}

	m.URLs = make(map[string]string, len(ms.Config.Hosts))

	// Parse the config, create URLs, and check for errors.
	var errs multierror.Errors
	for _, host := range ms.Config.Hosts {
		u, err := getURL(config.Username, config.Password, config.ServerStatusPath, host)
		if err != nil {
			errs = append(errs, err)
			continue
		}
		m.URLs[host] = u.String()
		debugf("apache-status URL=%s", redactPassword(*u))
	}

	return errs.Err()
}

// Validate validates the winEventLogConfig data and returns an error describing
// any problems or nil.
func (c *winEventLogConfig) Validate() error {
	var errs multierror.Errors
	if c.Name == "" {
		errs = append(errs, fmt.Errorf("event log is missing a 'name'"))
	}

	return errs.Err()
}

// UpdateAll remote repositories
func UpdateAll() error {
	var Errors multierror.Errors
	for _, repository := range *allRepositories {
		err := Update(repository.Name)
		if err != nil {
			Errors = append(Errors, err)
		}
	}
	return Errors.Err()
}

// newModuleWrappers creates new Modules and their associated MetricSets based
// on the given configuration. It constructs the supporting filters and
// publisher client and stores it all in a moduleWrapper.
func newModuleWrappers(
	modulesConfig []*common.Config,
	r *mb.Register,
	publisher *publisher.Publisher,
) ([]*moduleWrapper, error) {
	modules, err := mb.NewModules(modulesConfig, r)
	if err != nil {
		return nil, err
	}

	// Wrap the Modules and MetricSet's.
	var wrappers []*moduleWrapper
	var errs multierror.Errors
	for k, v := range modules {
		debugf("initializing Module type %s, %T=%+v", k.Name(), k, k)
		f, err := filter.New(k.Config().Filters)
		if err != nil {
			errs = append(errs, errors.Wrapf(err, "module %s", k.Name()))
			continue
		}

		mw := &moduleWrapper{
			Module:    k,
			filters:   f,
			pubClient: publisher.Connect(),
		}
		wrappers = append(wrappers, mw)

		msws := make([]*metricSetWrapper, 0, len(v))
		for _, ms := range v {
			debugf("initializing MetricSet type %s/%s, %T=%+v",
				ms.Module().Name(), ms.Name(), ms, ms)
			msw := &metricSetWrapper{
				MetricSet: ms,
				module:    mw,
				stats:     new(expvar.Map).Init(),
			}
			msws = append(msws, msw)

			// Initialize expvar stats for this MetricSet.
			fetches.Set(fmt.Sprintf("%s-%s", mw.Name(), msw.Name()), msw.stats)
			msw.stats.Add(successesKey, 0)
			msw.stats.Add(failuresKey, 0)
			msw.stats.Add(eventsKey, 0)
		}
		mw.metricSets = msws
	}

	return wrappers, errs.Err()
}

// LoadTLSConfig will load a certificate from config with all TLS based keys
// defined. If Certificate and CertificateKey are configured, client authentication
// will be configured. If no CAs are configured, the host CA will be used by go
// built-in TLS support.
func LoadTLSConfig(config *TLSConfig) (*transport.TLSConfig, error) {
	if !config.IsEnabled() {
		return nil, nil
	}

	fail := multierror.Errors{}
	logFail := func(es ...error) {
		for _, e := range es {
			if e != nil {
				fail = append(fail, e)
			}
		}
	}

	var cipherSuites []uint16
	for _, suite := range config.CipherSuites {
		cipherSuites = append(cipherSuites, uint16(suite))
	}

	var curves []tls.CurveID
	for _, id := range config.CurveTypes {
		curves = append(curves, tls.CurveID(id))
	}

	cert, err := loadCertificate(&config.Certificate)
	logFail(err)

	cas, errs := loadCertificateAuthorities(config.CAs)
	logFail(errs...)

	// fail, if any error occurred when loading certificate files
	if err = fail.Err(); err != nil {
		return nil, err
	}

	var certs []tls.Certificate
	if cert != nil {
		certs = []tls.Certificate{*cert}
	}

	// return config if no error occurred
	return &transport.TLSConfig{
		Versions:         config.Versions,
		Verification:     config.VerificationMode,
		Certificates:     certs,
		RootCAs:          cas,
		CipherSuites:     cipherSuites,
		CurvePreferences: curves,
	}, nil
}

// newBaseModulesFromConfig creates new BaseModules from a list of configs
// each containing ModuleConfig data.
func newBaseModulesFromConfig(config []*common.Config) ([]BaseModule, error) {
	var errs multierror.Errors
	baseModules := make([]BaseModule, 0, len(config))
	for _, rawConfig := range config {
		bm, err := newBaseModuleFromConfig(rawConfig)
		if err != nil {
			errs = append(errs, err)
			continue
		}

		if bm.config.Enabled {
			baseModules = append(baseModules, bm)
		}
	}

	return baseModules, errs.Err()
}

// NewModuleWrappers creates new Modules and their associated MetricSets based
// on the given configuration. It constructs the supporting filters and stores
// them all in a ModuleWrapper.
func NewModuleWrappers(modulesConfig []*common.Config, r *mb.Register) ([]*ModuleWrapper, error) {
	modules, err := mb.NewModules(modulesConfig, r)
	if err != nil {
		return nil, err
	}

	// Wrap the Modules and MetricSet's.
	var wrappers []*ModuleWrapper
	var errs multierror.Errors
	for k, v := range modules {
		debugf("Initializing Module type '%s': %T=%+v", k.Name(), k, k)
		f, err := filter.New(k.Config().Filters)
		if err != nil {
			errs = append(errs, errors.Wrapf(err, "module %s", k.Name()))
			continue
		}

		mw := &ModuleWrapper{
			Module:  k,
			filters: f,
		}
		wrappers = append(wrappers, mw)

		msws := make([]*metricSetWrapper, 0, len(v))
		for _, ms := range v {
			debugf("Initializing MetricSet type '%s/%s' for host '%s': %T=%+v",
				ms.Module().Name(), ms.Name(), ms.Host(), ms, ms)

			expMap, err := getMetricSetExpvarMap(mw.Name(), ms.Name())
			if err != nil {
				return nil, err
			}

			msw := &metricSetWrapper{
				MetricSet: ms,
				module:    mw,
				stats:     expMap,
			}
			msws = append(msws, msw)
		}
		mw.metricSets = msws
	}

	return wrappers, errs.Err()
}

// Validate validates the eventLoggingConfig data and returns an error
// describing any problems or nil.
func (c *eventLoggingConfig) Validate() error {
	var errs multierror.Errors
	if c.Name == "" {
		errs = append(errs, fmt.Errorf("event log is missing a 'name'"))
	}

	if c.ReadBufferSize > win.MaxEventBufferSize {
		errs = append(errs, fmt.Errorf("'read_buffer_size' must be less than "+
			"%d bytes", win.MaxEventBufferSize))
	}

	if c.FormatBufferSize > win.MaxFormatMessageBufferSize {
		errs = append(errs, fmt.Errorf("'format_buffer_size' must be less than "+
			"%d bytes", win.MaxFormatMessageBufferSize))
	}

	return errs.Err()
}

func Process(spec interface{}) error {
	var el multierror.Errors
	e := func(err error) {
		if err != nil {
			el = append(el, err)
		}
	}
	if conf.Settings.UseDB {
		e(db.Process(spec))
	}
	if conf.Settings.UseFile {
		e(file.Process(spec))
	}
	if conf.Settings.UseEnv {
		e(env.Process(conf.Settings.AppName, spec))
	}
	return el.Err()
}

// Process takes a spec and a list of files. The list of files is in
// **reverse** order of precedence, meaning that a value in the first file can
// be overridden by any subsequent file.
//
// Example:
// Process(mySpec, "/etc/myapp.json", "/usr/local/etc/myapp.json", "/home/me/.myapp.json")
// values in /home/me/.myapp.json will override any values set in /etc/myapp.json
func Process(spec interface{}) error {
	var el multierror.Errors
	res := map[string]interface{}{}
	for _, fname := range conf.Settings.FileLocations {
		contents, err := ioutil.ReadFile(fname)
		if err != nil {
			el = append(el, err)
			continue
		}
		json.Unmarshal(contents, &res)
	}

	if err := merger.MapAndStruct(res, spec); err != nil {
		el = append(el, err)
	}

	return el.Err()
}

func (d *DockerDaemon) KillAllContainers() error {
	containers, err := d.Client.ListContainers(dockerapi.ListContainersOptions{})
	if err != nil {
		return err
	}

	var errs multierror.Errors

	for _, container := range containers {
		err = d.Client.KillContainer(dockerapi.KillContainerOptions{
			ID: container.ID,
		})
		if err != nil {
			errs = append(errs, err)
		}
	}

	return errs.Err()
}

// Validate validates the Settings data and returns an error describing
// all problems or nil if there are none.
func (s Settings) Validate() error {
	validKeys := []string{"filters", "logging", "output", "shipper", "winlogbeat"}
	sort.Strings(validKeys)

	// Check for invalid top-level keys.
	var errs multierror.Errors
	for k := range s.Raw {
		k = strings.ToLower(k)
		i := sort.SearchStrings(validKeys, k)
		if i >= len(validKeys) || validKeys[i] != k {
			errs = append(errs, fmt.Errorf("Invalid top-level key '%s' "+
				"found. Valid keys are %s", k, strings.Join(validKeys, ", ")))
		}
	}

	err := s.Winlogbeat.Validate()
	if err != nil {
		errs = append(errs, err)
	}

	return errs.Err()
}

func createModules(r *Register, baseModules []BaseModule) ([]Module, error) {
	modules := make([]Module, 0, len(baseModules))
	var errs multierror.Errors
	for _, bm := range baseModules {
		f := r.moduleFactory(bm.Name())
		if f == nil {
			f = DefaultModuleFactory
		}

		module, err := f(bm)
		if err != nil {
			errs = append(errs, err)
			continue
		}
		modules = append(modules, module)
	}

	err := errs.Err()
	if err != nil {
		return nil, err
	}
	return modules, nil
}

// Build builds a query from the given parameters. The query is returned as a
// XML string and can be used with Subscribe function.
func (q Query) Build() (string, error) {
	var errs multierror.Errors
	if q.Log == "" {
		errs = append(errs, fmt.Errorf("empty log name"))
	}

	qp := &queryParams{Path: q.Log}
	builders := []func(Query) error{
		qp.ignoreOlderSelect,
		qp.eventIDSelect,
		qp.levelSelect,
		qp.providerSelect,
	}
	for _, build := range builders {
		if err := build(q); err != nil {
			errs = append(errs, err)
		}
	}
	if len(errs) > 0 {
		return "", errs.Err()
	}
	return executeTemplate(queryTemplate, qp)
}

func initMetricSets(r *Register, modules []Module) (map[Module][]MetricSet, error) {
	active := map[Module][]MetricSet{}
	var errs multierror.Errors
	for _, bms := range newBaseMetricSets(modules) {
		f, err := r.metricSetFactory(bms.Module().Name(), bms.Name())
		if err != nil {
			errs = append(errs, err)
			continue
		}

		metricSet, err := f(bms)
		if err != nil {
			errs = append(errs, err)
			continue
		}
		err = mustImplementFetcher(metricSet)
		if err != nil {
			errs = append(errs, err)
			continue
		}
		err = mustHaveModule(metricSet, bms)
		if err != nil {
			errs = append(errs, err)
			continue
		}

		module := metricSet.Module()
		active[module] = append(active[module], metricSet)
	}

	err := errs.Err()
	if err != nil {
		return nil, err
	}
	return active, nil

}

func readConfig(
	data map[string]interface{},
	config interface{},
	validKeys []string,
) error {
	c, err := common.NewConfigFrom(data)
	if err != nil {
		return fmt.Errorf("Failed reading config. %v", err)
	}

	if err := c.Unpack(config); err != nil {
		return fmt.Errorf("Failed unpacking config. %v", err)
	}

	var errs multierror.Errors
	if len(validKeys) > 0 {
		sort.Strings(validKeys)

		// Check for invalid keys.
		for k := range data {
			k = strings.ToLower(k)
			i := sort.SearchStrings(validKeys, k)
			if i >= len(validKeys) || validKeys[i] != k {
				errs = append(errs, fmt.Errorf("Invalid event log key '%s' "+
					"found. Valid keys are %s", k, strings.Join(validKeys, ", ")))
			}
		}
	}

	if v, ok := config.(validator); ok {
		if err := v.Validate(); err != nil {
			errs = append(errs, err)
		}
	}

	return errs.Err()
}