type HandlerConfig struct {
	// Gatherer sets the prometheus.Gatherer instance the middleware will use when generating the metric endpoint handler.
	// Defaults to: prometheus.DefaultGatherer
	Gatherer prometheus.Gatherer
}

type LabelValueFunc func(c *echo.Context, err error) string

type MiddlewareConfig struct {
	// Skipper defines a function to skip middleware.
	Skipper middleware.Skipper

	// Namespace is components of the fully-qualified name of the Metric (created by joining Namespace,Subsystem and Name components with "_")
	// Optional
	Namespace string

	// Subsystem is components of the fully-qualified name of the Metric (created by joining Namespace,Subsystem and Name components with "_")
	// Defaults to: "echo"
	Subsystem string

	// LabelFuncs allows adding custom labels in addition to default labels. When key has same name with default label
	// it replaces default one.
	LabelFuncs map[string]LabelValueFunc

	// HistogramOptsFunc allows to change options for metrics of type histogram before metric is registered to Registerer
	HistogramOptsFunc func(opts prometheus.HistogramOpts) prometheus.HistogramOpts

	// CounterOptsFunc allows to change options for metrics of type counter before metric is registered to Registerer
	CounterOptsFunc func(opts prometheus.CounterOpts) prometheus.CounterOpts

	// Registerer sets the prometheus.Registerer instance the middleware will register these metrics with.
	// Defaults to: prometheus.DefaultRegisterer
	Registerer prometheus.Registerer

	// BeforeNext is callback that is executed before next middleware/handler is called. Useful for case when you have own
	// metrics that need data to be stored for AfterNext.
	BeforeNext func(c *echo.Context)

	// AfterNext is callback that is executed after next middleware/handler returns. Useful for case when you have own
	// metrics that need incremented/observed.
	AfterNext func(c *echo.Context, err error)

	// If DoNotUseRequestPathFor404 is true, all 404 responses (due to non-matching route) will have the same `url` label and
	// thus won't generate new metrics.
	DoNotUseRequestPathFor404 bool
	// contains filtered or unexported fields
}

type PushGatewayConfig struct {
	// PushGatewayURL is push gateway URL in format http://domain:port
	PushGatewayURL string

	// PushInterval in ticker interval for pushing gathered metrics to the Gateway
	// Defaults to: 1 minute
	PushInterval time.Duration

	// Gatherer sets the prometheus.Gatherer instance the middleware will use when generating the metric endpoint handler.
	// Defaults to: prometheus.DefaultGatherer
	Gatherer prometheus.Gatherer

	// ErrorHandler is function that is called when errors occur. When callback returns error StartPushGateway also returns.
	ErrorHandler func(err error) error

	// ClientTransport specifies the mechanism by which individual HTTP POST requests are made.
	// Defaults to: http.DefaultTransport
	ClientTransport http.RoundTripper
}