package mempool

import (
	"github.com/go-kit/kit/metrics"
	"github.com/go-kit/kit/metrics/discard"
	prometheus "github.com/go-kit/kit/metrics/prometheus"
	stdprometheus "github.com/prometheus/client_golang/prometheus"
)

// Metrics contains metrics exposed by this package.
// see MetricsProvider for descriptions.
type Metrics struct {
	// Size of the mempool.
	Size metrics.Gauge
}

// PrometheusMetrics returns Metrics build using Prometheus client library.
func PrometheusMetrics(namespace string) *Metrics {
	return &Metrics{
		Size: prometheus.NewGaugeFrom(stdprometheus.GaugeOpts{
			Namespace: namespace,
			Subsystem: "mempool",
			Name:      "size",
			Help:      "Size of the mempool (number of uncommitted transactions).",
		}, []string{}),
	}
}

// NopMetrics returns no-op Metrics.
func NopMetrics() *Metrics {
	return &Metrics{
		Size: discard.NewGauge(),
	}
}