[#451] metrics: Move to internal

`metrics` don't look like something others want to import.

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

internal/metrics/morph.go

@@ -0,0 +1,72 @@
+package metrics
+
+import (
+	"strconv"
+	"time"
+
+	"git.frostfs.info/TrueCloudLab/frostfs-observability/metrics"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+type morphClientMetrics struct {
+	switchCount       prometheus.Counter
+	lastBlock         prometheus.Gauge
+	notificationCount *prometheus.CounterVec
+	invokeDuration    *prometheus.HistogramVec
+}
+
+func newMorphClientMetrics() *morphClientMetrics {
+	return &morphClientMetrics{
+		switchCount: metrics.NewCounter(prometheus.CounterOpts{
+			Namespace: namespace,
+			Subsystem: morphSubsystem,
+			Name:      "switches_total",
+			Help:      "Number of endpoint switches",
+		}),
+		lastBlock: metrics.NewGauge(prometheus.GaugeOpts{
+			Namespace: namespace,
+			Subsystem: morphSubsystem,
+			Name:      "last_block",
+			Help:      "Index of the last received block",
+		}),
+		notificationCount: metrics.NewCounterVec(prometheus.CounterOpts{
+			Namespace: namespace,
+			Subsystem: morphSubsystem,
+			Name:      "notifications_total",
+			Help:      "Number of notifications received by notification type",
+		}, []string{notificationTypeLabel}),
+		invokeDuration: metrics.NewHistogramVec(prometheus.HistogramOpts{
+			Namespace: namespace,
+			Subsystem: morphSubsystem,
+			Name:      "invoke_duration_seconds",
+			Help:      "Cummulative duration of contract invocations",
+		}, []string{invokeTypeLabel, contractLabel, methodLabel, successLabel}),
+	}
+}
+
+func (m *morphClientMetrics) IncSwitchCount() {
+	m.switchCount.Inc()
+}
+
+func (m *morphClientMetrics) SetLastBlock(index uint32) {
+	m.lastBlock.Set(float64(index))
+}
+
+func (m *morphClientMetrics) IncNotificationCount(typ string) {
+	m.notificationCount.With(
+		prometheus.Labels{
+			notificationTypeLabel: typ,
+		},
+	).Inc()
+}
+
+func (m *morphClientMetrics) ObserveInvoke(typ string, contract string, method string, success bool, d time.Duration) {
+	m.invokeDuration.With(
+		prometheus.Labels{
+			invokeTypeLabel: typ,
+			contractLabel:   contract,
+			methodLabel:     method,
+			successLabel:    strconv.FormatBool(success),
+		},
+	).Observe(d.Seconds())
+}