package metrics

import (
	"time"

	"git.frostfs.info/TrueCloudLab/frostfs-observability/metrics"
	"github.com/prometheus/client_golang/prometheus"
)

type (
	engineMetrics struct {
		methodDuration *prometheus.HistogramVec

		containerSize *prometheus.GaugeVec
		payloadSize   *prometheus.GaugeVec
		errorCounter  *prometheus.GaugeVec
	}
)

const (
	engineSubsystem = "engine"
	engineMethod    = "method"
)

func newEngineMetrics() engineMetrics {
	return engineMetrics{
		containerSize: newEngineGaugeVector("container_size_bytes", "Accumulated size of all objects in a container", []string{containerIDLabelKey}),
		payloadSize:   newEngineGaugeVector("payload_size_bytes", "Accumulated size of all objects in a shard", []string{shardIDLabelKey}),
		errorCounter:  newEngineGaugeVector("error_counter", "Shard's error counter", []string{shardIDLabelKey}),
		methodDuration: metrics.NewHistogramVec(prometheus.HistogramOpts{
			Namespace: namespace,
			Subsystem: engineSubsystem,
			Name:      "request_duration_seconds",
			Help:      "Duration of Engine requests",
		}, []string{engineMethod}),
	}
}

func newEngineGaugeVector(name, help string, labels []string) *prometheus.GaugeVec {
	return metrics.NewGaugeVec(prometheus.GaugeOpts{
		Namespace: namespace,
		Subsystem: engineSubsystem,
		Name:      name,
		Help:      help,
	}, labels)
}

func (m *engineMetrics) AddMethodDuration(method string, d time.Duration) {
	m.methodDuration.With(prometheus.Labels{
		engineMethod: method,
	}).Observe(d.Seconds())
}

func (m engineMetrics) AddToContainerSize(cnrID string, size int64) {
	m.containerSize.With(prometheus.Labels{containerIDLabelKey: cnrID}).Add(float64(size))
}

func (m engineMetrics) AddToPayloadCounter(shardID string, size int64) {
	m.payloadSize.With(prometheus.Labels{shardIDLabelKey: shardID}).Add(float64(size))
}

func (m engineMetrics) IncErrorCounter(shardID string) {
	m.errorCounter.With(prometheus.Labels{shardIDLabelKey: shardID}).Inc()
}

func (m engineMetrics) ClearErrorCounter(shardID string) {
	m.errorCounter.With(prometheus.Labels{shardIDLabelKey: shardID}).Set(0)
}

func (m engineMetrics) DeleteShardMetrics(shardID string) {
	m.errorCounter.Delete(prometheus.Labels{shardIDLabelKey: shardID})
	m.payloadSize.Delete(prometheus.Labels{shardIDLabelKey: shardID})
}