package snowflake_proxy

import (
	"net/http"

	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"
)

const (
	// metricNamespace represent prometheus namespace
	metricNamespace = "tor_snowflake_proxy"
)

type Metrics struct {
	totalInBoundTraffic    prometheus.Counter
	totalOutBoundTraffic   prometheus.Counter
	totalConnections       *prometheus.CounterVec
	totalFailedConnections prometheus.Counter
}

func NewMetrics() *Metrics {
	return &Metrics{
		totalConnections: prometheus.NewCounterVec(prometheus.CounterOpts{
			Namespace: metricNamespace,
			Name:      "connections_total",
			Help:      "The total number of successful connections handled by the snowflake proxy",
		},
			[]string{"country"},
		),
		totalFailedConnections: prometheus.NewCounter(prometheus.CounterOpts{
			Namespace: metricNamespace,
			Name:      "connection_timeouts_total",
			Help:      "The total number of client connection attempts that failed after successful rendezvous. Note that failures can occur for reasons outside of the proxy's control, such as the client's NAT and censorship situation.",
		}),
		totalInBoundTraffic: prometheus.NewCounter(prometheus.CounterOpts{
			Namespace: metricNamespace,
			Name:      "traffic_inbound_bytes_total",
			Help:      "The total in bound traffic by the snowflake proxy (KB)",
		}),
		totalOutBoundTraffic: prometheus.NewCounter(prometheus.CounterOpts{
			Namespace: metricNamespace,
			Name:      "traffic_outbound_bytes_total",
			Help:      "The total out bound traffic by the snowflake proxy (KB)",
		}),
	}
}

// Start register the metrics server and serve them on the given address
func (m *Metrics) Start(addr string) error {
	go func() {
		http.Handle("/internal/metrics", promhttp.Handler())
		if err := http.ListenAndServe(addr, nil); err != nil {
			panic(err)
		}
	}()

	return prometheus.Register(m)
}

func (m *Metrics) Collect(ch chan<- prometheus.Metric) {
	m.totalConnections.Collect(ch)
	m.totalFailedConnections.Collect(ch)
	m.totalInBoundTraffic.Collect(ch)
	m.totalOutBoundTraffic.Collect(ch)
}

func (m *Metrics) Describe(descs chan<- *prometheus.Desc) {
	prometheus.DescribeByCollect(m, descs)
}

// TrackInBoundTraffic counts the received traffic by the snowflake proxy
func (m *Metrics) TrackInBoundTraffic(value int64) {
	m.totalInBoundTraffic.Add(float64(value))
}

// TrackOutBoundTraffic counts the transmitted traffic by the snowflake proxy
func (m *Metrics) TrackOutBoundTraffic(value int64) {
	m.totalOutBoundTraffic.Add(float64(value))
}

// TrackNewConnection counts the new connections
func (m *Metrics) TrackNewConnection(country string) {
	m.totalConnections.
		With(prometheus.Labels{"country": country}).
		Inc()
}

// TrackFailedConnection counts failed connection attempts
func (m *Metrics) TrackFailedConnection() {
	m.totalFailedConnections.Inc()
}