package metrics

import (
	"fmt"
	"strings"

	"github.com/prometheus/client_golang/prometheus"
	"rgdd.se/silentct/internal/monitor"
	"rgdd.se/silentct/pkg/storage/index"
)

type Metrics struct {
	errorCounter               prometheus.Counter
	logIndex                   *prometheus.GaugeVec
	logSize                    *prometheus.GaugeVec
	logTimestamp               *prometheus.GaugeVec
	needRestart                prometheus.Gauge
	unexpectedCertificateCount *prometheus.GaugeVec
}

func NewMetrics(registry *prometheus.Registry) *Metrics {
	m := &Metrics{
		errorCounter: prometheus.NewCounter(
			prometheus.CounterOpts{
				Name: "silentct_error_counter",
				Help: "The number of errors propagated to the main loop.",
			},
		),
		logIndex: prometheus.NewGaugeVec(
			prometheus.GaugeOpts{
				Name: "silentct_log_index",
				Help: "The next log entry to be downloaded.",
			},
			[]string{"log_id"},
		),
		logSize: prometheus.NewGaugeVec(
			prometheus.GaugeOpts{
				Name: "silentct_log_size",
				Help: "The number of entries in the log.",
			},
			[]string{"log_id"},
		),
		logTimestamp: prometheus.NewGaugeVec(
			prometheus.GaugeOpts{
				Name: "silentct_log_timestamp",
				Help: "The log's UNIX timestamp in ms.",
			},
			[]string{"log_id"},
		),
		needRestart: prometheus.NewGauge(
			prometheus.GaugeOpts{
				Name: "silentct_need_restart",
				Help: "A non-zero value if the monitor needs restarting.",
			},
		),
		unexpectedCertificateCount: prometheus.NewGaugeVec(
			prometheus.GaugeOpts{
				Name: "silentct_unexpected_certificate_count",
				Help: "Number of certificates without any allowlisting",
			},
			[]string{"log_id", "log_index", "crt_sans"},
		),
	}
	registry.MustRegister(
		m.errorCounter,
		m.logIndex,
		m.logSize,
		m.logTimestamp,
		m.needRestart,
		m.unexpectedCertificateCount,
	)
	return m
}

func (m *Metrics) LogState(state monitor.State) {
	id := fmt.Sprintf("%x", state.LogID)
	m.logIndex.WithLabelValues(id).Set(float64(state.NextIndex))
	m.logSize.WithLabelValues(id).Set(float64(state.TreeSize))
	m.logTimestamp.WithLabelValues(id).Set(float64(state.Timestamp))
}

func (m *Metrics) RemoveLogState(state monitor.State) {
	id := fmt.Sprintf("%x", state.LogID)
	m.logIndex.Delete(prometheus.Labels{"id": id})
	m.logSize.Delete(prometheus.Labels{"id": id})
	m.logTimestamp.Delete(prometheus.Labels{"id": id})
}

func (m *Metrics) UnexpectedCertificateCount(alerts []index.CertificateInfo) {
	m.unexpectedCertificateCount.Reset()
	for _, alert := range alerts {
		labels := prometheus.Labels{
			"crt_sans":  strings.Join(alert.SANs, " "),
			"log_id":    fmt.Sprintf("%x", alert.LogID),
			"log_index": fmt.Sprintf("%d", alert.LogIndex),
		}
		m.unexpectedCertificateCount.With(labels).Set(1)
	}
}

func (m *Metrics) CountError() {
	m.errorCounter.Inc()
}

func (m *Metrics) NeedRestart() {
	m.needRestart.Set(float64(1))
}