package logmower

import (
	"context"
	"fmt"

	prom "github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promauto"
	mongoEvent "go.mongodb.org/mongo-driver/event"
	mongoOpt "go.mongodb.org/mongo-driver/mongo/options"
	"go.uber.org/zap"
)

func mongoMonitoredClientOptions(l *zap.Logger) *mongoOpt.ClientOptions {
	promDbHeartbeat := promauto.NewHistogramVec(prom.HistogramOpts{
		Namespace: PrometheusPrefix,
		Subsystem: "database",
		Name:      "heartbeat_time",
		Help:      "Time in ns for succeeded heartbeat, or 0 on failure",
		Buckets:   []float64{1},
	}, []string{"connection_id"})

	promDbCmd := promauto.NewHistogramVec(prom.HistogramOpts{
		Namespace: PrometheusPrefix,
		Subsystem: "database",
		Name:      "operation_latency", // "command_time",
		Help:      "Time in ns of commands",
		Buckets:   []float64{0.1, 0.2, 0.5, 1, 5, 10, 50},
	}, []string{"connection_id", "command_name"})

	promDbCmdErr := promauto.NewCounterVec(prom.CounterOpts{
		Namespace: PrometheusPrefix,
		Subsystem: "database",
		Name:      "errors",
		Help:      "Failed commands (also reflected elsewhere)",
	}, []string{"connection_id", "command_name"})

	return mongoOpt.Client().
		SetServerMonitor(&mongoEvent.ServerMonitor{
			ServerHeartbeatSucceeded: func(ev *mongoEvent.ServerHeartbeatSucceededEvent) {
				promDbHeartbeat.WithLabelValues(ev.ConnectionID).Observe(float64(ev.DurationNanos))
			},
			ServerHeartbeatFailed: func(ev *mongoEvent.ServerHeartbeatFailedEvent) {
				promDbHeartbeat.WithLabelValues(ev.ConnectionID).Observe(0)
				l.Error("database heartbeat", zap.Error(ev.Failure), zap.String("connection_id", ev.ConnectionID))
			},
		}).
		SetMonitor(&mongoEvent.CommandMonitor{
			Succeeded: func(_ context.Context, ev *mongoEvent.CommandSucceededEvent) {
				promDbCmd.WithLabelValues(ev.ConnectionID, ev.CommandName).Observe(float64(ev.DurationNanos))
			},
			Failed: func(_ context.Context, ev *mongoEvent.CommandFailedEvent) {
				promDbCmd.WithLabelValues(ev.ConnectionID, ev.CommandName).Observe(float64(ev.DurationNanos))

				promDbCmdErr.WithLabelValues(ev.ConnectionID, ev.CommandName).Add(1)
				l.Error("database command", zap.Error(fmt.Errorf("%s", ev.Failure)), zap.String("connection_id", ev.ConnectionID), zap.String("command_name", ev.CommandName)) // TODO: https://github.com/mongodb/mongo-go-driver/pull/1105
			},
		})
}