package alerting

import (
	"context"
	"fmt"
	"sync"
	"time"

	cl "dynatron.me/x/stillbox/pkg/calls"
	"dynatron.me/x/stillbox/pkg/gordio/database"

	"dynatron.me/x/stillbox/internal/timeseries"
	"dynatron.me/x/stillbox/internal/trending"

	"github.com/rs/zerolog/log"
)

const (
	StorageLookbackDays = 2
	HalfLife            = time.Hour
	RecentDuration      = time.Hour
)

type AlertSink struct {
	sync.RWMutex
	scorer trending.Scorer[cl.Talkgroup]
}

func NewSink(ctx context.Context) *AlertSink {
	as := &AlertSink{
		scorer: trending.NewScorer[cl.Talkgroup](
			trending.WithTimeSeries(newTimeSeries),
			trending.WithStorageDuration[cl.Talkgroup](StorageLookbackDays*24*time.Hour),
			trending.WithRecentDuration[cl.Talkgroup](RecentDuration),
			trending.WithHalfLife[cl.Talkgroup](HalfLife),
		),
	}

	go as.startBackfill(ctx)

	return as
}

func (as *AlertSink) startBackfill(ctx context.Context) {
	since := time.Now().Add(StorageLookbackDays * -24 * time.Hour)
	log.Debug().Time("since", since).Msg("starting stats backfill")
	count, err := as.backfill(ctx, since)
	if err != nil {
		log.Error().Err(err).Msg("backfill failed")
		return
	}
	log.Debug().Int("count", count).Int("len", as.scorer.Score().Len()).Msg("backfill finished")
	as.printScores()
}

type score[K comparable] struct {
	ID          K
	Score       float64
	Probability float64
	Expectation float64
	Maximum     float64
	KLScore     float64
}

func (as *AlertSink) printScores() {
	scores := as.scorer.Score()
	fmt.Printf("score len is %d\n", scores.Len())
	for _, s := range scores {
		fmt.Printf("%d:%d score %f prob %f exp %f max %f kl %f", s.ID.System, s.ID.Talkgroup, s.Score,
			s.Probability, s.Expectation, s.Maximum, s.KLScore)
	}
}

func (as *AlertSink) backfill(ctx context.Context, since time.Time) (count int, err error) {
	db := database.FromCtx(ctx)
	const backfillStatsQuery = `SELECT system, talkgroup, call_date FROM calls WHERE call_date > $1`

	rows, err := db.Query(ctx, backfillStatsQuery, since)
	if err != nil {
		return count, err
	}
	defer rows.Close()

	as.Lock()
	defer as.Unlock()

	for rows.Next() {
		var tg cl.Talkgroup
		var callDate time.Time
		if err := rows.Scan(&tg.System, &tg.Talkgroup, &callDate); err != nil {
			return count, err
		}
		as.scorer.AddEvent(tg, callDate)
		count++
	}

	if err := rows.Err(); err != nil {
		return count, err
	}

	return count, nil
}

func newTimeSeries(id cl.Talkgroup) trending.TimeSeries {
	ts, _ := timeseries.NewTimeSeries(timeseries.WithGranularities(
		[]timeseries.Granularity{
			{Granularity: time.Second, Count: 60},
			{Granularity: time.Minute, Count: 10},
			{Granularity: time.Hour, Count: 24},
			{Granularity: time.Hour * 24, Count: StorageLookbackDays},
		},
	))
	return ts
}

func (as *AlertSink) SinkType() string {
	return "alerting"
}

func (ns *AlertSink) Call(ctx context.Context, call *cl.Call) error {
	return nil
}