package api

import (
	"context"
	"fmt"
	"strconv"
	"strings"
	"time"

	"github.com/ponzischeme89/memby/server/internal/sonarr"
	"github.com/ponzischeme89/memby/server/internal/store"
)

// WatchSonarrLifecycle seeds the durable status history on startup, then refreshes it
// daily. History stores changes rather than identical daily snapshots: it still records
// the complete lifecycle while making an active-to-cancelled transition unambiguous.
func (s *Server) WatchSonarrLifecycle(ctx context.Context, interval time.Duration) {
	if s.sonarr == nil || interval <= 0 {
		return
	}
	scan := func() {
		if err := s.scanSonarrLifecycle(ctx); err != nil && ctx.Err() == nil {
			s.log.Warn("Sonarr lifecycle scan failed", "error", err)
		}
	}
	scan()
	ticker := time.NewTicker(interval)
	defer ticker.Stop()
	for {
		select {
		case <-ctx.Done():
			return
		case <-ticker.C:
			scan()
		}
	}
}

func (s *Server) scanSonarrLifecycle(ctx context.Context) error {
	series, err := s.sonarr.Series(ctx)
	if err != nil {
		return fmt.Errorf("read Sonarr series: %w", err)
	}
	now := time.Now().UTC()
	observations := make([]store.SonarrSeriesStatus, 0, len(series))
	for _, item := range series {
		key := sonarrSeriesStatusKey(item)
		if key == "" || strings.TrimSpace(item.Status) == "" {
			continue
		}
		observations = append(observations, store.SonarrSeriesStatus{
			SeriesKey: key, SonarrSeriesID: item.ID, TVDBID: item.TVDBID,
			Title: item.Title, Year: item.Year, Status: item.Status, ObservedAt: now,
		})
	}
	changes, err := s.store.RecordSonarrSeriesStatuses(ctx, observations)
	if err != nil {
		return err
	}
	cancellations := make([]store.SonarrSeriesStatusChange, 0, len(changes))
	additions := make([]store.SonarrSeriesStatusChange, 0, len(changes))
	for _, change := range changes {
		switch sonarrLifecycleNotificationKind(change.PreviousStatus, change.Current.Status) {
		case "show-added":
			additions = append(additions, change)
		case "show-cancelled":
			cancellations = append(cancellations, change)
		}
	}
	if len(cancellations) == 0 && len(additions) == 0 {
		s.log.Info("Sonarr lifecycle scan complete", "series", len(observations), "changes", len(changes))
		return nil
	}

	users, err := s.store.KnownUsers(ctx)
	if err != nil {
		return err
	}
	preferences := map[string]store.NotificationPreferences{}
	preferenceErrors := map[string]bool{}
	notifications := 0
	for _, change := range additions {
		for _, user := range users {
			prefs, ok := preferences[user.ID]
			if !ok && !preferenceErrors[user.ID] {
				prefs, err = s.store.NotificationPreferences(ctx, user.ID)
				if err != nil {
					preferenceErrors[user.ID] = true
					s.log.Warn("notification preferences unavailable during Sonarr lifecycle scan",
						"user", user.ID, "error", err)
					continue
				}
				preferences[user.ID] = prefs
			}
			if preferenceErrors[user.ID] || !prefs.Enabled {
				continue
			}
			eventAt := change.Current.ObservedAt
			sourceKey := fmt.Sprintf("show-added:%s:%d", change.Current.SeriesKey, change.HistoryID)
			message := change.Current.Title + " was added to Sonarr."
			if err := s.store.UpsertNotification(
				ctx, user.ID, sourceKey, "show-added", "",
				"Show added", message, &eventAt,
			); err != nil {
				s.log.Warn("Sonarr addition notification failed",
					"user", user.ID, "show", change.Current.Title, "error", err)
				continue
			}
			notifications++
		}
	}
	for _, change := range cancellations {
		for _, user := range users {
			prefs, ok := preferences[user.ID]
			if !ok && !preferenceErrors[user.ID] {
				prefs, err = s.store.NotificationPreferences(ctx, user.ID)
				if err != nil {
					preferenceErrors[user.ID] = true
					s.log.Warn("notification preferences unavailable during Sonarr lifecycle scan",
						"user", user.ID, "error", err)
					continue
				}
				preferences[user.ID] = prefs
			}
			if preferenceErrors[user.ID] || !prefs.Enabled {
				continue
			}
			eventAt := change.Current.ObservedAt
			sourceKey := fmt.Sprintf("show-cancelled:%s:%d", change.Current.SeriesKey, change.HistoryID)
			message := change.Current.Title + " is now listed as cancelled in Sonarr."
			if err := s.store.UpsertNotification(
				ctx, user.ID, sourceKey, "show-cancelled", "",
				"Show cancelled", message, &eventAt,
			); err != nil {
				s.log.Warn("Sonarr cancellation notification failed",
					"user", user.ID, "show", change.Current.Title, "error", err)
				continue
			}
			notifications++
		}
	}
	s.log.Info("Sonarr lifecycle scan complete",
		"series", len(observations), "changes", len(changes),
		"added", len(additions), "cancelled", len(cancellations), "notifications", notifications)
	return nil
}

func sonarrLifecycleNotificationKind(previous, current string) string {
	if strings.TrimSpace(previous) == "" {
		return "show-added"
	}
	if sonarrBecameCancelled(previous, current) {
		return "show-cancelled"
	}
	return ""
}

func sonarrSeriesStatusKey(series sonarr.Series) string {
	if series.TVDBID > 0 {
		return "tvdb:" + strconv.Itoa(series.TVDBID)
	}
	if series.ID > 0 {
		return "sonarr:" + strconv.Itoa(series.ID)
	}
	return ""
}

func sonarrBecameCancelled(previous, current string) bool {
	previous = strings.ToLower(strings.TrimSpace(previous))
	current = strings.ToLower(strings.TrimSpace(current))
	active := previous == "continuing" || previous == "upcoming"
	cancelled := current == "ended" || current == "deleted" ||
		current == "cancelled" || current == "canceled"
	return active && cancelled
}