package tasks

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"log/slog"
	"strconv"
	"strings"
	"sync"
	"sync/atomic"
	"time"
	"vctp/db"
	"vctp/db/queries"
	"vctp/internal/metrics"
	"vctp/internal/report"
	"vctp/internal/utils"
	"vctp/internal/vcenter"

	"github.com/jmoiron/sqlx"
	"github.com/vmware/govmomi/vim25/mo"
	"github.com/vmware/govmomi/vim25/types"
)

type ctxLoggerKey struct{}

type deletionCandidate struct {
	vmID       string
	vmUUID     string
	name       string
	cluster    string
	datacenter sql.NullString
}

type vcenterResources struct {
	vms          []mo.VirtualMachine
	hostLookup   map[string]vcenter.HostLookup
	folderLookup map[string]string
	rpLookup     map[string]string
}

func loggerFromCtx(ctx context.Context, fallback *slog.Logger) *slog.Logger {
	if ctx == nil {
		return fallback
	}
	if l, ok := ctx.Value(ctxLoggerKey{}).(*slog.Logger); ok && l != nil {
		return l
	}
	return fallback
}

// RunVcenterSnapshotHourly records hourly inventory snapshots into a daily table.
// If force is true, any in-progress marker will be cleared before starting (useful for manual recovery).
func (c *CronTask) RunVcenterSnapshotHourly(ctx context.Context, logger *slog.Logger, force bool) (err error) {
	jobCtx := ctx
	jobTimeout := durationFromSeconds(c.Settings.Values.Settings.HourlyJobTimeoutSeconds, 20*time.Minute)
	if jobTimeout > 0 {
		var cancel context.CancelFunc
		jobCtx, cancel = context.WithTimeout(ctx, jobTimeout)
		defer cancel()
	}
	snapshotFreq := durationFromSeconds(c.Settings.Values.Settings.VcenterInventorySnapshotSeconds, time.Hour)
	tracker := NewCronTracker(c.Database)
	// Clear stale marker for this job only (short timeout to avoid blocking).
	staleCtx, cancelStale := context.WithTimeout(context.Background(), 2*time.Second)
	defer cancelStale()
	if err := tracker.ClearStale(staleCtx, "hourly_snapshot", jobTimeout); err != nil {
		logger.Warn("failed to clear stale cron status", "error", err)
	}
	if force {
		if err := tracker.ClearAllInProgress(staleCtx); err != nil {
			logger.Warn("failed to clear in-progress flag (force run)", "error", err)
		} else {
			logger.Info("force run cleared in-progress marker before starting")
		}
	}

	startedAt := time.Now()
	defer func() {
		// gocron logs the next run on its side, but log here for quick visibility.
		logger.Info("Hourly snapshot job finished", "duration", time.Since(startedAt), "next_run_estimated", time.Now().Add(snapshotFreq))
	}()
	done, skip, err := tracker.Start(jobCtx, "hourly_snapshot")
	if err != nil {
		return err
	}
	if skip {
		if force {
			logger.Info("Force run requested; clearing in-progress marker and retrying")
			if err := tracker.ClearAllInProgress(jobCtx); err != nil {
				logger.Warn("failed to clear in-progress flag for force run", "error", err)
				return nil
			}
			done, skip, err = tracker.Start(jobCtx, "hourly_snapshot")
			if err != nil {
				return err
			}
			if skip {
				logger.Warn("Hourly snapshot still marked active after force clear; skipping")
				return nil
			}
		} else {
			logger.Warn("Hourly snapshot skipped because a previous run is still active", "force", force)
			return nil
		}
	}
	defer func() { done(err) }()

	ctx, cancel := context.WithCancel(jobCtx)
	defer cancel()
	startTime := time.Now()

	if err := db.CheckMigrationState(ctx, c.Database.DB()); err != nil {
		return err
	}
	if err := db.EnsureSnapshotRunTable(ctx, c.Database.DB()); err != nil {
		return err
	}
	// Best-effort cleanup of legacy IsPresent columns to simplify inserts.
	c.dropLegacyIsPresentColumns(jobCtx)

	// reload settings in case vcenter list has changed
	c.Settings.ReadYMLSettings()

	if c.FirstHourlySnapshotCheck {
		if err := report.EnsureSnapshotRegistry(ctx, c.Database); err != nil {
			return err
		}
		lastSnapshot, err := report.LatestSnapshotTime(ctx, c.Database, "hourly")
		if err != nil {
			return err
		}
		minIntervalSeconds := intWithDefault(c.Settings.Values.Settings.VcenterInventorySnapshotSeconds, 3600) / 2
		if !lastSnapshot.IsZero() && startTime.Sub(lastSnapshot) < time.Duration(minIntervalSeconds)*time.Second {
			c.Logger.Info("Skipping hourly snapshot, last snapshot too recent",
				"last_snapshot", lastSnapshot,
				"min_interval_seconds", minIntervalSeconds,
			)
			c.FirstHourlySnapshotCheck = false
			return nil
		}
		c.FirstHourlySnapshotCheck = false
	}

	tableName, err := hourlyInventoryTableName(startTime)
	if err != nil {
		return err
	}

	dbConn := c.Database.DB()
	db.ApplySQLiteTuning(ctx, dbConn)
	if err := ensureDailyInventoryTable(ctx, dbConn, tableName); err != nil {
		return err
	}

	var wg sync.WaitGroup
	var errCount int64
	concurrencyLimit := c.Settings.Values.Settings.HourlySnapshotConcurrency
	if override, ok := utils.EnvInt("VCTP_HOURLY_SNAPSHOT_CONCURRENCY"); ok && override >= 0 {
		concurrencyLimit = override
	}
	var sem chan struct{}
	if concurrencyLimit > 0 {
		sem = make(chan struct{}, concurrencyLimit)
	}
	c.Logger.Info("Starting hourly snapshots", "vcenter_count", len(c.Settings.Values.Settings.VcenterAddresses), "concurrency_limit", concurrencyLimit)
	for _, url := range c.Settings.Values.Settings.VcenterAddresses {
		wg.Add(1)
		go func(url string) {
			defer wg.Done()
			waitStarted := time.Now()
			vcStart := time.Now()
			if sem != nil {
				sem <- struct{}{}
				defer func() { <-sem }()
			}
			waitDuration := time.Since(waitStarted)

			timeout := durationFromSeconds(c.Settings.Values.Settings.HourlySnapshotTimeoutSeconds, 10*time.Minute)
			runCtx, cancel := context.WithTimeout(ctx, timeout)
			defer cancel()

			c.Logger.Info("Starting hourly snapshot for vcenter", "url", url)
			if err := c.captureHourlySnapshotForVcenter(runCtx, startTime, tableName, url); err != nil {
				atomic.AddInt64(&errCount, 1)
				c.Logger.Error("hourly snapshot failed", "error", err, "url", url)
			} else {
				c.Logger.Info("Finished hourly snapshot for vcenter",
					"url", url,
					"queue_wait", waitDuration,
					"duration", time.Since(vcStart),
					"timeout", timeout,
				)
			}
		}(url)
	}
	wg.Wait()
	if errCount > 0 {
		err = fmt.Errorf("hourly snapshot failed for %d vcenter(s)", errCount)
		return err
	}

	rowCount, err := db.TableRowCount(ctx, dbConn, tableName)
	if err != nil {
		c.Logger.Warn("unable to count hourly snapshot rows", "error", err, "table", tableName)
	}
	if err := report.RegisterSnapshot(ctx, c.Database, "hourly", tableName, startTime, rowCount); err != nil {
		c.Logger.Warn("failed to register hourly snapshot", "error", err, "table", tableName)
	}

	metrics.RecordHourlySnapshot(startTime, rowCount, err)
	if err := c.generateReport(ctx, tableName); err != nil {
		c.Logger.Warn("failed to generate hourly report", "error", err, "table", tableName)
	}

	c.Logger.Debug("Finished hourly vcenter snapshot", "vcenter_count", len(c.Settings.Values.Settings.VcenterAddresses), "table", tableName, "row_count", rowCount)
	return nil
}

// dropLegacyIsPresentColumns attempts to remove the old IsPresent column from hourly tables.
// This keeps inserts simple and avoids keeping unused data around.
func (c *CronTask) dropLegacyIsPresentColumns(ctx context.Context) {
	dbConn := c.Database.DB()
	if err := report.EnsureSnapshotRegistry(ctx, c.Database); err != nil {
		c.Logger.Debug("skip IsPresent cleanup; registry unavailable", "error", err)
		return
	}
	records, err := report.ListSnapshots(ctx, c.Database, "hourly")
	if err != nil {
		c.Logger.Debug("skip IsPresent cleanup; unable to list hourly snapshots", "error", err)
		return
	}
	for _, r := range records {
		if ok, err := db.ColumnExists(ctx, dbConn, r.TableName, "IsPresent"); err == nil && ok {
			if _, err := dbConn.ExecContext(ctx, fmt.Sprintf(`ALTER TABLE %s DROP COLUMN "IsPresent"`, r.TableName)); err != nil {
				c.Logger.Debug("unable to drop legacy IsPresent column", "table", r.TableName, "error", err)
			} else {
				c.Logger.Info("dropped legacy IsPresent column", "table", r.TableName)
			}
		}
	}
}

// RunHourlySnapshotRetry retries failed vCenter hourly snapshots up to a maximum attempt count.
func (c *CronTask) RunHourlySnapshotRetry(ctx context.Context, logger *slog.Logger) (err error) {
	jobStart := time.Now()
	defer func() {
		logger.Info("Hourly snapshot retry finished", "duration", time.Since(jobStart))
	}()

	maxRetries := c.Settings.Values.Settings.HourlySnapshotMaxRetries
	if maxRetries <= 0 {
		maxRetries = 3
	}

	dbConn := c.Database.DB()
	if err := db.EnsureSnapshotRunTable(ctx, dbConn); err != nil {
		return err
	}

	failed, err := db.ListFailedSnapshotRuns(ctx, dbConn, maxRetries)
	if err != nil {
		return err
	}
	if len(failed) == 0 {
		logger.Debug("No failed hourly snapshots to retry")
		return nil
	}

	for _, f := range failed {
		startTime := time.Unix(f.SnapshotTime, 0)
		tableName, tnErr := hourlyInventoryTableName(startTime)
		if tnErr != nil {
			logger.Warn("unable to derive table name for retry", "error", tnErr, "snapshot_time", startTime, "vcenter", f.Vcenter)
			continue
		}
		logger.Info("Retrying hourly snapshot", "vcenter", f.Vcenter, "snapshot_time", startTime, "attempt", f.Attempts+1)
		if err := c.captureHourlySnapshotForVcenter(ctx, startTime, tableName, f.Vcenter); err != nil {
			logger.Warn("retry failed", "vcenter", f.Vcenter, "error", err)
		}
	}
	return nil
}

// RunSnapshotCleanup drops hourly and daily snapshot tables older than retention.
func (c *CronTask) RunSnapshotCleanup(ctx context.Context, logger *slog.Logger) (err error) {
	jobCtx := ctx
	jobTimeout := durationFromSeconds(c.Settings.Values.Settings.CleanupJobTimeoutSeconds, 10*time.Minute)
	if jobTimeout > 0 {
		var cancel context.CancelFunc
		jobCtx, cancel = context.WithTimeout(ctx, jobTimeout)
		defer cancel()
	}
	tracker := NewCronTracker(c.Database)
	done, skip, err := tracker.Start(jobCtx, "snapshot_cleanup")
	if err != nil {
		return err
	}
	if skip {
		logger.Warn("Snapshot cleanup skipped because a previous run is still active")
		return nil
	}
	defer func() { done(err) }()

	if err := db.CheckMigrationState(jobCtx, c.Database.DB()); err != nil {
		return err
	}

	startedAt := time.Now()
	defer func() {
		logger.Info("Snapshot cleanup job finished", "duration", time.Since(startedAt))
	}()
	now := time.Now()
	hourlyMaxDays := intWithDefault(c.Settings.Values.Settings.HourlySnapshotMaxAgeDays, 60)
	dailyMaxMonths := intWithDefault(c.Settings.Values.Settings.DailySnapshotMaxAgeMonths, 12)

	hourlyCutoff := now.AddDate(0, 0, -hourlyMaxDays)
	dailyCutoff := now.AddDate(0, -dailyMaxMonths, 0)
	logger.Info("Starting snapshot cleanup",
		"now", now,
		"hourly_cutoff", truncateDate(hourlyCutoff),
		"daily_cutoff", truncateDate(dailyCutoff),
		"hourly_max_age_days", hourlyMaxDays,
		"daily_max_age_months", dailyMaxMonths,
	)

	dbConn := c.Database.DB()

	hourlyTables, err := report.ListTablesByPrefix(ctx, c.Database, "inventory_hourly_")
	if err != nil {
		return err
	}
	logger.Info("Snapshot cleanup hourly scan", "tables_found", len(hourlyTables))

	removedHourly := 0
	scannedHourly := 0
	for _, table := range hourlyTables {
		if strings.HasPrefix(table, "inventory_daily_summary_") {
			continue
		}
		tableDate, ok := parseSnapshotDate(table, "inventory_hourly_", "epoch")
		if !ok {
			continue
		}
		scannedHourly++
		if tableDate.Before(truncateDate(hourlyCutoff)) {
			if err := dropSnapshotTable(ctx, dbConn, table); err != nil {
				c.Logger.Error("failed to drop hourly snapshot table", "error", err, "table", table)
			} else {
				removedHourly++
				if err := report.DeleteSnapshotRecord(ctx, c.Database, table); err != nil {
					c.Logger.Warn("failed to remove hourly snapshot registry entry", "error", err, "table", table)
				}
			}
		}
	}

	dailyTables, err := report.ListTablesByPrefix(ctx, c.Database, "inventory_daily_summary_")
	if err != nil {
		return err
	}
	logger.Info("Snapshot cleanup daily scan", "tables_found", len(dailyTables))
	removedDaily := 0
	scannedDaily := 0
	for _, table := range dailyTables {
		tableDate, ok := parseSnapshotDate(table, "inventory_daily_summary_", "20060102")
		if !ok {
			continue
		}
		scannedDaily++
		if tableDate.Before(truncateDate(dailyCutoff)) {
			if err := dropSnapshotTable(ctx, dbConn, table); err != nil {
				c.Logger.Error("failed to drop daily snapshot table", "error", err, "table", table)
			} else {
				removedDaily++
				if err := report.DeleteSnapshotRecord(ctx, c.Database, table); err != nil {
					c.Logger.Warn("failed to remove daily snapshot registry entry", "error", err, "table", table)
				}
			}
		}
	}

	c.Logger.Info("Finished snapshot cleanup",
		"hourly_tables_scanned", scannedHourly,
		"daily_tables_scanned", scannedDaily,
		"removed_hourly_tables", removedHourly,
		"removed_daily_tables", removedDaily,
		"hourly_max_age_days", hourlyMaxDays,
		"daily_max_age_months", dailyMaxMonths,
	)
	return nil
}

func hourlyInventoryTableName(t time.Time) (string, error) {
	return db.SafeTableName(fmt.Sprintf("inventory_hourly_%d", t.Unix()))
}

func ensureDailyInventoryTable(ctx context.Context, dbConn *sqlx.DB, tableName string) error {
	if err := db.EnsureSnapshotTable(ctx, dbConn, tableName); err != nil {
		return err
	}
	if err := ensureSnapshotRowID(ctx, dbConn, tableName); err != nil {
		return err
	}

	return db.EnsureColumns(ctx, dbConn, tableName, []db.ColumnDef{
		{Name: "VcpuCount", Type: "BIGINT"},
		{Name: "RamGB", Type: "BIGINT"},
	})
}
func buildUnionQuery(tables []string, columns []string, whereClause string) (string, error) {
	if len(tables) == 0 {
		return "", fmt.Errorf("no tables provided for union")
	}
	if len(columns) == 0 {
		return "", fmt.Errorf("no columns provided for union")
	}

	columnList := strings.Join(columns, ", ")

	const maxCompoundTerms = 450
	if len(tables) <= maxCompoundTerms {
		queries := make([]string, 0, len(tables))
		for _, table := range tables {
			safeName, err := db.SafeTableName(table)
			if err != nil {
				return "", err
			}
			query := fmt.Sprintf("SELECT %s FROM %s", columnList, safeName)
			if whereClause != "" {
				query = fmt.Sprintf("%s WHERE %s", query, whereClause)
			}
			queries = append(queries, query)
		}
		if len(queries) == 0 {
			return "", fmt.Errorf("no valid tables provided for union")
		}
		union := strings.Join(queries, "\nUNION ALL\n")
		return fmt.Sprintf("SELECT * FROM (%s) AS union_all", union), nil
	}

	batches := make([]string, 0, (len(tables)/maxCompoundTerms)+1)
	batchIndex := 0
	for start := 0; start < len(tables); start += maxCompoundTerms {
		end := start + maxCompoundTerms
		if end > len(tables) {
			end = len(tables)
		}
		queries := make([]string, 0, end-start)
		for _, table := range tables[start:end] {
			safeName, err := db.SafeTableName(table)
			if err != nil {
				return "", err
			}
			query := fmt.Sprintf("SELECT %s FROM %s", columnList, safeName)
			if whereClause != "" {
				query = fmt.Sprintf("%s WHERE %s", query, whereClause)
			}
			queries = append(queries, query)
		}
		if len(queries) == 0 {
			continue
		}
		subUnion := strings.Join(queries, "\nUNION ALL\n")
		batches = append(batches, fmt.Sprintf("SELECT * FROM (%s) AS batch_%d", subUnion, batchIndex))
		batchIndex++
	}
	if len(batches) == 0 {
		return "", fmt.Errorf("no valid tables provided for union")
	}
	outerUnion := strings.Join(batches, "\nUNION ALL\n")
	return fmt.Sprintf("SELECT * FROM (%s) AS union_batches", outerUnion), nil
}

func templateExclusionFilter() string {
	return `COALESCE(CAST("IsTemplate" AS TEXT), '') NOT IN ('TRUE', 'true', '1')`
}

func parseSnapshotDate(table string, prefix string, layout string) (time.Time, bool) {
	if !strings.HasPrefix(table, prefix) {
		return time.Time{}, false
	}
	suffix := strings.TrimPrefix(table, prefix)
	if layout == "epoch" {
		epoch, err := strconv.ParseInt(suffix, 10, 64)
		if err != nil {
			return time.Time{}, false
		}
		return time.Unix(epoch, 0), true
	}
	parsed, err := time.Parse(layout, suffix)
	if err != nil {
		return time.Time{}, false
	}
	return parsed, true
}

func truncateDate(t time.Time) time.Time {
	return time.Date(t.Year(), t.Month(), t.Day(), 0, 0, 0, 0, t.Location())
}

func filterSnapshotsWithRows(ctx context.Context, dbConn *sqlx.DB, snapshots []report.SnapshotRecord) []report.SnapshotRecord {
	filtered := snapshots[:0]
	log := loggerFromCtx(ctx, nil)
	for _, snapshot := range snapshots {
		switch {
		case snapshot.SnapshotCount > 0:
			filtered = append(filtered, snapshot)
		case snapshot.SnapshotCount == 0:
			if log != nil {
				log.Debug("skipping snapshot table with zero count", "table", snapshot.TableName, "snapshot_time", snapshot.SnapshotTime)
			}
		default:
			if rowsExist, err := db.TableHasRows(ctx, dbConn, snapshot.TableName); err == nil && rowsExist {
				filtered = append(filtered, snapshot)
			} else if log != nil {
				log.Debug("snapshot table probe empty or failed", "table", snapshot.TableName, "snapshot_time", snapshot.SnapshotTime, "error", err)
			}
		}
	}
	return filtered
}

func filterRecordsInRange(records []report.SnapshotRecord, start, end time.Time) []report.SnapshotRecord {
	filtered := records[:0]
	for _, r := range records {
		if !r.SnapshotTime.Before(start) && r.SnapshotTime.Before(end) {
			filtered = append(filtered, r)
		}
	}
	return filtered
}

var summaryUnionColumns = []string{
	`"InventoryId"`, `"Name"`, `"Vcenter"`, `"VmId"`, `"EventKey"`, `"CloudId"`, `"CreationTime"`,
	`"DeletionTime"`, `"ResourcePool"`, `"Datacenter"`, `"Cluster"`, `"Folder"`,
	`"ProvisionedDisk"`, `"VcpuCount"`, `"RamGB"`, `"IsTemplate"`, `"PoweredOn"`,
	`"SrmPlaceholder"`, `"VmUuid"`, `"SnapshotTime"`,
}

// monthlyUnionColumns are the fields needed from daily summaries for monthly aggregation/refinement.
var monthlyUnionColumns = []string{
	`"InventoryId"`, `"Name"`, `"Vcenter"`, `"VmId"`, `"EventKey"`, `"CloudId"`, `"CreationTime"`,
	`"DeletionTime"`, `"ResourcePool"`, `"Datacenter"`, `"Cluster"`, `"Folder"`,
	`"ProvisionedDisk"`, `"VcpuCount"`, `"RamGB"`, `"IsTemplate"`, `"PoweredOn"`,
	`"SrmPlaceholder"`, `"VmUuid"`,
	`"SamplesPresent"`, `"AvgVcpuCount"`, `"AvgRamGB"`, `"AvgProvisionedDisk"`, `"AvgIsPresent"`,
	`"PoolTinPct"`, `"PoolBronzePct"`, `"PoolSilverPct"`, `"PoolGoldPct"`,
	`"Tin"`, `"Bronze"`, `"Silver"`, `"Gold"`, `"SnapshotTime"`,
}

func ensureSnapshotRowID(ctx context.Context, dbConn *sqlx.DB, tableName string) error {
	driver := strings.ToLower(dbConn.DriverName())
	switch driver {
	case "pgx", "postgres":
		hasColumn, err := db.ColumnExists(ctx, dbConn, tableName, "RowId")
		if err != nil {
			return err
		}
		if !hasColumn {
			if err := db.AddColumnIfMissing(ctx, dbConn, tableName, db.ColumnDef{Name: "RowId", Type: "BIGSERIAL"}); err != nil {
				return err
			}
		}
		if err := db.BackfillSerialColumn(ctx, dbConn, tableName, "RowId"); err != nil {
			return err
		}
	case "sqlite":
		return nil
	}
	return nil
}

func nullInt64ToInt(value sql.NullInt64) int64 {
	if value.Valid {
		return value.Int64
	}
	return 0
}

func nullFloat64ToFloat(value sql.NullFloat64) float64 {
	if value.Valid {
		return value.Float64
	}
	return 0
}

func intWithDefault(value int, fallback int) int {
	if value <= 0 {
		return fallback
	}
	return value
}

func durationFromSeconds(seconds int, fallback time.Duration) time.Duration {
	if seconds > 0 {
		return time.Duration(seconds) * time.Second
	}
	return fallback
}

func normalizeResourcePool(value string) string {
	trimmed := strings.TrimSpace(value)
	if trimmed == "" {
		return ""
	}
	lower := strings.ToLower(trimmed)
	canonical := map[string]string{
		"tin":    "Tin",
		"bronze": "Bronze",
		"silver": "Silver",
		"gold":   "Gold",
	}
	if val, ok := canonical[lower]; ok {
		return val
	}
	return trimmed
}

func (c *CronTask) reportsDir() string {
	if c.Settings != nil && c.Settings.Values != nil {
		if dir := strings.TrimSpace(c.Settings.Values.Settings.ReportsDir); dir != "" {
			return dir
		}
	}
	return "/var/lib/vctp/reports"
}

func (c *CronTask) generateReport(ctx context.Context, tableName string) error {
	dest := c.reportsDir()
	start := time.Now()
	c.Logger.Debug("Report generation start", "table", tableName, "dest", dest)
	filename, err := report.SaveTableReport(c.Logger, c.Database, ctx, tableName, dest)
	if err == nil {
		c.Logger.Debug("Report generation complete", "table", tableName, "file", filename, "duration", time.Since(start))
	} else {
		c.Logger.Debug("Report generation failed", "table", tableName, "duration", time.Since(start), "error", err)
	}
	return err
}

func snapshotFromVM(vmObject *mo.VirtualMachine, vc *vcenter.Vcenter, snapshotTime time.Time, inv *queries.Inventory, hostLookup map[string]vcenter.HostLookup, folderLookup vcenter.FolderLookup, rpLookup map[string]string) (InventorySnapshotRow, error) {
	if vmObject == nil {
		return InventorySnapshotRow{}, fmt.Errorf("missing VM object")
	}

	row := InventorySnapshotRow{
		Name:         vmObject.Name,
		Vcenter:      vc.Vurl,
		VmId:         sql.NullString{String: vmObject.Reference().Value, Valid: vmObject.Reference().Value != ""},
		SnapshotTime: snapshotTime.Unix(),
	}

	if inv != nil {
		row.InventoryId = sql.NullInt64{Int64: inv.Iid, Valid: inv.Iid > 0}
		row.EventKey = inv.EventKey
		row.CloudId = inv.CloudId
		row.DeletionTime = inv.DeletionTime
	}

	if vmObject.Config != nil {
		row.VmUuid = sql.NullString{String: vmObject.Config.Uuid, Valid: vmObject.Config.Uuid != ""}
		if !vmObject.Config.CreateDate.IsZero() {
			row.CreationTime = sql.NullInt64{Int64: vmObject.Config.CreateDate.Unix(), Valid: true}
		}
		row.VcpuCount = sql.NullInt64{Int64: int64(vmObject.Config.Hardware.NumCPU), Valid: vmObject.Config.Hardware.NumCPU > 0}
		row.RamGB = sql.NullInt64{Int64: int64(vmObject.Config.Hardware.MemoryMB) / 1024, Valid: vmObject.Config.Hardware.MemoryMB > 0}

		totalDiskBytes := int64(0)
		for _, device := range vmObject.Config.Hardware.Device {
			if disk, ok := device.(*types.VirtualDisk); ok {
				totalDiskBytes += disk.CapacityInBytes
			}
		}
		if totalDiskBytes > 0 {
			row.ProvisionedDisk = sql.NullFloat64{Float64: float64(totalDiskBytes / 1024 / 1024 / 1024), Valid: true}
		}

		if vmObject.Config.ManagedBy != nil && vmObject.Config.ManagedBy.ExtensionKey == "com.vmware.vcDr" && vmObject.Config.ManagedBy.Type == "placeholderVm" {
			row.SrmPlaceholder = "TRUE"
		} else {
			row.SrmPlaceholder = "FALSE"
		}

		if vmObject.Config.Template {
			row.IsTemplate = "TRUE"
		} else {
			row.IsTemplate = "FALSE"
		}
	}

	if vmObject.Runtime.PowerState == "poweredOff" {
		row.PoweredOn = "FALSE"
	} else {
		row.PoweredOn = "TRUE"
	}

	if inv != nil {
		if inv.ResourcePool.Valid {
			row.ResourcePool = sql.NullString{String: normalizeResourcePool(inv.ResourcePool.String), Valid: true}
		}
		row.Datacenter = inv.Datacenter
		row.Cluster = inv.Cluster
		row.Folder = inv.Folder
		if !row.CreationTime.Valid {
			row.CreationTime = inv.CreationTime
		}
		if !row.ProvisionedDisk.Valid {
			row.ProvisionedDisk = inv.ProvisionedDisk
		}
		if !row.VcpuCount.Valid {
			row.VcpuCount = inv.InitialVcpus
		}
		if !row.RamGB.Valid && inv.InitialRam.Valid {
			row.RamGB = sql.NullInt64{Int64: inv.InitialRam.Int64 / 1024, Valid: inv.InitialRam.Int64 > 0}
		}
		if row.IsTemplate == "" {
			row.IsTemplate = boolStringFromInterface(inv.IsTemplate)
		}
		if row.PoweredOn == "" {
			row.PoweredOn = boolStringFromInterface(inv.PoweredOn)
		}
		if row.SrmPlaceholder == "" {
			row.SrmPlaceholder = boolStringFromInterface(inv.SrmPlaceholder)
		}
		if !row.VmUuid.Valid {
			row.VmUuid = inv.VmUuid
		}
	}

	if row.ResourcePool.String == "" && vmObject.ResourcePool != nil {
		if rpLookup != nil {
			if rpName, ok := rpLookup[vmObject.ResourcePool.Value]; ok {
				row.ResourcePool = sql.NullString{String: normalizeResourcePool(rpName), Valid: rpName != ""}
			}
		}
	}

	if row.Folder.String == "" {
		if folderPath, ok := vc.GetVMFolderPathFromLookup(*vmObject, folderLookup); ok {
			row.Folder = sql.NullString{String: folderPath, Valid: folderPath != ""}
		} else {
			// Unable to resolve folder path from lookup; leave empty.
		}
	}

	if vmObject.Runtime.Host != nil && hostLookup != nil {
		if lookup, ok := hostLookup[vmObject.Runtime.Host.Value]; ok {
			if row.Cluster.String == "" && lookup.Cluster != "" {
				row.Cluster = sql.NullString{String: lookup.Cluster, Valid: true}
			}
			if row.Datacenter.String == "" && lookup.Datacenter != "" {
				row.Datacenter = sql.NullString{String: lookup.Datacenter, Valid: true}
			}
		}
	}

	if row.Cluster.String == "" && vmObject.Runtime.Host != nil {
		if clusterName, err := vc.GetClusterFromHost(vmObject.Runtime.Host); err == nil {
			row.Cluster = sql.NullString{String: clusterName, Valid: clusterName != ""}
		} else if vc.Logger != nil {
			vc.Logger.Warn("failed to resolve cluster from host", "vm_id", vmObject.Reference().Value, "error", err)
		}
	}

	if row.Datacenter.String == "" {
		if dcName, err := vc.GetDatacenterForVM(*vmObject); err == nil {
			row.Datacenter = sql.NullString{String: dcName, Valid: dcName != ""}
		}
	}

	return row, nil
}

func snapshotFromInventory(inv queries.Inventory, snapshotTime time.Time) InventorySnapshotRow {
	return InventorySnapshotRow{
		InventoryId:     sql.NullInt64{Int64: inv.Iid, Valid: inv.Iid > 0},
		Name:            inv.Name,
		Vcenter:         inv.Vcenter,
		VmId:            inv.VmId,
		EventKey:        inv.EventKey,
		CloudId:         inv.CloudId,
		CreationTime:    inv.CreationTime,
		DeletionTime:    inv.DeletionTime,
		ResourcePool:    sql.NullString{String: normalizeResourcePool(inv.ResourcePool.String), Valid: inv.ResourcePool.Valid},
		Datacenter:      inv.Datacenter,
		Cluster:         inv.Cluster,
		Folder:          inv.Folder,
		ProvisionedDisk: inv.ProvisionedDisk,
		VcpuCount:       inv.InitialVcpus,
		RamGB:           sql.NullInt64{Int64: inv.InitialRam.Int64 / 1024, Valid: inv.InitialRam.Valid && inv.InitialRam.Int64 > 0},
		IsTemplate:      boolStringFromInterface(inv.IsTemplate),
		PoweredOn:       boolStringFromInterface(inv.PoweredOn),
		SrmPlaceholder:  boolStringFromInterface(inv.SrmPlaceholder),
		VmUuid:          inv.VmUuid,
		SnapshotTime:    snapshotTime.Unix(),
	}
}

func loadInventoryMaps(ctx context.Context, dbConn *sqlx.DB, url string) ([]queries.Inventory, map[string]queries.Inventory, map[string]queries.Inventory, map[string]queries.Inventory, error) {
	inventoryRows, err := queries.New(dbConn).GetInventoryByVcenter(ctx, url)
	if err != nil {
		return nil, nil, nil, nil, fmt.Errorf("unable to query inventory table: %w", err)
	}
	inventoryByVmID := make(map[string]queries.Inventory, len(inventoryRows))
	inventoryByUuid := make(map[string]queries.Inventory, len(inventoryRows))
	inventoryByName := make(map[string]queries.Inventory, len(inventoryRows))
	for _, inv := range inventoryRows {
		if inv.VmId.Valid {
			inventoryByVmID[inv.VmId.String] = inv
		}
		if inv.VmUuid.Valid {
			inventoryByUuid[inv.VmUuid.String] = inv
		}
		if inv.Name != "" {
			inventoryByName[inv.Name] = inv
		}
	}
	return inventoryRows, inventoryByVmID, inventoryByUuid, inventoryByName, nil
}

func prepareDeletionCandidates(ctx context.Context, log *slog.Logger, dbConn *sqlx.DB, url string, inventoryRows []queries.Inventory,
	presentSnapshots map[string]InventorySnapshotRow, presentByUuid, presentByName map[string]struct{}, startTime time.Time) (int, bool, []deletionCandidate) {
	candidates := make([]deletionCandidate, 0)
	missingCount := 0
	deletionsMarked := false

	for _, inv := range inventoryRows {
		log.Debug("checking inventory for deletions", "vm_id", inv.VmId.String, "vm_uuid", inv.VmUuid.String, "name", inv.Name)
		if strings.HasPrefix(inv.Name, "vCLS-") {
			continue
		}
		vmID := inv.VmId.String
		uuid := ""
		if inv.VmUuid.Valid {
			uuid = inv.VmUuid.String
		}
		name := inv.Name

		found := false
		if vmID != "" {
			if _, ok := presentSnapshots[vmID]; ok {
				found = true
			}
		}
		if !found && uuid != "" {
			if _, ok := presentByUuid[uuid]; ok {
				found = true
			}
		}
		if !found && name != "" {
			if _, ok := presentByName[name]; ok {
				found = true
			}
		}
		if found {
			continue
		}

		row := snapshotFromInventory(inv, startTime)
		if !row.DeletionTime.Valid {
			deletionTime := startTime.Unix()
			row.DeletionTime = sql.NullInt64{Int64: deletionTime, Valid: true}
			if err := queries.New(dbConn).InventoryMarkDeleted(ctx, queries.InventoryMarkDeletedParams{
				DeletionTime:   row.DeletionTime,
				VmId:           inv.VmId,
				DatacenterName: inv.Datacenter,
			}); err != nil {
				log.Warn("failed to mark inventory record deleted", "error", err, "vm_id", row.VmId.String)
			}
			log.Debug("Marked VM as deleted", "name", inv.Name, "vm_id", inv.VmId.String, "vm_uuid", inv.VmUuid.String, "vcenter", url, "snapshot_time", startTime)
			deletionsMarked = true
		}
		clusterName := ""
		if inv.Cluster.Valid {
			clusterName = inv.Cluster.String
		}

		candidates = append(candidates, deletionCandidate{
			vmID:       vmID,
			vmUUID:     uuid,
			name:       name,
			cluster:    clusterName,
			datacenter: inv.Datacenter,
		})
		if err := db.MarkVmDeletedWithDetails(ctx, dbConn, url, inv.VmId.String, inv.VmUuid.String, inv.Name, clusterName, startTime.Unix()); err != nil {
			log.Warn("failed to mark vm deleted in lifecycle cache", "vcenter", url, "vm_id", inv.VmId, "vm_uuid", inv.VmUuid, "error", err)
		}
		if err := db.UpsertVmLifecycleCache(ctx, dbConn, url, inv.VmId.String, inv.VmUuid.String, inv.Name, clusterName, startTime); err != nil {
			log.Warn("failed to upsert vm lifecycle cache (deletion path)", "vcenter", url, "vm_id", inv.VmId, "vm_uuid", inv.VmUuid, "name", inv.Name, "error", err)
		}
		missingCount++
	}

	return missingCount, deletionsMarked, candidates
}

// buildPresentSnapshots converts vCenter VM objects into snapshot rows and aggregates totals.
func (c *CronTask) buildPresentSnapshots(ctx context.Context, dbConn *sqlx.DB, vc *vcenter.Vcenter, vcVms []mo.VirtualMachine, startTime time.Time, url string,
	inventoryByVmID map[string]queries.Inventory, hostLookup map[string]vcenter.HostLookup, folderLookup map[string]string, rpLookup map[string]string) (map[string]InventorySnapshotRow, map[string]struct{}, map[string]struct{}, snapshotTotals) {
	log := loggerFromCtx(ctx, c.Logger)
	presentSnapshots := make(map[string]InventorySnapshotRow, len(vcVms))
	presentByUuid := make(map[string]struct{}, len(vcVms))
	presentByName := make(map[string]struct{}, len(vcVms))
	totals := snapshotTotals{}

	for _, vm := range vcVms {
		if strings.HasPrefix(vm.Name, "vCLS-") {
			continue
		}
		if vm.Config != nil && vm.Config.Template {
			continue
		}

		var inv *queries.Inventory
		if existing, ok := inventoryByVmID[vm.Reference().Value]; ok {
			existingCopy := existing
			inv = &existingCopy
		}

		row, err := snapshotFromVM(&vm, vc, startTime, inv, hostLookup, folderLookup, rpLookup)
		if err != nil {
			log.Error("unable to build snapshot for VM", "vm_id", vm.Reference().Value, "error", err)
			continue
		}
		if err := db.UpsertVmIdentity(ctx, dbConn, url, row.VmId, row.VmUuid, row.Name, row.Cluster, startTime); err != nil {
			log.Warn("failed to upsert vm identity", "vcenter", url, "vm_id", row.VmId, "vm_uuid", row.VmUuid, "name", row.Name, "error", err)
		}
		clusterName := ""
		if row.Cluster.Valid {
			clusterName = row.Cluster.String
		}
		if err := db.UpsertVmLifecycleCache(ctx, dbConn, url, row.VmId.String, row.VmUuid.String, row.Name, clusterName, startTime); err != nil {
			log.Warn("failed to upsert vm lifecycle cache", "vcenter", url, "vm_id", row.VmId, "vm_uuid", row.VmUuid, "name", row.Name, "error", err)
		}
		presentSnapshots[vm.Reference().Value] = row
		if row.VmUuid.Valid {
			presentByUuid[row.VmUuid.String] = struct{}{}
		}
		if row.Name != "" {
			presentByName[row.Name] = struct{}{}
		}

		totals.VmCount++
		totals.VcpuTotal += nullInt64ToInt(row.VcpuCount)
		totals.RamTotal += nullInt64ToInt(row.RamGB)
		totals.DiskTotal += nullFloat64ToFloat(row.ProvisionedDisk)
	}

	return presentSnapshots, presentByUuid, presentByName, totals
}

// initVcenterResources logs into vCenter, fetches VMs, builds lookups, and returns a cleanup function for logout.
func (c *CronTask) initVcenterResources(ctx context.Context, log *slog.Logger, url string, startTime, started time.Time) (*vcenter.Vcenter, vcenterResources, func(), error) {
	res := vcenterResources{}
	vc := vcenter.New(c.Logger, c.VcCreds)
	if err := vc.Login(url); err != nil {
		metrics.RecordVcenterSnapshot(url, time.Since(started), 0, err)
		if upErr := db.UpsertSnapshotRun(ctx, c.Database.DB(), url, startTime, false, err.Error()); upErr != nil {
			log.Warn("failed to record snapshot run", "url", url, "error", upErr)
		}
		return nil, res, nil, fmt.Errorf("unable to connect to vcenter: %w", err)
	}

	cleanup := func() {
		logCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
		defer cancel()
		if err := vc.Logout(logCtx); err != nil {
			log.Warn("vcenter logout failed", "url", url, "error", err)
		} else {
			log.Debug("vcenter logout succeeded", "url", url)
		}
	}

	vms, err := vc.GetAllVMsWithProps()
	if err != nil {
		metrics.RecordVcenterSnapshot(url, time.Since(started), 0, err)
		if upErr := db.UpsertSnapshotRun(ctx, c.Database.DB(), url, startTime, false, err.Error()); upErr != nil {
			log.Warn("failed to record snapshot run", "url", url, "error", upErr)
		}
		cleanup()
		return nil, res, nil, fmt.Errorf("unable to get VMs from vcenter: %w", err)
	}
	log.Debug("retrieved VMs from vcenter", "url", url, "vm_count", len(vms))
	if err := db.EnsureVmIdentityTables(ctx, c.Database.DB()); err != nil {
		log.Warn("failed to ensure vm identity tables", "error", err)
	}

	hostLookup, err := vc.BuildHostLookup()
	if err != nil {
		log.Warn("failed to build host lookup", "url", url, "error", err)
		hostLookup = nil
	} else {
		log.Debug("built host lookup", "url", url, "hosts", len(hostLookup))
	}
	folderLookup, err := vc.BuildFolderPathLookup()
	if err != nil {
		log.Warn("failed to build folder lookup", "url", url, "error", err)
		folderLookup = nil
	} else {
		log.Debug("built folder lookup", "url", url, "folders", len(folderLookup))
	}
	rpLookup, err := vc.BuildResourcePoolLookup()
	if err != nil {
		log.Warn("failed to build resource pool lookup", "url", url, "error", err)
		rpLookup = nil
	} else {
		log.Debug("built resource pool lookup", "url", url, "pools", len(rpLookup))
	}

	res.vms = vms
	res.hostLookup = hostLookup
	res.folderLookup = folderLookup
	res.rpLookup = rpLookup
	return vc, res, cleanup, nil
}

func (c *CronTask) captureHourlySnapshotForVcenter(ctx context.Context, startTime time.Time, tableName string, url string) error {
	log := c.Logger.With("vcenter", url)
	ctx = context.WithValue(ctx, ctxLoggerKey{}, log)
	started := time.Now()
	log.Debug("connecting to vcenter for hourly snapshot", "url", url)
	vc, resources, cleanup, err := c.initVcenterResources(ctx, log, url, startTime, started)
	if err != nil {
		return err
	}
	defer cleanup()
	vcVms := resources.vms
	hostLookup := resources.hostLookup
	folderLookup := resources.folderLookup
	rpLookup := resources.rpLookup

	inventoryRows, inventoryByVmID, inventoryByUuid, inventoryByName, err := loadInventoryMaps(ctx, c.Database.DB(), url)
	if err != nil {
		return err
	}

	dbConn := c.Database.DB()
	presentSnapshots, presentByUuid, presentByName, totals := c.buildPresentSnapshots(ctx, dbConn, vc, vcVms, startTime, url, inventoryByVmID, hostLookup, folderLookup, rpLookup)
	deletionsMarked := false
	candidates := make([]deletionCandidate, 0)
	var prevVmCount sql.NullInt64
	countQuery := `SELECT "VmCount" FROM vcenter_totals WHERE "Vcenter" = ? ORDER BY "SnapshotTime" DESC LIMIT 1`
	countQuery = sqlx.Rebind(sqlx.BindType(dbConn.DriverName()), countQuery)
	if err := dbConn.QueryRowContext(ctx, countQuery, url).Scan(&prevVmCount); err != nil && !errors.Is(err, sql.ErrNoRows) {
		c.Logger.Warn("failed to read previous vcenter totals", "vcenter", url, "error", err)
	}
	c.Logger.Debug("hourly snapshot rows prepared", "vcenter", url, "rows", len(presentSnapshots))

	batch := make([]InventorySnapshotRow, 0, len(presentSnapshots)+len(inventoryRows))
	for _, row := range presentSnapshots {
		batch = append(batch, row)
	}
	log.Debug("checking inventory for missing VMs")

	missingCount, deletionsMarked, candidates := prepareDeletionCandidates(ctx, log, dbConn, url, inventoryRows, presentSnapshots, presentByUuid, presentByName, startTime)
	newCount := 0
	prevTableName := ""
	reportTables := make(map[string]struct{})

	// If deletions detected, refine deletion time using vCenter events in a small window.
	if missingCount > 0 {
		freq := time.Duration(c.Settings.Values.Settings.VcenterInventorySnapshotSeconds) * time.Second
		if freq <= 0 {
			freq = time.Hour
		}
		begin := startTime.Add(-4 * freq)
		end := startTime
		events, err := vc.FindVmDeletionEvents(ctx, begin, end)
		if err != nil {
			log.Warn("failed to fetch vcenter deletion events", "vcenter", url, "error", err)
		} else {
			log.Debug("fetched vcenter deletion events", "vcenter", url, "count", len(events), "window_start_local", begin, "window_end_local", end, "window_minutes", end.Sub(begin).Minutes(), "window_start_utc", begin.UTC(), "window_end_utc", end.UTC())
			for _, cand := range candidates {
				if t, ok := events[cand.vmID]; ok {
					delTs := sql.NullInt64{Int64: t.Unix(), Valid: true}
					if err := c.Database.Queries().InventoryMarkDeleted(ctx, queries.InventoryMarkDeletedParams{
						DeletionTime:   delTs,
						VmId:           sql.NullString{String: cand.vmID, Valid: cand.vmID != ""},
						DatacenterName: cand.datacenter,
					}); err != nil {
						log.Warn("failed to update inventory deletion time from event", "vm_id", cand.vmID, "vm_uuid", cand.vmUUID, "vcenter", url, "error", err)
					}
					if err := db.MarkVmDeletedWithDetails(ctx, dbConn, url, cand.vmID, cand.vmUUID, cand.name, cand.cluster, t.Unix()); err != nil {
						log.Warn("failed to refine lifecycle cache deletion time", "vm_id", cand.vmID, "vm_uuid", cand.vmUUID, "vcenter", url, "error", err)
					}
					if snapRow, snapTable, found := findVMInHourlySnapshots(ctx, dbConn, url, cand.vmID); found {
						vmUUID := cand.vmUUID
						if vmUUID == "" && snapRow.VmUuid.Valid {
							vmUUID = snapRow.VmUuid.String
						}
						name := cand.name
						if name == "" {
							name = snapRow.Name
						}
						if rowsAffected, err := updateDeletionTimeInSnapshot(ctx, dbConn, snapTable, url, cand.vmID, vmUUID, name, delTs.Int64); err != nil {
							log.Warn("failed to update hourly snapshot deletion time from event", "table", snapTable, "vm_id", cand.vmID, "vm_uuid", vmUUID, "vcenter", url, "error", err)
						} else if rowsAffected > 0 {
							reportTables[snapTable] = struct{}{}
							deletionsMarked = true
							log.Debug("updated hourly snapshot deletion time from event", "table", snapTable, "vm_id", cand.vmID, "vm_uuid", vmUUID, "vcenter", url, "event_time", t)
						}
					}
					log.Info("refined deletion time from vcenter event", "vm_id", cand.vmID, "vm_uuid", cand.vmUUID, "name", cand.name, "vcenter", url, "event_time", t)
				}
			}
		}
	}
	// If VM count dropped vs prior totals but we didn't mark missing, still look for events (best-effort logging).
	if missingCount == 0 && prevVmCount.Valid && prevVmCount.Int64 > int64(totals.VmCount) {
		freq := time.Duration(c.Settings.Values.Settings.VcenterInventorySnapshotSeconds) * time.Second
		if freq <= 0 {
			freq = time.Hour
		}
		begin := startTime.Add(-2 * freq)
		end := startTime
		events, err := vc.FindVmDeletionEvents(ctx, begin, end)
		if err != nil {
			log.Warn("count-drop: failed to fetch vcenter deletion events", "vcenter", url, "error", err, "prev_vm_count", prevVmCount.Int64, "current_vm_count", totals.VmCount)
		} else {
			log.Info("count-drop: deletion events fetched", "vcenter", url, "events", len(events), "prev_vm_count", prevVmCount.Int64, "current_vm_count", totals.VmCount, "window_start", begin, "window_end", end)
		}
	}

	log.Debug("inserting hourly snapshot batch", "vcenter", url, "rows", len(batch))

	if err := insertHourlyCache(ctx, dbConn, batch); err != nil {
		log.Warn("failed to insert hourly cache rows", "vcenter", url, "error", err)
	}

	if err := insertHourlyBatch(ctx, dbConn, tableName, batch); err != nil {
		metrics.RecordVcenterSnapshot(url, time.Since(started), totals.VmCount, err)
		if upErr := db.UpsertSnapshotRun(ctx, c.Database.DB(), url, startTime, false, err.Error()); upErr != nil {
			log.Warn("failed to record snapshot run", "url", url, "error", upErr)
		}
		return err
	}
	// Record per-vCenter totals snapshot.
	if err := db.InsertVcenterTotals(ctx, dbConn, url, startTime, totals.VmCount, totals.VcpuTotal, totals.RamTotal); err != nil {
		slog.Warn("failed to insert vcenter totals", "vcenter", url, "snapshot_time", startTime.Unix(), "error", err)
	}

	// Discover previous snapshots once per run (serial) to avoid concurrent probes across vCenters.
	var prevTableTouched bool
	prevTableName, newCount, missingCount, prevTableTouched = c.compareWithPreviousSnapshot(ctx, dbConn, url, startTime, presentSnapshots, presentByUuid, presentByName, inventoryByVmID, inventoryByUuid, inventoryByName, missingCount)
	if prevTableTouched && prevTableName != "" {
		reportTables[prevTableName] = struct{}{}
		deletionsMarked = true
	}

	// If VM count dropped versus totals and we still haven't marked missing, try another comparison + wider event window.
	if missingCount == 0 && prevVmCount.Valid && prevVmCount.Int64 > int64(totals.VmCount) {
		// Fallback: locate a previous table only if we didn't already find one.
		if prevTableName == "" {
			if prevTable, err := latestHourlySnapshotBefore(ctx, dbConn, startTime, loggerFromCtx(ctx, c.Logger)); err == nil && prevTable != "" {
				moreMissing, tableUpdated := c.markMissingFromPrevious(ctx, dbConn, prevTable, url, startTime, presentSnapshots, presentByUuid, presentByName, inventoryByVmID, inventoryByUuid, inventoryByName)
				if moreMissing > 0 {
					missingCount += moreMissing
				}
				if tableUpdated {
					reportTables[prevTable] = struct{}{}
					deletionsMarked = true
				}
				// Reuse this table name for later snapshot lookups when correlating deletion events.
				prevTableName = prevTable
			}
		}
		freq := time.Duration(c.Settings.Values.Settings.VcenterInventorySnapshotSeconds) * time.Second
		if freq <= 0 {
			freq = time.Hour
		}
		begin := startTime.Add(-4 * freq)
		end := startTime
		events, err := vc.FindVmDeletionEvents(ctx, begin, end)
		if err != nil {
			c.Logger.Warn("count-drop: failed to fetch vcenter deletion events", "vcenter", url, "error", err, "prev_vm_count", prevVmCount.Int64, "current_vm_count", totals.VmCount)
		} else {
			c.Logger.Info("count-drop: deletion events fetched", "vcenter", url, "events", len(events), "prev_vm_count", prevVmCount.Int64, "current_vm_count", totals.VmCount, "window_start_local", begin, "window_end_local", end, "window_start_utc", begin.UTC(), "window_end_utc", end.UTC(), "window_minutes", end.Sub(begin).Minutes())
			for vmID, t := range events {
				// Skip if VM is still present.
				if _, ok := presentSnapshots[vmID]; ok {
					continue
				}
				inv, ok := inventoryByVmID[vmID]
				var snapRow InventorySnapshotRow
				var snapTable string
				if !ok {
					var found bool
					snapRow, snapTable, found = findVMInHourlySnapshots(ctx, dbConn, url, vmID, prevTableName)
					if !found {
						c.Logger.Debug("count-drop: deletion event has no snapshot match", "vm_id", vmID, "vcenter", url, "event_time", t)
						continue
					}
					inv = queries.Inventory{
						VmId:       snapRow.VmId,
						VmUuid:     snapRow.VmUuid,
						Name:       snapRow.Name,
						Datacenter: snapRow.Datacenter,
					}
					c.Logger.Info("count-drop: correlated deletion via snapshot lookup", "vm_id", vmID, "vm_uuid", inv.VmUuid.String, "name", inv.Name, "vcenter", url, "event_time", t, "snapshot_table", snapTable)
				}
				// Prefer UUID from snapshot if inventory entry lacks it.
				if !inv.VmUuid.Valid && snapRow.VmUuid.Valid {
					inv.VmUuid = snapRow.VmUuid
				}
				delTs := sql.NullInt64{Int64: t.Unix(), Valid: true}
				if err := c.Database.Queries().InventoryMarkDeleted(ctx, queries.InventoryMarkDeletedParams{
					DeletionTime:   delTs,
					VmId:           inv.VmId,
					DatacenterName: inv.Datacenter,
				}); err != nil {
					c.Logger.Warn("count-drop: failed to update inventory deletion time from event", "vm_id", vmID, "vcenter", url, "error", err)
				} else {
					c.Logger.Info("count-drop: correlated deletion event to inventory", "vm_id", vmID, "vm_uuid", inv.VmUuid.String, "name", inv.Name, "vcenter", url, "event_time", t, "prev_vm_count", prevVmCount.Int64, "current_vm_count", totals.VmCount)
				}
				clusterName := ""
				if inv.Cluster.Valid {
					clusterName = inv.Cluster.String
				}
				if err := db.MarkVmDeletedWithDetails(ctx, dbConn, url, vmID, inv.VmUuid.String, inv.Name, clusterName, t.Unix()); err != nil {
					c.Logger.Warn("count-drop: failed to refine lifecycle cache deletion time", "vm_id", vmID, "vm_uuid", inv.VmUuid, "vcenter", url, "error", err)
				}
				tableToUpdate := snapTable
				if tableToUpdate == "" {
					tableToUpdate = prevTableName
				}
				if tableToUpdate != "" {
					if rowsAffected, err := updateDeletionTimeInSnapshot(ctx, dbConn, tableToUpdate, url, vmID, inv.VmUuid.String, inv.Name, delTs.Int64); err != nil {
						c.Logger.Warn("count-drop: failed to update hourly snapshot deletion time from event", "table", tableToUpdate, "vm_id", vmID, "vcenter", url, "error", err)
					} else if rowsAffected > 0 {
						reportTables[tableToUpdate] = struct{}{}
						deletionsMarked = true
						c.Logger.Debug("count-drop: updated hourly snapshot deletion time from event", "table", tableToUpdate, "vm_id", vmID, "vm_uuid", inv.VmUuid.String, "vcenter", url, "event_time", t)
					}
				}
				missingCount++
				deletionsMarked = true
			}
		}
	}

	// Backfill lifecycle deletions for VMs missing from inventory and without DeletedAt.
	if backfillTables, err := backfillLifecycleDeletionsToday(ctx, log, dbConn, url, startTime, presentSnapshots); err != nil {
		log.Warn("failed to backfill lifecycle deletions for today", "vcenter", url, "error", err)
	} else if len(backfillTables) > 0 {
		for _, table := range backfillTables {
			reportTables[table] = struct{}{}
		}
		deletionsMarked = true
	}

	log.Info("Hourly snapshot summary",
		"vcenter", url,
		"vm_count", totals.VmCount,
		"vcpu_total", totals.VcpuTotal,
		"ram_total_gb", totals.RamTotal,
		"disk_total_gb", totals.DiskTotal,
		"missing_marked", missingCount,
		"created_since_prev", newCount,
		"deleted_since_prev", missingCount,
	)
	metrics.RecordVcenterSnapshot(url, time.Since(started), totals.VmCount, nil)
	if upErr := db.UpsertSnapshotRun(ctx, c.Database.DB(), url, startTime, true, ""); upErr != nil {
		log.Warn("failed to record snapshot run", "url", url, "error", upErr)
	}
	if deletionsMarked {
		if len(reportTables) == 0 {
			reportTables[tableName] = struct{}{}
		}
		for reportTable := range reportTables {
			if err := c.generateReport(ctx, reportTable); err != nil {
				log.Warn("failed to regenerate hourly report after deletions", "error", err, "table", reportTable)
			} else {
				log.Debug("Regenerated hourly report after deletions", "table", reportTable)
			}
		}
	}
	return nil
}

// compareWithPreviousSnapshot cross-checks current vs. previous hourly snapshots:
// marks deletions, detects new VMs when no gap exists, and returns the previous table name along with new/missing counts.
func (c *CronTask) compareWithPreviousSnapshot(
	ctx context.Context,
	dbConn *sqlx.DB,
	url string,
	startTime time.Time,
	presentSnapshots map[string]InventorySnapshotRow,
	presentByUuid map[string]struct{},
	presentByName map[string]struct{},
	inventoryByVmID map[string]queries.Inventory,
	inventoryByUuid map[string]queries.Inventory,
	inventoryByName map[string]queries.Inventory,
	missingCount int,
) (string, int, int, bool) {
	prevTableName, prevTableErr := latestHourlySnapshotBefore(ctx, dbConn, startTime, loggerFromCtx(ctx, c.Logger))
	if prevTableErr != nil {
		c.Logger.Warn("failed to locate previous hourly snapshot for deletion comparison", "error", prevTableErr, "url", url)
	}

	prevSnapshotTime, _ := parseSnapshotTime(prevTableName)

	newCount := 0
	prevTableTouched := false
	if prevTableName != "" {
		moreMissing, tableUpdated := c.markMissingFromPrevious(ctx, dbConn, prevTableName, url, startTime, presentSnapshots, presentByUuid, presentByName, inventoryByVmID, inventoryByUuid, inventoryByName)
		missingCount += moreMissing
		if tableUpdated {
			prevTableTouched = true
		}
		expectedSeconds := int64(c.Settings.Values.Settings.VcenterInventorySnapshotSeconds) / 2
		// Skip only if snapshots are closer together than half the configured cadence
		if SnapshotTooSoon(prevSnapshotTime, startTime.Unix(), expectedSeconds) {
			c.Logger.Info("skipping new-VM detection because snapshots are too close together", "prev_table", prevTableName, "prev_snapshot_unix", prevSnapshotTime, "current_snapshot_unix", startTime.Unix(), "expected_interval_seconds", expectedSeconds)
		} else {
			newCount = countNewFromPrevious(ctx, dbConn, prevTableName, url, presentSnapshots)
			if newCount > 0 {
				newRows := listNewFromPrevious(ctx, dbConn, prevTableName, url, presentSnapshots)
				names := make([]string, 0, len(newRows))
				for _, r := range newRows {
					if r.Name != "" {
						names = append(names, r.Name)
					} else if r.VmId.Valid {
						names = append(names, r.VmId.String)
					}
				}
				c.Logger.Info("new VMs since previous snapshot", "prev_table", prevTableName, "count", newCount, "names", names)
			}
		}
		c.Logger.Debug("compared with previous snapshot", "prev_table", prevTableName, "new_since_prev", newCount, "missing_since_prev", missingCount)
	} else {
		newCount = len(presentSnapshots)
	}

	return prevTableName, newCount, missingCount, prevTableTouched
}