package server

import (
	"context"
	"log"
	"sort"
	"strings"
	"time"

	"scm.bstein.dev/bstein/soteria/internal/api"
	"scm.bstein.dev/bstein/soteria/internal/k8s"
)

func (s *Server) buildInventory(ctx context.Context) (api.InventoryResponse, error) {
	pvcs, err := s.client.ListBoundPVCs(ctx)
	if err != nil {
		return api.InventoryResponse{}, err
	}

	resticJobsByPVC, resticLookupErrors := s.prefetchResticBackupJobs(ctx, pvcs)

	groups := make(map[string][]api.PVCInventory)
	for _, summary := range pvcs {
		entry := api.PVCInventory{
			Namespace:    summary.Namespace,
			PVC:          summary.Name,
			Volume:       summary.VolumeName,
			Phase:        summary.Phase,
			StorageClass: summary.StorageClass,
			Capacity:     summary.Capacity,
			AccessModes:  summary.AccessModes,
			Driver:       s.cfg.BackupDriver,
		}
		s.enrichPVCInventory(ctx, &entry, resticJobsByPVC, resticLookupErrors)
		groups[summary.Namespace] = append(groups[summary.Namespace], entry)
	}

	namespaceNames := make([]string, 0, len(groups))
	for namespace := range groups {
		namespaceNames = append(namespaceNames, namespace)
	}
	sort.Strings(namespaceNames)

	response := api.InventoryResponse{
		GeneratedAt: time.Now().UTC().Format(time.RFC3339),
		Namespaces:  make([]api.NamespaceInventory, 0, len(namespaceNames)),
	}
	for _, namespace := range namespaceNames {
		response.Namespaces = append(response.Namespaces, api.NamespaceInventory{
			Name: namespace,
			PVCs: groups[namespace],
		})
	}
	return response, nil
}

func (s *Server) prefetchResticBackupJobs(ctx context.Context, pvcs []k8s.PVCSummary) (map[string][]k8s.BackupJobSummary, map[string]error) {
	if s.cfg.BackupDriver != "restic" {
		return nil, nil
	}

	namespaces := map[string]struct{}{}
	for _, pvc := range pvcs {
		namespaces[pvc.Namespace] = struct{}{}
	}

	namespaceNames := make([]string, 0, len(namespaces))
	for namespace := range namespaces {
		namespaceNames = append(namespaceNames, namespace)
	}
	sort.Strings(namespaceNames)

	jobsByPVC := map[string][]k8s.BackupJobSummary{}
	lookupErrors := map[string]error{}
	for _, namespace := range namespaceNames {
		jobs, err := s.client.ListBackupJobs(ctx, namespace)
		if err != nil {
			lookupErrors[namespace] = err
			continue
		}
		for _, job := range jobs {
			key := job.Namespace + "/" + job.PVC
			jobsByPVC[key] = append(jobsByPVC[key], job)
		}
	}

	for key := range jobsByPVC {
		sortBackupJobsNewestFirst(jobsByPVC[key])
	}

	return jobsByPVC, lookupErrors
}

func (s *Server) enrichPVCInventory(
	ctx context.Context,
	entry *api.PVCInventory,
	resticJobsByPVC map[string][]k8s.BackupJobSummary,
	resticLookupErrors map[string]error,
) {
	switch s.cfg.BackupDriver {
	case "longhorn":
		backups, err := s.longhorn.ListBackups(ctx, entry.Volume)
		if err != nil {
			entry.Healthy = false
			entry.HealthReason = "lookup_failed"
			entry.Error = err.Error()
			return
		}
		entry.BackupCount = len(backups)
		totalBackupSize := int64(0)
		completedBackups := 0
		for _, backup := range backups {
			totalBackupSize += parseSizeBytes(backup.Size)
			if strings.EqualFold(backup.State, "Completed") {
				completedBackups++
			}
		}
		entry.CompletedBackups = completedBackups
		entry.TotalBackupSizeBytes = float64(totalBackupSize)
		latest, latestTime, ok := latestCompletedBackup(backups)
		if !ok {
			entry.Healthy = false
			if len(backups) == 0 {
				entry.HealthReason = "missing"
			} else {
				entry.HealthReason = "no_completed"
			}
			return
		}
		entry.LastBackupAt = latest.Created
		entry.LastBackupSizeBytes = float64(parseSizeBytes(latest.Size))
		if latestTime.IsZero() {
			entry.Healthy = false
			entry.HealthReason = "unknown_timestamp"
			return
		}
		entry.LastBackupAgeHours = roundHours(time.Since(latestTime).Hours())
		entry.Healthy = time.Since(latestTime) <= s.cfg.BackupMaxAge
		if entry.Healthy {
			entry.HealthReason = "fresh"
		} else {
			entry.HealthReason = "stale"
		}
	case "restic":
		if err, hasErr := resticLookupErrors[entry.Namespace]; hasErr {
			entry.Healthy = false
			entry.HealthReason = "lookup_failed"
			entry.Error = err.Error()
			return
		}

		key := entry.Namespace + "/" + entry.PVC
		jobs := resticJobsByPVC[key]
		if jobs == nil {
			jobs = []k8s.BackupJobSummary{}
		}
		entry.BackupCount = len(jobs)
		if len(jobs) > 0 {
			entry.LastJobName = jobs[0].Name
			entry.LastJobState = jobs[0].State
			entry.LastJobProgressPct = backupJobProgressPct(jobs[0].State)
			if !jobs[0].CreatedAt.IsZero() {
				entry.LastJobStartedAt = jobs[0].CreatedAt.UTC().Format(time.RFC3339)
			}
		}

		completed := make([]k8s.BackupJobSummary, 0, len(jobs))
		active := 0
		for _, job := range jobs {
			if backupJobInProgress(job.State) {
				active++
			}
			if strings.EqualFold(job.State, "Completed") {
				completed = append(completed, job)
			}
		}
		entry.ActiveBackups = active
		entry.CompletedBackups = len(completed)
		sizeSamples := completed
		if len(sizeSamples) > 0 {
			retained := sizeSamples[0].KeepLast
			if retained > 0 && retained < len(sizeSamples) {
				sizeSamples = sizeSamples[:retained]
			}
		}
		totalStoredBytes := 0.0
		storedSamples := 0
		for index, job := range sizeSamples {
			if index >= maxUsageSampleJobs {
				break
			}
			storedBytes, ok := s.lookupResticStoredBytesForJob(ctx, entry.Namespace, job.Name)
			if !ok {
				continue
			}
			if index == 0 {
				entry.LastBackupSizeBytes = storedBytes
			}
			totalStoredBytes += storedBytes
			storedSamples++
		}
		if storedSamples > 0 {
			entry.TotalBackupSizeBytes = totalStoredBytes
		}
		if len(completed) == 0 {
			entry.Healthy = false
			switch {
			case active > 0:
				entry.HealthReason = "in_progress"
			case len(jobs) == 0:
				entry.HealthReason = "missing"
			default:
				entry.HealthReason = "no_completed"
			}
			return
		}

		latestTime := backupJobTimestamp(completed[0])
		if latestTime.IsZero() {
			entry.Healthy = false
			entry.HealthReason = "unknown_timestamp"
			return
		}
		entry.LastBackupAt = latestTime.UTC().Format(time.RFC3339)
		entry.LastBackupAgeHours = roundHours(time.Since(latestTime).Hours())
		entry.Healthy = time.Since(latestTime) <= s.cfg.BackupMaxAge
		if entry.Healthy {
			entry.HealthReason = "fresh"
		} else {
			entry.HealthReason = "stale"
		}
	default:
		entry.Healthy = false
		entry.HealthReason = "unsupported_driver"
	}
}

func sortBackupJobsNewestFirst(items []k8s.BackupJobSummary) {
	sort.Slice(items, func(i, j int) bool {
		left := items[i].CompletionTime
		if left.IsZero() {
			left = items[i].CreatedAt
		}
		right := items[j].CompletionTime
		if right.IsZero() {
			right = items[j].CreatedAt
		}
		if left.Equal(right) {
			return items[i].Name > items[j].Name
		}
		return left.After(right)
	})
}

func (s *Server) refreshTelemetry(ctx context.Context) {
	refreshCtx, cancel := context.WithTimeout(ctx, 2*time.Minute)
	defer cancel()

	inventory, err := s.buildInventory(refreshCtx)
	if err != nil {
		log.Printf("inventory refresh failed: %v", err)
		s.metrics.RecordInventoryFailure()
		return
	}
	s.metrics.RecordInventory(inventory)
}