package jetstream

import (
	"context"
	"encoding/json"
	"fmt"
	"log/slog"
	"strings"
	"time"

	"atcr.io/pkg/appview/db"
	"atcr.io/pkg/atproto"
)

// batchManifests decodes all manifest records for a repo and writes them as
// a small set of multi-row INSERTs: one per table (manifests, layers,
// manifest_references, repository_annotations). This replaces the previous
// per-record chunked-transaction loop, which exceeded Bunny Database's
// remote transaction timeout once chunks grew large.
//
// Returns the number of manifest records that were successfully decoded and
// included in the batch. Decode/validation failures are logged and skipped.
func (b *BackfillWorker) batchManifests(ctx context.Context, did string, records []atproto.Record) (int, error) {
	if len(records) == 0 {
		return 0, nil
	}

	type decoded struct {
		manifestRecord atproto.ManifestRecord
		manifest       db.Manifest
	}

	decodedRecords := make([]decoded, 0, len(records))
	for i := range records {
		r := &records[i]
		var mr atproto.ManifestRecord
		if err := json.Unmarshal(r.Value, &mr); err != nil {
			slog.Warn("Backfill skipping invalid manifest record", "uri", r.URI, "error", err)
			continue
		}
		if mr.Digest == "" || mr.Repository == "" {
			slog.Warn("Backfill skipping manifest with missing fields", "uri", r.URI)
			continue
		}

		// Resolve holdDID the same way the single-record path does.
		holdDID := mr.HoldDID
		if holdDID == "" && mr.HoldEndpoint != "" {
			if resolved, err := atproto.ResolveHoldDID(ctx, mr.HoldEndpoint); err == nil {
				holdDID = resolved
			}
		}

		isList := len(mr.Manifests) > 0
		artifactType := "container-image"
		if !isList && mr.Config != nil {
			artifactType = db.GetArtifactType(mr.Config.MediaType)
		}

		m := db.Manifest{
			DID:           did,
			Repository:    mr.Repository,
			Digest:        mr.Digest,
			MediaType:     mr.MediaType,
			SchemaVersion: mr.SchemaVersion,
			HoldEndpoint:  holdDID,
			ArtifactType:  artifactType,
			CreatedAt:     mr.CreatedAt,
		}
		if !isList && mr.Config != nil {
			m.ConfigDigest = mr.Config.Digest
			m.ConfigSize = mr.Config.Size
		}
		if mr.Subject != nil {
			m.SubjectDigest = mr.Subject.Digest
		}
		decodedRecords = append(decodedRecords, decoded{mr, m})
	}

	if len(decodedRecords) == 0 {
		return 0, nil
	}

	// Phase 1: upsert all manifests in one batch, fetch ids.
	manifests := make([]db.Manifest, len(decodedRecords))
	for i, d := range decodedRecords {
		manifests[i] = d.manifest
	}
	ids, err := db.BatchInsertManifests(b.db, manifests)
	if err != nil {
		return 0, fmt.Errorf("batch insert manifests: %w", err)
	}

	// Phase 2: derive layers, references, and annotations using the returned ids.
	var (
		layerRows []db.Layer
		refRows   []db.ManifestReference
	)

	// For annotations, we keep only the newest manifest per (did, repo) with a
	// non-empty annotation set. Matches reconcileAnnotations semantics at
	// backfill.go:573.
	type newest struct {
		createdAt   time.Time
		annotations map[string]string
	}
	newestByRepo := make(map[string]newest)

	for _, d := range decodedRecords {
		mid, ok := ids[db.ManifestKey(did, d.manifest.Repository, d.manifest.Digest)]
		if !ok {
			// BatchInsertManifests did not return an id for this row — either the
			// row was constraint-rejected or the SELECT missed it. Skip its
			// dependent rows rather than inserting with id 0.
			slog.Warn("Backfill manifest missing id after batch insert",
				"did", did, "repository", d.manifest.Repository, "digest", d.manifest.Digest)
			continue
		}

		if len(d.manifestRecord.Manifests) > 0 {
			for i, ref := range d.manifestRecord.Manifests {
				var pa, po, pv, pov string
				if ref.Platform != nil {
					pa = ref.Platform.Architecture
					po = ref.Platform.OS
					pv = ref.Platform.Variant
					pov = ref.Platform.OSVersion
				}
				isAttestation := false
				if refType, ok := ref.Annotations["vnd.docker.reference.type"]; ok {
					isAttestation = refType == "attestation-manifest"
				}
				refRows = append(refRows, db.ManifestReference{
					ManifestID:           mid,
					Digest:               ref.Digest,
					MediaType:            ref.MediaType,
					Size:                 ref.Size,
					PlatformArchitecture: pa,
					PlatformOS:           po,
					PlatformVariant:      pv,
					PlatformOSVersion:    pov,
					IsAttestation:        isAttestation,
					ReferenceIndex:       i,
				})
			}
		} else {
			for i, layer := range d.manifestRecord.Layers {
				layerRows = append(layerRows, db.Layer{
					ManifestID:  mid,
					Digest:      layer.Digest,
					MediaType:   layer.MediaType,
					Size:        layer.Size,
					LayerIndex:  i,
					Annotations: layer.Annotations,
				})
			}
		}

		if hasNonEmpty(d.manifestRecord.Annotations) {
			key := d.manifest.Repository
			prev, ok := newestByRepo[key]
			if !ok || d.manifestRecord.CreatedAt.After(prev.createdAt) {
				newestByRepo[key] = newest{d.manifestRecord.CreatedAt, d.manifestRecord.Annotations}
			}
		}
	}

	if err := db.BatchInsertLayers(b.db, layerRows); err != nil {
		return 0, err
	}
	if err := db.BatchInsertManifestReferences(b.db, refRows); err != nil {
		return 0, err
	}

	// Flatten annotations into AnnotationRows.
	var annotationRows []db.AnnotationRow
	for repo, n := range newestByRepo {
		for k, v := range n.annotations {
			if v == "" {
				continue
			}
			annotationRows = append(annotationRows, db.AnnotationRow{
				DID:        did,
				Repository: repo,
				Key:        k,
				Value:      v,
			})
		}
	}
	if err := db.BatchUpsertRepositoryAnnotations(b.db, annotationRows); err != nil {
		return 0, err
	}

	slog.Info("Backfill batch manifests",
		"did", did,
		"manifests", len(manifests),
		"layers", len(layerRows),
		"references", len(refRows),
		"annotations", len(annotationRows))

	return len(decodedRecords), nil
}

func hasNonEmpty(m map[string]string) bool {
	for _, v := range m {
		if v != "" {
			return true
		}
	}
	return false
}

// batchTags decodes tag records and writes them in one multi-row upsert.
func (b *BackfillWorker) batchTags(did string, records []atproto.Record) (int, error) {
	tags := make([]db.Tag, 0, len(records))
	for i := range records {
		r := &records[i]
		var tr atproto.TagRecord
		if err := json.Unmarshal(r.Value, &tr); err != nil {
			slog.Warn("Backfill skipping invalid tag record", "uri", r.URI, "error", err)
			continue
		}
		digest, err := tr.GetManifestDigest()
		if err != nil {
			slog.Warn("Backfill skipping tag record without digest", "uri", r.URI, "error", err)
			continue
		}
		if tr.Repository == "" || tr.Tag == "" {
			continue
		}
		tags = append(tags, db.Tag{
			DID:        did,
			Repository: tr.Repository,
			Tag:        tr.Tag,
			Digest:     digest,
			CreatedAt:  tr.UpdatedAt,
		})
	}
	if err := db.BatchUpsertTags(b.db, tags); err != nil {
		return 0, err
	}
	slog.Info("Backfill batch tags", "did", did, "rows", len(tags))
	return len(tags), nil
}

// batchStars decodes star records and writes them in one multi-row upsert.
// Ensures star subject owners exist as users first (FK requirement).
func (b *BackfillWorker) batchStars(ctx context.Context, did string, records []atproto.Record) (int, error) {
	stars := make([]db.StarInput, 0, len(records))
	ownerDIDs := make(map[string]struct{})

	for i := range records {
		r := &records[i]
		var sr atproto.StarRecord
		if err := json.Unmarshal(r.Value, &sr); err != nil {
			slog.Warn("Backfill skipping invalid star record", "uri", r.URI, "error", err)
			continue
		}
		owner, repo, err := sr.GetSubjectDIDAndRepository()
		if err != nil {
			slog.Warn("Backfill skipping star with bad subject", "uri", r.URI, "error", err)
			continue
		}
		ownerDIDs[owner] = struct{}{}
		stars = append(stars, db.StarInput{
			StarrerDID: did,
			OwnerDID:   owner,
			Repository: repo,
			CreatedAt:  sr.CreatedAt,
		})
	}

	// Ensure every star subject has a users row (FK to users.did on stars).
	// These calls are idempotent and cached, so repeated owners cost nothing.
	for owner := range ownerDIDs {
		if err := b.processor.EnsureUserExists(ctx, owner); err != nil {
			slog.Warn("Backfill failed to ensure star subject user", "owner_did", owner, "error", err)
		}
	}

	if err := db.BatchUpsertStars(b.db, stars); err != nil {
		return 0, err
	}
	slog.Info("Backfill batch stars", "did", did, "rows", len(stars))
	return len(stars), nil
}

// batchRepoPages decodes repo page records and writes them in one upsert.
func (b *BackfillWorker) batchRepoPages(did string, records []atproto.Record) (int, error) {
	pages := make([]db.RepoPage, 0, len(records))
	for i := range records {
		r := &records[i]
		var pr atproto.RepoPageRecord
		if err := json.Unmarshal(r.Value, &pr); err != nil {
			slog.Warn("Backfill skipping invalid repo page", "uri", r.URI, "error", err)
			continue
		}
		if pr.Repository == "" {
			continue
		}
		avatarCID := ""
		if pr.Avatar != nil && pr.Avatar.Ref.Link != "" {
			avatarCID = pr.Avatar.Ref.Link
		}
		pages = append(pages, db.RepoPage{
			DID:         did,
			Repository:  pr.Repository,
			Description: pr.Description,
			AvatarCID:   avatarCID,
			UserEdited:  pr.UserEdited,
			CreatedAt:   pr.CreatedAt,
			UpdatedAt:   pr.UpdatedAt,
		})
	}
	if err := db.BatchUpsertRepoPages(b.db, pages); err != nil {
		return 0, err
	}
	slog.Info("Backfill batch repo pages", "did", did, "rows", len(pages))
	return len(pages), nil
}

// batchDailyStats decodes daily stats records and writes them in one upsert.
// Ensures every distinct owner exists as a user first (FK requirement).
func (b *BackfillWorker) batchDailyStats(ctx context.Context, holdDID string, records []atproto.Record) (int, error) {
	stats := make([]db.DailyStats, 0, len(records))
	ownerDIDs := make(map[string]struct{})

	for i := range records {
		r := &records[i]
		var dr atproto.DailyStatsRecord
		if err := json.Unmarshal(r.Value, &dr); err != nil {
			slog.Warn("Backfill skipping invalid daily stats", "uri", r.URI, "error", err)
			continue
		}
		if dr.OwnerDID == "" || dr.Repository == "" || dr.Date == "" {
			continue
		}
		ownerDIDs[dr.OwnerDID] = struct{}{}
		stats = append(stats, db.DailyStats{
			DID:        dr.OwnerDID,
			Repository: dr.Repository,
			Date:       dr.Date,
			PullCount:  int(dr.PullCount),
			PushCount:  int(dr.PushCount),
		})
	}

	for owner := range ownerDIDs {
		if err := b.processor.EnsureUserExists(ctx, owner); err != nil {
			slog.Warn("Backfill failed to ensure daily stats owner user", "owner_did", owner, "error", err)
		}
	}

	if err := db.BatchUpsertDailyStats(b.db, stats); err != nil {
		return 0, err
	}
	slog.Info("Backfill batch daily stats", "hold_did", holdDID, "rows", len(stats))
	return len(stats), nil
}

// batchStats updates the in-memory stats cache from a hold's stats records,
// then flushes the aggregated view of every touched (owner, repo) to the
// repository_stats table in a single multi-row upsert. Aggregation is across
// all holds known to the cache, preserving the single-record semantics.
func (b *BackfillWorker) batchStats(ctx context.Context, holdDID string, records []atproto.Record) (int, error) {
	type key struct{ owner, repo string }
	touched := make(map[key]struct{})
	ownerDIDs := make(map[string]struct{})

	for i := range records {
		r := &records[i]
		var sr atproto.StatsRecord
		if err := json.Unmarshal(r.Value, &sr); err != nil {
			slog.Warn("Backfill skipping invalid stats record", "uri", r.URI, "error", err)
			continue
		}
		if sr.OwnerDID == "" || sr.Repository == "" {
			continue
		}

		var lastPull, lastPush *time.Time
		if sr.LastPull != "" {
			if t, err := time.Parse(time.RFC3339, sr.LastPull); err == nil {
				lastPull = &t
			}
		}
		if sr.LastPush != "" {
			if t, err := time.Parse(time.RFC3339, sr.LastPush); err == nil {
				lastPush = &t
			}
		}

		b.processor.statsCache.Update(holdDID, sr.OwnerDID, sr.Repository,
			sr.PullCount, sr.PushCount, lastPull, lastPush)
		touched[key{sr.OwnerDID, sr.Repository}] = struct{}{}
		ownerDIDs[sr.OwnerDID] = struct{}{}
	}

	for owner := range ownerDIDs {
		if err := b.processor.EnsureUserExists(ctx, owner); err != nil {
			slog.Warn("Backfill failed to ensure stats owner user", "owner_did", owner, "error", err)
		}
	}

	// Build aggregated rows from the cache.
	rows := make([]db.RepositoryStats, 0, len(touched))
	for k := range touched {
		totalPull, totalPush, latestPull, latestPush := b.processor.statsCache.GetAggregated(k.owner, k.repo)
		rows = append(rows, db.RepositoryStats{
			DID:        k.owner,
			Repository: k.repo,
			PullCount:  int(totalPull),
			PushCount:  int(totalPush),
			LastPull:   latestPull,
			LastPush:   latestPush,
		})
	}
	if err := db.BatchUpsertRepositoryStats(b.db, rows); err != nil {
		return 0, err
	}
	slog.Info("Backfill batch stats", "hold_did", holdDID, "rows", len(rows))
	return len(rows), nil
}

// batchCaptains decodes captain records and writes them in one upsert.
// Records whose publishing DID does not advertise an atcr_hold service in its
// DID document are skipped — only real holds may enter the discovery cache.
func (b *BackfillWorker) batchCaptains(ctx context.Context, holdDID string, records []atproto.Record) (int, error) {
	captains := make([]db.HoldCaptainRecord, 0, len(records))
	now := time.Now()
	verified := make(map[string]bool)
	for i := range records {
		r := &records[i]
		var cr atproto.CaptainRecord
		if err := json.Unmarshal(r.Value, &cr); err != nil {
			slog.Warn("Backfill skipping invalid captain record", "uri", r.URI, "error", err)
			continue
		}
		if cr.Owner == "" || !strings.HasPrefix(cr.Owner, "did:") {
			slog.Warn("Backfill skipping captain with invalid owner", "uri", r.URI)
			continue
		}
		// Captain rkey is the hold DID (collections are stored on each hold's PDS,
		// so record.URI already encodes the hold DID in the authority segment).
		recordHoldDID := extractDIDFromURI(r.URI)
		if recordHoldDID == "" {
			recordHoldDID = holdDID
		}
		isHold, ok := verified[recordHoldDID]
		if !ok {
			var err error
			isHold, err = atproto.HasHoldService(ctx, recordHoldDID)
			if err != nil {
				slog.Warn("Backfill skipping captain, hold DID unresolvable", "uri", r.URI, "error", err)
				isHold = false
			} else if !isHold {
				slog.Info("Backfill skipping captain from non-hold DID", "hold_did", recordHoldDID)
			}
			verified[recordHoldDID] = isHold
		}
		if !isHold {
			continue
		}
		captains = append(captains, db.HoldCaptainRecord{
			HoldDID:      recordHoldDID,
			OwnerDID:     cr.Owner,
			Public:       cr.Public,
			AllowAllCrew: cr.AllowAllCrew,
			DeployedAt:   cr.DeployedAt,
			Region:       cr.Region,
			Successor:    cr.Successor,
			UpdatedAt:    now,
		})
	}
	if err := db.BatchUpsertCaptainRecords(b.db, captains); err != nil {
		return 0, err
	}
	slog.Info("Backfill batch captains", "rows", len(captains))
	return len(captains), nil
}

// batchCrew decodes crew records and writes them in one upsert.
func (b *BackfillWorker) batchCrew(holdDID string, records []atproto.Record) (int, error) {
	members := make([]db.CrewMember, 0, len(records))
	for i := range records {
		r := &records[i]
		var cr atproto.CrewRecord
		if err := json.Unmarshal(r.Value, &cr); err != nil {
			slog.Warn("Backfill skipping invalid crew record", "uri", r.URI, "error", err)
			continue
		}
		if cr.Member == "" || !strings.HasPrefix(cr.Member, "did:") {
			slog.Warn("Backfill skipping crew with invalid member", "uri", r.URI)
			continue
		}
		recordHoldDID := extractDIDFromURI(r.URI)
		if recordHoldDID == "" {
			recordHoldDID = holdDID
		}
		permsJSON := ""
		if len(cr.Permissions) > 0 {
			if b, err := json.Marshal(cr.Permissions); err == nil {
				permsJSON = string(b)
			}
		}
		rkey := extractRkeyFromURI(r.URI)
		members = append(members, db.CrewMember{
			HoldDID:     recordHoldDID,
			MemberDID:   cr.Member,
			Rkey:        rkey,
			Role:        cr.Role,
			Permissions: permsJSON,
			Tier:        cr.Tier,
			AddedAt:     cr.AddedAt,
		})
	}
	if err := db.BatchUpsertCrewMembers(b.db, members); err != nil {
		return 0, err
	}
	slog.Info("Backfill batch crew", "hold_did", holdDID, "rows", len(members))
	return len(members), nil
}

// extractDIDFromURI pulls the DID authority segment out of an AT-URI.
// Format: at://did:…/collection/rkey → "did:…".
func extractDIDFromURI(uri string) string {
	const prefix = "at://"
	if !strings.HasPrefix(uri, prefix) {
		return ""
	}
	rest := uri[len(prefix):]
	if before, _, ok := strings.Cut(rest, "/"); ok {
		return before
	}
	return rest
}