package feeds

import (
	"context"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"errors"
	"io"
	"strings"

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5"
)

const upsertChunkSize = 100

type syncStats struct {
	Total         int
	Synced        int
	Skipped       int
	Unchanged     int
	Progress      int
	ContentHash   string
	UnchangedFeed bool
	Deltas        syncDeltaCounts
}

type pendingProduct struct {
	GTIN        string
	RawData     map[string]string
	MappedData  map[string]any
	ContentHash string
}

// Sync downloads the feed URL, parses CSV/XML, applies mappings, and upserts raw_products
// in chunks with progress updates on feed_sync_jobs. Replaces SyncStub.
func (s *Service) Sync(ctx context.Context, companyID, feedID uuid.UUID) (map[string]any, error) {
	feed, err := s.Get(ctx, companyID, feedID)
	if err != nil {
		if IsNotFound(err) {
			return nil, ErrNotFound
		}
		return nil, err
	}
	if err := s.ensureMappingsReadyForSync(ctx, companyID, feedID); err != nil {
		return nil, err
	}

	jobID, err := s.createSyncJob(ctx, companyID, feedID)
	if err != nil {
		return nil, err
	}
	if err := s.markJobRunning(ctx, jobID); err != nil {
		return nil, err
	}

	stats, runErr := s.runSync(ctx, companyID, feedID, jobID, feed)
	if runErr != nil {
		_ = s.failJob(ctx, jobID, runErr.Error(), stats)
		return nil, runErr
	}
	if err := s.completeJob(ctx, jobID, stats); err != nil {
		return nil, err
	}
	_ = s.persistFeedSyncMeta(ctx, companyID, feedID, jobID, stats)

	job, err := s.GetSyncJob(ctx, companyID, feedID, jobID)
	if err != nil {
		return nil, err
	}
	return enrichJobWithDeltas(job, stats.Deltas), nil
}

// EnqueueSync creates a pending feed_sync_jobs row and wakes the worker via NOTIFY.
// Same-feed pending jobs are reused (no duplicate pending stack). The API process
// does not run sync work (no unbound goroutines). Returns the job id immediately
// for 202/poll (dashboard) or legacy 200 + jobId (v1).
func (s *Service) EnqueueSync(ctx context.Context, companyID, feedID uuid.UUID) (uuid.UUID, error) {
	if _, err := s.Get(ctx, companyID, feedID); err != nil {
		if IsNotFound(err) {
			return uuid.Nil, ErrNotFound
		}
		return uuid.Nil, err
	}
	if err := s.ensureMappingsReadyForSync(ctx, companyID, feedID); err != nil {
		return uuid.Nil, err
	}
	jobID, err := s.findOrCreatePendingSyncJob(ctx, companyID, feedID)
	if err != nil {
		return uuid.Nil, err
	}
	_, _ = s.Pool.Exec(ctx, `SELECT pg_notify('feed_sync_jobs', $1)`, jobID.String())
	return jobID, nil
}

// ClaimNextPendingSyncJob claims one pending feed_sync_jobs row (FOR UPDATE SKIP LOCKED)
// and marks it running for the worker.
func (s *Service) ClaimNextPendingSyncJob(ctx context.Context) (jobID, companyID, feedID uuid.UUID, err error) {
	err = s.Pool.QueryRow(ctx, `
		WITH candidate AS (
			SELECT id FROM feed_sync_jobs
			WHERE status = 'pending'
			ORDER BY created_at ASC, id ASC
			LIMIT 1
			FOR UPDATE SKIP LOCKED
		)
		UPDATE feed_sync_jobs j
		SET status = 'running', started_at = now(), updated_at = now()
		FROM candidate
		WHERE j.id = candidate.id
		RETURNING j.id, j.company_id, j.feed_id`).Scan(&jobID, &companyID, &feedID)
	if errors.Is(err, pgx.ErrNoRows) {
		return uuid.Nil, uuid.Nil, uuid.Nil, pgx.ErrNoRows
	}
	return jobID, companyID, feedID, err
}

// ProcessSyncJob runs sync for a job already claimed (status=running) by ClaimNextPendingSyncJob.
func (s *Service) ProcessSyncJob(ctx context.Context, companyID, feedID, jobID uuid.UUID) error {
	feed, err := s.Get(ctx, companyID, feedID)
	if err != nil {
		msg := err.Error()
		if IsNotFound(err) {
			msg = "feed not found"
		}
		_ = s.failJob(ctx, jobID, msg, syncStats{})
		return err
	}
	stats, runErr := s.runSync(ctx, companyID, feedID, jobID, feed)
	if runErr != nil {
		_ = s.failJob(ctx, jobID, runErr.Error(), stats)
		return runErr
	}
	if err := s.completeJob(ctx, jobID, stats); err != nil {
		_ = s.failJob(ctx, jobID, err.Error(), stats)
		return err
	}
	_ = s.persistFeedSyncMeta(ctx, companyID, feedID, jobID, stats)
	return nil
}

// SyncStub is retained as a compatibility alias for Sync.
func (s *Service) SyncStub(ctx context.Context, companyID, feedID uuid.UUID) (map[string]any, error) {
	return s.Sync(ctx, companyID, feedID)
}

func (s *Service) GetSyncJob(ctx context.Context, companyID, feedID, jobID uuid.UUID) (map[string]any, error) {
	row := s.Pool.QueryRow(ctx, `
		SELECT id, feed_id, company_id, status, started_at, completed_at,
			products_synced, products_total, products_skipped, products_unchanged,
			progress, content_hash, error, created_at, updated_at
		FROM feed_sync_jobs
		WHERE id = $1 AND company_id = $2 AND feed_id = $3`, jobID, companyID, feedID)
	job, err := scanMap(row, []string{
		"id", "feed_id", "company_id", "status", "started_at", "completed_at",
		"products_synced", "products_total", "products_skipped", "products_unchanged",
		"progress", "content_hash", "error", "created_at", "updated_at",
	})
	if err != nil {
		return nil, err
	}
	if deltas, ok := s.loadFeedLastSyncDeltas(ctx, companyID, feedID); ok {
		if matchJobID(deltas["job_id"], jobID) {
			return enrichJobWithDeltasMap(job, deltas), nil
		}
	}
	return job, nil
}

func (s *Service) persistFeedSyncMeta(ctx context.Context, companyID, feedID, jobID uuid.UUID, stats syncStats) error {
	stats.Deltas.JobID = jobID.String()
	stats.Deltas.Unchanged = stats.Unchanged
	stats.Deltas.Skipped = stats.Skipped
	deltaJSON, err := json.Marshal(stats.Deltas.asMap())
	if err != nil {
		return err
	}
	_, err = s.Pool.Exec(ctx, `
		UPDATE input_feeds SET last_synced_at = now(), updated_at = now(),
			options = COALESCE(options, '{}'::jsonb) || jsonb_build_object(
				'last_content_hash', to_jsonb($2::text),
				'last_sync_deltas', $3::jsonb
			)
		WHERE id = $1 AND company_id = $4`, feedID, stats.ContentHash, deltaJSON, companyID)
	return err
}

func (s *Service) loadFeedLastSyncDeltas(ctx context.Context, companyID, feedID uuid.UUID) (map[string]any, bool) {
	var raw []byte
	err := s.Pool.QueryRow(ctx, `
		SELECT options->'last_sync_deltas' FROM input_feeds
		WHERE id = $1 AND company_id = $2`, feedID, companyID).Scan(&raw)
	if err != nil || len(raw) == 0 || string(raw) == "null" {
		return nil, false
	}
	var m map[string]any
	if err := json.Unmarshal(raw, &m); err != nil || m == nil {
		return nil, false
	}
	return m, true
}

func enrichJobWithDeltas(job map[string]any, d syncDeltaCounts) map[string]any {
	return enrichJobWithDeltasMap(job, d.asMap())
}

func enrichJobWithDeltasMap(job map[string]any, deltas map[string]any) map[string]any {
	if job == nil {
		return nil
	}
	out := make(map[string]any, len(job)+1)
	for k, v := range job {
		out[k] = v
	}
	out["deltas"] = deltas
	out["price_changed"] = deltas["price_changed"]
	out["stock_changed"] = deltas["stock_changed"]
	out["availability_changed"] = deltas["availability_changed"]
	out["title_changed"] = deltas["title_changed"]
	out["other_changed"] = deltas["other_changed"]
	out["products_new"] = deltas["new"]
	return out
}

func matchJobID(v any, id uuid.UUID) bool {
	switch t := v.(type) {
	case string:
		return strings.EqualFold(strings.TrimSpace(t), id.String())
	case uuid.UUID:
		return t == id
	default:
		return false
	}
}

func (s *Service) ListSyncJobs(ctx context.Context, companyID, feedID uuid.UUID, limit int) ([]map[string]any, error) {
	if limit <= 0 {
		limit = 50
	}
	if limit > 200 {
		limit = 200
	}
	rows, err := s.Pool.Query(ctx, `
		SELECT id, feed_id, status, started_at, completed_at,
			products_synced, products_total, products_skipped, products_unchanged,
			progress, content_hash, error, created_at
		FROM feed_sync_jobs
		WHERE company_id = $1 AND feed_id = $2
		ORDER BY created_at DESC LIMIT $3`, companyID, feedID, limit)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	return scanMaps(rows, []string{
		"id", "feed_id", "status", "started_at", "completed_at",
		"products_synced", "products_total", "products_skipped", "products_unchanged",
		"progress", "content_hash", "error", "created_at",
	})
}

func (s *Service) runSync(ctx context.Context, companyID, feedID, jobID uuid.UUID, feed map[string]any) (syncStats, error) {
	var stats syncStats
	urlStr, _ := feed["url"].(string)
	feedType, _ := feed["feed_type"].(string)

	src, err := s.loadFeedSource(ctx, companyID, feed)
	if err != nil {
		return stats, err
	}
	defer src.Close()

	hash, err := sha256HexFile(src)
	if err != nil {
		return stats, err
	}
	stats.ContentHash = hash

	prev, _ := s.lastContentHash(ctx, feedID)
	if prev != "" && prev == hash {
		stats.UnchangedFeed = true
		stats.Progress = 100
		_ = s.updateJobProgress(ctx, jobID, stats)
		return stats, nil
	}

	mappingsRaw, mapErr := s.loadMappingsRaw(ctx, companyID, feedID)
	if mapErr != nil && !errors.Is(mapErr, pgx.ErrNoRows) {
		return stats, mapErr
	}
	mappings := activeMappings(parseMappings(mappingsRaw))
	if len(mappings) == 0 {
		return stats, ClientMsg("no field mappings defined for feed")
	}

	itemPath := "item"
	if path := itemPathFromMappings(mappingsRaw); path != "" {
		itemPath = itemLocalFromPath(path)
	} else if opts, ok := feed["options"].(map[string]any); ok {
		if v, ok := opts["item_path"].(string); ok && strings.TrimSpace(v) != "" {
			itemPath = itemLocalFromPath(v)
		}
	}
	if itemPath == "" {
		itemPath = "item"
	}

	sample, sniffErr := src.Sniff(4096)
	if sniffErr != nil {
		return stats, sniffErr
	}
	format := detectFeedFormat(feedType, contentTypeFromBlob(src), urlStr, sample)
	chunk := make([]pendingProduct, 0, upsertChunkSize)

	flush := func(force bool) error {
		if len(chunk) == 0 {
			return nil
		}
		if !force && len(chunk) < upsertChunkSize {
			return nil
		}
		synced, unchanged, skipped, deltas, err := s.upsertChunk(ctx, companyID, feedID, jobID, chunk)
		if err != nil {
			return err
		}
		stats.Synced += synced
		stats.Unchanged += unchanged
		stats.Skipped += skipped
		stats.Deltas.New += deltas.New
		stats.Deltas.PriceChanged += deltas.PriceChanged
		stats.Deltas.StockChanged += deltas.StockChanged
		stats.Deltas.AvailabilityChanged += deltas.AvailabilityChanged
		stats.Deltas.TitleChanged += deltas.TitleChanged
		stats.Deltas.OtherChanged += deltas.OtherChanged
		chunk = chunk[:0]
		done := stats.Synced + stats.Unchanged + stats.Skipped
		if stats.Total > 0 {
			stats.Progress = done * 100 / stats.Total
			if stats.Progress > 99 {
				stats.Progress = 99
			}
		}
		_ = s.updateJobProgress(ctx, jobID, stats)
		return nil
	}

	onRow := func(row feedRow) error {
		stats.Total++
		mapped, gtin := applyMappings(row, mappings)
		if gtin == "" {
			stats.Skipped++
			return nil
		}
		rawCopy := make(map[string]string, len(row))
		for k, v := range row {
			rawCopy[k] = v
		}
		mh := sha256Hex([]byte(mustJSON(mapped)))
		chunk = append(chunk, pendingProduct{
			GTIN: gtin, RawData: rawCopy, MappedData: mapped, ContentHash: mh,
		})
		return flush(false)
	}

	body, err := src.Open()
	if err != nil {
		return stats, err
	}
	defer body.Close()

	var parseCount int
	switch format {
	case "xml":
		parseCount, err = parseXMLItems(body, itemPath, onRow)
	default:
		parseCount, err = parseCSV(body, onRow)
	}
	if err != nil {
		return stats, err
	}
	if parseCount == 0 {
		return stats, ClientMsg("feed contained no rows")
	}
	if err := flush(true); err != nil {
		return stats, err
	}
	stats.Progress = 100
	_ = s.updateJobProgress(ctx, jobID, stats)
	return stats, nil
}

type existingProduct struct {
	ID         uuid.UUID
	MappedData []byte
}

const (
	// Set-based upserts (UNNEST / ANY) — one statement per op kind, queued in a single
	// pgx.Batch round-trip. Mirrors catalog/import_csv.go patterns.
	upsertSQLInsertSet = `
		INSERT INTO raw_products (
			company_id, gtin, feed_id, raw_data, mapped_data, sync_job_id,
			is_processed, processing_status, updated_at
		)
		SELECT $1, v.gtin, $2, v.raw_data::jsonb, v.mapped_data::jsonb, $3, false, 'unprocessed', now()
		FROM unnest($4::text[], $5::text[], $6::text[]) AS v(gtin, raw_data, mapped_data)
		ON CONFLICT (company_id, gtin) DO UPDATE SET
			feed_id = EXCLUDED.feed_id,
			raw_data = EXCLUDED.raw_data,
			mapped_data = EXCLUDED.mapped_data,
			sync_job_id = EXCLUDED.sync_job_id,
			is_processed = false,
			processing_status = 'unprocessed',
			updated_at = now()`
	upsertSQLTouchSet = `
		UPDATE raw_products SET sync_job_id = $3, feed_id = $4, updated_at = now()
		WHERE company_id = $1 AND id = ANY($2::uuid[])`
	upsertSQLUpdateSet = `
		UPDATE raw_products AS r SET
			feed_id = $2,
			raw_data = v.raw_data::jsonb,
			mapped_data = v.mapped_data::jsonb,
			sync_job_id = $3,
			is_processed = false,
			processing_status = 'unprocessed',
			updated_at = now()
		FROM unnest($4::uuid[], $5::text[], $6::text[]) AS v(id, raw_data, mapped_data)
		WHERE r.id = v.id AND r.company_id = $1`
)

type upsertOpKind int

const (
	upsertOpInsert upsertOpKind = iota
	upsertOpTouch
	upsertOpUpdate
)

type upsertOp struct {
	kind       upsertOpKind
	gtin       string
	id         uuid.UUID
	rawJSON    []byte
	mappedJSON []byte
	changes    []string
}

// classifyUpsertOps decides insert / touch / update per row without DB I/O so a chunk
// can be applied with set-based UNNEST statements (≤3) in one pgx.Batch round-trip.
// Touch keeps is_processed/processing_status when mapped_data is equal (canonical JSON).
// Updates/inserts stamp mapped_data._sync_changes for seller filters (price/stock/…).
func classifyUpsertOps(chunk []pendingProduct, existing map[string]existingProduct) (ops []upsertOp, skipped int) {
	ops = make([]upsertOp, 0, len(chunk))
	for _, p := range chunk {
		rawJSON, err := json.Marshal(p.RawData)
		if err != nil {
			skipped++
			continue
		}
		ex, found := existing[p.GTIN]
		cleanMapped := stripSyncChanges(p.MappedData)
		if !found {
			withFlags := withSyncChanges(cleanMapped, []string{"new"})
			mappedJSON, err := json.Marshal(withFlags)
			if err != nil {
				skipped++
				continue
			}
			ops = append(ops, upsertOp{
				kind: upsertOpInsert, gtin: p.GTIN, rawJSON: rawJSON, mappedJSON: mappedJSON,
				changes: []string{"new"},
			})
			continue
		}
		// Category (and similar extras) live outside feed mappings — keep them.
		cleanMapped = preserveSyncedExtras(ex.MappedData, cleanMapped)
		plainJSON, err := json.Marshal(cleanMapped)
		if err != nil {
			skipped++
			continue
		}
		if bytesEqualJSON(stripSyncChangesBytes(ex.MappedData), plainJSON) {
			ops = append(ops, upsertOp{kind: upsertOpTouch, id: ex.ID})
			continue
		}
		changes := detectMappedChanges(ex.MappedData, cleanMapped)
		withFlags := withSyncChanges(cleanMapped, changes)
		mappedJSON, err := json.Marshal(withFlags)
		if err != nil {
			skipped++
			continue
		}
		ops = append(ops, upsertOp{
			kind: upsertOpUpdate, id: ex.ID, rawJSON: rawJSON, mappedJSON: mappedJSON,
			changes: changes,
		})
	}
	return ops, skipped
}

func stripSyncChangesBytes(raw []byte) []byte {
	if len(raw) == 0 {
		return raw
	}
	var m map[string]any
	if err := json.Unmarshal(raw, &m); err != nil {
		return raw
	}
	out, err := json.Marshal(stripSyncChanges(m))
	if err != nil {
		return raw
	}
	return out
}

// dedupePendingByGTIN keeps first-seen order but last-seen payload per GTIN so a single
// UNNEST INSERT cannot hit "cannot affect row a second time".
func dedupePendingByGTIN(chunk []pendingProduct) []pendingProduct {
	if len(chunk) < 2 {
		return chunk
	}
	by := make(map[string]pendingProduct, len(chunk))
	order := make([]string, 0, len(chunk))
	for _, p := range chunk {
		if _, ok := by[p.GTIN]; !ok {
			order = append(order, p.GTIN)
		}
		by[p.GTIN] = p
	}
	if len(order) == len(chunk) {
		return chunk
	}
	out := make([]pendingProduct, 0, len(order))
	for _, gtin := range order {
		out = append(out, by[gtin])
	}
	return out
}

func partitionUpsertOps(ops []upsertOp) (inserts, touches, updates []upsertOp) {
	for _, op := range ops {
		switch op.kind {
		case upsertOpInsert:
			inserts = append(inserts, op)
		case upsertOpTouch:
			touches = append(touches, op)
		default:
			updates = append(updates, op)
		}
	}
	return inserts, touches, updates
}

func (s *Service) upsertChunk(ctx context.Context, companyID, feedID, jobID uuid.UUID, chunk []pendingProduct) (synced, unchanged, skipped int, deltas syncDeltaCounts, err error) {
	chunk = dedupePendingByGTIN(chunk)
	if len(chunk) == 0 {
		return 0, 0, 0, deltas, nil
	}
	gtins := make([]string, 0, len(chunk))
	for _, p := range chunk {
		gtins = append(gtins, p.GTIN)
	}
	existing, err := s.loadExistingByGTIN(ctx, companyID, gtins)
	if err != nil {
		return 0, 0, 0, deltas, err
	}

	ops, skipped := classifyUpsertOps(chunk, existing)
	if len(ops) == 0 {
		deltas.Skipped = skipped
		return 0, 0, skipped, deltas, nil
	}

	inserts, touches, updates := partitionUpsertOps(ops)
	batch := &pgx.Batch{}
	queued := 0
	if len(inserts) > 0 {
		gtinCol := make([]string, len(inserts))
		rawCol := make([]string, len(inserts))
		mappedCol := make([]string, len(inserts))
		for i, op := range inserts {
			gtinCol[i] = op.gtin
			rawCol[i] = string(op.rawJSON)
			mappedCol[i] = string(op.mappedJSON)
			deltas.addChanges(op.changes)
		}
		batch.Queue(upsertSQLInsertSet, companyID, feedID, jobID, gtinCol, rawCol, mappedCol)
		queued++
	}
	if len(touches) > 0 {
		ids := make([]uuid.UUID, len(touches))
		for i, op := range touches {
			ids[i] = op.id
		}
		batch.Queue(upsertSQLTouchSet, companyID, ids, jobID, feedID)
		queued++
	}
	if len(updates) > 0 {
		ids := make([]uuid.UUID, len(updates))
		rawCol := make([]string, len(updates))
		mappedCol := make([]string, len(updates))
		for i, op := range updates {
			ids[i] = op.id
			rawCol[i] = string(op.rawJSON)
			mappedCol[i] = string(op.mappedJSON)
			deltas.addChanges(op.changes)
		}
		batch.Queue(upsertSQLUpdateSet, companyID, feedID, jobID, ids, rawCol, mappedCol)
		queued++
	}

	br := s.Pool.SendBatch(ctx, batch)
	defer br.Close()
	for i := 0; i < queued; i++ {
		if _, err := br.Exec(); err != nil {
			return synced, unchanged, skipped, deltas, err
		}
	}
	// Content inserts/updates stamp raw as unprocessed — drop catalog rows so
	// processed_products cannot outlive that reset (matches resetRawProducts).
	// Touches keep processing_status and must not invalidate catalog.
	if len(inserts) > 0 || len(updates) > 0 {
		invalidateIDs := make([]uuid.UUID, 0, len(updates))
		for _, op := range updates {
			invalidateIDs = append(invalidateIDs, op.id)
		}
		invalidateGTINs := make([]string, 0, len(inserts))
		for _, op := range inserts {
			invalidateGTINs = append(invalidateGTINs, op.gtin)
		}
		if _, err := s.Pool.Exec(ctx, `
			DELETE FROM processed_products
			WHERE company_id = $1
				AND (
				raw_product_id = ANY($2::uuid[])
				OR raw_product_id IN (
					SELECT id FROM raw_products
					WHERE company_id = $1 AND gtin = ANY($3::text[])
				)
			)`, companyID, invalidateIDs, invalidateGTINs); err != nil {
			return synced, unchanged, skipped, deltas, err
		}
	}
	synced = len(inserts) + len(updates)
	unchanged = len(touches)
	deltas.Unchanged = unchanged
	deltas.Skipped = skipped
	return synced, unchanged, skipped, deltas, nil
}

func (s *Service) loadExistingByGTIN(ctx context.Context, companyID uuid.UUID, gtins []string) (map[string]existingProduct, error) {
	out := make(map[string]existingProduct, len(gtins))
	if len(gtins) == 0 {
		return out, nil
	}
	rows, err := s.Pool.Query(ctx, `
		SELECT id, gtin, mapped_data FROM raw_products
		WHERE company_id = $1 AND gtin = ANY($2::text[])`, companyID, gtins)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	for rows.Next() {
		var ex existingProduct
		var gtin string
		if err := rows.Scan(&ex.ID, &gtin, &ex.MappedData); err != nil {
			return nil, err
		}
		out[gtin] = ex
	}
	return out, rows.Err()
}

func (s *Service) createSyncJob(ctx context.Context, companyID, feedID uuid.UUID) (uuid.UUID, error) {
	var id uuid.UUID
	err := s.Pool.QueryRow(ctx, `
		INSERT INTO feed_sync_jobs (feed_id, company_id, status)
		VALUES ($1, $2, 'pending') RETURNING id`, feedID, companyID).Scan(&id)
	return id, err
}

// findOrCreatePendingSyncJob returns an existing pending job for the feed, or inserts one.
// Uses a transaction advisory lock so concurrent enqueues do not stack duplicates.
func (s *Service) findOrCreatePendingSyncJob(ctx context.Context, companyID, feedID uuid.UUID) (uuid.UUID, error) {
	tx, err := s.Pool.Begin(ctx)
	if err != nil {
		return uuid.Nil, err
	}
	defer tx.Rollback(ctx)

	if _, err := tx.Exec(ctx, `SELECT pg_advisory_xact_lock(hashtextextended($1::text, 0))`, feedID.String()); err != nil {
		return uuid.Nil, err
	}

	var id uuid.UUID
	err = tx.QueryRow(ctx, `
		SELECT id FROM feed_sync_jobs
		WHERE feed_id = $1 AND company_id = $2 AND status = 'pending'
		ORDER BY created_at
		LIMIT 1`, feedID, companyID).Scan(&id)
	if err == nil {
		if err := tx.Commit(ctx); err != nil {
			return uuid.Nil, err
		}
		return id, nil
	}
	if !errors.Is(err, pgx.ErrNoRows) {
		return uuid.Nil, err
	}

	err = tx.QueryRow(ctx, `
		INSERT INTO feed_sync_jobs (feed_id, company_id, status)
		VALUES ($1, $2, 'pending') RETURNING id`, feedID, companyID).Scan(&id)
	if err != nil {
		return uuid.Nil, err
	}
	if err := tx.Commit(ctx); err != nil {
		return uuid.Nil, err
	}
	return id, nil
}

func (s *Service) markJobRunning(ctx context.Context, jobID uuid.UUID) error {
	_, err := s.Pool.Exec(ctx, `
		UPDATE feed_sync_jobs SET status = 'running', started_at = now(), updated_at = now()
		WHERE id = $1`, jobID)
	return err
}

func (s *Service) updateJobProgress(ctx context.Context, jobID uuid.UUID, stats syncStats) error {
	_, err := s.Pool.Exec(ctx, `
		UPDATE feed_sync_jobs SET
			products_synced = $2,
			products_total = $3,
			products_skipped = $4,
			products_unchanged = $5,
			progress = $6,
			content_hash = NULLIF($7, ''),
			updated_at = now()
		WHERE id = $1`,
		jobID, stats.Synced, stats.Total, stats.Skipped, stats.Unchanged, stats.Progress, stats.ContentHash)
	return err
}

func (s *Service) completeJob(ctx context.Context, jobID uuid.UUID, stats syncStats) error {
	_, err := s.Pool.Exec(ctx, `
		UPDATE feed_sync_jobs SET
			status = 'completed',
			completed_at = now(),
			products_synced = $2,
			products_total = $3,
			products_skipped = $4,
			products_unchanged = $5,
			progress = 100,
			content_hash = NULLIF($6, ''),
			updated_at = now()
		WHERE id = $1`,
		jobID, stats.Synced, stats.Total, stats.Skipped, stats.Unchanged, stats.ContentHash)
	return err
}

func (s *Service) failJob(ctx context.Context, jobID uuid.UUID, msg string, stats syncStats) error {
	_, err := s.Pool.Exec(ctx, `
		UPDATE feed_sync_jobs SET
			status = 'failed',
			error = $2,
			completed_at = now(),
			products_synced = $3,
			products_total = $4,
			products_skipped = $5,
			products_unchanged = $6,
			progress = $7,
			content_hash = NULLIF($8, ''),
			updated_at = now()
		WHERE id = $1`,
		jobID, truncateErr(msg), stats.Synced, stats.Total, stats.Skipped, stats.Unchanged, stats.Progress, stats.ContentHash)
	return err
}

func (s *Service) lastContentHash(ctx context.Context, feedID uuid.UUID) (string, error) {
	var hash *string
	err := s.Pool.QueryRow(ctx, `
		SELECT content_hash FROM feed_sync_jobs
		WHERE feed_id = $1 AND status = 'completed' AND content_hash IS NOT NULL AND content_hash <> ''
		ORDER BY completed_at DESC NULLS LAST LIMIT 1`, feedID).Scan(&hash)
	if errors.Is(err, pgx.ErrNoRows) {
		return "", nil
	}
	if err != nil {
		return "", err
	}
	if hash == nil {
		return "", nil
	}
	return *hash, nil
}

func (s *Service) loadMappingsRaw(ctx context.Context, companyID, feedID uuid.UUID) (any, error) {
	var raw []byte
	err := s.Pool.QueryRow(ctx, `
		SELECT mappings FROM feed_mappings
		WHERE feed_id = $1 AND company_id = $2 AND is_active = true
		ORDER BY version DESC LIMIT 1`, feedID, companyID).Scan(&raw)
	if err != nil {
		return nil, err
	}
	var m any
	if err := json.Unmarshal(raw, &m); err != nil {
		return nil, err
	}
	return m, nil
}

func sha256Hex(b []byte) string {
	sum := sha256.Sum256(b)
	return hex.EncodeToString(sum[:])
}

func sha256HexFile(src *feedBlob) (string, error) {
	f, err := src.Open()
	if err != nil {
		return "", err
	}
	defer f.Close()
	h := sha256.New()
	if _, err := io.Copy(h, f); err != nil {
		return "", err
	}
	return hex.EncodeToString(h.Sum(nil)), nil
}

func contentTypeFromBlob(src *feedBlob) string {
	if src == nil {
		return ""
	}
	return src.contentType
}

func mustJSON(v any) string {
	b, err := json.Marshal(v)
	if err != nil {
		return ""
	}
	return string(b)
}

func bytesEqualJSON(a, b []byte) bool {
	if len(a) == 0 && len(b) == 0 {
		return true
	}
	var xa, xb any
	if json.Unmarshal(a, &xa) != nil || json.Unmarshal(b, &xb) != nil {
		return string(a) == string(b)
	}
	ba, _ := json.Marshal(xa)
	bb, _ := json.Marshal(xb)
	return string(ba) == string(bb)
}

func truncateErr(msg string) string {
	if len(msg) > 2000 {
		return msg[:2000]
	}
	return msg
}