package postgres

import (
	"context"
	"errors"
	"knowledge-governance/internal/governance"
)

// Query the source identity before applying LIMIT: target/prebackup events and
// other source instances can never push the candidate out of a history window.
func (s *Store) LibrarySourceCandidate(ctx context.Context, scope, sourceID string) (governance.LibraryVersion, bool, error) {
	if sourceID == "" {
		return governance.LibraryVersion{}, false, errors.New("source identity required")
	}
	rows, err := s.db.Query(ctx, `SELECT id,scope,kind,snapshot_id,version_label,source_job_id,operation_id,attempt_epoch,evidence,created_by,created_at,superseded_at
 FROM library_versions WHERE scope=$1 AND kind='test_sealed' AND evidence->>'source_id'=$2
 ORDER BY created_at DESC,id DESC LIMIT 1`, scope, sourceID)
	if err != nil {
		return governance.LibraryVersion{}, false, err
	}
	items, err := scanLibraryVersions(rows, 1)
	if err != nil || len(items) == 0 {
		return governance.LibraryVersion{}, false, err
	}
	return items[0], true, nil
}