vaultik/internal/snapshot/scanner.go

package snapshot

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"sync"
	"time"

	"github.com/dustin/go-humanize"
	"github.com/gobwas/glob"
	"github.com/spf13/afero"
	"sneak.berlin/go/vaultik/internal/blob"
	"sneak.berlin/go/vaultik/internal/chunker"
	"sneak.berlin/go/vaultik/internal/database"
	"sneak.berlin/go/vaultik/internal/log"
	"sneak.berlin/go/vaultik/internal/storage"
	"sneak.berlin/go/vaultik/internal/types"
	"sneak.berlin/go/vaultik/internal/ui"
)

// FileToProcess holds information about a file that needs processing
type FileToProcess struct {
	Path     string
	FileInfo os.FileInfo
	File     *database.File
}

// pendingFileData holds all data needed to commit a file to the database
type pendingFileData struct {
	file       *database.File
	fileChunks []database.FileChunk
	chunkFiles []database.ChunkFile
}

// compiledPattern holds a compiled glob pattern and whether it's anchored
type compiledPattern struct {
	pattern  glob.Glob
	anchored bool // If true, only matches from root of source dir
	original string
}

// Scanner scans directories and populates the database with file and chunk information
type Scanner struct {
	fs                afero.Fs
	chunker           *chunker.Chunker
	packer            *blob.Packer
	repos             *database.Repositories
	storage           storage.Storer
	maxBlobSize       int64
	compressionLevel  int
	ageRecipient      string
	snapshotID        string            // Current snapshot being processed
	currentSourcePath string            // Current source directory being scanned (for restore path stripping)
	exclude           []string          // Glob patterns for files/directories to exclude
	compiledExclude   []compiledPattern // Compiled glob patterns
	progress          *ProgressReporter
	skipErrors        bool       // Skip file read errors (log loudly but continue)
	ui                *ui.Writer // User-facing output; never nil (defaults to a discarding writer)

	// In-memory cache of known chunk hashes for fast existence checks
	knownChunks   map[string]struct{}
	knownChunksMu sync.RWMutex

	// Pending chunk hashes - chunks that have been added to packer but not yet committed to DB
	// When a blob finalizes, the committed chunks are removed from this set
	pendingChunkHashes   map[string]struct{}
	pendingChunkHashesMu sync.Mutex

	// Pending file data buffer for batch insertion
	// Files are flushed when all their chunks have been committed to DB
	pendingFiles   []pendingFileData
	pendingFilesMu sync.Mutex

	// Mutex for coordinating blob creation
	packerMu sync.Mutex // Blocks chunk production during blob creation

	// Context for cancellation
	scanCtx context.Context
}

// ScannerConfig contains configuration for the scanner
type ScannerConfig struct {
	FS               afero.Fs
	ChunkSize        int64
	Repositories     *database.Repositories
	Storage          storage.Storer
	MaxBlobSize      int64
	CompressionLevel int
	AgeRecipients    []string   // Optional, empty means no encryption
	EnableProgress   bool       // Enable the live progress reporter (ETAs, throughput)
	UI               *ui.Writer // Where user-facing scanner messages go; nil = discard
	Exclude          []string   // Glob patterns for files/directories to exclude
	SkipErrors       bool       // Skip file read errors (log loudly but continue)
}

// ScanResult contains the results of a scan operation
type ScanResult struct {
	FilesScanned  int
	FilesSkipped  int
	FilesDeleted  int
	BytesScanned  int64
	BytesSkipped  int64
	BytesDeleted  int64
	ChunksCreated int
	BlobsCreated  int
	StartTime     time.Time
	EndTime       time.Time
}

// NewScanner creates a new scanner instance
func NewScanner(cfg ScannerConfig) *Scanner {
	// Create encryptor (required for blob packing)
	if len(cfg.AgeRecipients) == 0 {
		log.Error("No age recipients configured - encryption is required")
		return nil
	}

	// Create blob packer with encryption
	packerCfg := blob.PackerConfig{
		MaxBlobSize:      cfg.MaxBlobSize,
		CompressionLevel: cfg.CompressionLevel,
		Recipients:       cfg.AgeRecipients,
		Repositories:     cfg.Repositories,
		Fs:               cfg.FS,
	}
	packer, err := blob.NewPacker(packerCfg)
	if err != nil {
		log.Error("Failed to create packer", "error", err)
		return nil
	}

	var progress *ProgressReporter
	if cfg.EnableProgress {
		progress = NewProgressReporter()
	}

	// Compile exclude patterns
	compiledExclude := compileExcludePatterns(cfg.Exclude)

	uiw := cfg.UI
	if uiw == nil {
		uiw = ui.NewWithColor(io.Discard, false)
	}

	return &Scanner{
		fs:                 cfg.FS,
		chunker:            chunker.NewChunker(cfg.ChunkSize),
		packer:             packer,
		repos:              cfg.Repositories,
		storage:            cfg.Storage,
		maxBlobSize:        cfg.MaxBlobSize,
		compressionLevel:   cfg.CompressionLevel,
		ageRecipient:       strings.Join(cfg.AgeRecipients, ","),
		exclude:            cfg.Exclude,
		compiledExclude:    compiledExclude,
		progress:           progress,
		skipErrors:         cfg.SkipErrors,
		ui:                 uiw,
		pendingChunkHashes: make(map[string]struct{}),
	}
}

// Scan scans a directory and populates the database
func (s *Scanner) Scan(ctx context.Context, path string, snapshotID string) (*ScanResult, error) {
	s.snapshotID = snapshotID
	s.currentSourcePath = path // Store source path for file records (used during restore)
	s.scanCtx = ctx
	result := &ScanResult{
		StartTime: time.Now().UTC(),
	}

	// Set blob handler for concurrent upload
	if s.storage != nil {
		log.Debug("Setting blob handler for storage uploads")
		s.packer.SetBlobHandler(s.handleBlobReady)
	} else {
		log.Debug("No storage configured, blobs will not be uploaded")
	}

	// Start progress reporting if enabled
	if s.progress != nil {
		s.progress.Start()
		defer s.progress.Stop()
	}

	// Phase 0: Load known files and chunks from database into memory for fast lookup
	knownFiles, err := s.loadDatabaseState(ctx, path)
	if err != nil {
		return nil, err
	}

	// Phase 1: Scan directory, collect files to process, and track existing files
	// (builds existingFiles map during walk to avoid double traversal)
	log.Info("Phase 1/3: Scanning directory structure")
	existingFiles := make(map[string]struct{})
	scanResult, err := s.scanPhase(ctx, path, result, existingFiles, knownFiles)
	if err != nil {
		return nil, fmt.Errorf("scan phase failed: %w", err)
	}
	filesToProcess := scanResult.FilesToProcess

	// Phase 1b: Detect deleted files by comparing DB against scanned files
	if err := s.detectDeletedFilesFromMap(ctx, knownFiles, existingFiles, result); err != nil {
		return nil, fmt.Errorf("detecting deleted files: %w", err)
	}

	// Phase 1c: Associate unchanged files with this snapshot (no new records needed)
	if len(scanResult.UnchangedFileIDs) > 0 {
		s.ui.Begin("Associating %s unchanged files with the snapshot.", s.ui.Count(len(scanResult.UnchangedFileIDs)))
		if err := s.batchAddFilesToSnapshot(ctx, scanResult.UnchangedFileIDs); err != nil {
			return nil, fmt.Errorf("associating unchanged files: %w", err)
		}
	}

	// Summarize scan phase results and update progress
	s.summarizeScanPhase(result, filesToProcess)

	// Phase 2: Process files and create chunks
	if len(filesToProcess) > 0 {
		s.ui.Begin("Processing %s snapshot source files (chunking, compressing, encrypting, uploading).", s.ui.Count(len(filesToProcess)))
		log.Info("Phase 2/3: Creating snapshot (chunking, compressing, encrypting, and uploading blobs)")
		if err := s.processPhase(ctx, filesToProcess, result); err != nil {
			return nil, fmt.Errorf("process phase failed: %w", err)
		}
	} else {
		s.ui.Info("Snapshot file processing skipped: no changed files (creating metadata-only snapshot).")
		log.Info("Phase 2/3: Skipping (no files need processing, metadata-only snapshot)")
	}

	// Finalize result with blob statistics
	s.finalizeScanResult(ctx, result)

	return result, nil
}

// loadDatabaseState loads known files and chunks from the database into memory for fast lookup
// This avoids per-file and per-chunk database queries during the scan and process phases
func (s *Scanner) loadDatabaseState(ctx context.Context, path string) (map[string]*database.File, error) {
	s.ui.Begin("Loading known files from local index database.")
	knownFiles, err := s.loadKnownFiles(ctx, path)
	if err != nil {
		return nil, fmt.Errorf("loading known files: %w", err)
	}
	s.ui.Complete("Loaded %s known files from local index database.", s.ui.Count(len(knownFiles)))

	s.ui.Begin("Loading known chunks from local index database.")
	if err := s.loadKnownChunks(ctx); err != nil {
		return nil, fmt.Errorf("loading known chunks: %w", err)
	}
	s.ui.Complete("Loaded %s known chunks from local index database.", s.ui.Count(len(s.knownChunks)))

	return knownFiles, nil
}

// summarizeScanPhase calculates total size to process, updates progress tracking,
// and prints the scan phase summary with file counts and sizes
func (s *Scanner) summarizeScanPhase(result *ScanResult, filesToProcess []*FileToProcess) {
	var totalSizeToProcess int64
	for _, file := range filesToProcess {
		totalSizeToProcess += file.FileInfo.Size()
	}

	if s.progress != nil {
		s.progress.SetTotalSize(totalSizeToProcess)
		s.progress.GetStats().TotalFiles.Store(int64(len(filesToProcess)))
	}

	log.Info("Phase 1 complete",
		"total_files", len(filesToProcess),
		"total_size", humanize.Bytes(uint64(totalSizeToProcess)),
		"files_skipped", result.FilesSkipped,
		"bytes_skipped", humanize.Bytes(uint64(result.BytesSkipped)))

	msg := fmt.Sprintf("Enumerated %s snapshot source files (%s total), %s to process (%s)",
		s.ui.Count(result.FilesScanned),
		s.ui.Size(totalSizeToProcess+result.BytesSkipped),
		s.ui.Count(len(filesToProcess)),
		s.ui.Size(totalSizeToProcess))
	if result.FilesDeleted > 0 {
		msg += fmt.Sprintf(", %s deleted (%s)",
			s.ui.Count(result.FilesDeleted),
			s.ui.Size(result.BytesDeleted))
	}
	s.ui.Complete("%s.", msg)
}

// finalizeScanResult populates final blob statistics in the scan result
// by querying the packer and database for blob/upload counts
func (s *Scanner) finalizeScanResult(ctx context.Context, result *ScanResult) {
	blobs := s.packer.GetFinishedBlobs()
	result.BlobsCreated += len(blobs)

	// Query database for actual blob count created during this snapshot
	// The database is authoritative, especially for concurrent blob uploads
	// We count uploads rather than all snapshot_blobs to get only NEW blobs
	if s.snapshotID != "" {
		uploadCount, err := s.repos.Uploads.GetCountBySnapshot(ctx, s.snapshotID)
		if err != nil {
			log.Warn("Failed to query upload count from database", "error", err)
		} else {
			result.BlobsCreated = int(uploadCount)
		}
	}

	result.EndTime = time.Now().UTC()
}

// loadKnownFiles loads all known files from the database into a map for fast lookup
// This avoids per-file database queries during the scan phase
func (s *Scanner) loadKnownFiles(ctx context.Context, path string) (map[string]*database.File, error) {
	files, err := s.repos.Files.ListByPrefix(ctx, path)
	if err != nil {
		return nil, fmt.Errorf("listing files by prefix: %w", err)
	}

	result := make(map[string]*database.File, len(files))
	for _, f := range files {
		result[f.Path.String()] = f
	}

	return result, nil
}

// loadKnownChunks loads all known chunk hashes from the database into a map for fast lookup
// This avoids per-chunk database queries during file processing
func (s *Scanner) loadKnownChunks(ctx context.Context) error {
	chunks, err := s.repos.Chunks.List(ctx)
	if err != nil {
		return fmt.Errorf("listing chunks: %w", err)
	}

	s.knownChunksMu.Lock()
	s.knownChunks = make(map[string]struct{}, len(chunks))
	for _, c := range chunks {
		s.knownChunks[c.ChunkHash.String()] = struct{}{}
	}
	s.knownChunksMu.Unlock()

	return nil
}

// chunkExists checks if a chunk hash exists in the in-memory cache
func (s *Scanner) chunkExists(hash string) bool {
	s.knownChunksMu.RLock()
	_, exists := s.knownChunks[hash]
	s.knownChunksMu.RUnlock()
	return exists
}

// addKnownChunk adds a chunk hash to the in-memory cache
func (s *Scanner) addKnownChunk(hash string) {
	s.knownChunksMu.Lock()
	s.knownChunks[hash] = struct{}{}
	s.knownChunksMu.Unlock()
}

// addPendingChunkHash marks a chunk as pending (not yet committed to DB)
func (s *Scanner) addPendingChunkHash(hash string) {
	s.pendingChunkHashesMu.Lock()
	s.pendingChunkHashes[hash] = struct{}{}
	s.pendingChunkHashesMu.Unlock()
}

// removePendingChunkHashes removes committed chunk hashes from the pending set
func (s *Scanner) removePendingChunkHashes(hashes []string) {
	log.Debug("removePendingChunkHashes: starting", "count", len(hashes))
	start := time.Now()
	s.pendingChunkHashesMu.Lock()
	for _, hash := range hashes {
		delete(s.pendingChunkHashes, hash)
	}
	s.pendingChunkHashesMu.Unlock()
	log.Debug("removePendingChunkHashes: done", "count", len(hashes), "duration", time.Since(start))
}

// isChunkPending returns true if the chunk is still pending (not yet committed to DB)
func (s *Scanner) isChunkPending(hash string) bool {
	s.pendingChunkHashesMu.Lock()
	_, pending := s.pendingChunkHashes[hash]
	s.pendingChunkHashesMu.Unlock()
	return pending
}

// addPendingFile adds a file to the pending buffer
// Files are NOT auto-flushed here - they are flushed when their chunks are committed
// (in handleBlobReady after blob finalize)
func (s *Scanner) addPendingFile(_ context.Context, data pendingFileData) {
	s.pendingFilesMu.Lock()
	s.pendingFiles = append(s.pendingFiles, data)
	s.pendingFilesMu.Unlock()
}

// flushPendingFiles writes all pending files to the database in a single transaction
func (s *Scanner) flushPendingFiles(ctx context.Context) error {
	s.pendingFilesMu.Lock()
	files := s.pendingFiles
	s.pendingFiles = nil
	s.pendingFilesMu.Unlock()

	if len(files) == 0 {
		return nil
	}

	return s.repos.WithTx(ctx, func(txCtx context.Context, tx *sql.Tx) error {
		for _, data := range files {
			// Create or update the file record
			if err := s.repos.Files.Create(txCtx, tx, data.file); err != nil {
				return fmt.Errorf("creating file record: %w", err)
			}

			// Delete any existing file_chunks and chunk_files for this file
			if err := s.repos.FileChunks.DeleteByFileID(txCtx, tx, data.file.ID); err != nil {
				return fmt.Errorf("deleting old file chunks: %w", err)
			}
			if err := s.repos.ChunkFiles.DeleteByFileID(txCtx, tx, data.file.ID); err != nil {
				return fmt.Errorf("deleting old chunk files: %w", err)
			}

			// Create file-chunk mappings
			for i := range data.fileChunks {
				if err := s.repos.FileChunks.Create(txCtx, tx, &data.fileChunks[i]); err != nil {
					return fmt.Errorf("creating file chunk: %w", err)
				}
			}

			// Create chunk-file mappings
			for i := range data.chunkFiles {
				if err := s.repos.ChunkFiles.Create(txCtx, tx, &data.chunkFiles[i]); err != nil {
					return fmt.Errorf("creating chunk file: %w", err)
				}
			}

			// Add file to snapshot
			if err := s.repos.Snapshots.AddFileByID(txCtx, tx, s.snapshotID, data.file.ID); err != nil {
				return fmt.Errorf("adding file to snapshot: %w", err)
			}
		}
		return nil
	})
}

// flushAllPending flushes all pending files to the database
func (s *Scanner) flushAllPending(ctx context.Context) error {
	return s.flushPendingFiles(ctx)
}

// flushCompletedPendingFiles flushes only files whose chunks are all committed to DB
// Files with pending chunks are kept in the queue for later flushing
func (s *Scanner) flushCompletedPendingFiles(ctx context.Context) error {
	flushStart := time.Now()
	log.Debug("flushCompletedPendingFiles: starting")

	// Partition pending files into those ready to flush and those still waiting
	canFlush, stillPendingCount := s.partitionPendingByChunkStatus()

	if len(canFlush) == 0 {
		log.Debug("flushCompletedPendingFiles: nothing to flush")
		return nil
	}

	log.Debug("Flushing completed files after blob finalize",
		"files_to_flush", len(canFlush),
		"files_still_pending", stillPendingCount)

	// Collect all data for batch operations
	allFiles, allFileIDs, allFileChunks, allChunkFiles := s.collectBatchFlushData(canFlush)

	// Execute the batch flush in a single transaction
	log.Debug("flushCompletedPendingFiles: starting transaction")
	txStart := time.Now()
	err := s.executeBatchFileFlush(ctx, allFiles, allFileIDs, allFileChunks, allChunkFiles)
	log.Debug("flushCompletedPendingFiles: transaction done", "duration", time.Since(txStart))
	log.Debug("flushCompletedPendingFiles: total duration", "duration", time.Since(flushStart))
	return err
}

// partitionPendingByChunkStatus separates pending files into those whose chunks
// are all committed to DB (ready to flush) and those still waiting on pending chunks.
// Updates s.pendingFiles to contain only the still-pending files.
func (s *Scanner) partitionPendingByChunkStatus() (canFlush []pendingFileData, stillPendingCount int) {
	log.Debug("flushCompletedPendingFiles: acquiring pendingFilesMu lock")
	s.pendingFilesMu.Lock()
	log.Debug("flushCompletedPendingFiles: acquired lock", "pending_files", len(s.pendingFiles))

	var stillPending []pendingFileData

	log.Debug("flushCompletedPendingFiles: checking which files can flush")
	checkStart := time.Now()
	for _, data := range s.pendingFiles {
		allChunksCommitted := true
		for _, fc := range data.fileChunks {
			if s.isChunkPending(fc.ChunkHash.String()) {
				allChunksCommitted = false
				break
			}
		}
		if allChunksCommitted {
			canFlush = append(canFlush, data)
		} else {
			stillPending = append(stillPending, data)
		}
	}
	log.Debug("flushCompletedPendingFiles: check done", "duration", time.Since(checkStart), "can_flush", len(canFlush), "still_pending", len(stillPending))

	s.pendingFiles = stillPending
	s.pendingFilesMu.Unlock()
	log.Debug("flushCompletedPendingFiles: released lock")

	return canFlush, len(stillPending)
}

// collectBatchFlushData aggregates file records, IDs, file-chunk mappings, and chunk-file
// mappings from the given pending file data for efficient batch database operations
func (s *Scanner) collectBatchFlushData(canFlush []pendingFileData) ([]*database.File, []types.FileID, []database.FileChunk, []database.ChunkFile) {
	log.Debug("flushCompletedPendingFiles: collecting data for batch ops")
	collectStart := time.Now()

	var allFileChunks []database.FileChunk
	var allChunkFiles []database.ChunkFile
	var allFileIDs []types.FileID
	var allFiles []*database.File

	for _, data := range canFlush {
		allFileChunks = append(allFileChunks, data.fileChunks...)
		allChunkFiles = append(allChunkFiles, data.chunkFiles...)
		allFileIDs = append(allFileIDs, data.file.ID)
		allFiles = append(allFiles, data.file)
	}

	log.Debug("flushCompletedPendingFiles: collected data",
		"duration", time.Since(collectStart),
		"file_chunks", len(allFileChunks),
		"chunk_files", len(allChunkFiles),
		"files", len(allFiles))

	return allFiles, allFileIDs, allFileChunks, allChunkFiles
}

// executeBatchFileFlush writes all collected file data to the database in a single transaction,
// including deleting old mappings, creating file records, and adding snapshot associations
func (s *Scanner) executeBatchFileFlush(ctx context.Context, allFiles []*database.File, allFileIDs []types.FileID, allFileChunks []database.FileChunk, allChunkFiles []database.ChunkFile) error {
	return s.repos.WithTx(ctx, func(txCtx context.Context, tx *sql.Tx) error {
		log.Debug("flushCompletedPendingFiles: inside transaction")

		// Batch delete old file_chunks and chunk_files
		log.Debug("flushCompletedPendingFiles: deleting old file_chunks")
		opStart := time.Now()
		if err := s.repos.FileChunks.DeleteByFileIDs(txCtx, tx, allFileIDs); err != nil {
			return fmt.Errorf("batch deleting old file chunks: %w", err)
		}
		log.Debug("flushCompletedPendingFiles: deleted file_chunks", "duration", time.Since(opStart))

		log.Debug("flushCompletedPendingFiles: deleting old chunk_files")
		opStart = time.Now()
		if err := s.repos.ChunkFiles.DeleteByFileIDs(txCtx, tx, allFileIDs); err != nil {
			return fmt.Errorf("batch deleting old chunk files: %w", err)
		}
		log.Debug("flushCompletedPendingFiles: deleted chunk_files", "duration", time.Since(opStart))

		// Batch create/update file records
		log.Debug("flushCompletedPendingFiles: creating files")
		opStart = time.Now()
		if err := s.repos.Files.CreateBatch(txCtx, tx, allFiles); err != nil {
			return fmt.Errorf("batch creating file records: %w", err)
		}
		log.Debug("flushCompletedPendingFiles: created files", "duration", time.Since(opStart))

		// Batch insert file_chunks
		log.Debug("flushCompletedPendingFiles: inserting file_chunks")
		opStart = time.Now()
		if err := s.repos.FileChunks.CreateBatch(txCtx, tx, allFileChunks); err != nil {
			return fmt.Errorf("batch creating file chunks: %w", err)
		}
		log.Debug("flushCompletedPendingFiles: inserted file_chunks", "duration", time.Since(opStart))

		// Batch insert chunk_files
		log.Debug("flushCompletedPendingFiles: inserting chunk_files")
		opStart = time.Now()
		if err := s.repos.ChunkFiles.CreateBatch(txCtx, tx, allChunkFiles); err != nil {
			return fmt.Errorf("batch creating chunk files: %w", err)
		}
		log.Debug("flushCompletedPendingFiles: inserted chunk_files", "duration", time.Since(opStart))

		// Batch add files to snapshot
		log.Debug("flushCompletedPendingFiles: adding files to snapshot")
		opStart = time.Now()
		if err := s.repos.Snapshots.AddFilesByIDBatch(txCtx, tx, s.snapshotID, allFileIDs); err != nil {
			return fmt.Errorf("batch adding files to snapshot: %w", err)
		}
		log.Debug("flushCompletedPendingFiles: added files to snapshot", "duration", time.Since(opStart))

		log.Debug("flushCompletedPendingFiles: transaction complete")
		return nil
	})
}

// ScanPhaseResult contains the results of the scan phase
type ScanPhaseResult struct {
	FilesToProcess   []*FileToProcess
	UnchangedFileIDs []types.FileID // IDs of unchanged files to associate with snapshot
}

// scanPhase performs the initial directory scan to identify files to process
// It uses the pre-loaded knownFiles map for fast change detection without DB queries
// It also populates existingFiles map for deletion detection
// Returns files needing processing and IDs of unchanged files for snapshot association
func (s *Scanner) scanPhase(ctx context.Context, path string, result *ScanResult, existingFiles map[string]struct{}, knownFiles map[string]*database.File) (*ScanPhaseResult, error) {
	// Use known file count as estimate for progress (accurate for subsequent backups)
	estimatedTotal := int64(len(knownFiles))

	var filesToProcess []*FileToProcess
	var unchangedFileIDs []types.FileID // Just IDs - no new records needed
	var mu sync.Mutex

	// Set up periodic status output
	startTime := time.Now()
	lastStatusTime := time.Now()
	statusInterval := 15 * time.Second
	var filesScanned int64

	log.Debug("Starting directory walk", "path", path)
	err := afero.Walk(s.fs, path, func(filePath string, info os.FileInfo, err error) error {
		if err != nil {
			if s.skipErrors {
				log.Error("Failed to access file (skipping due to --skip-errors)", "path", filePath, "error", err)
				s.ui.Error("Failed to access %s: %v. Skipping (--skip-errors).", s.ui.Path(filePath), err)
				return nil // Continue scanning
			}
			log.Debug("Error accessing filesystem entry", "path", filePath, "error", err)
			return wrapPermissionError(filePath, err)
		}

		// Check context cancellation
		select {
		case <-ctx.Done():
			return ctx.Err()
		default:
		}

		// Check exclude patterns - for directories, skip the entire subtree
		if s.shouldExclude(filePath, path) {
			if info.IsDir() {
				return filepath.SkipDir
			}
			return nil
		}

		// Handle symlinks
		if info.Mode()&os.ModeSymlink != 0 {
			file := s.buildSymlinkEntry(filePath, info)
			if file != nil {
				existingFiles[filePath] = struct{}{}
				mu.Lock()
				filesToProcess = append(filesToProcess, &FileToProcess{
					Path:     filePath,
					FileInfo: info,
					File:     file,
				})
				filesScanned++
				mu.Unlock()
				s.updateScanEntryStats(result, true, info)
			}
			return nil
		}

		// Handle directories (record for permission/ownership preservation and empty-dir support)
		if info.IsDir() {
			file := s.buildDirectoryEntry(filePath, info)
			existingFiles[filePath] = struct{}{}
			mu.Lock()
			filesToProcess = append(filesToProcess, &FileToProcess{
				Path:     filePath,
				FileInfo: info,
				File:     file,
			})
			filesScanned++
			mu.Unlock()
			return nil
		}

		// Skip other non-regular files (devices, sockets, etc.)
		if !info.Mode().IsRegular() {
			return nil
		}

		// Track this file as existing (for deletion detection)
		existingFiles[filePath] = struct{}{}

		// Check file against in-memory map (no DB query!)
		file, needsProcessing := s.checkFileInMemory(filePath, info, knownFiles)

		mu.Lock()
		if needsProcessing {
			// New or changed file - will create record after processing
			filesToProcess = append(filesToProcess, &FileToProcess{
				Path:     filePath,
				FileInfo: info,
				File:     file,
			})
		} else if !file.ID.IsZero() {
			// Unchanged file with existing ID - just need snapshot association
			unchangedFileIDs = append(unchangedFileIDs, file.ID)
		}
		filesScanned++
		changedCount := len(filesToProcess)
		mu.Unlock()

		// Update result stats
		s.updateScanEntryStats(result, needsProcessing, info)

		// Output periodic status
		if time.Since(lastStatusTime) >= statusInterval {
			s.printScanProgressLine(filesScanned, changedCount, estimatedTotal, startTime)
			lastStatusTime = time.Now()
		}

		return nil
	})

	if err != nil {
		return nil, err
	}

	return &ScanPhaseResult{
		FilesToProcess:   filesToProcess,
		UnchangedFileIDs: unchangedFileIDs,
	}, nil
}

// updateScanEntryStats updates the scan result and progress reporter statistics
// for a single scanned file entry based on whether it needs processing
func (s *Scanner) updateScanEntryStats(result *ScanResult, needsProcessing bool, info os.FileInfo) {
	if needsProcessing {
		result.BytesScanned += info.Size()
		if s.progress != nil {
			s.progress.GetStats().BytesScanned.Add(info.Size())
		}
	} else {
		result.FilesSkipped++
		result.BytesSkipped += info.Size()
		if s.progress != nil {
			s.progress.GetStats().FilesSkipped.Add(1)
			s.progress.GetStats().BytesSkipped.Add(info.Size())
		}
	}
	result.FilesScanned++
	if s.progress != nil {
		s.progress.GetStats().FilesScanned.Add(1)
	}
}

// printScanProgressLine prints a periodic progress line during the scan phase,
// showing files scanned, percentage complete (if estimate available), and ETA
func (s *Scanner) printScanProgressLine(filesScanned int64, changedCount int, estimatedTotal int64, startTime time.Time) {
	elapsed := time.Since(startTime)
	rate := float64(filesScanned) / elapsed.Seconds()

	if estimatedTotal > 0 {
		// Show actual scanned vs estimate (may exceed estimate if files were added)
		pct := float64(filesScanned) / float64(estimatedTotal) * 100
		if pct > 100 {
			pct = 100 // Cap at 100% for display
		}
		remaining := estimatedTotal - filesScanned
		if remaining < 0 {
			remaining = 0
		}
		var eta time.Duration
		if rate > 0 && remaining > 0 {
			eta = time.Duration(float64(remaining)/rate) * time.Second
		}
		if eta > 0 {
			s.ui.Progress("Snapshot source files enumeration: %s files (~%s), %s changed or new, %.0f files/sec, enumeration elapsed %s, enumeration estimated remaining time (%s), finish at %s.",
				s.ui.Count(int(filesScanned)),
				s.ui.Percent(pct),
				s.ui.Count(changedCount),
				rate,
				s.ui.Duration(elapsed),
				s.ui.Duration(eta),
				s.ui.Time(time.Now().Add(eta)))
		} else {
			s.ui.Progress("Snapshot source files enumeration: %s files (~%s), %s changed or new, %.0f files/sec, enumeration elapsed %s.",
				s.ui.Count(int(filesScanned)),
				s.ui.Percent(pct),
				s.ui.Count(changedCount),
				rate,
				s.ui.Duration(elapsed))
		}
	} else {
		s.ui.Progress("Snapshot source files enumeration: %s files seen, %s changed or new, %.0f files/sec, enumeration elapsed %s.",
			s.ui.Count(int(filesScanned)),
			s.ui.Count(changedCount),
			rate,
			s.ui.Duration(elapsed))
	}
}

// buildSymlinkEntry creates a File record for a symlink.
// Returns nil if the link target cannot be read.
func (s *Scanner) buildSymlinkEntry(path string, info os.FileInfo) *database.File {
	target, err := os.Readlink(path)
	if err != nil {
		log.Debug("Cannot read symlink target", "path", path, "error", err)
		return nil
	}

	var uid, gid uint32
	if stat, ok := info.Sys().(interface {
		Uid() uint32
		Gid() uint32
	}); ok {
		uid = stat.Uid()
		gid = stat.Gid()
	}

	return &database.File{
		ID:         types.NewFileID(),
		Path:       types.FilePath(path),
		SourcePath: types.SourcePath(s.currentSourcePath),
		MTime:      info.ModTime(),
		Size:       0,
		Mode:       uint32(info.Mode()),
		UID:        uid,
		GID:        gid,
		LinkTarget: types.FilePath(target),
	}
}

// buildDirectoryEntry creates a File record for a directory.
func (s *Scanner) buildDirectoryEntry(path string, info os.FileInfo) *database.File {
	var uid, gid uint32
	if stat, ok := info.Sys().(interface {
		Uid() uint32
		Gid() uint32
	}); ok {
		uid = stat.Uid()
		gid = stat.Gid()
	}

	return &database.File{
		ID:         types.NewFileID(),
		Path:       types.FilePath(path),
		SourcePath: types.SourcePath(s.currentSourcePath),
		MTime:      info.ModTime(),
		Size:       0,
		Mode:       uint32(info.Mode()),
		UID:        uid,
		GID:        gid,
	}
}

// recordNonRegularFile writes a symlink or directory entry to the database
// and associates it with the current snapshot. No chunking is performed.
func (s *Scanner) recordNonRegularFile(ctx context.Context, ftp *FileToProcess) error {
	return s.repos.WithTx(ctx, func(txCtx context.Context, tx *sql.Tx) error {
		if err := s.repos.Files.Create(txCtx, tx, ftp.File); err != nil {
			return fmt.Errorf("creating non-regular file record: %w", err)
		}
		return s.repos.Snapshots.AddFileByID(txCtx, tx, s.snapshotID, ftp.File.ID)
	})
}

// checkFileInMemory checks if a file needs processing using the in-memory map
// No database access is performed - this is purely CPU/memory work
func (s *Scanner) checkFileInMemory(path string, info os.FileInfo, knownFiles map[string]*database.File) (*database.File, bool) {
	// Get file stats
	stat, ok := info.Sys().(interface {
		Uid() uint32
		Gid() uint32
	})

	var uid, gid uint32
	if ok {
		uid = stat.Uid()
		gid = stat.Gid()
	}

	// Check against in-memory map first to get existing ID if available
	existingFile, exists := knownFiles[path]

	// Create file record with ID set upfront
	// For new files, generate UUID immediately so it's available for chunk associations
	// For existing files, reuse the existing ID
	var fileID types.FileID
	if exists {
		fileID = existingFile.ID
	} else {
		fileID = types.NewFileID()
	}

	file := &database.File{
		ID:         fileID,
		Path:       types.FilePath(path),
		SourcePath: types.SourcePath(s.currentSourcePath), // Store source directory for restore path stripping
		MTime:      info.ModTime(),
		Size:       info.Size(),
		Mode:       uint32(info.Mode()),
		UID:        uid,
		GID:        gid,
	}

	// New file - needs processing
	if !exists {
		return file, true
	}

	// Check if file has changed
	if existingFile.Size != file.Size ||
		existingFile.MTime.Unix() != file.MTime.Unix() ||
		existingFile.Mode != file.Mode ||
		existingFile.UID != file.UID ||
		existingFile.GID != file.GID {
		return file, true
	}

	// File unchanged
	return file, false
}

// batchAddFilesToSnapshot adds existing file IDs to the snapshot association table
// This is used for unchanged files that already have records in the database
func (s *Scanner) batchAddFilesToSnapshot(ctx context.Context, fileIDs []types.FileID) error {
	const batchSize = 1000

	startTime := time.Now()
	lastStatusTime := time.Now()
	statusInterval := 5 * time.Second

	for i := 0; i < len(fileIDs); i += batchSize {
		// Check context cancellation
		select {
		case <-ctx.Done():
			return ctx.Err()
		default:
		}

		end := i + batchSize
		if end > len(fileIDs) {
			end = len(fileIDs)
		}
		batch := fileIDs[i:end]

		err := s.repos.WithTx(ctx, func(ctx context.Context, tx *sql.Tx) error {
			for _, fileID := range batch {
				if err := s.repos.Snapshots.AddFileByID(ctx, tx, s.snapshotID, fileID); err != nil {
					return fmt.Errorf("adding file to snapshot: %w", err)
				}
			}
			return nil
		})
		if err != nil {
			return err
		}

		// Periodic status
		if time.Since(lastStatusTime) >= statusInterval {
			elapsed := time.Since(startTime)
			rate := float64(end) / elapsed.Seconds()
			pct := float64(end) / float64(len(fileIDs)) * 100
			s.ui.Progress("Snapshot unchanged-file association: %s/%s (%s), %.0f files/sec.",
				s.ui.Count(end), s.ui.Count(len(fileIDs)), s.ui.Percent(pct), rate)
			lastStatusTime = time.Now()
		}
	}

	elapsed := time.Since(startTime)
	rate := float64(len(fileIDs)) / elapsed.Seconds()
	s.ui.Complete("Associated %s unchanged files with the snapshot in %s (%.0f files/sec).",
		s.ui.Count(len(fileIDs)), s.ui.Duration(elapsed), rate)

	return nil
}

// processPhase processes the files that need backing up
func (s *Scanner) processPhase(ctx context.Context, filesToProcess []*FileToProcess, result *ScanResult) error {
	// Calculate total bytes to process
	var totalBytes int64
	for _, f := range filesToProcess {
		totalBytes += f.FileInfo.Size()
	}

	// Set up periodic status output
	lastStatusTime := time.Now()
	statusInterval := 15 * time.Second
	startTime := time.Now()
	filesProcessed := 0
	var bytesProcessed int64
	totalFiles := len(filesToProcess)

	// Process each file
	for _, fileToProcess := range filesToProcess {
		// Update progress
		if s.progress != nil {
			s.progress.GetStats().CurrentFile.Store(fileToProcess.Path)
		}

		// Process file with error handling for deleted files and skip-errors mode
		skipped, err := s.processFileWithErrorHandling(ctx, fileToProcess, result)
		if err != nil {
			return err
		}
		if skipped {
			continue
		}

		// Update files processed counter
		if s.progress != nil {
			s.progress.GetStats().FilesProcessed.Add(1)
		}

		filesProcessed++
		bytesProcessed += fileToProcess.FileInfo.Size()

		// Output periodic status
		if time.Since(lastStatusTime) >= statusInterval {
			s.printProcessingProgress(filesProcessed, totalFiles, bytesProcessed, totalBytes, startTime)
			lastStatusTime = time.Now()
		}
	}

	// Finalize: flush packer, pending files, and handle local blobs
	return s.finalizeProcessPhase(ctx, result)
}

// processFileWithErrorHandling wraps processFileStreaming with error recovery for
// deleted files and skip-errors mode. Returns (skipped, error).
func (s *Scanner) processFileWithErrorHandling(ctx context.Context, fileToProcess *FileToProcess, result *ScanResult) (bool, error) {
	if err := s.processFileStreaming(ctx, fileToProcess, result); err != nil {
		// Handle files that were deleted between scan and process phases
		if errors.Is(err, os.ErrNotExist) {
			log.Warn("File was deleted during backup, skipping", "path", fileToProcess.Path)
			result.FilesSkipped++
			return true, nil
		}
		// Skip file read errors if --skip-errors is enabled
		if s.skipErrors {
			log.Error("Failed to process file (skipping due to --skip-errors)", "path", fileToProcess.Path, "error", err)
			s.ui.Error("Failed to process %s: %v. Skipping (--skip-errors).", s.ui.Path(fileToProcess.Path), err)
			result.FilesSkipped++
			return true, nil
		}
		return false, fmt.Errorf("processing file %s: %w", fileToProcess.Path, err)
	}
	return false, nil
}

// printProcessingProgress prints a periodic progress line during the process phase,
// showing files processed, bytes transferred, throughput, and ETA
func (s *Scanner) printProcessingProgress(filesProcessed, totalFiles int, bytesProcessed, totalBytes int64, startTime time.Time) {
	elapsed := time.Since(startTime)
	pct := float64(bytesProcessed) / float64(totalBytes) * 100
	byteRate := float64(bytesProcessed) / elapsed.Seconds()
	fileRate := float64(filesProcessed) / elapsed.Seconds()

	// Calculate ETA based on bytes (more accurate than files)
	remainingBytes := totalBytes - bytesProcessed
	var eta time.Duration
	if byteRate > 0 {
		eta = time.Duration(float64(remainingBytes)/byteRate) * time.Second
	}

	if eta > 0 {
		s.ui.Progress("Snapshot file processing: %s/%s files (%s), %s/%s, %s, %.0f files/sec, processing elapsed %s, processing estimated remaining time (%s), finish at %s.",
			s.ui.Count(filesProcessed),
			s.ui.Count(totalFiles),
			s.ui.Percent(pct),
			s.ui.Size(bytesProcessed),
			s.ui.Size(totalBytes),
			s.ui.Speed(byteRate),
			fileRate,
			s.ui.Duration(elapsed),
			s.ui.Duration(eta),
			s.ui.Time(time.Now().Add(eta)))
	} else {
		s.ui.Progress("Snapshot file processing: %s/%s files (%s), %s/%s, %s, %.0f files/sec, processing elapsed %s.",
			s.ui.Count(filesProcessed),
			s.ui.Count(totalFiles),
			s.ui.Percent(pct),
			s.ui.Size(bytesProcessed),
			s.ui.Size(totalBytes),
			s.ui.Speed(byteRate),
			fileRate,
			s.ui.Duration(elapsed))
	}
}

// finalizeProcessPhase flushes the packer, writes remaining pending files to the database,
// and handles local blob storage when no remote storage is configured
func (s *Scanner) finalizeProcessPhase(ctx context.Context, result *ScanResult) error {
	// Final packer flush first - this commits remaining chunks to DB
	// and handleBlobReady will flush files whose chunks are now committed
	s.packerMu.Lock()
	if err := s.packer.Flush(); err != nil {
		s.packerMu.Unlock()
		return fmt.Errorf("flushing packer: %w", err)
	}
	s.packerMu.Unlock()

	// Flush any remaining pending files (e.g., files with only pre-existing chunks
	// that didn't trigger a blob finalize)
	if err := s.flushAllPending(ctx); err != nil {
		return fmt.Errorf("flushing remaining pending files: %w", err)
	}

	// If no storage configured, store any remaining blobs locally
	if s.storage == nil {
		blobs := s.packer.GetFinishedBlobs()
		for _, b := range blobs {
			// Blob metadata is already stored incrementally during packing
			// Just add the blob to the snapshot
			blobID, err := types.ParseBlobID(b.ID)
			if err != nil {
				return fmt.Errorf("parsing blob ID: %w", err)
			}
			err = s.repos.WithTx(ctx, func(ctx context.Context, tx *sql.Tx) error {
				return s.repos.Snapshots.AddBlob(ctx, tx, s.snapshotID, blobID, types.BlobHash(b.Hash))
			})
			if err != nil {
				return fmt.Errorf("storing blob metadata: %w", err)
			}
		}
		result.BlobsCreated += len(blobs)
	}

	return nil
}

// handleBlobReady is called by the packer when a blob is finalized
func (s *Scanner) handleBlobReady(blobWithReader *blob.BlobWithReader) error {
	startTime := time.Now().UTC()
	finishedBlob := blobWithReader.FinishedBlob

	if s.progress != nil {
		s.progress.ReportUploadStart(finishedBlob.Hash, finishedBlob.Compressed)
		s.progress.GetStats().BlobsCreated.Add(1)
	}

	ctx := s.scanCtx
	if ctx == nil {
		ctx = context.Background()
	}

	blobPath := fmt.Sprintf("blobs/%s/%s/%s", finishedBlob.Hash[:2], finishedBlob.Hash[2:4], finishedBlob.Hash)
	blobExists, err := s.uploadBlobIfNeeded(ctx, blobPath, blobWithReader, startTime)
	if err != nil {
		s.cleanupBlobTempFile(blobWithReader)
		return fmt.Errorf("uploading blob %s: %w", finishedBlob.Hash, err)
	}

	if err := s.recordBlobMetadata(ctx, finishedBlob, blobExists, startTime); err != nil {
		s.cleanupBlobTempFile(blobWithReader)
		return err
	}

	s.cleanupBlobTempFile(blobWithReader)

	// Chunks from this blob are now committed to DB - remove from pending set
	s.removePendingChunkHashes(blobWithReader.InsertedChunkHashes)

	// Flush files whose chunks are now all committed
	if err := s.flushCompletedPendingFiles(ctx); err != nil {
		return fmt.Errorf("flushing completed files: %w", err)
	}

	return nil
}

// uploadBlobIfNeeded uploads the blob to storage if it doesn't already exist, returns whether it existed
func (s *Scanner) uploadBlobIfNeeded(ctx context.Context, blobPath string, blobWithReader *blob.BlobWithReader, startTime time.Time) (bool, error) {
	finishedBlob := blobWithReader.FinishedBlob

	// Check if blob already exists (deduplication after restart)
	if _, err := s.storage.Stat(ctx, blobPath); err == nil {
		log.Info("Blob already exists in storage, skipping upload",
			"hash", finishedBlob.Hash, "size", humanize.Bytes(uint64(finishedBlob.Compressed)))
		s.ui.Info("Blob %s (%s) already exists in backup destination store. Skipping upload.",
			s.ui.Hex(finishedBlob.Hash), s.ui.Size(finishedBlob.Compressed))
		return true, nil
	}

	s.ui.Begin("Uploading blob %s (%s) to backup destination store.",
		s.ui.Hex(finishedBlob.Hash), s.ui.Size(finishedBlob.Compressed))

	progressCallback := s.makeUploadProgressCallback(ctx, finishedBlob, startTime)

	if err := s.storage.PutWithProgress(ctx, blobPath, blobWithReader.Reader, finishedBlob.Compressed, progressCallback); err != nil {
		log.Error("Failed to upload blob", "hash", finishedBlob.Hash, "error", err)
		return false, fmt.Errorf("uploading blob to storage: %w", err)
	}

	uploadDuration := time.Since(startTime)
	uploadSpeedBps := float64(finishedBlob.Compressed) / uploadDuration.Seconds()

	s.ui.Complete("Uploaded blob %s (%s) in %s at %s.",
		s.ui.Hex(finishedBlob.Hash),
		s.ui.Size(finishedBlob.Compressed),
		s.ui.Duration(uploadDuration),
		s.ui.Speed(uploadSpeedBps))

	log.Info("Successfully uploaded blob to storage",
		"path", blobPath,
		"size", humanize.Bytes(uint64(finishedBlob.Compressed)),
		"duration", uploadDuration,
		"speed", humanize.SI(uploadSpeedBps*8, "bps"))

	if s.progress != nil {
		s.progress.ReportUploadComplete(finishedBlob.Hash, finishedBlob.Compressed, uploadDuration)
		stats := s.progress.GetStats()
		stats.BlobsUploaded.Add(1)
		stats.BytesUploaded.Add(finishedBlob.Compressed)
	}

	return false, nil
}

// makeUploadProgressCallback creates a progress callback for blob uploads.
// It updates the live progress reporter ~twice/sec for ETAs and prints a
// human-readable status line to s.output at most every 15 seconds.
func (s *Scanner) makeUploadProgressCallback(ctx context.Context, finishedBlob *blob.FinishedBlob, uploadStart time.Time) func(int64) error {
	lastProgressTime := time.Now()
	lastProgressBytes := int64(0)
	lastStdoutTime := time.Now()
	const stdoutInterval = 15 * time.Second

	return func(uploaded int64) error {
		now := time.Now()
		elapsed := now.Sub(lastProgressTime).Seconds()
		if elapsed > 0.5 {
			bytesSinceLastUpdate := uploaded - lastProgressBytes
			speed := float64(bytesSinceLastUpdate) / elapsed
			if s.progress != nil {
				s.progress.ReportUploadProgress(finishedBlob.Hash, uploaded, finishedBlob.Compressed, speed)
			}
			lastProgressTime = now
			lastProgressBytes = uploaded
		}

		// Periodic stdout status line so the user knows the upload is alive.
		if now.Sub(lastStdoutTime) >= stdoutInterval {
			totalElapsed := now.Sub(uploadStart)
			pct := float64(uploaded) / float64(finishedBlob.Compressed) * 100
			avgSpeed := float64(uploaded) / totalElapsed.Seconds()
			var eta time.Duration
			if avgSpeed > 0 {
				eta = time.Duration(float64(finishedBlob.Compressed-uploaded)/avgSpeed) * time.Second
			}
			s.ui.Progress("Blob upload %s: %s / %s (%s) at %s, blob upload elapsed %s, blob upload estimated remaining time (%s), finish at %s.",
				s.ui.Hex(finishedBlob.Hash),
				s.ui.Size(uploaded),
				s.ui.Size(finishedBlob.Compressed),
				s.ui.Percent(pct),
				s.ui.Speed(avgSpeed),
				s.ui.Duration(totalElapsed),
				s.ui.Duration(eta),
				s.ui.Time(now.Add(eta)))
			lastStdoutTime = now
		}

		select {
		case <-ctx.Done():
			return ctx.Err()
		default:
			return nil
		}
	}
}

// recordBlobMetadata stores blob upload metadata in the database
func (s *Scanner) recordBlobMetadata(ctx context.Context, finishedBlob *blob.FinishedBlob, blobExists bool, startTime time.Time) error {
	finishedBlobID, err := types.ParseBlobID(finishedBlob.ID)
	if err != nil {
		return fmt.Errorf("parsing finished blob ID: %w", err)
	}

	uploadDuration := time.Since(startTime)

	return s.repos.WithTx(ctx, func(txCtx context.Context, tx *sql.Tx) error {
		if err := s.repos.Blobs.UpdateUploaded(txCtx, tx, finishedBlob.ID); err != nil {
			return fmt.Errorf("updating blob upload timestamp: %w", err)
		}

		if err := s.repos.Snapshots.AddBlob(txCtx, tx, s.snapshotID, finishedBlobID, types.BlobHash(finishedBlob.Hash)); err != nil {
			return fmt.Errorf("adding blob to snapshot: %w", err)
		}

		if !blobExists {
			upload := &database.Upload{
				BlobHash:   finishedBlob.Hash,
				SnapshotID: s.snapshotID,
				UploadedAt: startTime,
				Size:       finishedBlob.Compressed,
				DurationMs: uploadDuration.Milliseconds(),
			}
			if err := s.repos.Uploads.Create(txCtx, tx, upload); err != nil {
				return fmt.Errorf("recording upload metrics: %w", err)
			}
		}

		return nil
	})
}

// cleanupBlobTempFile closes and removes the blob's temporary file
func (s *Scanner) cleanupBlobTempFile(blobWithReader *blob.BlobWithReader) {
	if blobWithReader.TempFile != nil {
		tempName := blobWithReader.TempFile.Name()
		if err := blobWithReader.TempFile.Close(); err != nil {
			log.Fatal("Failed to close temp file", "file", tempName, "error", err)
		}
		if err := s.fs.Remove(tempName); err != nil {
			log.Fatal("Failed to remove temp file", "file", tempName, "error", err)
		}
	}
}

// streamingChunkInfo tracks chunk metadata collected during streaming
type streamingChunkInfo struct {
	fileChunk database.FileChunk
	offset    int64
	size      int64
}

// processFileStreaming processes a file by streaming chunks directly to the packer
func (s *Scanner) processFileStreaming(ctx context.Context, fileToProcess *FileToProcess, result *ScanResult) error {
	// Symlinks and directories have no data to chunk — just record them in the DB.
	mode := os.FileMode(fileToProcess.File.Mode)
	if mode&os.ModeSymlink != 0 || mode.IsDir() {
		return s.recordNonRegularFile(ctx, fileToProcess)
	}

	file, err := s.fs.Open(fileToProcess.Path)
	if err != nil {
		return fmt.Errorf("opening file: %w", wrapPermissionError(fileToProcess.Path, err))
	}
	defer func() { _ = file.Close() }()

	var chunks []streamingChunkInfo
	chunkIndex := 0

	fileHash, err := s.chunker.ChunkReaderStreaming(file, func(chunk chunker.Chunk) error {
		select {
		case <-ctx.Done():
			return ctx.Err()
		default:
		}

		chunkExists := s.chunkExists(chunk.Hash)
		if !chunkExists {
			s.packer.AddPendingChunk(chunk.Hash, chunk.Size)
			s.addKnownChunk(chunk.Hash)
			s.addPendingChunkHash(chunk.Hash)
		}

		chunks = append(chunks, streamingChunkInfo{
			fileChunk: database.FileChunk{
				FileID:    fileToProcess.File.ID,
				Idx:       chunkIndex,
				ChunkHash: types.ChunkHash(chunk.Hash),
			},
			offset: chunk.Offset,
			size:   chunk.Size,
		})

		s.updateChunkStats(chunkExists, chunk.Size, result)

		if !chunkExists {
			if err := s.addChunkToPacker(chunk); err != nil {
				return err
			}
		}

		chunk.Data = nil
		chunkIndex++
		return nil
	})

	if err != nil {
		return fmt.Errorf("chunking file: %w", err)
	}

	log.Debug("Completed snapshotting file",
		"path", fileToProcess.Path, "file_hash", fileHash, "chunks", len(chunks))

	s.queueFileForBatchInsert(ctx, fileToProcess, chunks)
	return nil
}

// updateChunkStats updates scan result and progress stats for a processed chunk
func (s *Scanner) updateChunkStats(chunkExists bool, chunkSize int64, result *ScanResult) {
	if chunkExists {
		result.FilesSkipped++
		result.BytesSkipped += chunkSize
		if s.progress != nil {
			s.progress.GetStats().BytesSkipped.Add(chunkSize)
		}
	} else {
		result.ChunksCreated++
		result.BytesScanned += chunkSize
		if s.progress != nil {
			s.progress.GetStats().ChunksCreated.Add(1)
			s.progress.GetStats().BytesProcessed.Add(chunkSize)
			s.progress.UpdateChunkingActivity()
		}
	}
}

// addChunkToPacker adds a chunk to the blob packer, finalizing the current blob if needed
func (s *Scanner) addChunkToPacker(chunk chunker.Chunk) error {
	s.packerMu.Lock()
	err := s.packer.AddChunk(&blob.ChunkRef{Hash: chunk.Hash, Data: chunk.Data})
	if err == blob.ErrBlobSizeLimitExceeded {
		if err := s.packer.FinalizeBlob(); err != nil {
			s.packerMu.Unlock()
			return fmt.Errorf("finalizing blob: %w", err)
		}
		if err := s.packer.AddChunk(&blob.ChunkRef{Hash: chunk.Hash, Data: chunk.Data}); err != nil {
			s.packerMu.Unlock()
			return fmt.Errorf("adding chunk after finalize: %w", err)
		}
	} else if err != nil {
		s.packerMu.Unlock()
		return fmt.Errorf("adding chunk to packer: %w", err)
	}
	s.packerMu.Unlock()
	return nil
}

// queueFileForBatchInsert builds file/chunk associations and queues the file for batch DB insert
func (s *Scanner) queueFileForBatchInsert(ctx context.Context, fileToProcess *FileToProcess, chunks []streamingChunkInfo) {
	fileChunks := make([]database.FileChunk, len(chunks))
	chunkFiles := make([]database.ChunkFile, len(chunks))
	for i, ci := range chunks {
		fileChunks[i] = database.FileChunk{
			FileID:    fileToProcess.File.ID,
			Idx:       ci.fileChunk.Idx,
			ChunkHash: ci.fileChunk.ChunkHash,
		}
		chunkFiles[i] = database.ChunkFile{
			ChunkHash:  ci.fileChunk.ChunkHash,
			FileID:     fileToProcess.File.ID,
			FileOffset: ci.offset,
			Length:     ci.size,
		}
	}

	s.addPendingFile(ctx, pendingFileData{
		file:       fileToProcess.File,
		fileChunks: fileChunks,
		chunkFiles: chunkFiles,
	})
}

// GetProgress returns the progress reporter for this scanner
func (s *Scanner) GetProgress() *ProgressReporter {
	return s.progress
}

// detectDeletedFilesFromMap finds files that existed in previous snapshots but no longer exist
// Uses pre-loaded maps to avoid any filesystem or database access
func (s *Scanner) detectDeletedFilesFromMap(ctx context.Context, knownFiles map[string]*database.File, existingFiles map[string]struct{}, result *ScanResult) error {
	if len(knownFiles) == 0 {
		return nil
	}

	// Check each known file against the enumerated set (no filesystem access needed)
	for path, file := range knownFiles {
		// Check context cancellation periodically
		select {
		case <-ctx.Done():
			return ctx.Err()
		default:
		}

		// Check if the file exists in our enumerated set
		if _, exists := existingFiles[path]; !exists {
			// File has been deleted
			result.FilesDeleted++
			result.BytesDeleted += file.Size
			log.Debug("Detected deleted file", "path", path, "size", file.Size)
		}
	}

	if result.FilesDeleted > 0 {
		s.ui.Info("Snapshot source files enumeration detected %s deleted files.", s.ui.Count(result.FilesDeleted))
	}

	return nil
}

// wrapPermissionError augments permission errors with platform-specific
// remediation instructions. On macOS, TCC-protected directories (Calendars,
// Reminders, Photos, etc.) return EPERM unless the running application has
// been granted Full Disk Access.
func wrapPermissionError(path string, err error) error {
	if !errors.Is(err, os.ErrPermission) {
		return err
	}
	if runtime.GOOS == "darwin" {
		return fmt.Errorf("cannot read %s: %w\n\n"+
			"macOS is blocking access to this path. Grant Full Disk Access to your\n"+
			"terminal application (or the app running vaultik):\n\n"+
			"  System Settings → Privacy & Security → Full Disk Access\n\n"+
			"then quit and reopen the terminal and re-run the backup", path, err)
	}
	return fmt.Errorf("cannot read %s: %w (check file permissions, or run with --skip-errors to continue past unreadable files)", path, err)
}

// compileExcludePatterns compiles the exclude patterns into glob matchers
func compileExcludePatterns(patterns []string) []compiledPattern {
	var compiled []compiledPattern
	for _, p := range patterns {
		if p == "" {
			continue
		}

		// Check if pattern is anchored (starts with /)
		anchored := strings.HasPrefix(p, "/")
		pattern := p
		if anchored {
			pattern = p[1:] // Remove leading /
		}

		// Remove trailing slash if present (directory indicator)
		pattern = strings.TrimSuffix(pattern, "/")

		// Compile the glob pattern
		// For patterns without path separators, we need to match them as components
		// e.g., ".git" should match ".git" anywhere in the path
		g, err := glob.Compile(pattern, '/')
		if err != nil {
			log.Warn("Invalid exclude pattern, skipping", "pattern", p, "error", err)
			continue
		}

		compiled = append(compiled, compiledPattern{
			pattern:  g,
			anchored: anchored,
			original: p,
		})
	}
	return compiled
}

// shouldExclude checks if a path should be excluded based on exclude patterns
// filePath is the full path to the file
// rootPath is the root of the backup source directory
func (s *Scanner) shouldExclude(filePath, rootPath string) bool {
	if len(s.compiledExclude) == 0 {
		return false
	}

	// Get the relative path from root
	relPath, err := filepath.Rel(rootPath, filePath)
	if err != nil {
		return false
	}

	// Never exclude the root directory itself
	if relPath == "." {
		return false
	}

	// Normalize path separators
	relPath = filepath.ToSlash(relPath)

	// Check each pattern
	for _, cp := range s.compiledExclude {
		if cp.anchored {
			// Anchored pattern: must match from the root
			// Match the relative path directly
			if cp.pattern.Match(relPath) {
				return true
			}
			// Also check if any prefix of the path matches (for directory patterns)
			parts := strings.Split(relPath, "/")
			for i := 1; i <= len(parts); i++ {
				prefix := strings.Join(parts[:i], "/")
				if cp.pattern.Match(prefix) {
					return true
				}
			}
		} else {
			// Unanchored pattern: can match anywhere in path
			// Check the full relative path
			if cp.pattern.Match(relPath) {
				return true
			}
			// Check each path component and subpath
			parts := strings.Split(relPath, "/")
			for i := range parts {
				// Match individual component (e.g., ".git" matches ".git" directory)
				if cp.pattern.Match(parts[i]) {
					return true
				}
				// Match subpath from this component onwards
				subpath := strings.Join(parts[i:], "/")
				if cp.pattern.Match(subpath) {
					return true
				}
			}
		}
	}

	return false
}