warpbox-dev/backend/libs/jobs/thumbnails.go

package jobs

import (
	"archive/zip"
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"html"
	"image"
	"image/color"
	"image/draw"
	_ "image/gif"
	"image/jpeg"
	_ "image/png"
	"io"
	"log/slog"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"sort"
	"strconv"
	"strings"
	"sync"
	"time"

	"golang.org/x/image/font"
	"golang.org/x/image/font/basicfont"
	"golang.org/x/image/math/fixed"
	_ "golang.org/x/image/webp"
	"warpbox.dev/backend/libs/config"
	"warpbox.dev/backend/libs/services"
)

type ThumbnailJobResult struct {
	Scanned   int
	Generated int
	Failed    int
}

var thumbnailJobs sync.WaitGroup

func GenerateThumbnailsForBoxAsync(uploadService *services.UploadService, logger *slog.Logger, boxID string) {
	thumbnailJobs.Add(1)
	go func() {
		defer thumbnailJobs.Done()
		box, err := uploadService.GetBox(boxID)
		if err != nil {
			logger.Warn("thumbnail box lookup failed", "source", "thumbnail", "severity", "warn", "code", 4204, "box_id", boxID, "error", err.Error())
			return
		}
		if services.BoxHasTrouble(box) {
			logger.Warn("thumbnail one-shot skipped trouble box", "source", "thumbnail", "severity", "warn", "code", 4206, "box_id", boxID, "error", services.BoxTroubleReason(box))
			return
		}

		result, err := generateMissingThumbnailsForBox(uploadService, logger, box)
		if err != nil {
			logger.Warn("thumbnail one-shot job failed", "source", "thumbnail", "severity", "warn", "code", 4205, "box_id", boxID, "error", err.Error())
			return
		}
		if result.Generated > 0 || result.Failed > 0 {
			logger.Info("thumbnail one-shot job complete", "source", "thumbnail", "severity", "user_activity", "code", 2205, "box_id", boxID, "generated", result.Generated, "failed", result.Failed)
		}
	}()
}

func WaitForThumbnailJobs() {
	thumbnailJobs.Wait()
}

func newThumbnailsJob(cfg config.Config, logger *slog.Logger, uploadService *services.UploadService) job {
	return job{
		name:     "thumbnail",
		enabled:  cfg.ThumbnailEnabled,
		interval: cfg.ThumbnailEvery,
		run: func() {
			result, err := generateMissingThumbnails(uploadService, logger)
			if err != nil {
				logger.Warn("thumbnail job failed", "source", "thumbnail", "severity", "warn", "code", 4203, "error", err.Error())
				return
			}
			if result.Generated > 0 || result.Failed > 0 {
				logger.Info("thumbnail job complete", "source", "thumbnail", "severity", "user_activity", "code", 2204, "generated", result.Generated, "failed", result.Failed)
			}
		},
	}
}

func RunThumbnailsNow(uploadService *services.UploadService, logger *slog.Logger) (ThumbnailJobResult, error) {
	return generateMissingThumbnails(uploadService, logger)
}

func generateMissingThumbnails(uploadService *services.UploadService, logger *slog.Logger) (ThumbnailJobResult, error) {
	boxes, err := uploadService.ListBoxes(0)
	if err != nil {
		return ThumbnailJobResult{}, err
	}

	var result ThumbnailJobResult
	now := time.Now().UTC()
	for _, box := range boxes {
		if !box.ExpiresAt.After(now) {
			continue
		}
		if services.BoxHasTrouble(box) {
			continue
		}

		boxResult, err := generateMissingThumbnailsForBox(uploadService, logger, box)
		result.Scanned += boxResult.Scanned
		result.Generated += boxResult.Generated
		result.Failed += boxResult.Failed
		if err != nil {
			return result, err
		}
	}

	return result, nil
}

func generateMissingThumbnailsForBox(uploadService *services.UploadService, logger *slog.Logger, box services.Box) (ThumbnailJobResult, error) {
	var result ThumbnailJobResult
	if !box.ExpiresAt.After(time.Now().UTC()) {
		return result, nil
	}
	if services.BoxHasTrouble(box) {
		return result, nil
	}

	changed := false
	for i := range box.Files {
		file := &box.Files[i]
		if file.Processing || services.FileHasTrouble(*file) {
			continue
		}
		needsPrimary := file.Thumbnail == "" && needsThumbnail(*file)
		needsScenes := file.SceneThumbnail == "" && needsVideoScenes(*file)
		needsArchive := !archiveListingCurrent(*file) && needsArchiveListing(*file)
		if !needsPrimary && !needsScenes && !needsArchive {
			continue
		}
		result.Scanned++

		if needsPrimary {
			thumbnail, err := generateThumbnail(uploadService, box, *file)
			if err != nil {
				logger.Warn("thumbnail generation failed", "source", "thumbnail", "severity", "warn", "code", 4101, "file_id", file.ID, "error", err.Error())
				result.Failed++
			} else if thumbnail == "" {
				result.Failed++
			} else {
				file.Thumbnail = thumbnail
				changed = true
				result.Generated++
			}
		}

		if needsScenes {
			sceneThumbnail, err := generateVideoScenesThumbnail(uploadService, box, *file)
			if err != nil {
				logger.Warn("video scenes preview generation failed", "source", "thumbnail", "severity", "warn", "code", 4104, "file_id", file.ID, "error", err.Error())
				result.Failed++
			} else if sceneThumbnail == "" {
				result.Failed++
			} else {
				file.SceneThumbnail = sceneThumbnail
				changed = true
				result.Generated++
			}
		}

		if needsArchive {
			archiveListing, err := generateArchiveListing(uploadService, box, *file)
			if err != nil {
				logger.Warn("archive listing generation failed", "source", "thumbnail", "severity", "warn", "code", 4107, "file_id", file.ID, "error", err.Error())
				result.Failed++
			} else if archiveListing == "" {
				result.Failed++
			} else {
				file.ArchiveListing = archiveListing
				file.ArchiveListingObjectKey = ""
				changed = true
				result.Generated++
			}
		}
	}

	if changed {
		if err := uploadService.SaveBox(box); err != nil {
			return result, err
		}
	}
	return result, nil
}

func needsThumbnail(file services.File) bool {
	return file.PreviewKind == "image" || file.PreviewKind == "video" || isTextThumbnailCandidate(file)
}

func needsVideoScenes(file services.File) bool {
	return file.PreviewKind == "video" || strings.HasPrefix(strings.ToLower(file.ContentType), "video/")
}

func NeedsThumbnail(file services.File) bool {
	return needsThumbnail(file)
}

func NeedsVideoScenes(file services.File) bool {
	return needsVideoScenes(file)
}

func NeedsArchiveListing(file services.File) bool {
	return needsArchiveListing(file)
}

func GenerateThumbnailForFile(uploadService *services.UploadService, box services.Box, file services.File) (string, error) {
	return generateThumbnail(uploadService, box, file)
}

func GenerateVideoScenesForFile(uploadService *services.UploadService, box services.Box, file services.File) (string, error) {
	return generateVideoScenesThumbnail(uploadService, box, file)
}

func GenerateArchiveListingForFile(uploadService *services.UploadService, box services.Box, file services.File) (string, error) {
	return generateArchiveListing(uploadService, box, file)
}

func generateThumbnail(uploadService *services.UploadService, box services.Box, file services.File) (string, error) {
	if services.BoxHasTrouble(box) {
		return "", fmt.Errorf("box is marked as trouble: %s", services.BoxTroubleReason(box))
	}
	if file.Processing {
		return "", fmt.Errorf("file is still processing")
	}
	if services.FileHasTrouble(file) {
		return "", fmt.Errorf("file processing failed: %s", file.ProcessingError)
	}
	thumbnailName := "@thumb@" + file.ID + ".jpg"
	object, err := uploadService.OpenFileObject(context.Background(), box, file)
	if err != nil {
		return "", err
	}
	defer object.Body.Close()

	switch {
	case strings.HasPrefix(file.ContentType, "image/"):
		data, err := createImageThumbnail(object.Body)
		if err != nil {
			return "", err
		}
		_, err = uploadService.PutThumbnailObject(context.Background(), box, thumbnailName, bytes.NewReader(data), int64(len(data)), "image/jpeg")
		return thumbnailName, err
	case strings.HasPrefix(file.ContentType, "video/"):
		data, err := createVideoThumbnail(object.Body)
		if err != nil {
			return "", err
		}
		_, err = uploadService.PutThumbnailObject(context.Background(), box, thumbnailName, bytes.NewReader(data), int64(len(data)), "image/jpeg")
		return thumbnailName, err
	case isTextThumbnailCandidate(file):
		data, err := createTextThumbnail(file, object.Body)
		if err != nil {
			return "", err
		}
		_, err = uploadService.PutThumbnailObject(context.Background(), box, thumbnailName, bytes.NewReader(data), int64(len(data)), "image/jpeg")
		return thumbnailName, err
	default:
		return "", nil
	}
}

func generateVideoScenesThumbnail(uploadService *services.UploadService, box services.Box, file services.File) (string, error) {
	if !needsVideoScenes(file) {
		return "", nil
	}
	if services.BoxHasTrouble(box) {
		return "", fmt.Errorf("box is marked as trouble: %s", services.BoxTroubleReason(box))
	}
	if file.Processing {
		return "", fmt.Errorf("file is still processing")
	}
	if services.FileHasTrouble(file) {
		return "", fmt.Errorf("file processing failed: %s", file.ProcessingError)
	}
	sceneName := "@scene@" + file.ID + ".jpg"
	object, err := uploadService.OpenFileObject(context.Background(), box, file)
	if err != nil {
		return "", err
	}
	defer object.Body.Close()

	data, err := createVideoScenesThumbnail(file, object.Body)
	if err != nil {
		return "", err
	}
	_, err = uploadService.PutThumbnailObject(context.Background(), box, sceneName, bytes.NewReader(data), int64(len(data)), "image/jpeg")
	return sceneName, err
}

func generateArchiveListing(uploadService *services.UploadService, box services.Box, file services.File) (string, error) {
	if !needsArchiveListing(file) {
		return "", nil
	}
	if services.BoxHasTrouble(box) {
		return "", fmt.Errorf("box is marked as trouble: %s", services.BoxTroubleReason(box))
	}
	if file.Processing {
		return "", fmt.Errorf("file is still processing")
	}
	if services.FileHasTrouble(file) {
		return "", fmt.Errorf("file processing failed: %s", file.ProcessingError)
	}
	listingName := "@archive@" + file.ID + ".json"
	object, err := uploadService.OpenFileObject(context.Background(), box, file)
	if err != nil {
		return "", err
	}
	defer object.Body.Close()

	data, err := createArchiveListing(file, object.Body)
	if err != nil {
		return "", err
	}
	_, err = uploadService.PutThumbnailObject(context.Background(), box, listingName, bytes.NewReader(data), int64(len(data)), "application/json")
	return listingName, err
}

func isTextThumbnailCandidate(file services.File) bool {
	contentType := strings.ToLower(strings.TrimSpace(file.ContentType))
	if i := strings.IndexByte(contentType, ';'); i >= 0 {
		contentType = strings.TrimSpace(contentType[:i])
	}
	if strings.HasPrefix(contentType, "text/") {
		return true
	}
	switch contentType {
	case "application/json", "application/ld+json", "application/xml", "application/javascript", "application/x-javascript", "application/markdown":
		return true
	}
	ext := strings.TrimPrefix(strings.ToLower(filepath.Ext(file.Name)), ".")
	switch ext {
	case "c", "cc", "conf", "cpp", "cs", "css", "csv", "diff", "dockerfile", "go", "h", "hpp", "htm", "html", "ini", "java", "js", "json", "jsx", "kt", "log", "lua", "md", "mdown", "markdown", "php", "pl", "properties", "py", "rb", "rs", "sh", "sql", "swift", "toml", "ts", "tsx", "txt", "xml", "yaml", "yml", "zig":
		return true
	default:
		return false
	}
}

func needsArchiveListing(file services.File) bool {
	contentType := strings.ToLower(strings.TrimSpace(file.ContentType))
	if i := strings.IndexByte(contentType, ';'); i >= 0 {
		contentType = strings.TrimSpace(contentType[:i])
	}
	switch contentType {
	case "application/zip", "application/x-zip-compressed", "application/java-archive", "application/vnd.android.package-archive", "application/epub+zip":
		return true
	}
	ext := strings.TrimPrefix(strings.ToLower(filepath.Ext(file.Name)), ".")
	switch ext {
	case "zip", "jar", "war", "ear", "apk", "epub", "docx", "xlsx", "pptx":
		return true
	default:
		return false
	}
}

func archiveListingCurrent(file services.File) bool {
	return strings.ToLower(filepath.Ext(file.ArchiveListing)) == ".json"
}

type archiveTreeNode struct {
	Name     string                      `json:"name"`
	Size     uint64                      `json:"size,omitempty"`
	Dir      bool                        `json:"dir"`
	Icon     string                      `json:"icon,omitempty"`
	Children map[string]*archiveTreeNode `json:"-"`
	Items    []*archiveTreeNode          `json:"items,omitempty"`
}

type archiveListingData struct {
	Name             string           `json:"name"`
	Type             string           `json:"type"`
	FileCount        int              `json:"fileCount"`
	FolderCount      int              `json:"folderCount"`
	UncompressedSize uint64           `json:"uncompressedSize"`
	Root             *archiveTreeNode `json:"root"`
}

func createArchiveListing(file services.File, source io.Reader) ([]byte, error) {
	sourceFile, err := os.CreateTemp("", "warpbox-archive-*")
	if err != nil {
		return nil, err
	}
	defer os.Remove(sourceFile.Name())
	if _, err := io.Copy(sourceFile, source); err != nil {
		sourceFile.Close()
		return nil, err
	}
	if err := sourceFile.Close(); err != nil {
		return nil, err
	}

	archive, err := zip.OpenReader(sourceFile.Name())
	if err != nil {
		return nil, err
	}
	defer archive.Close()

	root := &archiveTreeNode{Name: ".", Dir: true, Children: map[string]*archiveTreeNode{}}
	var totalSize uint64
	var fileCount int
	var dirCount int
	for _, entry := range archive.File {
		name := strings.Trim(entry.Name, "/")
		if name == "" || strings.HasPrefix(name, "__MACOSX/") {
			continue
		}
		parts := strings.Split(name, "/")
		node := root
		for i, part := range parts {
			if part == "" {
				continue
			}
			if node.Children == nil {
				node.Children = map[string]*archiveTreeNode{}
			}
			child, ok := node.Children[part]
			if !ok {
				child = &archiveTreeNode{Name: part, Dir: i < len(parts)-1 || entry.FileInfo().IsDir(), Children: map[string]*archiveTreeNode{}}
				node.Children[part] = child
				if child.Dir {
					dirCount++
				}
			}
			node = child
		}
		if !entry.FileInfo().IsDir() {
			node.Dir = false
			node.Size = entry.UncompressedSize64
			totalSize += entry.UncompressedSize64
			fileCount++
		}
	}

	finalizeArchiveTree(root)
	data := archiveListingData{
		Name:             file.Name,
		Type:             archiveLabel(file),
		FileCount:        fileCount,
		FolderCount:      dirCount,
		UncompressedSize: totalSize,
		Root:             root,
	}
	return json.MarshalIndent(data, "", "  ")
}

func finalizeArchiveTree(node *archiveTreeNode) {
	node.Items = sortedArchiveChildren(node)
	for _, child := range node.Items {
		if child.Dir {
			child.Icon = "folder"
			finalizeArchiveTree(child)
		} else {
			child.Icon = archiveFileIconName(child.Name)
		}
	}
}

func writeArchiveTree(out *strings.Builder, node *archiveTreeNode, prefix string) {
	children := sortedArchiveChildren(node)
	for i, child := range children {
		last := i == len(children)-1
		branch := "|-- "
		nextPrefix := prefix + "|   "
		if last {
			branch = "`-- "
			nextPrefix = prefix + "    "
		}

		out.WriteString(prefix)
		out.WriteString(branch)
		out.WriteString(archiveNodeLabel(child))
		out.WriteString("\n")
		if child.Dir {
			writeArchiveTree(out, child, nextPrefix)
		}
	}
}

func sortedArchiveChildren(node *archiveTreeNode) []*archiveTreeNode {
	children := make([]*archiveTreeNode, 0, len(node.Children))
	for _, child := range node.Children {
		children = append(children, child)
	}
	sort.Slice(children, func(i, j int) bool {
		if children[i].Dir != children[j].Dir {
			return children[i].Dir
		}
		return strings.ToLower(children[i].Name) < strings.ToLower(children[j].Name)
	})
	return children
}

func archiveNodeLabel(node *archiveTreeNode) string {
	if node.Dir {
		return "[DIR] " + node.Name + "/"
	}
	return archiveFileIcon(node.Name) + " " + node.Name + " (" + formatArchiveBytes(node.Size) + ")"
}

func archiveFileIcon(name string) string {
	return "[" + strings.ToUpper(archiveFileIconName(name)) + "]"
}

func archiveFileIconName(name string) string {
	switch strings.TrimPrefix(strings.ToLower(filepath.Ext(name)), ".") {
	case "jpg", "jpeg", "png", "gif", "webp", "avif", "svg":
		return "img"
	case "mp4", "mov", "webm", "mkv", "avi":
		return "vid"
	case "mp3", "wav", "flac", "ogg", "m4a":
		return "aud"
	case "md", "txt", "log", "csv":
		return "txt"
	case "html", "css", "js", "ts", "go", "rs", "py", "json", "xml", "yaml", "yml":
		return "code"
	case "zip", "jar", "war", "ear", "apk", "epub", "docx", "xlsx", "pptx":
		return "arc"
	default:
		return "file"
	}
}

func archiveLabel(file services.File) string {
	ext := strings.TrimPrefix(strings.ToLower(filepath.Ext(file.Name)), ".")
	if ext != "" {
		return strings.ToUpper(ext) + " archive"
	}
	if file.ContentType != "" {
		return file.ContentType
	}
	return "ZIP-compatible archive"
}

func formatArchiveBytes(size uint64) string {
	const unit = 1024
	if size < unit {
		return fmt.Sprintf("%d B", size)
	}
	div := float64(unit)
	value := float64(size) / div
	units := []string{"KiB", "MiB", "GiB", "TiB"}
	for _, suffix := range units {
		if value < unit {
			return fmt.Sprintf("%.1f %s", value, suffix)
		}
		value /= div
	}
	return fmt.Sprintf("%.1f PiB", value)
}

func createImageThumbnail(source io.Reader) ([]byte, error) {
	img, _, err := image.Decode(source)
	if err != nil {
		return nil, err
	}

	thumb := resizeNearest(img, 360, 240)
	var target bytes.Buffer
	err = jpeg.Encode(&target, thumb, &jpeg.Options{Quality: 82})
	if err != nil {
		return nil, err
	}
	return target.Bytes(), nil
}

func createVideoThumbnail(source io.Reader) ([]byte, error) {
	sourceFile, err := os.CreateTemp("", "warpbox-video-*")
	if err != nil {
		return nil, err
	}
	defer os.Remove(sourceFile.Name())
	if _, err := io.Copy(sourceFile, source); err != nil {
		sourceFile.Close()
		return nil, err
	}
	if err := sourceFile.Close(); err != nil {
		return nil, err
	}
	sourcePath := sourceFile.Name()
	candidates := []string{"00:00:01", "00:00:03", "00:00:06"}
	var fallback []byte
	for _, timestamp := range candidates {
		targetFile, err := os.CreateTemp("", "warpbox-thumb-*.jpg")
		if err != nil {
			return nil, err
		}
		targetPath := targetFile.Name()
		targetFile.Close()
		if err := extractVideoFrame(sourcePath, timestamp, targetPath, "scale=360:-1"); err != nil {
			os.Remove(targetPath)
			continue
		}
		data, err := os.ReadFile(targetPath)
		os.Remove(targetPath)
		if err != nil {
			continue
		}
		if len(fallback) == 0 {
			fallback = data
		}
		if usableVideoFrame(data) {
			return data, nil
		}
	}

	scenes, err := createVideoScenesThumbnailFromPath(services.File{Name: "video", ContentType: "video"}, sourcePath)
	if err == nil {
		img, err := jpeg.Decode(bytes.NewReader(scenes))
		if err == nil {
			thumb := resizeNearest(img, 360, 240)
			var target bytes.Buffer
			if err := jpeg.Encode(&target, thumb, &jpeg.Options{Quality: 82}); err == nil {
				return target.Bytes(), nil
			}
		}
	}
	if len(fallback) > 0 {
		return fallback, nil
	}
	return nil, fmt.Errorf("could not extract a usable video thumbnail")
}

func createVideoScenesThumbnail(file services.File, source io.Reader) ([]byte, error) {
	sourceFile, err := os.CreateTemp("", "warpbox-video-*")
	if err != nil {
		return nil, err
	}
	defer os.Remove(sourceFile.Name())
	if _, err := io.Copy(sourceFile, source); err != nil {
		sourceFile.Close()
		return nil, err
	}
	if err := sourceFile.Close(); err != nil {
		return nil, err
	}
	return createVideoScenesThumbnailFromPath(file, sourceFile.Name())
}

func createVideoScenesThumbnailFromPath(file services.File, sourcePath string) ([]byte, error) {
	info := probeVideoInfo(sourcePath, file)
	timestamps := videoSceneTimestamps(info.Duration)
	frames := make([]videoSceneFrame, 0, len(timestamps))

	for _, timestamp := range timestamps {
		targetFile, err := os.CreateTemp("", "warpbox-scene-*.jpg")
		if err != nil {
			continue
		}
		targetPath := targetFile.Name()
		targetFile.Close()
		if err := extractVideoFrame(sourcePath, timestamp, targetPath, "scale=640:-1"); err != nil {
			os.Remove(targetPath)
			continue
		}
		data, err := os.ReadFile(targetPath)
		os.Remove(targetPath)
		if err != nil {
			continue
		}
		img, err := jpeg.Decode(bytes.NewReader(data))
		if err != nil {
			continue
		}
		frames = append(frames, videoSceneFrame{Timestamp: timestamp, Image: img})
	}

	return renderVideoScenesThumbnail(file, info, frames), nil
}

func extractVideoFrame(sourcePath, timestamp, targetPath, scaleFilter string) error {
	return exec.Command("ffmpeg", "-y", "-loglevel", "error", "-ss", timestamp, "-i", sourcePath, "-frames:v", "1", "-vf", scaleFilter, targetPath).Run()
}

type videoSceneFrame struct {
	Timestamp string
	Image     image.Image
}

type videoInfo struct {
	Codec     string
	Width     int
	Height    int
	Duration  float64
	FrameRate string
}

func probeVideoInfo(sourcePath string, file services.File) videoInfo {
	info := videoInfo{Codec: "unknown", FrameRate: "unknown"}
	output, err := exec.Command("ffprobe", "-v", "error", "-select_streams", "v:0", "-show_entries", "stream=codec_name,width,height,duration,avg_frame_rate", "-of", "default=noprint_wrappers=1", sourcePath).Output()
	if err != nil {
		if file.ContentType != "" {
			info.Codec = file.ContentType
		}
		return info
	}
	for _, line := range strings.Split(string(output), "\n") {
		key, value, ok := strings.Cut(strings.TrimSpace(line), "=")
		if !ok || value == "" || value == "N/A" {
			continue
		}
		switch key {
		case "codec_name":
			info.Codec = value
		case "width":
			info.Width, _ = strconv.Atoi(value)
		case "height":
			info.Height, _ = strconv.Atoi(value)
		case "duration":
			info.Duration, _ = strconv.ParseFloat(value, 64)
		case "avg_frame_rate":
			info.FrameRate = simplifyFrameRate(value)
		}
	}
	return info
}

func simplifyFrameRate(value string) string {
	if value == "0/0" || value == "" {
		return "unknown"
	}
	parts := strings.Split(value, "/")
	if len(parts) != 2 {
		return value
	}
	n, errN := strconv.ParseFloat(parts[0], 64)
	d, errD := strconv.ParseFloat(parts[1], 64)
	if errN != nil || errD != nil || d == 0 {
		return value
	}
	return fmt.Sprintf("%.2f fps", n/d)
}

func videoSceneTimestamps(duration float64) []string {
	if duration > 4 {
		points := []float64{0.12, 0.33, 0.58, 0.82}
		timestamps := make([]string, 0, len(points))
		for _, point := range points {
			seconds := duration * point
			if seconds < 1 {
				seconds = 1
			}
			timestamps = append(timestamps, secondsToTimestamp(seconds))
		}
		return timestamps
	}
	return []string{"00:00:01", "00:00:03", "00:00:06", "00:00:10"}
}

func secondsToTimestamp(seconds float64) string {
	total := int(seconds + 0.5)
	hours := total / 3600
	minutes := total % 3600 / 60
	secs := total % 60
	return fmt.Sprintf("%02d:%02d:%02d", hours, minutes, secs)
}

func usableVideoFrame(data []byte) bool {
	img, err := jpeg.Decode(bytes.NewReader(data))
	if err != nil {
		return false
	}
	return averageLuma(img) >= 18
}

func averageLuma(img image.Image) float64 {
	bounds := img.Bounds()
	width := bounds.Dx()
	height := bounds.Dy()
	if width <= 0 || height <= 0 {
		return 0
	}
	stepX := max(1, width/80)
	stepY := max(1, height/80)
	var total float64
	var samples int
	for y := bounds.Min.Y; y < bounds.Max.Y; y += stepY {
		for x := bounds.Min.X; x < bounds.Max.X; x += stepX {
			r, g, b, _ := img.At(x, y).RGBA()
			total += 0.2126*float64(r>>8) + 0.7152*float64(g>>8) + 0.0722*float64(b>>8)
			samples++
		}
	}
	if samples == 0 {
		return 0
	}
	return total / float64(samples)
}

func renderVideoScenesThumbnail(file services.File, info videoInfo, frames []videoSceneFrame) []byte {
	canvas := image.NewRGBA(image.Rect(0, 0, 1200, 630))
	drawSolid(canvas, canvas.Bounds(), color.RGBA{R: 0x0b, G: 0x0b, B: 0x12, A: 0xff})
	drawSolid(canvas, image.Rect(0, 0, 1200, 630), color.RGBA{R: 0x10, G: 0x13, B: 0x1f, A: 0xff})
	drawSolid(canvas, image.Rect(36, 36, 1164, 594), color.RGBA{R: 0x17, G: 0x17, B: 0x22, A: 0xff})
	drawSolid(canvas, image.Rect(36, 36, 1164, 96), color.RGBA{R: 0x20, G: 0x1b, B: 0x34, A: 0xff})
	drawSolid(canvas, image.Rect(36, 96, 1164, 100), color.RGBA{R: 0x7c, G: 0x3a, B: 0xed, A: 0xff})

	face := basicfont.Face7x13
	drawThumbText(canvas, face, "VIDEO SCENES PREVIEW", 62, 63, color.RGBA{R: 0xc4, G: 0xb5, B: 0xfd, A: 0xff})
	drawThumbText(canvas, face, trimThumbnailText(file.Name, 72), 62, 84, color.RGBA{R: 0xff, G: 0xfb, B: 0xeb, A: 0xff})

	meta := videoMetaLines(file, info)
	y := 122
	for _, line := range meta {
		drawThumbText(canvas, face, line, 62, y, color.RGBA{R: 0xcb, G: 0xd5, B: 0xe1, A: 0xff})
		y += 20
	}

	cells := []image.Rectangle{
		image.Rect(62, 212, 586, 388),
		image.Rect(614, 212, 1138, 388),
		image.Rect(62, 414, 586, 566),
		image.Rect(614, 414, 1138, 566),
	}
	for i, rect := range cells {
		drawSolid(canvas, rect, color.RGBA{R: 0x0f, G: 0x17, B: 0x22, A: 0xff})
		if i < len(frames) {
			drawImageCover(canvas, rect, frames[i].Image)
			drawSolid(canvas, image.Rect(rect.Min.X, rect.Min.Y, rect.Min.X+88, rect.Min.Y+24), color.RGBA{R: 0x00, G: 0x00, B: 0x00, A: 0xcc})
			drawThumbText(canvas, face, frames[i].Timestamp, rect.Min.X+10, rect.Min.Y+17, color.RGBA{R: 0xff, G: 0xff, B: 0xff, A: 0xff})
		} else {
			drawThumbText(canvas, face, "No frame available", rect.Min.X+18, rect.Min.Y+34, color.RGBA{R: 0x94, G: 0xa3, B: 0xb8, A: 0xff})
		}
	}

	var target bytes.Buffer
	_ = jpeg.Encode(&target, canvas, &jpeg.Options{Quality: 86})
	return target.Bytes()
}

func videoMetaLines(file services.File, info videoInfo) []string {
	resolution := "unknown resolution"
	if info.Width > 0 && info.Height > 0 {
		resolution = fmt.Sprintf("%dx%d", info.Width, info.Height)
	}
	duration := "unknown duration"
	if info.Duration > 0 {
		duration = secondsToHumanDuration(info.Duration)
	}
	contentType := file.ContentType
	if contentType == "" {
		contentType = "video"
	}
	return []string{
		"Duration: " + duration + "     Codec: " + info.Codec,
		"Resolution: " + resolution + "     Frame rate: " + info.FrameRate,
		"Type: " + contentType + "     Generated by Warpbox",
	}
}

func secondsToHumanDuration(seconds float64) string {
	total := int(seconds + 0.5)
	hours := total / 3600
	minutes := total % 3600 / 60
	secs := total % 60
	if hours > 0 {
		return fmt.Sprintf("%d:%02d:%02d", hours, minutes, secs)
	}
	return fmt.Sprintf("%d:%02d", minutes, secs)
}

func drawImageCover(dst *image.RGBA, rect image.Rectangle, src image.Image) {
	bounds := src.Bounds()
	srcW := bounds.Dx()
	srcH := bounds.Dy()
	dstW := rect.Dx()
	dstH := rect.Dy()
	if srcW <= 0 || srcH <= 0 || dstW <= 0 || dstH <= 0 {
		return
	}

	srcRatio := float64(srcW) / float64(srcH)
	dstRatio := float64(dstW) / float64(dstH)
	crop := bounds
	if srcRatio > dstRatio {
		newW := int(float64(srcH) * dstRatio)
		x0 := bounds.Min.X + (srcW-newW)/2
		crop = image.Rect(x0, bounds.Min.Y, x0+newW, bounds.Max.Y)
	} else if srcRatio < dstRatio {
		newH := int(float64(srcW) / dstRatio)
		y0 := bounds.Min.Y + (srcH-newH)/2
		crop = image.Rect(bounds.Min.X, y0, bounds.Max.X, y0+newH)
	}

	for y := rect.Min.Y; y < rect.Max.Y; y++ {
		for x := rect.Min.X; x < rect.Max.X; x++ {
			u := float64(x-rect.Min.X) / float64(dstW)
			v := float64(y-rect.Min.Y) / float64(dstH)
			srcX := crop.Min.X + min(crop.Dx()-1, int(u*float64(crop.Dx())))
			srcY := crop.Min.Y + min(crop.Dy()-1, int(v*float64(crop.Dy())))
			dst.Set(x, y, src.At(srcX, srcY))
		}
	}
}

func createTextThumbnail(file services.File, source io.Reader) ([]byte, error) {
	data, err := io.ReadAll(io.LimitReader(source, 128*1024))
	if err != nil {
		return nil, err
	}
	sourceText := strings.ReplaceAll(string(data), "\r\n", "\n")
	sourceText = strings.ReplaceAll(sourceText, "\r", "\n")

	mode := textThumbnailMode(file)
	title := strings.ToUpper(mode)
	var lines []string
	if mode == "HTML" {
		lines = renderedHTMLThumbnailLines(sourceText)
	} else if mode == "MARKDOWN" {
		lines = renderedMarkdownThumbnailLines(sourceText)
	} else {
		title = "CODE"
		lines = codeThumbnailLines(sourceText)
	}
	return renderTextThumbnail(file.Name, title, lines), nil
}

func textThumbnailMode(file services.File) string {
	contentType := strings.ToLower(strings.TrimSpace(file.ContentType))
	if i := strings.IndexByte(contentType, ';'); i >= 0 {
		contentType = strings.TrimSpace(contentType[:i])
	}
	ext := strings.TrimPrefix(strings.ToLower(filepath.Ext(file.Name)), ".")
	if ext == "html" || ext == "htm" || contentType == "text/html" {
		return "HTML"
	}
	if ext == "md" || ext == "mdown" || ext == "markdown" || contentType == "text/markdown" || contentType == "application/markdown" {
		return "MARKDOWN"
	}
	return "CODE"
}

func renderedHTMLThumbnailLines(source string) []string {
	text := regexp.MustCompile(`(?is)<script[^>]*>.*?</script>`).ReplaceAllString(source, " ")
	text = regexp.MustCompile(`(?is)<style[^>]*>.*?</style>`).ReplaceAllString(text, " ")
	text = regexp.MustCompile(`(?i)</?(p|div|section|article|main|header|footer|br|li|ul|ol|h[1-6]|tr|table|blockquote|pre|code)[^>]*>`).ReplaceAllString(text, "\n")
	text = regexp.MustCompile(`(?s)<[^>]+>`).ReplaceAllString(text, " ")
	text = html.UnescapeString(text)
	return documentThumbnailLines(text)
}

func renderedMarkdownThumbnailLines(source string) []string {
	text := regexp.MustCompile("(?s)```.*?```").ReplaceAllStringFunc(source, func(block string) string {
		block = strings.Trim(block, "` \n\t")
		lines := strings.Split(block, "\n")
		if len(lines) > 1 {
			lines = lines[1:]
		}
		return "\n" + strings.Join(lines, "\n") + "\n"
	})
	text = regexp.MustCompile(`(?m)^#{1,6}\s*`).ReplaceAllString(text, "")
	text = regexp.MustCompile(`!\[([^\]]*)\]\([^)]+\)`).ReplaceAllString(text, "$1")
	text = regexp.MustCompile(`\[([^\]]+)\]\([^)]+\)`).ReplaceAllString(text, "$1")
	text = regexp.MustCompile("`([^`]+)`").ReplaceAllString(text, "$1")
	text = strings.NewReplacer("**", "", "__", "", "*", "", "_", "", "~~", "").Replace(text)
	return documentThumbnailLines(text)
}

func documentThumbnailLines(source string) []string {
	source = regexp.MustCompile(`[ \t]+`).ReplaceAllString(source, " ")
	rawLines := strings.Split(source, "\n")
	lines := make([]string, 0, 9)
	for _, raw := range rawLines {
		raw = strings.TrimSpace(raw)
		if raw == "" {
			continue
		}
		for _, line := range wrapTextThumbnailLine(raw, 43) {
			lines = append(lines, line)
			if len(lines) >= 9 {
				return lines
			}
		}
	}
	if len(lines) == 0 {
		return []string{"Rendered preview is empty."}
	}
	return lines
}

func codeThumbnailLines(source string) []string {
	rawLines := strings.Split(source, "\n")
	lines := make([]string, 0, 10)
	for _, raw := range rawLines {
		raw = strings.ReplaceAll(raw, "\t", "  ")
		raw = strings.TrimRight(raw, " ")
		if strings.TrimSpace(raw) == "" && len(lines) == 0 {
			continue
		}
		if len(raw) > 48 {
			raw = raw[:45] + "..."
		}
		lines = append(lines, raw)
		if len(lines) >= 10 {
			break
		}
	}
	if len(lines) == 0 {
		return []string{"(empty file)"}
	}
	return lines
}

func renderTextThumbnail(name, mode string, lines []string) []byte {
	canvas := image.NewRGBA(image.Rect(0, 0, 360, 240))
	drawSolid(canvas, canvas.Bounds(), color.RGBA{R: 0x0b, G: 0x0b, B: 0x16, A: 0xff})
	drawSolid(canvas, image.Rect(10, 10, 350, 230), color.RGBA{R: 0x17, G: 0x14, B: 0x2d, A: 0xff})
	drawSolid(canvas, image.Rect(10, 10, 350, 16), color.RGBA{R: 0xa7, G: 0x8b, B: 0xfa, A: 0xff})

	face := basicfont.Face7x13
	drawThumbText(canvas, face, trimThumbnailText(name, 38), 22, 36, color.RGBA{R: 0xf5, G: 0xf3, B: 0xff, A: 0xff})
	drawThumbText(canvas, face, mode+" PREVIEW", 22, 55, color.RGBA{R: 0x67, G: 0xe8, B: 0xf9, A: 0xff})

	codePane := image.Rect(22, 72, 338, 210)
	if mode == "CODE" {
		drawSolid(canvas, codePane, color.RGBA{R: 0x0f, G: 0x11, B: 0x1a, A: 0xff})
	} else {
		drawSolid(canvas, codePane, color.RGBA{R: 0x21, G: 0x1b, B: 0x3e, A: 0xff})
	}

	y := 91
	for _, line := range lines {
		drawThumbText(canvas, face, line, 32, y, color.RGBA{R: 0xf8, G: 0xfa, B: 0xfc, A: 0xff})
		y += 14
		if y > 202 {
			break
		}
	}

	var target bytes.Buffer
	_ = jpeg.Encode(&target, canvas, &jpeg.Options{Quality: 84})
	return target.Bytes()
}

func drawSolid(dst *image.RGBA, rect image.Rectangle, c color.Color) {
	draw.Draw(dst, rect, &image.Uniform{c}, image.Point{}, draw.Src)
}

func drawThumbText(dst *image.RGBA, face font.Face, text string, x, y int, c color.Color) {
	d := font.Drawer{
		Dst:  dst,
		Src:  image.NewUniform(c),
		Face: face,
		Dot:  fixed.P(x, y),
	}
	d.DrawString(text)
}

func wrapTextThumbnailLine(text string, maxChars int) []string {
	if len(text) <= maxChars {
		return []string{text}
	}
	words := strings.Fields(text)
	if len(words) == 0 {
		return []string{text[:maxChars-3] + "..."}
	}
	lines := []string{}
	current := ""
	for _, word := range words {
		if current == "" {
			current = word
			continue
		}
		if len(current)+1+len(word) <= maxChars {
			current += " " + word
			continue
		}
		lines = append(lines, trimThumbnailText(current, maxChars))
		current = word
	}
	if current != "" {
		lines = append(lines, trimThumbnailText(current, maxChars))
	}
	return lines
}

func trimThumbnailText(text string, maxChars int) string {
	if len(text) <= maxChars {
		return text
	}
	if maxChars <= 3 {
		return text[:maxChars]
	}
	return strings.TrimSpace(text[:maxChars-3]) + "..."
}

func resizeNearest(src image.Image, maxWidth, maxHeight int) *image.RGBA {
	bounds := src.Bounds()
	width := bounds.Dx()
	height := bounds.Dy()
	if width <= 0 || height <= 0 {
		return image.NewRGBA(image.Rect(0, 0, 1, 1))
	}

	scale := min(float64(maxWidth)/float64(width), float64(maxHeight)/float64(height))
	if scale > 1 {
		scale = 1
	}
	targetWidth := max(1, int(float64(width)*scale))
	targetHeight := max(1, int(float64(height)*scale))
	dst := image.NewRGBA(image.Rect(0, 0, targetWidth, targetHeight))

	for y := 0; y < targetHeight; y++ {
		for x := 0; x < targetWidth; x++ {
			srcX := bounds.Min.X + int(float64(x)/scale)
			srcY := bounds.Min.Y + int(float64(y)/scale)
			dst.Set(x, y, src.At(srcX, srcY))
		}
	}

	return dst
}