// library.go implements the file library subsystem.
//
// This replaces LCOM.C from the original TAG-BBS. The original stored
// library metadata in Library.Keys files (arrays of Library_Data structs)
// and the actual files on disk in per-library directories. File transfer
// used XMODEM over serial (TRANSFER.C).
//
// Our version stores metadata in SQLite and keeps files on disk in the
// library's FilePath directory. The catalog browsing experience is fully
// preserved: three-level navigation matching the message board pattern
// (library selection → per-library commands → between-file prompts).
//
// File transfer: the original's XMODEM is specific to serial. Over
// telnet, the standard is ZMODEM (via external sz/rz tools). This step
// implements full catalog browsing and file metadata management. Actual
// binary transfer (ZMODEM integration) is noted as a future enhancement.
// Text files can be viewed inline.
package menu

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"github.com/urit/urit/internal/models"
	"github.com/urit/urit/internal/session"
)

// cmdLibrary is the entry point for the file library subsystem.
// Replaces LCom() from LCOM.C — the top-level library selection menu.
func cmdLibrary(ctx *Context) error {
	libs, err := ctx.Store.ListLibraries()
	if err != nil {
		ctx.Sess.WriteString("  Error loading libraries.\r\n")
		return nil
	}

	// Filter to those the user can access
	var visible []*models.Library
	for _, l := range libs {
		if l.CanDownload(ctx.User.SecLibrary) || l.CanUpload(ctx.User.SecLibrary) {
			visible = append(visible, l)
		}
	}

	if len(visible) == 0 {
		ctx.Sess.WriteString("  No file libraries available.\r\n\r\n")
		return nil
	}

	ctx.Sess.NewLine()

	for {
		ctx.Sess.CheckTime()
		ctx.Sess.Color(session.AnsiFgCyan)
		ctx.Sess.WriteString("N>ew  S>ome  A>ll  L>ist  Q>uit\r\n")
		ctx.Sess.Printf("%s Library> ", ctx.Cfg.System.Name)
		ctx.Sess.Color(session.AnsiReset)

		ch, err := ctx.Sess.ReadKey(idleTimeout)
		if err != nil {
			return nil
		}

		switch toUpper(ch) {
		case 'L':
			ctx.Sess.WriteString("List\r\n\r\n")
			libList(ctx, visible)

		case 'A':
			ctx.Sess.WriteString("All Libraries\r\n\r\n")
			for i, l := range visible {
				ctx.Sess.Printf("[%d] %s\r\n", i+1, l.Name)
				quit := libPrompt(ctx, l, i+1)
				if quit {
					goto done
				}
			}
			ctx.Sess.WriteString("Completed visiting ALL\r\n")

		case 'N':
			ctx.Sess.WriteString("New Files\r\n\r\n")
			found := false
			for i, l := range visible {
				if !l.CanDownload(ctx.User.SecLibrary) {
					continue
				}
				if ctx.User.LastOn != nil && l.LatestFile != nil &&
					!l.LatestFile.After(*ctx.User.LastOn) {
					continue
				}
				found = true
				ctx.Sess.Printf("\r\n[%d] %s\r\n", i+1, l.Name)
				libReadNew(ctx, l)
				quit := libPrompt(ctx, l, i+1)
				if quit {
					goto done
				}
			}
			if !found {
				ctx.Sess.WriteString("Nothing new.\r\n")
			}
			ctx.Sess.WriteString("Completed visiting NEW\r\n")

		case 'S':
			ctx.Sess.WriteString("Some Libraries\r\n\r\n")
			for i, l := range visible {
				ctx.Sess.Printf("Visit [%d] %s? ", i+1, l.Name)
				ych, err := ctx.Sess.ReadKey(idleTimeout)
				if err != nil {
					return nil
				}
				switch toUpper(ych) {
				case 'Y':
					ctx.Sess.WriteString("Yes\r\n")
					quit := libPrompt(ctx, l, i+1)
					if quit {
						goto done
					}
				case 'Q':
					ctx.Sess.WriteString("Quit\r\n")
					goto done
				default:
					ctx.Sess.WriteString("No\r\n")
				}
			}
			ctx.Sess.WriteString("Completed visiting SOME\r\n")

		case 'Q', '\x1b':
			ctx.Sess.WriteString("Quit\r\n")
			goto done

		case '?', '/':
			ctx.Sess.WriteString("Help\r\n")
			libList(ctx, visible)
		}
	}

done:
	return nil
}

// libList displays the list of visible libraries with file counts.
func libList(ctx *Context, libs []*models.Library) {
	ctx.Sess.Color(session.AnsiFgGreen, session.AnsiBold)
	ctx.Sess.WriteString("File Libraries\r\n")
	ctx.Sess.Color(session.AnsiReset)
	ctx.Sess.WriteString(strings.Repeat("─", 55) + "\r\n")

	for i, l := range libs {
		access := ""
		if l.CanDownload(ctx.User.SecLibrary) && l.CanUpload(ctx.User.SecLibrary) {
			access = "DL/UL"
		} else if l.CanDownload(ctx.User.SecLibrary) {
			access = "DL   "
		} else if l.CanUpload(ctx.User.SecLibrary) {
			access = "   UL"
		}

		latest := "no files"
		if l.LatestFile != nil {
			latest = l.LatestFile.Format("Jan 02")
		}

		ctx.Sess.Printf("  [%d] %-20s %3d files  %s  %s\r\n",
			i+1, l.Name, l.FileCount, access, latest)
	}
	ctx.Sess.NewLine()
}

// libPrompt is the per-library command loop.
// Replaces Lib_Prompt() from LCOM.C.
// Returns true if the user wants to return to the main menu (@).
func libPrompt(ctx *Context, lib *models.Library, num int) bool {
	canDL := lib.CanDownload(ctx.User.SecLibrary)
	canUL := lib.CanUpload(ctx.User.SecLibrary)

	for {
		ctx.Sess.CheckTime()
		ctx.Sess.NewLine()
		ctx.Sess.Color(session.AnsiFgCyan)

		opts := ""
		if canDL {
			opts += "N>ew L>ist C>atalog D>ownload "
		}
		if canUL {
			opts += "U>pload "
		}
		if ctx.User.SecStatus >= 150 {
			opts += "R>emove "
		}
		opts += "Q>uit @>Main"
		ctx.Sess.WriteString(opts + "\r\n")
		ctx.Sess.Printf("[%d] %s> ", num, lib.Name)
		ctx.Sess.Color(session.AnsiReset)

		ch, err := ctx.Sess.ReadKey(idleTimeout)
		if err != nil {
			return true
		}

		switch toUpper(ch) {
		case 'N':
			if !canDL {
				continue
			}
			ctx.Sess.WriteString("New\r\n")
			libReadNew(ctx, lib)

		case 'L':
			if !canDL {
				continue
			}
			ctx.Sess.WriteString("List\r\n")
			libListFrontend(ctx, lib)

		case 'C':
			if !canDL {
				continue
			}
			ctx.Sess.WriteString("Catalog\r\n")
			libCatalog(ctx, lib)

		case 'D', 'I':
			if !canDL {
				continue
			}
			ctx.Sess.WriteString("Download\r\n")
			libDownload(ctx, lib)

		case 'U':
			if !canUL {
				continue
			}
			ctx.Sess.WriteString("Upload\r\n")
			libUpload(ctx, lib)

		case 'R':
			if ctx.User.SecStatus < 150 {
				continue
			}
			ctx.Sess.WriteString("Remove\r\n")
			libRemove(ctx, lib)

		case 'Q':
			ctx.Sess.WriteString("Quit\r\n")
			return false

		case '@':
			ctx.Sess.WriteString("Main Menu\r\n")
			return true

		case '?', '/':
			ctx.Sess.WriteString("Help\r\n")
			ctx.Sess.WriteString("  N - List new files since last login\r\n")
			ctx.Sess.WriteString("  L - List files by number range\r\n")
			ctx.Sess.WriteString("  C - Quick catalog (names only)\r\n")
			ctx.Sess.WriteString("  D - Download a file\r\n")
			ctx.Sess.WriteString("  U - Upload a file\r\n")
			if ctx.User.SecStatus >= 150 {
				ctx.Sess.WriteString("  R - Remove a file entry\r\n")
			}
			ctx.Sess.WriteString("  Q - Return to library selection\r\n")
			ctx.Sess.WriteString("  @ - Return to main menu\r\n")
		}
	}
}

// libReadNew lists files added since the user's last login.
// Replaces Lib_ReadNew() from LCOM.C.
func libReadNew(ctx *Context, lib *models.Library) {
	if lib.FileCount == 0 {
		ctx.Sess.WriteString("  No files in this library.\r\n")
		return
	}

	files, err := ctx.Store.ListLibraryFiles(lib.ID, 0, lib.MaxFiles)
	if err != nil {
		ctx.Sess.WriteString("  Error loading files.\r\n")
		return
	}

	// Filter to new files
	var newFiles []*models.LibraryFile
	for _, f := range files {
		if ctx.User.LastOn == nil || f.CreatedAt.After(*ctx.User.LastOn) {
			newFiles = append(newFiles, f)
		}
	}

	if len(newFiles) == 0 {
		ctx.Sess.WriteString("  Nothing new.\r\n")
		return
	}

	ctx.Sess.Printf("  %d new file(s)\r\n\r\n", len(newFiles))
	libReadSequence(ctx, lib, newFiles)
}

// libListFrontend prompts for a range and lists files with full details.
// Replaces Lib_Read_Frontend() from LCOM.C.
func libListFrontend(ctx *Context, lib *models.Library) {
	if lib.FileCount == 0 {
		ctx.Sess.WriteString("  No files in this library.\r\n")
		return
	}

	ctx.Sess.Printf("  List FROM [1-%d]: ", lib.FileCount)
	fromStr, err := ctx.Sess.ReadLine("1", 5, inputTimeout)
	if err != nil {
		return
	}
	from := parseIntDefault(fromStr, 1)
	if from < 1 || from > lib.FileCount {
		ctx.Sess.Printf("  Invalid. Range is 1-%d\r\n", lib.FileCount)
		return
	}

	ctx.Sess.Printf("  List TO [%d-%d]: ", from, lib.FileCount)
	toStr, err := ctx.Sess.ReadLine(fmt.Sprintf("%d", lib.FileCount), 5, inputTimeout)
	if err != nil {
		return
	}
	to := parseIntDefault(toStr, lib.FileCount)
	if to < from || to > lib.FileCount {
		ctx.Sess.Printf("  Invalid. Range is %d-%d\r\n", from, lib.FileCount)
		return
	}

	files, err := ctx.Store.ListLibraryFiles(lib.ID, from-1, to-from+1)
	if err != nil {
		ctx.Sess.WriteString("  Error loading files.\r\n")
		return
	}

	libReadSequence(ctx, lib, files)
}

// libCatalog shows a quick filename-only listing.
// Replaces Lib_Catalog() from LCOM.C.
func libCatalog(ctx *Context, lib *models.Library) {
	if lib.FileCount == 0 {
		ctx.Sess.WriteString("  No files in this library.\r\n")
		return
	}

	files, err := ctx.Store.ListLibraryFiles(lib.ID, 0, lib.MaxFiles)
	if err != nil {
		ctx.Sess.WriteString("  Error loading files.\r\n")
		return
	}

	ctx.Sess.NewLine()
	var lines []string
	for i, f := range files {
		lines = append(lines, fmt.Sprintf("  [%d] %-30s %s  %s",
			i+1, f.Filename, formatSize(f.FileSize),
			f.CreatedAt.Format("Jan 02")))
	}
	ctx.Sess.Paginate(strings.Join(lines, "\n"), idleTimeout)
	ctx.Sess.NewLine()
}

// libReadSequence displays files in order with between-file prompts.
// Replaces Lib_Read() from LCOM.C.
func libReadSequence(ctx *Context, lib *models.Library, files []*models.LibraryFile) {
	if len(files) == 0 {
		return
	}

	idx := 0
	for idx >= 0 && idx < len(files) {
		f := files[idx]
		libDisplayFile(ctx, lib, f, idx+1, len(files))

		action := libBetweenPrompt(ctx, lib, f, idx+1)
		switch action {
		case libActNext:
			idx++
		case libActAgain:
			// stay
		case libActLast:
			if idx > 0 {
				idx--
			}
		case libActQuit:
			return
		case libActMainMenu:
			return
		}
	}
}

// libDisplayFile renders a single file entry.
// Replaces Send_Message() (the library version) from LCOM.C.
func libDisplayFile(ctx *Context, lib *models.Library, f *models.LibraryFile, num, total int) {
	ctx.Sess.NewLine()

	ctx.Sess.Color(session.AnsiFgBrightWhite)
	ctx.Sess.Printf("File Number: [%d] of [%d]\r\n", num, total)
	ctx.Sess.Color(session.AnsiReset)

	ctx.Sess.Color(session.AnsiFgCyan)
	ctx.Sess.Printf("   Filename: %s\r\n", f.Filename)
	ctx.Sess.Color(session.AnsiReset)

	ctx.Sess.Printf("     Origin: %s [%d]\r\n", f.Uploader, f.UploaderID)
	ctx.Sess.Printf("       Size: %s\r\n", formatSize(f.FileSize))
	ctx.Sess.Printf("  Validated: %s\r\n", f.CreatedAt.Format("Mon Jan 02 15:04:05 2006"))
	ctx.Sess.Printf("  Downloads: %d\r\n", f.Downloads)

	if f.Description != "" {
		ctx.Sess.NewLine()
		ctx.Sess.WriteString(f.Description + "\r\n")
	} else {
		ctx.Sess.WriteString("  No description available.\r\n")
	}
}

type libAction int

const (
	libActNext     libAction = iota
	libActAgain
	libActLast
	libActQuit
	libActMainMenu
)

// libBetweenPrompt shows navigation options between file entries.
// Replaces Between_Lib_Prompt() from LCOM.C.
func libBetweenPrompt(ctx *Context, lib *models.Library, f *models.LibraryFile, num int) libAction {
	for {
		ctx.Sess.CheckTime()
		ctx.Sess.Color(session.AnsiFgCyan)

		opts := "N>ext A>gain L>ast S>tats D>ownload Q>uit @>Main"
		if ctx.User.SecStatus >= 150 {
			opts += " R>emove"
		}
		ctx.Sess.WriteString("\r\n" + opts + "\r\n")
		ctx.Sess.WriteString("File> ")
		ctx.Sess.Color(session.AnsiReset)

		ch, err := ctx.Sess.ReadKey(idleTimeout)
		if err != nil {
			return libActQuit
		}

		switch toUpper(ch) {
		case 'N', 'C', '\r':
			ctx.Sess.WriteString("Next\r\n")
			return libActNext

		case 'A':
			ctx.Sess.WriteString("Again\r\n")
			return libActAgain

		case 'L':
			ctx.Sess.WriteString("Last\r\n")
			return libActLast

		case 'S':
			ctx.Sess.WriteString("Statistics\r\n")
			libShowStats(ctx, lib, f)

		case 'D':
			ctx.Sess.WriteString("Download\r\n")
			libDoDownload(ctx, lib, f)
			return libActNext

		case 'R':
			if ctx.User.SecStatus < 150 {
				continue
			}
			ctx.Sess.WriteString("Remove\r\n")
			yes, err := ctx.Sess.Confirm("  Remove this file entry? ", inputTimeout)
			if err != nil {
				return libActQuit
			}
			if yes {
				ctx.Store.DeleteLibraryFile(f.ID)
				if updated, err := ctx.Store.GetLibrary(lib.ID); err == nil {
					*lib = *updated
				}
				ctx.Sess.Color(session.AnsiFgGreen)
				ctx.Sess.WriteString("  File entry removed.\r\n")
				ctx.Sess.WriteString("  (The file itself remains on disk.)\r\n")
				ctx.Sess.Color(session.AnsiReset)
			}
			return libActNext

		case 'Q':
			ctx.Sess.WriteString("Quit\r\n")
			return libActQuit

		case '@':
			ctx.Sess.WriteString("Main Menu\r\n")
			return libActMainMenu

		case '?', '/':
			ctx.Sess.WriteString("Help\r\n")
			ctx.Sess.WriteString("  N/Enter - Next file\r\n")
			ctx.Sess.WriteString("  A       - View again\r\n")
			ctx.Sess.WriteString("  L       - Previous file\r\n")
			ctx.Sess.WriteString("  S       - File statistics\r\n")
			ctx.Sess.WriteString("  D       - Download file\r\n")
			ctx.Sess.WriteString("  Q       - Return to library menu\r\n")
			ctx.Sess.WriteString("  @       - Return to main menu\r\n")
		}
	}
}

// libShowStats displays detailed OS-level stats for a file.
// Replaces the 'S' (statistics / report()) command from LCOM.C.
func libShowStats(ctx *Context, lib *models.Library, f *models.LibraryFile) {
	fullPath := filepath.Join(lib.FilePath, f.Filename)
	info, err := os.Stat(fullPath)
	if err != nil {
		ctx.Sess.Printf("  File not found on disk: %s\r\n", fullPath)
		return
	}

	ctx.Sess.NewLine()
	ctx.Sess.Printf("  Filename: %s\r\n", f.Filename)
	ctx.Sess.Printf("  On disk:  %s\r\n", fullPath)
	ctx.Sess.Printf("  Size:     %s (%d bytes)\r\n", formatSize(info.Size()), info.Size())
	ctx.Sess.Printf("  Modified: %s\r\n", info.ModTime().Format("Mon Jan 02 15:04:05 2006"))
	ctx.Sess.Printf("  DL count: %d\r\n", f.Downloads)
	ctx.Sess.NewLine()
}

// libDoDownload handles a file download request.
//
// The original used XMODEM over serial (Xmodem_Send from TRANSFER.C).
// Over telnet, binary transfer requires ZMODEM or similar. For now:
//   - Text files (.txt, .nfo, .diz, .ans): displayed inline
//   - Binary files: show path and size, note ZMODEM needed
//
// Future enhancement: integrate external sz (ZMODEM send) tool.
func libDoDownload(ctx *Context, lib *models.Library, f *models.LibraryFile) {
	fullPath := filepath.Join(lib.FilePath, f.Filename)

	info, err := os.Stat(fullPath)
	if err != nil {
		ctx.Sess.WriteString("  File not found on disk.\r\n")
		return
	}

	ext := strings.ToLower(filepath.Ext(f.Filename))
	isText := ext == ".txt" || ext == ".nfo" || ext == ".diz" ||
		ext == ".ans" || ext == ".asc" || ext == ".doc" ||
		ext == ".1st" || ext == ".me" || ext == ""

	if isText && info.Size() < 64*1024 {
		// Small text files — display inline (like a bulletin)
		data, err := os.ReadFile(fullPath)
		if err != nil {
			ctx.Sess.WriteString("  Error reading file.\r\n")
			return
		}
		ctx.Sess.NewLine()
		ctx.Sess.Paginate(string(data), idleTimeout)
		ctx.Sess.NewLine()

		// Increment download counter
		f.Downloads++
		ctx.User.Downloads++
		ctx.Store.UpdateUser(ctx.User)
	} else {
		// Binary or large file — inform the user
		ctx.Sess.NewLine()
		ctx.Sess.Printf("  File: %s (%s)\r\n", f.Filename, formatSize(info.Size()))
		ctx.Sess.Printf("  Path: %s\r\n", fullPath)
		ctx.Sess.NewLine()
		ctx.Sess.Color(session.AnsiFgBrightYellow)
		ctx.Sess.WriteString("  Binary file transfer requires a ZMODEM-capable terminal.\r\n")
		ctx.Sess.WriteString("  (ZMODEM integration coming in a future update.)\r\n")
		ctx.Sess.Color(session.AnsiReset)
	}
}

// libDownload prompts for a file number and initiates download.
// Replaces Lib_Immediate() from LCOM.C.
func libDownload(ctx *Context, lib *models.Library) {
	if lib.FileCount == 0 {
		ctx.Sess.WriteString("  No files in this library.\r\n")
		return
	}

	ctx.Sess.Printf("  Download which [1-%d]: ", lib.FileCount)
	numStr, err := ctx.Sess.ReadLine("", 5, inputTimeout)
	if err != nil {
		return
	}
	num := parseIntDefault(numStr, 0)
	if num < 1 || num > lib.FileCount {
		ctx.Sess.WriteString("  Cancelled.\r\n")
		return
	}

	files, err := ctx.Store.ListLibraryFiles(lib.ID, num-1, 1)
	if err != nil || len(files) == 0 {
		ctx.Sess.WriteString("  File not found.\r\n")
		return
	}

	libDoDownload(ctx, lib, files[0])
}

// libUpload registers a new file in the library.
// Replaces Lib_Upload() from LCOM.C.
//
// The original received the file via XMODEM, then stored the metadata.
// Our version records the metadata and expects the sysop to place the
// actual file in the library directory (or, for future ZMODEM, receive
// the file into that directory).
func libUpload(ctx *Context, lib *models.Library) {
	if lib.FileCount >= lib.MaxFiles {
		ctx.Sess.WriteString("  Library is full.\r\n")
		return
	}

	ctx.Sess.NewLine()

	// Filename
	ctx.Sess.Color(session.AnsiFgCyan)
	ctx.Sess.WriteString("Filename (Q to quit): ")
	ctx.Sess.Color(session.AnsiReset)

	filename, err := ctx.Sess.ReadLine("", 30, inputTimeout)
	if err != nil {
		return
	}
	filename = strings.TrimSpace(filename)
	if filename == "" || strings.EqualFold(filename, "Q") {
		ctx.Sess.WriteString("  Cancelled.\r\n")
		return
	}

	// Security check: no path traversal
	// Matches original's check for : / * characters
	if strings.ContainsAny(filename, ":/\\*?\"<>|") {
		ctx.Sess.WriteString("  Filename cannot contain special characters (: / \\ * ? \" < > |).\r\n")
		return
	}

	// Check for duplicate — replaces Lib_Crossref()
	existing, _ := ctx.Store.ListLibraryFiles(lib.ID, 0, lib.MaxFiles)
	for _, f := range existing {
		if strings.EqualFold(f.Filename, filename) {
			ctx.Sess.WriteString("  A file with that name already exists.\r\n")
			return
		}
	}

	ctx.Sess.WriteString("  Filename accepted.\r\n\r\n")

	// Description
	ctx.Sess.WriteString("Description (79 chars): ")
	desc, err := ctx.Sess.ReadLine("", 79, inputTimeout)
	if err != nil {
		return
	}

	// Uploader name — sysops can override
	uploader := ctx.User.Name
	if ctx.User.SecStatus >= 150 {
		ctx.Sess.WriteString("Name to use: ")
		nameInput, err := ctx.Sess.ReadLine(uploader, 30, inputTimeout)
		if err != nil {
			return
		}
		nameInput = strings.TrimSpace(nameInput)
		if nameInput != "" {
			uploader = nameInput
		}
	}

	// Check if file actually exists on disk
	fullPath := filepath.Join(lib.FilePath, filename)
	var fileSize int64
	if info, err := os.Stat(fullPath); err == nil {
		fileSize = info.Size()
		ctx.Sess.Printf("  File found on disk: %s\r\n", formatSize(fileSize))
	} else {
		ctx.Sess.Color(session.AnsiFgBrightYellow)
		ctx.Sess.WriteString("  File not yet on disk.\r\n")
		ctx.Sess.Printf("  Place it at: %s\r\n", fullPath)
		ctx.Sess.Color(session.AnsiReset)
	}

	// Save the entry
	entry := &models.LibraryFile{
		LibraryID:   lib.ID,
		Filename:    filename,
		Description: strings.TrimSpace(desc),
		UploaderID:  ctx.User.ID,
		Uploader:    uploader,
		FileSize:    fileSize,
	}

	if err := ctx.Store.CreateLibraryFile(entry); err != nil {
		ctx.Sess.WriteString("  Error saving file entry.\r\n")
		return
	}

	ctx.User.Uploads++
	ctx.Store.UpdateUser(ctx.User)

	// Refresh library
	if updated, err := ctx.Store.GetLibrary(lib.ID); err == nil {
		*lib = *updated
	}

	ctx.Sess.Color(session.AnsiFgGreen)
	ctx.Sess.Printf("  File entry #%d created.\r\n", entry.ID)
	ctx.Sess.Color(session.AnsiReset)
}

// libRemove deletes a file entry from the library.
// Replaces Lib_Delete_Frontend() from LCOM.C.
func libRemove(ctx *Context, lib *models.Library) {
	if lib.FileCount == 0 {
		ctx.Sess.WriteString("  No files to remove.\r\n")
		return
	}

	ctx.Sess.Printf("  Remove which [1-%d] (0 to cancel): ", lib.FileCount)
	numStr, err := ctx.Sess.ReadLine("", 5, inputTimeout)
	if err != nil {
		return
	}
	num := parseIntDefault(numStr, 0)
	if num < 1 || num > lib.FileCount {
		ctx.Sess.WriteString("  Cancelled.\r\n")
		return
	}

	files, err := ctx.Store.ListLibraryFiles(lib.ID, num-1, 1)
	if err != nil || len(files) == 0 {
		ctx.Sess.WriteString("  File not found.\r\n")
		return
	}

	f := files[0]
	ctx.Sess.Printf("  Remove \"%s\" by %s? ", f.Filename, f.Uploader)
	yes, err := ctx.Sess.Confirm("", inputTimeout)
	if err != nil || !yes {
		ctx.Sess.WriteString("  Not removed.\r\n")
		return
	}

	ctx.Store.DeleteLibraryFile(f.ID)
	if updated, err := ctx.Store.GetLibrary(lib.ID); err == nil {
		*lib = *updated
	}

	ctx.Sess.Color(session.AnsiFgGreen)
	ctx.Sess.WriteString("  File entry removed.\r\n")
	ctx.Sess.WriteString("  (The file itself remains on disk.)\r\n")
	ctx.Sess.Color(session.AnsiReset)
}

// formatSize formats a byte count as a human-readable string.
func formatSize(bytes int64) string {
	switch {
	case bytes >= 1024*1024:
		return fmt.Sprintf("%.1f MB", float64(bytes)/(1024*1024))
	case bytes >= 1024:
		return fmt.Sprintf("%.1f KB", float64(bytes)/1024)
	default:
		return fmt.Sprintf("%d B", bytes)
	}
}