nav.go

package main

import (
	"bufio"
	"errors"
	"fmt"
	"io"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"sort"
	"strconv"
	"strings"
	"time"

	times "gopkg.in/djherbis/times.v1"
)

type linkState byte

const (
	notLink linkState = iota
	working
	broken
)

type file struct {
	os.FileInfo
	linkState  linkState
	path       string
	dirCount   int
	accessTime time.Time
	changeTime time.Time
	ext        string
}

func readdir(path string) ([]*file, error) {
	f, err := os.Open(path)
	if err != nil {
		return nil, err
	}
	names, err := f.Readdirnames(-1)
	f.Close()

	files := make([]*file, 0, len(names))
	for _, fname := range names {
		fpath := filepath.Join(path, fname)

		lstat, err := os.Lstat(fpath)
		if os.IsNotExist(err) {
			continue
		}
		if err != nil {
			return files, err
		}

		var linkState linkState

		if lstat.Mode()&os.ModeSymlink != 0 {
			stat, err := os.Stat(fpath)
			if err == nil {
				linkState = working
				lstat = stat
			} else {
				linkState = broken
			}
		}

		ts := times.Get(lstat)
		at := ts.AccessTime()
		var ct time.Time
		// from times docs: ChangeTime() panics unless HasChangeTime() is true
		if ts.HasChangeTime() {
			ct = ts.ChangeTime()
		} else {
			// fall back to ModTime if ChangeTime cannot be determined
			ct = lstat.ModTime()
		}

		// returns an empty string if extension could not be determined
		// i.e. directories, filenames without extensions
		ext := filepath.Ext(fpath)

		files = append(files, &file{
			FileInfo:   lstat,
			linkState:  linkState,
			path:       fpath,
			dirCount:   -1,
			accessTime: at,
			changeTime: ct,
			ext:        ext,
		})
	}

	return files, err
}

type dir struct {
	loading  bool      // directory is loading from disk
	loadTime time.Time // current loading or last load time
	ind      int       // index of current entry in files
	pos      int       // position of current entry in ui
	path     string    // full path of directory
	files    []*file   // displayed files in directory including or excluding hidden ones
	allFiles []*file   // all files in directory including hidden ones (same array as files)
	sortType sortType  // sort method and options from last sort
	noPerm   bool      // whether lf has no permission to open the directory
}

func newDir(path string) *dir {
	time := time.Now()

	files, err := readdir(path)
	if err != nil {
		log.Printf("reading directory: %s", err)
	}

	return &dir{
		loadTime: time,
		path:     path,
		files:    files,
		allFiles: files,
		noPerm:   os.IsPermission(err),
	}
}

func (dir *dir) sort() {
	dir.sortType = gOpts.sortType

	dir.files = dir.allFiles

	switch gOpts.sortType.method {
	case naturalSort:
		sort.SliceStable(dir.files, func(i, j int) bool {
			return naturalLess(strings.ToLower(dir.files[i].Name()), strings.ToLower(dir.files[j].Name()))
		})
	case nameSort:
		sort.SliceStable(dir.files, func(i, j int) bool {
			return strings.ToLower(dir.files[i].Name()) < strings.ToLower(dir.files[j].Name())
		})
	case sizeSort:
		sort.SliceStable(dir.files, func(i, j int) bool {
			return dir.files[i].Size() < dir.files[j].Size()
		})
	case timeSort:
		sort.SliceStable(dir.files, func(i, j int) bool {
			return dir.files[i].ModTime().Before(dir.files[j].ModTime())
		})
	case atimeSort:
		sort.SliceStable(dir.files, func(i, j int) bool {
			return dir.files[i].accessTime.Before(dir.files[j].accessTime)
		})
	case ctimeSort:
		sort.SliceStable(dir.files, func(i, j int) bool {
			return dir.files[i].changeTime.Before(dir.files[j].changeTime)
		})
	case extSort:
		sort.SliceStable(dir.files, func(i, j int) bool {
			leftExt := strings.ToLower(dir.files[i].ext)
			rightExt := strings.ToLower(dir.files[j].ext)

			// if the extension could not be determined (directories, files without)
			// use a zero byte so that these files can be ranked higher
			if leftExt == "" {
				leftExt = "\x00"
			}
			if rightExt == "" {
				rightExt = "\x00"
			}

			// in order to also have natural sorting with the filenames
			// combine the name with the ext but have the ext at the front
			left := leftExt + strings.ToLower(dir.files[i].Name())
			right := rightExt + strings.ToLower(dir.files[j].Name())
			return left < right
		})
	}

	if gOpts.sortType.option&reverseSort != 0 {
		for i, j := 0, len(dir.files)-1; i < j; i, j = i+1, j-1 {
			dir.files[i], dir.files[j] = dir.files[j], dir.files[i]
		}
	}

	if gOpts.sortType.option&dirfirstSort != 0 {
		sort.SliceStable(dir.files, func(i, j int) bool {
			if dir.files[i].IsDir() == dir.files[j].IsDir() {
				return i < j
			}
			return dir.files[i].IsDir()
		})
	}

	// when hidden option is disabled, we move hidden files to the
	// beginning of our file list and then set the beginning of displayed
	// files to the first non-hidden file in the list
	if gOpts.sortType.option&hiddenSort == 0 {
		sort.SliceStable(dir.files, func(i, j int) bool {
			if isHidden(dir.files[i]) && isHidden(dir.files[j]) {
				return i < j
			}
			return isHidden(dir.files[i])
		})
		for i, f := range dir.files {
			if !isHidden(f) {
				dir.files = dir.files[i:]
				return
			}
		}
		dir.files = dir.files[len(dir.files):]
	}
}

func (dir *dir) name() string {
	if len(dir.files) == 0 {
		return ""
	}
	return dir.files[dir.ind].Name()
}

func (dir *dir) sel(name string, height int) {
	if len(dir.files) == 0 {
		dir.ind, dir.pos = 0, 0
		return
	}

	dir.ind = min(dir.ind, len(dir.files)-1)

	if dir.files[dir.ind].Name() != name {
		for i, f := range dir.files {
			if f.Name() == name {
				dir.ind = i
				break
			}
		}
	}

	edge := min(min(height/2, gOpts.scrolloff), len(dir.files)-dir.ind-1)
	dir.pos = min(dir.ind, height-edge-1)
}

type nav struct {
	dirs            []*dir
	copyBytes       int64
	copyTotal       int64
	copyUpdate      int
	moveCount       int
	moveTotal       int
	moveUpdate      int
	deleteCount     int
	deleteTotal     int
	deleteUpdate    int
	copyBytesChan   chan int64
	copyTotalChan   chan int64
	moveCountChan   chan int
	moveTotalChan   chan int
	deleteCountChan chan int
	deleteTotalChan chan int
	dirChan         chan *dir
	regChan         chan *reg
	dirCache        map[string]*dir
	regCache        map[string]*reg
	saves           map[string]bool
	marks           map[string]string
	renameCache     []string
	selections      map[string]int
	selectionInd    int
	height          int
	find            string
	findBack        bool
	search          string
	searchBack      bool
	searchInd       int
	searchPos       int
}

func (nav *nav) loadDir(path string) *dir {
	d, ok := nav.dirCache[path]
	if !ok {
		go func() {
			d := newDir(path)
			d.sort()
			d.ind, d.pos = 0, 0
			nav.dirChan <- d
		}()
		d := &dir{loading: true, path: path, sortType: gOpts.sortType}
		nav.dirCache[path] = d
		return d
	}

	s, err := os.Stat(d.path)
	if err != nil {
		return d
	}

	switch {
	case s.ModTime().After(d.loadTime):
		go func() {
			d.loadTime = time.Now()
			nd := newDir(path)
			nd.sort()
			nd.sel(d.name(), nav.height)
			nav.dirChan <- nd
		}()
	case d.sortType != gOpts.sortType:
		go func() {
			d.loading = true
			name := d.name()
			d.sort()
			d.sel(name, nav.height)
			d.loading = false
			nav.dirChan <- d
		}()
	}

	return d
}

func (nav *nav) getDirs(wd string) {
	var dirs []*dir

	for curr, base := wd, ""; !isRoot(base); curr, base = filepath.Dir(curr), filepath.Base(curr) {
		dir := nav.loadDir(curr)
		dir.sel(base, nav.height)
		dirs = append(dirs, dir)
	}

	for i, j := 0, len(dirs)-1; i < j; i, j = i+1, j-1 {
		dirs[i], dirs[j] = dirs[j], dirs[i]
	}

	nav.dirs = dirs
}

func newNav(height int) *nav {
	wd, err := os.Getwd()
	if err != nil {
		log.Printf("getting current directory: %s", err)
	}

	nav := &nav{
		copyBytesChan:   make(chan int64, 1024),
		copyTotalChan:   make(chan int64, 1024),
		moveCountChan:   make(chan int, 1024),
		moveTotalChan:   make(chan int, 1024),
		deleteCountChan: make(chan int, 1024),
		deleteTotalChan: make(chan int, 1024),
		dirChan:         make(chan *dir),
		regChan:         make(chan *reg),
		dirCache:        make(map[string]*dir),
		regCache:        make(map[string]*reg),
		saves:           make(map[string]bool),
		marks:           make(map[string]string),
		renameCache:     make([]string, 2),
		selections:      make(map[string]int),
		selectionInd:    0,
		height:          height,
	}

	nav.getDirs(wd)

	return nav
}

func (nav *nav) renew() {
	for _, d := range nav.dirs {
		go func(d *dir) {
			s, err := os.Stat(d.path)
			if err != nil {
				log.Printf("getting directory info: %s", err)
				return
			}
			if d.loadTime.After(s.ModTime()) {
				return
			}
			d.loadTime = time.Now()
			nd := newDir(d.path)
			nd.sort()
			nav.dirChan <- nd
		}(d)
	}

	for m := range nav.selections {
		if _, err := os.Stat(m); os.IsNotExist(err) {
			delete(nav.selections, m)
		}
	}
	if len(nav.selections) == 0 {
		nav.selectionInd = 0
	}
}

func (nav *nav) reload() error {
	nav.dirCache = make(map[string]*dir)
	nav.regCache = make(map[string]*reg)

	wd, err := os.Getwd()
	if err != nil {
		return fmt.Errorf("getting current directory: %s", err)
	}

	curr, err := nav.currFile()
	nav.getDirs(wd)
	if err == nil {
		last := nav.dirs[len(nav.dirs)-1]
		last.files = append(last.files, curr)
	}

	return nil
}

func (nav *nav) position() {
	path := nav.currDir().path
	for i := len(nav.dirs) - 2; i >= 0; i-- {
		nav.dirs[i].sel(filepath.Base(path), nav.height)
		path = filepath.Dir(path)
	}
}

func (nav *nav) preview() {
	curr, err := nav.currFile()
	if err != nil {
		return
	}

	var reader io.Reader

	if len(gOpts.previewer) != 0 {
		cmd := exec.Command(gOpts.previewer, curr.path, strconv.Itoa(nav.height))

		out, err := cmd.StdoutPipe()
		if err != nil {
			log.Printf("previewing file: %s", err)
		}

		if err := cmd.Start(); err != nil {
			log.Printf("previewing file: %s", err)
		}

		defer cmd.Wait()
		defer out.Close()
		reader = out
	} else {
		f, err := os.Open(curr.path)
		if err != nil {
			log.Printf("opening file: %s", err)
		}

		defer f.Close()
		reader = f
	}

	reg := &reg{loadTime: time.Now(), path: curr.path}

	buf := bufio.NewScanner(reader)

	for i := 0; i < nav.height && buf.Scan(); i++ {
		for _, r := range buf.Text() {
			if r == 0 {
				reg.lines = []string{"\033[7mbinary\033[0m"}
				nav.regChan <- reg
				return
			}
		}
		reg.lines = append(reg.lines, buf.Text())
	}

	if buf.Err() != nil {
		log.Printf("loading file: %s", buf.Err())
	}

	nav.regChan <- reg
}

func (nav *nav) loadReg(path string) *reg {
	r, ok := nav.regCache[path]
	if !ok {
		go nav.preview()
		r := &reg{loading: true, path: path}
		nav.regCache[path] = r
		return r
	}

	s, err := os.Stat(r.path)
	if err != nil {
		return r
	}

	if s.ModTime().After(r.loadTime) {
		r.loadTime = time.Now()
		go nav.preview()
	}

	return r
}

func (nav *nav) sort() {
	for _, d := range nav.dirs {
		name := d.name()
		d.sort()
		d.sel(name, nav.height)
	}
}

func (nav *nav) up(dist int) {
	dir := nav.currDir()

	if dir.ind == 0 {
		if gOpts.wrapscroll {
			nav.bottom()
		}
		return
	}

	dir.ind -= dist
	dir.ind = max(0, dir.ind)

	dir.pos -= dist
	edge := min(min(nav.height/2, gOpts.scrolloff), dir.ind)
	dir.pos = max(dir.pos, edge)
}

func (nav *nav) down(dist int) {
	dir := nav.currDir()

	maxind := len(dir.files) - 1

	if dir.ind >= maxind {
		if gOpts.wrapscroll {
			nav.top()
		}
		return
	}

	dir.ind += dist
	dir.ind = min(maxind, dir.ind)

	dir.pos += dist
	edge := min(min(nav.height/2, gOpts.scrolloff), maxind-dir.ind)

	// use a smaller value when the height is even and scrolloff is maxed
	// in order to stay at the same row as much as possible while up/down
	edge = min(edge, nav.height/2+nav.height%2-1)

	dir.pos = min(dir.pos, nav.height-edge-1)
	dir.pos = min(dir.pos, maxind)
}

func (nav *nav) updir() error {
	if len(nav.dirs) <= 1 {
		return nil
	}

	dir := nav.currDir()

	nav.dirs = nav.dirs[:len(nav.dirs)-1]

	if err := os.Chdir(filepath.Dir(dir.path)); err != nil {
		return fmt.Errorf("updir: %s", err)
	}

	return nil
}

func (nav *nav) open() error {
	curr, err := nav.currFile()
	if err != nil {
		return fmt.Errorf("open: %s", err)
	}

	path := curr.path

	dir := nav.loadDir(path)

	nav.dirs = append(nav.dirs, dir)

	if err := os.Chdir(path); err != nil {
		return fmt.Errorf("open: %s", err)
	}

	return nil
}

func (nav *nav) top() {
	dir := nav.currDir()

	dir.ind = 0
	dir.pos = 0
}

func (nav *nav) bottom() {
	dir := nav.currDir()

	dir.ind = len(dir.files) - 1
	dir.pos = min(dir.ind, nav.height-1)
}

func (nav *nav) toggleSelection(path string) {
	if _, ok := nav.selections[path]; ok {
		delete(nav.selections, path)
		if len(nav.selections) == 0 {
			nav.selectionInd = 0
		}
	} else {
		nav.selections[path] = nav.selectionInd
		nav.selectionInd++
	}
}

func (nav *nav) toggle() {
	curr, err := nav.currFile()
	if err != nil {
		return
	}

	nav.toggleSelection(curr.path)

	nav.down(1)
}

func (nav *nav) invert() {
	last := nav.currDir()
	for _, f := range last.files {
		path := filepath.Join(last.path, f.Name())
		nav.toggleSelection(path)
	}
}

func (nav *nav) unselect() {
	nav.selections = make(map[string]int)
	nav.selectionInd = 0
}

func (nav *nav) save(cp bool) error {
	list, err := nav.currFileOrSelections()
	if err != nil {
		return err
	}

	if err := saveFiles(list, cp); err != nil {
		return err
	}

	nav.saves = make(map[string]bool)
	for _, f := range list {
		nav.saves[f] = cp
	}

	return nil
}

func (nav *nav) copyAsync(ui *ui, srcs []string, dstDir string) {
	echo := &callExpr{"echoerr", []string{""}, 1}

	_, err := os.Stat(dstDir)
	if os.IsNotExist(err) {
		echo.args[0] = err.Error()
		ui.exprChan <- echo
		return
	}

	total, err := copySize(srcs)
	if err != nil {
		echo.args[0] = err.Error()
		ui.exprChan <- echo
		return
	}

	nav.copyTotalChan <- total

	nums, errs := copyAll(srcs, dstDir)

	errCount := 0
loop:
	for {
		select {
		case n := <-nums:
			nav.copyBytesChan <- n
		case err, ok := <-errs:
			if !ok {
				break loop
			}
			errCount++
			echo.args[0] = fmt.Sprintf("[%d] %s", errCount, err)
			ui.exprChan <- echo
		}
	}

	nav.copyTotalChan <- -total

	if err := remote("send load"); err != nil {
		errCount++
		echo.args[0] = fmt.Sprintf("[%d] %s", errCount, err)
		ui.exprChan <- echo
	}
}

func (nav *nav) moveAsync(ui *ui, srcs []string, dstDir string) {
	echo := &callExpr{"echoerr", []string{""}, 1}

	_, err := os.Stat(dstDir)
	if os.IsNotExist(err) {
		echo.args[0] = err.Error()
		ui.exprChan <- echo
		return
	}

	nav.moveTotalChan <- len(srcs)

	errCount := 0
	for _, src := range srcs {
		nav.moveCountChan <- 1

		srcStat, err := os.Stat(src)
		if err != nil {
			errCount++
			echo.args[0] = fmt.Sprintf("[%d] %s", errCount, err)
			ui.exprChan <- echo
			continue
		}

		dst := filepath.Join(dstDir, filepath.Base(src))

		dstStat, err := os.Stat(dst)
		if os.SameFile(srcStat, dstStat) {
			errCount++
			echo.args[0] = fmt.Sprintf("[%d] rename %s %s: source and destination are the same file", errCount, src, dst)
			ui.exprChan <- echo
			continue
		} else if !os.IsNotExist(err) {
			var newPath string
			for i := 1; !os.IsNotExist(err); i++ {
				newPath = fmt.Sprintf("%s.~%d~", dst, i)
				_, err = os.Stat(newPath)
			}
			dst = newPath
		}

		if err := os.Rename(src, dst); err != nil {
			errCount++
			echo.args[0] = fmt.Sprintf("[%d] %s", errCount, err)
			ui.exprChan <- echo
		}
	}

	nav.moveTotalChan <- -len(srcs)

	if err := remote("send load"); err != nil {
		errCount++
		echo.args[0] = fmt.Sprintf("[%d] %s", errCount, err)
		ui.exprChan <- echo
	}
}

func (nav *nav) paste(ui *ui) error {
	srcs, cp, err := loadFiles()
	if err != nil {
		return err
	}

	if len(srcs) == 0 {
		return errors.New("no file in copy/cut buffer")
	}

	dstDir := nav.currDir().path

	if cp {
		go nav.copyAsync(ui, srcs, dstDir)
	} else {
		go nav.moveAsync(ui, srcs, dstDir)
	}

	if err := saveFiles(nil, false); err != nil {
		return fmt.Errorf("clearing copy/cut buffer: %s", err)
	}

	if err := remote("send sync"); err != nil {
		return fmt.Errorf("paste: %s", err)
	}

	return nil
}

func (nav *nav) del(ui *ui) error {
	list, err := nav.currFileOrSelections()
	if err != nil {
		return err
	}

	go func() {
		echo := &callExpr{"echoerr", []string{""}, 1}
		errCount := 0

		nav.deleteTotalChan <- len(list)

		for _, path := range list {
			nav.deleteCountChan <- 1

			if err := os.RemoveAll(path); err != nil {
				errCount++
				echo.args[0] = fmt.Sprintf("[%d] %s", errCount, err)
				ui.exprChan <- echo
			}
		}

		nav.deleteTotalChan <- -len(list)

		if err := remote("send load"); err != nil {
			errCount++
			echo.args[0] = fmt.Sprintf("[%d] %s", errCount, err)
			ui.exprChan <- echo
		}
	}()

	return nil
}

func (nav *nav) rename() error {
	oldPath := nav.renameCache[0]
	newPath := nav.renameCache[1]
	dir, _ := filepath.Split(newPath)
	os.MkdirAll(dir, os.ModePerm)

	if _, err := os.Stat(newPath); err == nil { // file exists
		if err := os.Remove(newPath); err != nil {
			return err
		}
	}

	if err := os.Rename(oldPath, newPath); err != nil {
		return err
	}

	// TODO: change selection
	if err := nav.sel(newPath); err != nil {
		return err
	}

	return nil
}

func (nav *nav) sync() error {
	list, cp, err := loadFiles()
	if err != nil {
		return err
	}

	nav.saves = make(map[string]bool)
	for _, f := range list {
		nav.saves[f] = cp
	}

	return nav.readMarks()
}

func (nav *nav) cd(wd string) error {
	wd = strings.Replace(wd, "~", gUser.HomeDir, -1)
	wd = filepath.Clean(wd)

	if !filepath.IsAbs(wd) {
		wd = filepath.Join(nav.currDir().path, wd)
	}

	if err := os.Chdir(wd); err != nil {
		return fmt.Errorf("cd: %s", err)
	}

	nav.getDirs(wd)

	return nil
}

func (nav *nav) sel(path string) error {
	path = strings.Replace(path, "~", gUser.HomeDir, -1)
	path = filepath.Clean(path)

	lstat, err := os.Stat(path)
	if err != nil {
		return fmt.Errorf("select: %s", err)
	}

	dir := filepath.Dir(path)

	if err := nav.cd(dir); err != nil {
		return fmt.Errorf("select: %s", err)
	}

	base := filepath.Base(path)

	last := nav.dirs[len(nav.dirs)-1]
	if last.loading {
		last.files = append(last.files, &file{FileInfo: lstat})
	} else {
		last.sel(base, nav.height)
	}

	return nil
}

func (nav *nav) globSel(pattern string, invert bool) error {
	curDir := nav.currDir()
	anyMatches := false

	for i := 0; i < len(curDir.files); i++ {
		match, err := filepath.Match(pattern, curDir.files[i].Name())
		if err != nil {
			return fmt.Errorf("glob-select: %s", err)
		}
		if match {
			anyMatches = true
			fpath := filepath.Join(curDir.path, curDir.files[i].Name())
			if _, ok := nav.selections[fpath]; ok == invert {
				nav.toggleSelection(fpath)
			}
		}
	}
	if !anyMatches {
		return fmt.Errorf("glob-select: pattern not found: %s", pattern)
	}
	return nil
}

func findMatch(name, pattern string) bool {
	if gOpts.ignorecase {
		lpattern := strings.ToLower(pattern)
		if !gOpts.smartcase || lpattern == pattern {
			pattern = lpattern
			name = strings.ToLower(name)
		}
	}
	if gOpts.ignoredia {
		lpattern := removeDiacritics(pattern)
		if !gOpts.smartdia || lpattern == pattern {
			pattern = lpattern
			name = removeDiacritics(name)
		}
	}
	if gOpts.anchorfind {
		return strings.HasPrefix(name, pattern)
	}
	return strings.Contains(name, pattern)
}

func (nav *nav) findSingle() int {
	count := 0
	index := 0
	last := nav.currDir()
	for i := 0; i < len(last.files); i++ {
		if findMatch(last.files[i].Name(), nav.find) {
			count++
			if count > 1 {
				return count
			}
			index = i
		}
	}
	if count == 1 {
		if index > last.ind {
			nav.down(index - last.ind)
		} else {
			nav.up(last.ind - index)
		}
	}
	return count
}

func (nav *nav) findNext() bool {
	last := nav.currDir()
	for i := last.ind + 1; i < len(last.files); i++ {
		if findMatch(last.files[i].Name(), nav.find) {
			nav.down(i - last.ind)
			return true
		}
	}
	if gOpts.wrapscan {
		for i := 0; i < last.ind; i++ {
			if findMatch(last.files[i].Name(), nav.find) {
				nav.up(last.ind - i)
				return true
			}
		}
	}
	return false
}

func (nav *nav) findPrev() bool {
	last := nav.currDir()
	for i := last.ind - 1; i >= 0; i-- {
		if findMatch(last.files[i].Name(), nav.find) {
			nav.up(last.ind - i)
			return true
		}
	}
	if gOpts.wrapscan {
		for i := len(last.files) - 1; i > last.ind; i-- {
			if findMatch(last.files[i].Name(), nav.find) {
				nav.down(i - last.ind)
				return true
			}
		}
	}
	return false
}

func searchMatch(name, pattern string) (matched bool, err error) {
	if gOpts.ignorecase {
		lpattern := strings.ToLower(pattern)
		if !gOpts.smartcase || lpattern == pattern {
			pattern = lpattern
			name = strings.ToLower(name)
		}
	}
	if gOpts.ignoredia {
		lpattern := removeDiacritics(pattern)
		if !gOpts.smartdia || lpattern == pattern {
			pattern = lpattern
			name = removeDiacritics(name)
		}
	}
	if gOpts.globsearch {
		return filepath.Match(pattern, name)
	}
	return strings.Contains(name, pattern), nil
}

func (nav *nav) searchNext() error {
	last := nav.currDir()
	for i := last.ind + 1; i < len(last.files); i++ {
		matched, err := searchMatch(last.files[i].Name(), nav.search)
		if err != nil {
			return err
		}
		if matched {
			nav.down(i - last.ind)
			return nil
		}
	}
	if gOpts.wrapscan {
		for i := 0; i < last.ind; i++ {
			matched, err := searchMatch(last.files[i].Name(), nav.search)
			if err != nil {
				return err
			}
			if matched {
				nav.up(last.ind - i)
				return nil
			}
		}
	}
	return nil
}

func (nav *nav) searchPrev() error {
	last := nav.currDir()
	for i := last.ind - 1; i >= 0; i-- {
		matched, err := searchMatch(last.files[i].Name(), nav.search)
		if err != nil {
			return err
		}
		if matched {
			nav.up(last.ind - i)
			return nil
		}
	}
	if gOpts.wrapscan {
		for i := len(last.files) - 1; i > last.ind; i-- {
			matched, err := searchMatch(last.files[i].Name(), nav.search)
			if err != nil {
				return err
			}
			if matched {
				nav.down(i - last.ind)
				return nil
			}
		}
	}
	return nil
}

func (nav *nav) removeMark(mark string) error {
	if _, ok := nav.marks[mark]; ok {
		delete(nav.marks, mark)
		return nil
	}
	return fmt.Errorf("no such mark")
}

func (nav *nav) readMarks() error {
	nav.marks = make(map[string]string)
	f, err := os.Open(gMarksPath)
	if os.IsNotExist(err) {
		return nil
	}
	if err != nil {
		return fmt.Errorf("opening marks file: %s", err)
	}
	defer f.Close()

	scanner := bufio.NewScanner(f)
	for scanner.Scan() {
		toks := strings.SplitN(scanner.Text(), ":", 2)
		if _, ok := nav.marks[toks[0]]; !ok {
			nav.marks[toks[0]] = toks[1]
		}
	}

	if err := scanner.Err(); err != nil {
		return fmt.Errorf("reading marks file: %s", err)
	}

	return nil
}

func (nav *nav) writeMarks() error {
	if err := os.MkdirAll(filepath.Dir(gMarksPath), os.ModePerm); err != nil {
		return fmt.Errorf("creating data directory: %s", err)
	}

	f, err := os.Create(gMarksPath)
	if err != nil {
		return fmt.Errorf("creating marks file: %s", err)
	}
	defer f.Close()

	var keys []string
	for k := range nav.marks {
		keys = append(keys, k)
	}
	sort.Strings(keys)

	for _, k := range keys {
		_, err = f.WriteString(fmt.Sprintf("%s:%s\n", k, nav.marks[k]))
		if err != nil {
			return fmt.Errorf("writing marks file: %s", err)
		}
	}

	return nil
}

func (nav *nav) currDir() *dir {
	return nav.dirs[len(nav.dirs)-1]
}

func (nav *nav) currFile() (*file, error) {
	last := nav.dirs[len(nav.dirs)-1]

	if len(last.files) == 0 {
		return nil, fmt.Errorf("empty directory")
	}
	return last.files[last.ind], nil
}

type indexedSelections struct {
	paths   []string
	indices []int
}

func (m indexedSelections) Len() int { return len(m.paths) }

func (m indexedSelections) Swap(i, j int) {
	m.paths[i], m.paths[j] = m.paths[j], m.paths[i]
	m.indices[i], m.indices[j] = m.indices[j], m.indices[i]
}

func (m indexedSelections) Less(i, j int) bool { return m.indices[i] < m.indices[j] }

func (nav *nav) currSelections() []string {
	paths := make([]string, 0, len(nav.selections))
	indices := make([]int, 0, len(nav.selections))
	for path, index := range nav.selections {
		paths = append(paths, path)
		indices = append(indices, index)
	}
	sort.Sort(indexedSelections{paths: paths, indices: indices})
	return paths
}

func (nav *nav) currFileOrSelections() (list []string, err error) {
	if len(nav.selections) == 0 {
		curr, err := nav.currFile()
		if err != nil {
			return nil, errors.New("no file selected")
		}

		return []string{curr.path}, nil
	}

	return nav.currSelections(), nil
}