package ui

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

	"github.com/charmbracelet/bubbles/help"
	"github.com/charmbracelet/bubbles/key"
	"github.com/charmbracelet/bubbles/textinput"
	"github.com/charmbracelet/bubbles/viewport"
	tea "github.com/charmbracelet/bubbletea"
	"github.com/charmbracelet/lipgloss"

	"vcom/internal/config"
	vfs "vcom/internal/fs"
	"vcom/internal/theme"
)

type modalKind int

const (
	modalNone modalKind = iota
	modalMkdir
	modalConfirm
)

type fileOpKind int

const (
	opCopy fileOpKind = iota
	opMove
	opDelete
	opMkdir
	opEdit
	opView
)

type pendingOperation struct {
	kind       fileOpKind
	sourcePath string
	targetDir  string
	overwrite  bool
}

type modalState struct {
	kind    modalKind
	title   string
	body    string
	note    string
	input   textinput.Model
	pending *pendingOperation
}

type previewMsg struct {
	entryPath string
	preview   vfs.Preview
}

type dirSizeMsg struct {
	path string
	size int64
	err  error
}

type opMsg struct {
	kind       fileOpKind
	sourcePath string
	targetPath string
	err        error
}

type mouseClickState struct {
	pane  PaneID
	index int
	at    time.Time
}

type hoverState struct {
	pane  PaneID
	index int
	ok    bool
}

type Model struct {
	cfg        config.Config
	configPath string
	palette    theme.Palette
	keys       KeyMap

	width  int
	height int

	left     BrowserPane
	right    BrowserPane
	active   PaneID
	infoMode bool

	helpModel    help.Model
	previewModel viewport.Model
	previewData  vfs.Preview

	modal  modalState
	status string
	busy   bool

	lastClick mouseClickState
	hover     hoverState
}

func NewModel(cfg config.Config, configPath string) (Model, error) {
	palette, err := theme.Resolve(cfg.UI.Theme)
	if err != nil {
		return Model{}, err
	}

	cwd, err := os.Getwd()
	if err != nil {
		return Model{}, err
	}

	leftPath, err := resolveStartPath(cfg.Startup.LeftPath, cwd)
	if err != nil {
		return Model{}, err
	}
	rightPath, err := resolveStartPath(cfg.Startup.RightPath, cwd)
	if err != nil {
		return Model{}, err
	}

	model := Model{
		cfg:        cfg,
		configPath: configPath,
		palette:    palette,
		keys:       DefaultKeyMap(),
		left:       BrowserPane{ID: PaneLeft, Path: leftPath},
		right:      BrowserPane{ID: PaneRight, Path: rightPath},
		active:     PaneLeft,
		status:     "Ready",
	}

	model.helpModel = help.New()
	model.helpModel.ShowAll = false
	model.helpModel.Styles = help.Styles{
		ShortKey:       lipgloss.NewStyle().Foreground(palette.FooterKey).Bold(true),
		ShortDesc:      lipgloss.NewStyle().Foreground(palette.Text),
		ShortSeparator: lipgloss.NewStyle().Foreground(palette.Border),
		Ellipsis:       lipgloss.NewStyle().Foreground(palette.Muted),
		FullKey:        lipgloss.NewStyle().Foreground(palette.FooterKey).Bold(true),
		FullDesc:       lipgloss.NewStyle().Foreground(palette.Text),
		FullSeparator:  lipgloss.NewStyle().Foreground(palette.Border),
	}
	model.previewModel = viewport.New(0, 0)
	if err := model.reloadPane(PaneLeft, ""); err != nil {
		return Model{}, err
	}
	if err := model.reloadPane(PaneRight, ""); err != nil {
		return Model{}, err
	}
	return model, nil
}

func (m Model) Init() tea.Cmd {
	return m.loadPreviewCmd()
}

func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	switch msg := msg.(type) {
	case tea.WindowSizeMsg:
		m.width = msg.Width
		m.height = msg.Height
		m.resizePreview()
		m.syncPreviewContent()
		return m, nil

	case previewMsg:
		if selected, ok := m.activePane().Selected(); ok && selected.Path == msg.entryPath {
			m.applyPreview(msg.preview)
		}
		return m, nil

	case dirSizeMsg:
		m.busy = false
		if msg.err != nil {
			m.status = fmt.Sprintf("Dir size failed: %v", msg.err)
			return m, nil
		}
		m.applyDirSize(msg.path, msg.size)
		m.status = fmt.Sprintf("Directory size calculated: %s", vfs.HumanSize(msg.size))
		return m, m.loadPreviewCmd()

	case opMsg:
		m.busy = false
		if msg.err != nil {
			m.status = msg.err.Error()
			return m, nil
		}

		m.modal = modalState{}
		switch msg.kind {
		case opCopy:
			m.status = fmt.Sprintf("Copied to %s", msg.targetPath)
		case opMove:
			m.status = fmt.Sprintf("Moved to %s", msg.targetPath)
		case opDelete:
			m.status = "Deleted"
		case opMkdir:
			m.status = fmt.Sprintf("Created %s", msg.targetPath)
		case opEdit:
			m.status = "Editor closed"
			return m, tea.Batch(m.loadPreviewCmd(), enableMouseCmd())
		case opView:
			m.status = "Viewer closed"
			return m, enableMouseCmd()
		}

		activeSelection := selectedName(m.activePane())
		_ = m.reloadPane(PaneLeft, activeSelection)
		_ = m.reloadPane(PaneRight, activeSelection)
		return m, m.loadPreviewCmd()

	case tea.KeyMsg:
		if m.modal.kind != modalNone {
			return m.handleModalKey(msg)
		}

		switch {
		case key.Matches(msg, m.keys.Quit):
			return m, tea.Quit
		case key.Matches(msg, m.keys.View):
			return m.handleView()
		case key.Matches(msg, m.keys.Edit):
			return m.handleEdit()
		case key.Matches(msg, m.keys.Info):
			return m.toggleInfo()
		case key.Matches(msg, m.keys.ToggleHidden):
			return m.toggleHidden()
		case key.Matches(msg, m.keys.CycleTheme):
			return m.cycleTheme()
		case key.Matches(msg, m.keys.CycleSort):
			return m.cycleSort()
		case key.Matches(msg, m.keys.Switch):
			if m.active == PaneLeft {
				m.active = PaneRight
			} else {
				m.active = PaneLeft
			}
			m.status = fmt.Sprintf("Active pane: %s", strings.ToUpper(string(m.active)))
			return m, m.loadPreviewCmd()
		case key.Matches(msg, m.keys.Up):
			m.moveCursor(-1)
			return m, m.loadPreviewCmd()
		case key.Matches(msg, m.keys.Down):
			m.moveCursor(1)
			return m, m.loadPreviewCmd()
		case key.Matches(msg, m.keys.PageUp):
			m.moveCursor(-max(m.bodyHeight()-6, 5))
			return m, m.loadPreviewCmd()
		case key.Matches(msg, m.keys.PageDown):
			m.moveCursor(max(m.bodyHeight()-6, 5))
			return m, m.loadPreviewCmd()
		case key.Matches(msg, m.keys.Open):
			return m.handleOpenSelected()
		case key.Matches(msg, m.keys.Back):
			if err := m.goParent(); err != nil {
				m.status = err.Error()
			}
			return m, m.loadPreviewCmd()
		case key.Matches(msg, m.keys.Refresh):
			return m.refreshAllPanes("Refreshed")
		case key.Matches(msg, m.keys.DirSize):
			return m.handleDirSize()
		case key.Matches(msg, m.keys.Copy):
			return m.handleTransfer(opCopy)
		case key.Matches(msg, m.keys.Move):
			return m.handleTransfer(opMove)
		case key.Matches(msg, m.keys.Mkdir):
			m.openMkdirModal()
			return m, nil
		case key.Matches(msg, m.keys.Delete):
			return m.handleDelete()
		}

	case tea.MouseMsg:
		return m.handleMouse(msg)
	}

	return m, nil
}

func (m Model) View() string {
	if m.width < 72 || m.height < 18 {
		return lipgloss.NewStyle().
			Foreground(m.palette.Warning).
			Padding(1, 2).
			Render("Terminal is too small for vcom. Resize the window.")
	}

	leftWidth, previewWidth, rightWidth := m.layoutWidths()
	bodyHeight := m.bodyHeight()
	gap := strings.Repeat(" ", m.cfg.UI.PaneGap)

	var panels string
	if m.infoMode {
		if m.active == PaneLeft {
			panels = lipgloss.JoinHorizontal(
				lipgloss.Top,
				renderPane(m.left, m.cfg, m.palette, leftWidth, bodyHeight, true, m.hoverIndexFor(PaneLeft)),
				gap,
				renderPreviewPane(m.previewData, &m.previewModel, m.cfg, m.palette, previewWidth, bodyHeight),
			)
		} else {
			panels = lipgloss.JoinHorizontal(
				lipgloss.Top,
				renderPreviewPane(m.previewData, &m.previewModel, m.cfg, m.palette, previewWidth, bodyHeight),
				gap,
				renderPane(m.right, m.cfg, m.palette, rightWidth, bodyHeight, true, m.hoverIndexFor(PaneRight)),
			)
		}
	} else {
		panels = lipgloss.JoinHorizontal(
			lipgloss.Top,
			renderPane(m.left, m.cfg, m.palette, leftWidth, bodyHeight, m.active == PaneLeft, m.hoverIndexFor(PaneLeft)),
			gap,
			renderPane(m.right, m.cfg, m.palette, rightWidth, bodyHeight, m.active == PaneRight, m.hoverIndexFor(PaneRight)),
		)
	}

	parts := make([]string, 0, 4)
	if m.cfg.UI.ShowTitleBar {
		parts = append(parts, renderTitleBar(m))
	}
	parts = append(parts, panels)
	parts = append(parts, renderStatus(m))
	if m.cfg.UI.ShowFooter {
		parts = append(parts, renderFooter(m))
	}

	view := lipgloss.JoinVertical(lipgloss.Left, parts...)
	if m.modal.kind != modalNone {
		view = overlayCenter(view, renderModal(m.modal, m.palette, min(64, m.width-8)), m.width)
	}
	return view
}

func (m Model) handleModalKey(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
	switch m.modal.kind {
	case modalMkdir:
		switch {
		case key.Matches(msg, m.keys.Cancel):
			m.modal = modalState{}
			m.status = "Cancelled"
			return m, nil
		case key.Matches(msg, m.keys.Confirm):
			value := strings.TrimSpace(m.modal.input.Value())
			if value == "" {
				m.status = "Directory name must not be empty"
				return m, nil
			}
			m.busy = true
			return m, mkdirCmd(m.activePane().Path, value)
		}

		var cmd tea.Cmd
		m.modal.input, cmd = m.modal.input.Update(msg)
		return m, cmd

	case modalConfirm:
		switch {
		case key.Matches(msg, m.keys.Cancel):
			m.modal = modalState{}
			m.status = "Cancelled"
			return m, nil
		case key.Matches(msg, m.keys.Confirm):
			if m.modal.pending == nil {
				m.modal = modalState{}
				m.status = "Nothing to confirm"
				return m, nil
			}
			m.busy = true
			cmd := m.modal.pending.cmd()
			m.modal = modalState{}
			return m, cmd
		}
	}

	return m, nil
}

func (m *Model) reloadPane(id PaneID, preserve string) error {
	pane := m.paneByID(id)
	entries, err := vfs.ListDir(pane.Path, vfs.ListOptions{
		ShowHidden:  m.cfg.Browser.ShowHidden,
		DirsFirst:   m.cfg.Browser.DirsFirst,
		SortBy:      m.cfg.Browser.Sort.By,
		SortReverse: m.cfg.Browser.Sort.Reverse,
	})
	if err != nil {
		return err
	}
	pane.SetEntries(entries, strings.ToLower(preserve))
	return nil
}

func (m *Model) refreshAllPanes(status string) (tea.Model, tea.Cmd) {
	leftSelected := selectedName(&m.left)
	rightSelected := selectedName(&m.right)
	if err := m.reloadPane(PaneLeft, leftSelected); err != nil {
		m.status = err.Error()
		return m, nil
	}
	if err := m.reloadPane(PaneRight, rightSelected); err != nil {
		m.status = err.Error()
		return m, nil
	}
	m.status = status
	return m, m.loadPreviewCmd()
}

func (m *Model) moveCursor(delta int) {
	pane := m.activePane()
	pane.Move(delta, max(m.bodyHeight()-4, 1))
	m.hover = hoverState{}
}

func (m *Model) enterSelected() error {
	m.hover = hoverState{}
	pane := m.activePane()
	selected, ok := pane.Selected()
	if !ok {
		return nil
	}
	if !selected.IsDir {
		m.status = "File is shown in the middle pane. Use F3 for pager or F4 for editor."
		return nil
	}
	currentName := selected.Name
	pane.Path = selected.Path
	if err := m.reloadPane(pane.ID, currentName); err != nil {
		return err
	}
	m.status = fmt.Sprintf("Entered %s", pane.Path)
	return nil
}

func (m *Model) handleOpenSelected() (tea.Model, tea.Cmd) {
	selected, ok := m.activePane().Selected()
	if !ok {
		return m, nil
	}

	if selected.IsDir {
		if err := m.enterSelected(); err != nil {
			m.status = err.Error()
			return m, nil
		}
		return m, m.loadPreviewCmd()
	}

	if isEditableEntry(selected) {
		return m.handleEdit()
	}
	return m.handleOpenExternal()
}

func (m *Model) goParent() error {
	m.hover = hoverState{}
	pane := m.activePane()
	parent := filepath.Dir(pane.Path)
	if parent == pane.Path {
		return nil
	}
	currentName := filepath.Base(pane.Path)
	pane.Path = parent
	if err := m.reloadPane(pane.ID, currentName); err != nil {
		return err
	}
	m.status = fmt.Sprintf("Moved to %s", parent)
	return nil
}

func (m Model) loadPreviewCmd() tea.Cmd {
	selected, ok := m.activePane().Selected()
	if !ok {
		return func() tea.Msg {
			return previewMsg{
				entryPath: "",
				preview: vfs.Preview{
					Kind:  vfs.PreviewKindEmpty,
					Title: "Nothing selected",
					Body:  "No entry selected.",
				},
			}
		}
	}

	options := vfs.PreviewOptions{
		ShowHidden:            m.cfg.Browser.ShowHidden,
		DirsFirst:             m.cfg.Browser.DirsFirst,
		SortBy:                m.cfg.Browser.Sort.By,
		SortReverse:           m.cfg.Browser.Sort.Reverse,
		MaxPreviewBytes:       m.cfg.Preview.MaxPreviewBytes,
		DirectoryPreviewLimit: m.cfg.Preview.DirectoryPreviewLimit,
		HumanReadableSize:     m.cfg.Browser.HumanReadableSize,
	}

	return func() tea.Msg {
		return previewMsg{
			entryPath: selected.Path,
			preview:   vfs.BuildPreview(selected, options),
		}
	}
}

func (m *Model) handleDirSize() (tea.Model, tea.Cmd) {
	if !m.cfg.Behavior.CalculateDirSizeOnSpace {
		m.status = "Directory size on Space is disabled in config"
		return m, nil
	}
	selected, ok := m.activePane().Selected()
	if !ok || !selected.IsDir || selected.IsParent {
		m.status = "Select a directory first"
		return m, nil
	}
	if selected.DirSizeKnown {
		m.status = fmt.Sprintf("Directory size: %s", formatSize(selected.Size, m.cfg.Browser.HumanReadableSize))
		return m, nil
	}

	m.busy = true
	m.status = fmt.Sprintf("Calculating directory size for %s", selected.DisplayName())
	return m, dirSizeCmd(selected.Path)
}

func (m *Model) handleTransfer(kind fileOpKind) (tea.Model, tea.Cmd) {
	selected, ok := m.activePane().Selected()
	if !ok || selected.IsParent {
		m.status = fmt.Sprintf("Nothing to %s", operationVerb(kind))
		return m, nil
	}

	targetDir := m.passivePane().Path
	targetPath := filepath.Join(targetDir, filepath.Base(selected.Path))
	exists, err := vfs.PathExists(targetPath)
	if err != nil {
		m.status = err.Error()
		return m, nil
	}

	if exists && m.cfg.Behavior.ConfirmOverwrite {
		title := fmt.Sprintf("Overwrite existing target before %s?", operationVerb(kind))
		body := fmt.Sprintf("%s\n\n-> %s", selected.Path, targetPath)
		note := "Enter/y to overwrite, Esc/n to cancel"
		m.openConfirmModal(title, body, note, pendingOperation{
			kind:       kind,
			sourcePath: selected.Path,
			targetDir:  targetDir,
			overwrite:  true,
		})
		return m, nil
	}

	m.busy = true
	m.status = fmt.Sprintf("%s %s", strings.Title(operationVerb(kind)), selected.DisplayName())
	return m, operationCmd(kind, selected.Path, targetDir, exists)
}

func (m *Model) handleDelete() (tea.Model, tea.Cmd) {
	selected, ok := m.activePane().Selected()
	if !ok || selected.IsParent {
		m.status = "Nothing to delete"
		return m, nil
	}
	if !m.cfg.Behavior.ConfirmDelete {
		m.busy = true
		m.status = fmt.Sprintf("Deleting %s", selected.DisplayName())
		return m, deleteCmd(selected.Path)
	}

	m.openConfirmModal(
		"Delete selected entry?",
		selected.Path,
		"Enter/y to delete permanently, Esc/n to cancel",
		pendingOperation{
			kind:       opDelete,
			sourcePath: selected.Path,
		},
	)
	return m, nil
}

func (m *Model) handleView() (tea.Model, tea.Cmd) {
	selected, ok := m.activePane().Selected()
	if !ok || selected.IsParent || selected.IsDir {
		m.status = "Preview refreshed"
		return m, m.loadPreviewCmd()
	}

	command, name, err := externalCommand("PAGER", []string{"less", "more"}, selected.Path)
	if err != nil {
		m.status = "Preview refreshed in center pane"
		return m, m.loadPreviewCmd()
	}

	m.status = fmt.Sprintf("Opening %s with %s", selected.DisplayName(), name)
	return m, tea.ExecProcess(command, func(err error) tea.Msg {
		return opMsg{kind: opView, sourcePath: selected.Path, err: err}
	})
}

func (m *Model) handleOpenExternal() (tea.Model, tea.Cmd) {
	selected, ok := m.activePane().Selected()
	if !ok || selected.IsParent || selected.IsDir {
		m.status = "Select a file to open"
		return m, nil
	}

	command, name, err := externalCommand("", []string{"xdg-open", "open"}, selected.Path)
	if err != nil {
		m.status = "No system opener found (tried xdg-open/open)"
		return m, nil
	}

	m.status = fmt.Sprintf("Opening %s with %s", selected.DisplayName(), name)
	return m, tea.ExecProcess(command, func(err error) tea.Msg {
		return opMsg{kind: opView, sourcePath: selected.Path, err: err}
	})
}

func (m *Model) handleEdit() (tea.Model, tea.Cmd) {
	selected, ok := m.activePane().Selected()
	if !ok || selected.IsParent || selected.IsDir {
		m.status = "Select a file to edit"
		return m, nil
	}

	command, name, err := externalCommandFromEnv([]string{"VISUAL", "EDITOR"}, []string{"nvim", "vim", "vi", "nano"}, selected.Path)
	if err != nil {
		m.status = "Set $VISUAL/$EDITOR or install nvim/vim/vi/nano to enable F4 editing"
		return m, nil
	}

	m.status = fmt.Sprintf("Opening %s with %s", selected.DisplayName(), name)
	return m, tea.ExecProcess(command, func(err error) tea.Msg {
		return opMsg{kind: opEdit, sourcePath: selected.Path, err: err}
	})
}

func (m *Model) handleMouse(msg tea.MouseMsg) (tea.Model, tea.Cmd) {
	switch {
	case msg.Action == tea.MouseActionMotion:
		paneID, index, ok := m.mouseTarget(msg.X, msg.Y)
		if ok {
			m.hover = hoverState{pane: paneID, index: index, ok: true}
		} else {
			m.hover = hoverState{}
		}
		return m, nil
	case msg.Action == tea.MouseActionPress && msg.Button == tea.MouseButtonWheelUp:
		if m.infoMode && m.mouseOverPreview(msg.X, msg.Y) {
			m.previewModel.LineUp(3)
			return m, nil
		}
		m.moveCursor(-1)
		return m, m.loadPreviewCmd()
	case msg.Action == tea.MouseActionPress && msg.Button == tea.MouseButtonWheelDown:
		if m.infoMode && m.mouseOverPreview(msg.X, msg.Y) {
			m.previewModel.LineDown(3)
			return m, nil
		}
		m.moveCursor(1)
		return m, m.loadPreviewCmd()
	case msg.Action == tea.MouseActionPress && msg.Button == tea.MouseButtonLeft:
		paneID, index, ok := m.mouseTarget(msg.X, msg.Y)
		if !ok {
			return m, nil
		}
		m.hover = hoverState{pane: paneID, index: index, ok: true}
		m.active = paneID
		pane := m.paneByID(paneID)
		if index >= 0 && index < len(pane.Entries) {
			pane.Cursor = index
			pane.EnsureVisible(max(m.bodyHeight()-4, 1))
		}

		now := time.Now()
		doubleClick := m.lastClick.pane == paneID && m.lastClick.index == index && now.Sub(m.lastClick.at) <= 450*time.Millisecond
		m.lastClick = mouseClickState{pane: paneID, index: index, at: now}
		if doubleClick {
			return m.handleOpenSelected()
		}
		m.status = fmt.Sprintf("Selected %s pane", strings.ToUpper(string(paneID)))
		return m, m.loadPreviewCmd()
	case msg.Action == tea.MouseActionPress && msg.Button == tea.MouseButtonRight:
		if m.infoMode && m.mouseOverPreview(msg.X, msg.Y) {
			m.infoMode = false
			m.resizePreview()
			m.syncPreviewContent()
			m.status = "Info mode: off"
			return m, nil
		}

		paneID, index, ok := m.mouseTarget(msg.X, msg.Y)
		if !ok {
			return m, nil
		}

		if m.infoMode && paneID == m.active && index == m.activePane().Cursor {
			m.infoMode = false
			m.hover = hoverState{pane: paneID, index: index, ok: true}
			m.status = "Info mode: off"
			return m, nil
		}

		m.hover = hoverState{pane: paneID, index: index, ok: true}
		m.active = paneID
		pane := m.paneByID(paneID)
		if index >= 0 && index < len(pane.Entries) {
			pane.Cursor = index
			pane.EnsureVisible(max(m.bodyHeight()-4, 1))
		}
		m.infoMode = true
		m.resizePreview()
		m.syncPreviewContent()
		m.status = fmt.Sprintf("Info mode: %s selection", strings.ToUpper(string(paneID)))
		return m, m.loadPreviewCmd()
	default:
		return m, nil
	}
}

func (m *Model) toggleInfo() (tea.Model, tea.Cmd) {
	m.infoMode = !m.infoMode
	m.resizePreview()
	m.syncPreviewContent()
	if m.infoMode {
		m.status = fmt.Sprintf("Info mode: %s selection", strings.ToUpper(string(m.active)))
		return m, m.loadPreviewCmd()
	}
	m.status = "Info mode: off"
	return m, nil
}

func (m *Model) toggleHidden() (tea.Model, tea.Cmd) {
	m.cfg.Browser.ShowHidden = !m.cfg.Browser.ShowHidden
	return m.refreshAllPanes(fmt.Sprintf("Show hidden: %t", m.cfg.Browser.ShowHidden))
}

func (m *Model) cycleTheme() (tea.Model, tea.Cmd) {
	next := theme.Next(m.cfg.UI.Theme)
	palette, err := theme.Resolve(next)
	if err != nil {
		m.status = err.Error()
		return m, nil
	}
	m.cfg.UI.Theme = next
	m.palette = palette
	m.status = fmt.Sprintf("Theme: %s", next)
	return m, nil
}

func (m *Model) cycleSort() (tea.Model, tea.Cmd) {
	order := []string{"name", "modified", "size", "created", "extension"}
	current := strings.ToLower(strings.TrimSpace(m.cfg.Browser.Sort.By))
	next := order[0]
	for idx, value := range order {
		if value == current {
			next = order[(idx+1)%len(order)]
			break
		}
	}
	m.cfg.Browser.Sort.By = next
	return m.refreshAllPanes(fmt.Sprintf("Sort: %s", next))
}

func (m *Model) openMkdirModal() {
	input := textinput.New()
	input.Placeholder = "new-directory"
	input.Focus()
	input.CharLimit = 128
	input.Width = 42

	m.modal = modalState{
		kind:  modalMkdir,
		title: "Create directory",
		body:  fmt.Sprintf("Active pane: %s", m.activePane().Path),
		note:  "Enter to confirm, Esc to cancel",
		input: input,
	}
}

func (m *Model) openConfirmModal(title, body, note string, pending pendingOperation) {
	m.modal = modalState{
		kind:    modalConfirm,
		title:   title,
		body:    body,
		note:    note,
		pending: &pending,
	}
}

func (m *Model) applyDirSize(path string, size int64) {
	for _, pane := range []*BrowserPane{&m.left, &m.right} {
		for idx := range pane.Entries {
			if pane.Entries[idx].Path == path {
				pane.Entries[idx].Size = size
				pane.Entries[idx].DirSizeKnown = true
			}
		}
	}
}

func (m *Model) applyPreview(preview vfs.Preview) {
	m.previewData = preview
	m.syncPreviewContent()
}

func (m *Model) syncPreviewContent() {
	content := m.previewData.Body
	if m.cfg.Preview.WrapText && m.previewModel.Width > 0 {
		content = lipgloss.NewStyle().Width(m.previewModel.Width).Render(content)
	}
	m.previewModel.SetContent(content)
}

func (m *Model) activePane() *BrowserPane {
	if m.active == PaneLeft {
		return &m.left
	}
	return &m.right
}

func (m *Model) passivePane() *BrowserPane {
	if m.active == PaneLeft {
		return &m.right
	}
	return &m.left
}

func (m *Model) paneByID(id PaneID) *BrowserPane {
	if id == PaneLeft {
		return &m.left
	}
	return &m.right
}

func (m *Model) layoutWidths() (int, int, int) {
	total := m.width
	gaps := m.cfg.UI.PaneGap
	usable := max(total-gaps, 60)
	left := usable / 2
	right := usable - left

	if m.active == PaneLeft {
		if m.infoMode {
			return left, right, 0
		}
		return left, 0, right
	}
	if m.infoMode {
		return 0, left, right
	}
	return left, 0, right
}

func (m *Model) bodyHeight() int {
	height := m.height - 1
	if m.cfg.UI.ShowTitleBar {
		height--
	}
	if m.cfg.UI.ShowFooter {
		height--
	}
	return max(height, 8)
}

func (m *Model) resizePreview() {
	_, previewWidth, _ := m.layoutWidths()
	metaHeight := 0
	if m.cfg.Preview.ShowMetadata {
		metaHeight = 6
	}
	m.previewModel.Width = max(previewWidth-4, 10)
	m.previewModel.Height = max(m.bodyHeight()-metaHeight-4, 3)
}

func renderPreviewPane(preview vfs.Preview, viewportModel *viewport.Model, cfg config.Config, palette theme.Palette, width int, height int) string {
	box := lipgloss.NewStyle().
		Width(width).
		Height(height).
		Background(palette.Panel).
		Foreground(palette.Text).
		BorderStyle(borderStyle(cfg.UI.Border)).
		BorderForeground(palette.BorderActive)

	title := lipgloss.NewStyle().
		Width(width-2).
		Padding(0, 1).
		Background(palette.Accent).
		Foreground(palette.Background).
		Bold(true).
		Render("PREVIEW " + previewIcon(preview) + " " + preview.Title)

	parts := []string{title}
	if cfg.Preview.ShowMetadata {
		parts = append(parts, renderMetadata(preview.Metadata, palette, width-2))
	}
	parts = append(parts, renderPreviewContent(viewportModel, palette, width-2))

	return box.Render(lipgloss.JoinVertical(lipgloss.Left, parts...))
}

func renderMetadata(meta vfs.Metadata, palette theme.Palette, width int) string {
	leftRows := []string{
		fmt.Sprintf("kind: %s", fallback(meta.Kind, "n/a")),
		fmt.Sprintf("size: %s", metaSize(meta)),
		fmt.Sprintf("created: %s", fallback(meta.CreatedAt, "n/a")),
	}
	rightRows := []string{
		fmt.Sprintf("modified: %s", fallback(meta.ModifiedAt, "n/a")),
		fmt.Sprintf("mode: %s", fallback(meta.Permissions, "n/a")),
	}
	if meta.ImageFormat != "" {
		rightRows = append(rightRows, fmt.Sprintf("image: %s %s", meta.ImageFormat, meta.ImageSize))
	}

	leftWidth := max(width/2, 18)
	rightWidth := max(width-leftWidth, 18)
	left := lipgloss.NewStyle().
		Width(leftWidth).
		Foreground(palette.Muted).
		Render(strings.Join(leftRows, "\n"))
	right := lipgloss.NewStyle().
		Width(rightWidth).
		Foreground(palette.Text).
		Render(strings.Join(rightRows, "\n"))

	pathLine := lipgloss.NewStyle().
		Width(width).
		Foreground(palette.Text).
		Render(fmt.Sprintf("path: %s", truncateMiddle(meta.Path, max(width-8, 16))))

	return lipgloss.NewStyle().
		Width(width).
		Padding(0, 1).
		Background(palette.PanelElevated).
		BorderStyle(lipgloss.NormalBorder()).
		BorderBottom(true).
		BorderForeground(palette.Border).
		Render(lipgloss.JoinVertical(
			lipgloss.Left,
			lipgloss.JoinHorizontal(lipgloss.Top, left, right),
			"",
			pathLine,
		))
}

func renderTitleBar(m Model) string {
	left := lipgloss.NewStyle().
		Foreground(m.palette.Background).
		Background(m.palette.Accent).
		Bold(true).
		Padding(0, 1).
		Render(strings.ToUpper(m.cfg.UI.AppTitle))

	centerParts := []string{
		fmt.Sprintf("theme:%s", m.cfg.UI.Theme),
		fmt.Sprintf("hidden:%t", m.cfg.Browser.ShowHidden),
		fmt.Sprintf("sort:%s", m.cfg.Browser.Sort.By),
		fmt.Sprintf("info:%t", m.infoMode),
	}
	center := lipgloss.NewStyle().
		Foreground(m.palette.Text).
		Background(m.palette.Panel).
		Padding(0, 1).
		Render(strings.Join(centerParts, "  "))

	configLabel := "cfg:default"
	if m.configPath != "" {
		configLabel = "cfg:" + filepath.Base(m.configPath)
	}
	right := lipgloss.NewStyle().
		Foreground(m.palette.Muted).
		Background(m.palette.Panel).
		Padding(0, 1).
		Render(configLabel)

	fillWidth := max(m.width-lipgloss.Width(left)-lipgloss.Width(center)-lipgloss.Width(right), 0)
	fill := lipgloss.NewStyle().
		Width(fillWidth).
		Background(m.palette.Panel).
		Render("")

	return left + center + fill + right
}

func renderStatus(m Model) string {
	active := m.activePane()
	selected, _ := active.Selected()
	summary := fmt.Sprintf(
		"%s | %s | items:%d | selected:%s",
		strings.ToUpper(string(m.active)),
		compactPath(active.Path, m.cfg.UI.PathDisplay),
		len(active.Entries),
		fallback(selected.DisplayName(), "n/a"),
	)

	return lipgloss.NewStyle().
		Width(m.width).
		Padding(0, 1).
		Background(m.palette.PanelInactive).
		Foreground(m.palette.Text).
		Render(summary + "  ::  " + m.status)
}

func renderFooter(m Model) string {
	helpModel := m.helpModel
	helpModel.Width = max(m.width-28, 20)
	helpView := helpModel.View(m.keys)
	legend := lipgloss.NewStyle().
		Foreground(m.palette.Muted).
		Render(" dir  󰈙 text   config  󰆍 exec  󰋩 image  󰈔 bin")
	return lipgloss.NewStyle().
		Width(m.width).
		Padding(0, 1).
		Background(m.palette.Panel).
		Render(lipgloss.JoinHorizontal(lipgloss.Top, helpView, "   ", legend))
}

func renderModal(modal modalState, palette theme.Palette, width int) string {
	box := lipgloss.NewStyle().
		Width(width).
		Padding(1, 2).
		Background(palette.Panel).
		Foreground(palette.Text).
		BorderStyle(lipgloss.DoubleBorder()).
		BorderForeground(palette.BorderActive)

	lines := []string{
		lipgloss.NewStyle().Bold(true).Foreground(palette.Accent).Render(modal.title),
		lipgloss.NewStyle().Foreground(palette.Muted).Render(modal.body),
	}

	if modal.kind == modalMkdir {
		lines = append(lines, modal.input.View())
	}
	if modal.note != "" {
		lines = append(lines, lipgloss.NewStyle().Foreground(palette.Muted).Render(modal.note))
	}

	return box.Render(strings.Join(lines, "\n\n"))
}

func overlayCenter(base string, overlay string, width int) string {
	if width <= 0 {
		return base + "\n" + overlay
	}
	centered := lipgloss.Place(width, lipgloss.Height(overlay), lipgloss.Center, lipgloss.Top, overlay)
	return base + "\n" + centered
}

func renderPreviewContent(viewportModel *viewport.Model, palette theme.Palette, width int) string {
	header := lipgloss.NewStyle().
		Width(width).
		Padding(0, 1).
		Background(palette.PanelInactive).
		Foreground(palette.FooterKey).
		Bold(true).
		Render("CONTENT")

	body := lipgloss.NewStyle().
		Width(width).
		Padding(0, 1).
		Background(palette.Panel).
		Render(viewportModel.View())

	return lipgloss.NewStyle().
		Width(width).
		BorderStyle(lipgloss.NormalBorder()).
		BorderTop(true).
		BorderForeground(palette.Border).
		Render(lipgloss.JoinVertical(lipgloss.Left, header, body))
}

func previewIcon(preview vfs.Preview) string {
	switch preview.Kind {
	case vfs.PreviewKindDirectory:
		return ""
	case vfs.PreviewKindImage:
		return "󰋩"
	case vfs.PreviewKindText:
		return "󰈙"
	case vfs.PreviewKindBinary:
		return "󰈔"
	case vfs.PreviewKindError:
		return ""
	default:
		return "󰇙"
	}
}

func (p pendingOperation) cmd() tea.Cmd {
	switch p.kind {
	case opCopy:
		return copyCmd(p.sourcePath, p.targetDir, p.overwrite)
	case opMove:
		return moveCmd(p.sourcePath, p.targetDir, p.overwrite)
	case opDelete:
		return deleteCmd(p.sourcePath)
	default:
		return nil
	}
}

func operationCmd(kind fileOpKind, sourcePath, targetDir string, overwrite bool) tea.Cmd {
	switch kind {
	case opCopy:
		return copyCmd(sourcePath, targetDir, overwrite)
	case opMove:
		return moveCmd(sourcePath, targetDir, overwrite)
	default:
		return nil
	}
}

func dirSizeCmd(path string) tea.Cmd {
	return func() tea.Msg {
		size, err := vfs.DirectorySize(path)
		return dirSizeMsg{path: path, size: size, err: err}
	}
}

func copyCmd(sourcePath, targetDir string, overwrite bool) tea.Cmd {
	return func() tea.Msg {
		targetPath, err := vfs.CopyPath(sourcePath, targetDir, overwrite)
		return opMsg{kind: opCopy, sourcePath: sourcePath, targetPath: targetPath, err: err}
	}
}

func moveCmd(sourcePath, targetDir string, overwrite bool) tea.Cmd {
	return func() tea.Msg {
		targetPath, err := vfs.MovePath(sourcePath, targetDir, overwrite)
		return opMsg{kind: opMove, sourcePath: sourcePath, targetPath: targetPath, err: err}
	}
}

func deleteCmd(path string) tea.Cmd {
	return func() tea.Msg {
		err := vfs.DeletePath(path)
		return opMsg{kind: opDelete, sourcePath: path, err: err}
	}
}

func mkdirCmd(parent, name string) tea.Cmd {
	return func() tea.Msg {
		targetPath, err := vfs.MakeDir(parent, name)
		return opMsg{kind: opMkdir, targetPath: targetPath, err: err}
	}
}

func selectedName(pane *BrowserPane) string {
	selected, ok := pane.Selected()
	if !ok {
		return ""
	}
	return selected.Name
}

func metaSize(meta vfs.Metadata) string {
	if !meta.SizeKnown {
		return "press Space"
	}
	return vfs.HumanSize(meta.Size)
}

func fallback(value string, defaultValue string) string {
	if strings.TrimSpace(value) == "" {
		return defaultValue
	}
	return value
}

func formatSize(size int64, human bool) string {
	if human {
		return vfs.HumanSize(size)
	}
	return fmt.Sprintf("%d", size)
}

func operationVerb(kind fileOpKind) string {
	switch kind {
	case opCopy:
		return "copy"
	case opMove:
		return "move"
	case opDelete:
		return "delete"
	default:
		return "operate on"
	}
}

func externalCommand(envVar string, fallbacks []string, path string) (*exec.Cmd, string, error) {
	envVars := []string{}
	if envVar != "" {
		envVars = append(envVars, envVar)
	}
	return externalCommandFromEnv(envVars, fallbacks, path)
}

func externalCommandFromEnv(envVars []string, fallbacks []string, path string) (*exec.Cmd, string, error) {
	commandLine := ""
	source := "fallbacks"
	for _, envVar := range envVars {
		commandLine = strings.TrimSpace(os.Getenv(envVar))
		if commandLine != "" {
			source = envVar
			break
		}
	}
	if commandLine == "" {
		for _, candidate := range fallbacks {
			if resolved, err := exec.LookPath(candidate); err == nil {
				commandLine = resolved
				source = candidate
				break
			}
		}
	}
	if commandLine == "" {
		if len(envVars) > 0 {
			return nil, "", fmt.Errorf("no command for %s", strings.Join(envVars, "/"))
		}
		return nil, "", fmt.Errorf("no fallback command found")
	}

	parts := strings.Fields(commandLine)
	if len(parts) == 0 {
		return nil, "", fmt.Errorf("invalid command for %s", source)
	}

	args := append(parts[1:], path)
	return exec.Command(parts[0], args...), filepath.Base(parts[0]), nil
}

func enableMouseCmd() tea.Cmd {
	return func() tea.Msg {
		return tea.EnableMouseCellMotion()
	}
}

func resolveStartPath(raw string, fallback string) (string, error) {
	value := strings.TrimSpace(raw)
	if value == "" {
		return fallback, nil
	}
	if strings.HasPrefix(value, "~/") {
		home, err := os.UserHomeDir()
		if err != nil {
			return "", err
		}
		value = filepath.Join(home, strings.TrimPrefix(value, "~/"))
	}
	abs, err := filepath.Abs(value)
	if err != nil {
		return "", err
	}
	info, err := os.Stat(abs)
	if err != nil {
		return "", err
	}
	if !info.IsDir() {
		return "", fmt.Errorf("startup path is not a directory: %s", abs)
	}
	return abs, nil
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

func (m *Model) mouseTarget(x, y int) (PaneID, int, bool) {
	if m.width <= 0 || m.height <= 0 {
		return "", 0, false
	}

	leftWidth, previewWidth, rightWidth := m.layoutWidths()
	top := 0
	if m.cfg.UI.ShowTitleBar {
		top++
	}
	bodyHeight := m.bodyHeight()
	if y < top || y >= top+bodyHeight {
		return "", 0, false
	}

	gap := m.cfg.UI.PaneGap
	leftStart := 0
	rightStart := leftWidth + gap
	if m.infoMode && m.active == PaneRight {
		rightStart = previewWidth + gap
	}

	switch {
	case x >= leftStart && x < leftStart+leftWidth:
		if m.infoMode && m.active == PaneRight {
			return "", 0, false
		}
		return PaneLeft, paneIndexFromMouse(y-top, bodyHeight, &m.left), true
	case x >= rightStart && x < rightStart+rightWidth:
		if m.infoMode && m.active == PaneLeft {
			return "", 0, false
		}
		return PaneRight, paneIndexFromMouse(y-top, bodyHeight, &m.right), true
	default:
		return "", 0, false
	}
}

func paneIndexFromMouse(localY int, height int, pane *BrowserPane) int {
	if localY < 1 || localY >= height-1 {
		return pane.Cursor
	}
	row := localY - 1
	index := pane.Offset + row
	if index < 0 {
		index = 0
	}
	if index >= len(pane.Entries) {
		index = len(pane.Entries) - 1
	}
	if index < 0 {
		return 0
	}
	return index
}

func isEditableEntry(entry vfs.Entry) bool {
	switch entry.Category() {
	case "text", "config", "executable":
		return true
	default:
		return false
	}
}

func (m *Model) hoverIndexFor(pane PaneID) int {
	if m.hover.ok && m.hover.pane == pane {
		return m.hover.index
	}
	return -1
}

func (m *Model) mouseOverPreview(x, y int) bool {
	if !m.infoMode || m.width <= 0 || m.height <= 0 {
		return false
	}

	leftWidth, previewWidth, _ := m.layoutWidths()
	top := 0
	if m.cfg.UI.ShowTitleBar {
		top++
	}
	bodyHeight := m.bodyHeight()
	if y < top || y >= top+bodyHeight {
		return false
	}

	gap := m.cfg.UI.PaneGap
	if m.active == PaneLeft {
		startX := leftWidth + gap
		return x >= startX && x < startX+previewWidth
	}

	return x >= 0 && x < previewWidth
}