package tui

import (
	"context"
	"fmt"
	"io"
	"os"
	"path"
	"path/filepath"
	"sort"
	"strings"
	"sync"
	"time"

	"github.com/charmbracelet/bubbles/textinput"
	tea "github.com/charmbracelet/bubbletea"
	"github.com/charmbracelet/lipgloss"
	"github.com/pkg/sftp"

	"git.tukangketik.id/swanadiva/hostkeeper/internal/models"
	sshclient "git.tukangketik.id/swanadiva/hostkeeper/pkg/ssh"
)

type paneType int

const (
	paneLocal paneType = iota
	paneRemote
)

// sftpPane holds state for one side of the dual-pane browser
type sftpPane struct {
	cwd     string
	entries []os.FileInfo
	selIdx  int
	scroll  int

	filterMode bool
	filter     string

	// Remote only
	sftpClient *sftp.Client

	// Local only
	localRoot string
}

// SFTPBrowserTab provides a dual-pane (local ↔ remote) SFTP file browser
type SFTPBrowserTab struct {
	host    *models.Host
	dataDir string

	sshClient *sshclient.Client
	sftp      *sftp.Client

	left        sftpPane
	right       sftpPane
	active      paneType
	connected   bool
	err         error
	width       int
	height      int

	filterInput textinput.Model

	transferring bool
	transferMsg  string

	mu        sync.Mutex
	closeOnce sync.Once
}

func NewSFTPBrowserTab(host *models.Host, dataDir string) *SFTPBrowserTab {
	fi := textinput.New()
	fi.Placeholder = "Filter..."

	home, _ := os.UserHomeDir()

	return &SFTPBrowserTab{
		host:    host,
		dataDir: dataDir,
		active:  paneRemote,
		left: sftpPane{
			cwd:       home,
			localRoot: home,
		},
		right: sftpPane{
			cwd: "/",
		},
		filterInput: fi,
	}
}

func (t *SFTPBrowserTab) Name() string { return "SFTP: " + t.host.Name }

func (t *SFTPBrowserTab) Init() tea.Cmd {
	go t.connect()
	go t.refreshLocal()
	return t.poll
}

func (t *SFTPBrowserTab) poll() tea.Msg {
	t.mu.Lock()
	conn := t.connected
	err := t.err
	t.mu.Unlock()

	if err != nil {
		return sftpRefreshMsg{err: err}
	}
	if conn {
		return sftpRefreshMsg{}
	}
	return nil
}

func (t *SFTPBrowserTab) connect() {
	timeout := 30 * time.Second
	cl := sshclient.NewClient(t.host, timeout)

	ctx := context.Background()
	if err := cl.Connect(ctx); err != nil {
		t.mu.Lock()
		t.err = fmt.Errorf("SSH connect: %w", err)
		t.mu.Unlock()
		return
	}

	sftpClient, err := sftp.NewClient(cl.GetClient())
	if err != nil {
		cl.Close()
		t.mu.Lock()
		t.err = fmt.Errorf("SFTP init: %w", err)
		t.mu.Unlock()
		return
	}

	home, err := sftpClient.Getwd()
	if err != nil {
		home = "/"
	}

	t.mu.Lock()
	t.sshClient = cl
	t.sftp = sftpClient
	t.right.sftpClient = sftpClient
	t.right.cwd = home
	t.connected = true
	t.mu.Unlock()

	t.refreshRemote()
}

func (t *SFTPBrowserTab) refreshLocal() {
	t.mu.Lock()
	p := &t.left
	p.entries = nil
	t.mu.Unlock()

	entries, err := os.ReadDir(p.cwd)
	if err != nil {
		return
	}

	var infos []os.FileInfo
	for _, e := range entries {
		info, err := e.Info()
		if err == nil {
			infos = append(infos, info)
		}
	}

	sort.Slice(infos, func(i, j int) bool {
		if infos[i].IsDir() != infos[j].IsDir() {
			return infos[i].IsDir()
		}
		return strings.ToLower(infos[i].Name()) < strings.ToLower(infos[j].Name())
	})

	t.mu.Lock()
	p.entries = infos
	if p.selIdx >= len(infos) {
		p.selIdx = 0
	}
	t.mu.Unlock()
}

func (t *SFTPBrowserTab) refreshRemote() {
	t.mu.Lock()
	p := &t.right
	sftpClient := p.sftpClient
	cwd := p.cwd
	t.mu.Unlock()

	if sftpClient == nil {
		return
	}

	entries, err := sftpClient.ReadDir(cwd)
	if err != nil {
		return
	}

	sort.Slice(entries, func(i, j int) bool {
		if entries[i].IsDir() != entries[j].IsDir() {
			return entries[i].IsDir()
		}
		return strings.ToLower(entries[i].Name()) < strings.ToLower(entries[j].Name())
	})

	t.mu.Lock()
	p.entries = entries
	if p.selIdx >= len(entries) {
		p.selIdx = 0
	}
	t.mu.Unlock()
}

func (t *SFTPBrowserTab) activePane() *sftpPane {
	if t.active == paneLocal {
		return &t.left
	}
	return &t.right
}

func (t *SFTPBrowserTab) Update(msg tea.Msg) (Tab, tea.Cmd) {
	switch msg := msg.(type) {
	case tea.WindowSizeMsg:
		t.mu.Lock()
		t.width = msg.Width
		t.height = msg.Height
		t.mu.Unlock()
		return t, nil

	case sftpRefreshMsg:
		if msg.err != nil {
			t.mu.Lock()
			t.err = msg.err
			t.mu.Unlock()
			return t, nil
		}
		// Re-render only
		return t, t.poll

	case tea.KeyMsg:
		p := t.activePane()

		if p.filterMode {
			switch msg.String() {
			case "esc", "enter":
				p.filterMode = false
				p.filter = ""
				return t, nil
			case "backspace":
				if len(p.filter) > 0 {
					p.filter = p.filter[:len(p.filter)-1]
				}
				return t, nil
			default:
				if len(msg.Runes) == 1 {
					p.filter += string(msg.Runes[0])
				}
				return t, nil
			}
		}

		switch msg.String() {
		case "tab":
			t.mu.Lock()
			if t.active == paneLocal {
				t.active = paneRemote
			} else {
				t.active = paneLocal
			}
			t.mu.Unlock()
			return t, nil

		case "up", "k":
			t.mu.Lock()
			if p.selIdx > 0 {
				p.selIdx--
			}
			t.mu.Unlock()

		case "down", "j":
			t.mu.Lock()
			if p.selIdx < len(p.entries)-1 {
				p.selIdx++
			}
			t.mu.Unlock()

		case "enter", "right":
			t.mu.Lock()
			entries := p.entries
			idx := p.selIdx
			t.mu.Unlock()

			if idx >= 0 && idx < len(entries) && entries[idx].IsDir() {
				t.mu.Lock()
				p.cwd = path.Join(p.cwd, entries[idx].Name())
				p.selIdx = 0
				t.mu.Unlock()
				if t.active == paneRemote {
					go t.refreshRemote()
				} else {
					go t.refreshLocal()
				}
			}

		case "left", "backspace":
			t.mu.Lock()
			parent := path.Dir(p.cwd)
			if parent == "." {
				parent = "/"
			}
			if (t.active == paneLocal && parent != p.cwd) || (t.active == paneRemote && parent != p.cwd) {
				p.cwd = parent
				p.selIdx = 0
			}
			t.mu.Unlock()
			if t.active == paneRemote {
				go t.refreshRemote()
			} else {
				go t.refreshLocal()
			}

		case "/":
			p.filterMode = true
			p.filter = ""

		case "r":
			if t.active == paneRemote {
				go t.refreshRemote()
			} else {
				go t.refreshLocal()
			}

		case "c":
			t.mu.Lock()
			src, dst := t.left, t.right
			srcType, dstType := paneLocal, paneRemote
			if t.active == paneRemote {
				src, dst = t.right, t.left
				srcType, dstType = paneRemote, paneLocal
			}
			idx := src.selIdx
			srcEntries := src.entries
			srcCwd := src.cwd
			dstCwd := dst.cwd
			t.mu.Unlock()

			if idx >= 0 && idx < len(srcEntries) && !srcEntries[idx].IsDir() {
				srcPath := path.Join(srcCwd, srcEntries[idx].Name())
				dstPath := path.Join(dstCwd, srcEntries[idx].Name())

				go t.copyFile(srcType, dstType, srcPath, dstPath, srcEntries[idx].Name())
			}

		case "d":
			t.mu.Lock()
			p := t.activePane()
			entries := p.entries
			idx := p.selIdx
			cwd := p.cwd
			isRemote := t.active == paneRemote
			t.mu.Unlock()

			if idx >= 0 && idx < len(entries) {
				fullPath := path.Join(cwd, entries[idx].Name())
				go t.deleteItem(fullPath, entries[idx].IsDir(), isRemote)
			}

		case "n":
			if t.active == paneRemote {
				go t.mkdirRemote()
			}

		case "esc":
			return t, func() tea.Msg { return closeFormMsg{} }

		default:
		}
	}

	return t, t.poll
}

func (t *SFTPBrowserTab) copyFile(srcType, dstType paneType, srcPath, dstPath, name string) {
	t.mu.Lock()
	t.transferring = true
	t.transferMsg = fmt.Sprintf("Copying %s...", name)
	t.mu.Unlock()

	var err error
	if srcType == paneRemote && dstType == paneLocal {
		// Download
		t.mu.Lock()
		client := t.right.sftpClient
		t.mu.Unlock()
		if client != nil {
			err = downloadFile(client, srcPath, dstPath)
		}
	} else if srcType == paneLocal && dstType == paneRemote {
		// Upload
		t.mu.Lock()
		client := t.right.sftpClient
		t.mu.Unlock()
		if client != nil {
			err = uploadFile(client, srcPath, dstPath)
		}
	}

	t.mu.Lock()
	if err != nil {
		t.err = fmt.Errorf("copy %s: %w", name, err)
	} else {
		t.transferMsg = ""
	}
	t.transferring = false
	t.mu.Unlock()

	if dstType == paneRemote {
		t.refreshRemote()
	} else {
		t.refreshLocal()
	}
}

func downloadFile(client *sftp.Client, remotePath, localPath string) error {
	src, err := client.Open(remotePath)
	if err != nil {
		return err
	}
	defer src.Close()

	dst, err := os.Create(localPath)
	if err != nil {
		return err
	}
	defer dst.Close()

	_, err = io.Copy(dst, src)
	return err
}

func uploadFile(client *sftp.Client, localPath, remotePath string) error {
	src, err := os.Open(localPath)
	if err != nil {
		return err
	}
	defer src.Close()

	dst, err := client.Create(remotePath)
	if err != nil {
		return err
	}
	defer dst.Close()

	_, err = io.Copy(dst, src)
	return err
}

func (t *SFTPBrowserTab) deleteItem(fullPath string, isDir bool, isRemote bool) {
	t.mu.Lock()
	t.transferring = true
	t.transferMsg = fmt.Sprintf("Deleting %s...", filepath.Base(fullPath))
	t.mu.Unlock()

	var err error
	if isRemote {
		t.mu.Lock()
		client := t.right.sftpClient
		t.mu.Unlock()
		if client != nil {
			if isDir {
				err = client.RemoveDirectory(fullPath)
			} else {
				err = client.Remove(fullPath)
			}
		}
	} else {
		if isDir {
			err = os.RemoveAll(fullPath)
		} else {
			err = os.Remove(fullPath)
		}
	}

	t.mu.Lock()
	if err != nil {
		t.err = fmt.Errorf("delete: %w", err)
	}
	t.transferring = false
	t.transferMsg = ""
	t.mu.Unlock()

	if isRemote {
		go t.refreshRemote()
	} else {
		go t.refreshLocal()
	}
}

func (t *SFTPBrowserTab) mkdirRemote() {
	t.mu.Lock()
	client := t.right.sftpClient
	cwd := t.right.cwd
	t.mu.Unlock()

	if client == nil {
		return
	}

	name := fmt.Sprintf("new-dir-%d", time.Now().Unix())
	if err := client.Mkdir(path.Join(cwd, name)); err != nil {
		t.mu.Lock()
		t.err = fmt.Errorf("mkdir: %w", err)
		t.mu.Unlock()
		return
	}
	t.refreshRemote()
}

func (t *SFTPBrowserTab) View() string {
	t.mu.Lock()
	defer t.mu.Unlock()

	if !t.connected && t.err != nil {
		var b strings.Builder
		b.WriteString(lipgloss.PlaceHorizontal(t.width, lipgloss.Center,
			ErrorStyle.Render(fmt.Sprintf("SFTP Error: %v", t.err))))
		b.WriteString("\n\n")
		b.WriteString(lipgloss.PlaceHorizontal(t.width, lipgloss.Center,
			SubtitleStyle.Render("Press Esc to close")))
		return b.String()
	}

	if !t.connected {
		return lipgloss.PlaceHorizontal(t.width, lipgloss.Center,
			SubtitleStyle.Render(fmt.Sprintf("Connecting SFTP to %s...", t.host.Name)))
	}

	// Responsive pane layout: stack vertically on narrow terminals
	var leftView, rightView string
	if t.width < 50 {
		// Stack vertically — each pane gets full width
		leftView = t.renderPane(&t.left, paneLocal, t.width)
		rightView = t.renderPane(&t.right, paneRemote, t.width)
	} else {
		// Side by side — each pane gets half width
		halfW := t.width / 2
		if halfW < 20 {
			halfW = 20
		}
		leftView = t.renderPane(&t.left, paneLocal, halfW)
		rightView = t.renderPane(&t.right, paneRemote, halfW)
	}

	var b strings.Builder

	b.WriteString(lipgloss.PlaceHorizontal(t.width, lipgloss.Center,
		AppTitleStyle.Render(fmt.Sprintf("SFTP: %s@%s", t.host.Username, t.host.Hostname))))
	b.WriteString("\n")

	if t.width < 50 {
		b.WriteString(lipgloss.JoinVertical(lipgloss.Left, leftView, rightView))
	} else {
		b.WriteString(lipgloss.JoinHorizontal(lipgloss.Top, leftView, rightView))
	}

	if t.err != nil {
		b.WriteString("\n" + lipgloss.PlaceHorizontal(t.width, lipgloss.Center,
			ErrorStyle.Render(fmt.Sprintf("Error: %v", t.err))))
	}

	if t.transferring && t.transferMsg != "" {
		b.WriteString("\n" + lipgloss.PlaceHorizontal(t.width, lipgloss.Center,
			InfoStyle.Render(t.transferMsg)))
	}

	// Footer (wrapped to terminal width)
	footerText := "Ctrl+Tab:switch  Ctrl+Q:close  Tab:pane  ↑↓:nav  Enter/→:open  ←/Backspace:up  /:filter  C:copy  D:delete  N:mkdir  R:refresh  Esc:close"
	footerWrapped := wrapFooter(footerText, t.width)
	for _, line := range strings.Split(footerWrapped, "\n") {
		b.WriteString("\n" + lipgloss.PlaceHorizontal(t.width, lipgloss.Center, SubtitleStyle.Render(line)))
	}

	return b.String()
}

func (t *SFTPBrowserTab) renderPane(p *sftpPane, pt paneType, maxW int) string {
	isActive := t.active == pt

	title := "Local"
	if pt == paneRemote {
		title = "Remote"
	}

	paneStyle := StylePaneInactive
	if isActive {
		paneStyle = StylePaneActive
	}

	// Inner content width: border(2) + padding(2) = 4 overhead
	innerW := maxW - 4
	if innerW < 5 {
		innerW = 5
	}

	// Title
	titleBar := fmt.Sprintf(" %s ", title)
	if isActive {
		titleBar = StatusBarStyle.Render(" " + title + " ")
	} else {
		titleBar = SubtitleStyle.Render(" " + title + " ")
	}

	// CWD (truncated with proper visual width)
	cwdDisplay := fmt.Sprintf(" %s", p.cwd)
	if lipgloss.Width(cwdDisplay) > innerW {
		cwdDisplay = truncateStr(cwdDisplay, innerW)
	}

	var content strings.Builder
	content.WriteString(SubtitleStyle.Render(cwdDisplay))
	content.WriteString("\n\n")

	// Filter
	var visible []os.FileInfo
	if p.filter != "" {
		lower := strings.ToLower(p.filter)
		for _, e := range p.entries {
			if strings.Contains(strings.ToLower(e.Name()), lower) {
				visible = append(visible, e)
			}
		}
	} else {
		visible = p.entries
	}

	if len(visible) == 0 {
		content.WriteString(SubtitleStyle.Render("  (empty)"))
	} else {
		maxDisplay := t.height - 6
		if maxDisplay < 5 {
			maxDisplay = 5
		}
		start := 0
		if p.selIdx >= maxDisplay {
			start = p.selIdx - maxDisplay + 1
		}
		end := start + maxDisplay
		if end > len(visible) {
			end = len(visible)
		}

		for i := start; i < end; i++ {
			entry := visible[i]
			name := entry.Name()
			var line string

			if entry.IsDir() {
				line = fmt.Sprintf("  %s/", name)
			} else if innerW < 30 {
				line = fmt.Sprintf("  %s", name)
			} else {
				size := formatSize(entry.Size())
				line = fmt.Sprintf("  %s  (%s)", name, size)
			}

			// Truncate — account for SelectedStyle Padding(0,1) = 2 extra chars
			lineMaxW := innerW
			if i == p.selIdx {
				lineMaxW = innerW - 2
			}
			if lipgloss.Width(line) > lineMaxW {
				line = truncateStr(line, lineMaxW)
			}

			if i == p.selIdx {
				content.WriteString(SelectedStyle.Render(line))
			} else if entry.IsDir() {
				content.WriteString(InfoStyle.Render(line))
			} else {
				content.WriteString(HostDetailStyle.Render(line))
			}
			content.WriteString("\n")
		}
	}

	if p.filterMode {
		content.WriteString("\n" + SubtitleStyle.Render("Filter: "+p.filter+"_"))
	}

	inner := titleBar + "\n" + content.String()
	return paneStyle.Width(maxW).Render(inner)
}

func (t *SFTPBrowserTab) Close() {
	t.closeOnce.Do(func() {
		if t.sftp != nil {
			t.sftp.Close()
		}
		if t.sshClient != nil {
			t.sshClient.Close()
		}
	})
}

type sftpRefreshMsg struct {
	err error
}

func formatSize(size int64) string {
	switch {
	case size >= 1<<30:
		return fmt.Sprintf("%.1f GiB", float64(size)/float64(1<<30))
	case size >= 1<<20:
		return fmt.Sprintf("%.1f MiB", float64(size)/float64(1<<20))
	case size >= 1<<10:
		return fmt.Sprintf("%.1f KiB", float64(size)/float64(1<<10))
	default:
		return fmt.Sprintf("%d B", size)
	}
}