package screens

import (
	"fmt"
	"strings"

	"github.com/calmcacil/wg-admin/internal/backup"
	"github.com/calmcacil/wg-admin/internal/tui/components"
	"github.com/charmbracelet/bubbles/table"
	tea "github.com/charmbracelet/bubbletea"
	"github.com/charmbracelet/lipgloss"
)

// RestoreScreen displays a list of available backups for restoration
type RestoreScreen struct {
	table          table.Model
	backups        []backup.Backup
	selectedBackup *backup.Backup
	confirmModal   *components.ConfirmModel
	showConfirm    bool
	isRestoring    bool
	restoreError   error
	restoreSuccess bool
	message        string
}

// Styles
var (
	restoreTitleStyle = lipgloss.NewStyle().
				Foreground(lipgloss.Color("62")).
				Bold(true)
	restoreHelpStyle = lipgloss.NewStyle().
				Foreground(lipgloss.Color("63")).
				MarginTop(1)
	restoreSuccessStyle = lipgloss.NewStyle().
				Foreground(lipgloss.Color("46")).
				Bold(true)
	restoreErrorStyle = lipgloss.NewStyle().
				Foreground(lipgloss.Color("196")).
				Bold(true)
	restoreInfoStyle = lipgloss.NewStyle().
				Foreground(lipgloss.Color("241")).
				MarginTop(1)
)

// NewRestoreScreen creates a new restore screen
func NewRestoreScreen() *RestoreScreen {
	return &RestoreScreen{
		showConfirm: false,
	}
}

// Init initializes the restore screen
func (s *RestoreScreen) Init() tea.Cmd {
	return s.loadBackups
}

// Update handles messages for the restore screen
func (s *RestoreScreen) Update(msg tea.Msg) (Screen, tea.Cmd) {
	var cmd tea.Cmd

	// Handle confirmation modal
	if s.showConfirm && s.confirmModal != nil {
		_, cmd = s.confirmModal.Update(msg)

		// Handle confirmation result
		if !s.confirmModal.Visible {
			if s.confirmModal.IsConfirmed() && s.selectedBackup != nil {
				// User confirmed restore
				s.isRestoring = true
				s.showConfirm = false
				return s, s.performRestore()
			}
			// User cancelled - close modal
			s.showConfirm = false
			return s, nil
		}

		// Handle Enter key to confirm
		switch msg := msg.(type) {
		case tea.KeyMsg:
			if msg.String() == "enter" && s.confirmModal.IsConfirmed() && s.selectedBackup != nil {
				s.isRestoring = true
				s.showConfirm = false
				return s, s.performRestore()
			}
		}

		return s, cmd
	}

	// Handle normal screen messages
	switch msg := msg.(type) {
	case backupsLoadedMsg:
		s.backups = msg.backups
		s.buildTable()
	case tea.KeyMsg:
		switch msg.String() {
		case "q", "esc":
			// Return to list screen - signal parent to switch screens
			return nil, nil
		case "enter":
			// Show confirmation for selected backup
			if len(s.table.Rows()) > 0 {
				selected := s.table.SelectedRow()
				if len(selected) > 0 {
					// Find the backup by name
					for _, b := range s.backups {
						if b.Name == selected[0] {
							s.selectedBackup = &b
							s.confirmModal = components.NewConfirm(
								fmt.Sprintf(
									"Are you sure you want to restore from backup '%s'?\n\nOperation: %s\nDate: %s\n\nThis will replace current WireGuard configuration.\nA safety backup will be created first.",
									b.Name,
									b.Operation,
									b.Timestamp.Format("2006-01-02 15:04:05"),
								),
								80,
								24,
							)
							s.showConfirm = true
							break
						}
					}
				}
			}
		}
	case restoreCompletedMsg:
		s.isRestoring = false
		if msg.err != nil {
			s.restoreError = msg.err
			s.message = fmt.Sprintf("Restore failed: %v", msg.err)
		} else {
			s.restoreSuccess = true
			s.message = fmt.Sprintf("Restore successful! Safety backup created at: %s", msg.safetyBackupPath)
		}
	}

	if !s.showConfirm && s.confirmModal != nil {
		s.table, cmd = s.table.Update(msg)
	}
	return s, cmd
}

// View renders the restore screen
func (s *RestoreScreen) View() string {
	if s.showConfirm && s.confirmModal != nil {
		// Render underlying content dimmed
		content := s.renderContent()
		dimmedContent := lipgloss.NewStyle().
			Foreground(lipgloss.Color("244")).
			Render(content)

		// Overlay confirmation modal
		return lipgloss.JoinVertical(
			lipgloss.Left,
			dimmedContent,
			s.confirmModal.View(),
		)
	}

	return s.renderContent()
}

// renderContent renders the main restore screen content
func (s *RestoreScreen) renderContent() string {
	var content strings.Builder

	content.WriteString(restoreTitleStyle.Render("Restore WireGuard Configuration"))
	content.WriteString("\n\n")

	if len(s.backups) == 0 && !s.isRestoring && s.message == "" {
		content.WriteString("No backups found. Press 'q' to return.")
		return content.String()
	}

	if s.isRestoring {
		content.WriteString("Restoring from backup, please wait...")
		return content.String()
	}

	if s.restoreSuccess {
		content.WriteString(restoreSuccessStyle.Render("✓ " + s.message))
		content.WriteString("\n\n")
		content.WriteString(restoreInfoStyle.Render("Press 'q' to return to client list."))
		return content.String()
	}

	if s.restoreError != nil {
		content.WriteString(restoreErrorStyle.Render("✗ " + s.message))
		content.WriteString("\n\n")
		content.WriteString(s.table.View())
		content.WriteString("\n\n")
		content.WriteString(restoreHelpStyle.Render("Actions: [Enter] Restore Selected • [↑/↓] Navigate • [q] Back"))
		return content.String()
	}

	// Show backup list
	content.WriteString(s.table.View())
	content.WriteString("\n\n")

	// Show selected backup details
	if len(s.table.Rows()) > 0 && s.selectedBackup != nil {
		content.WriteString(restoreInfoStyle.Render(
			fmt.Sprintf(
				"Selected: %s (%s) - %s\nSize: %s",
				s.selectedBackup.Operation,
				s.selectedBackup.Timestamp.Format("2006-01-02 15:04:05"),
				s.selectedBackup.Name,
				formatBytes(s.selectedBackup.Size),
			),
		))
		content.WriteString("\n")
	}

	content.WriteString(restoreHelpStyle.Render("Actions: [Enter] Restore Selected • [↑/↓] Navigate • [q] Back"))

	return content.String()
}

// loadBackups loads the list of available backups
func (s *RestoreScreen) loadBackups() tea.Msg {
	backups, err := backup.ListBackups()
	if err != nil {
		return errMsg{err: err}
	}
	return backupsLoadedMsg{backups: backups}
}

// buildTable creates and configures the backup list table
func (s *RestoreScreen) buildTable() {
	columns := []table.Column{
		{Title: "Name", Width: 40},
		{Title: "Operation", Width: 15},
		{Title: "Date", Width: 20},
		{Title: "Size", Width: 12},
	}

	var rows []table.Row
	for _, b := range s.backups {
		row := table.Row{
			b.Name,
			b.Operation,
			b.Timestamp.Format("2006-01-02 15:04"),
			formatBytes(b.Size),
		}
		rows = append(rows, row)
	}

	s.table = table.New(
		table.WithColumns(columns),
		table.WithRows(rows),
		table.WithFocused(true),
		table.WithHeight(len(rows)+2), // Header + rows
	)

	// Apply styles
	s.setTableStyles()
}

// setTableStyles applies styling to the table
func (s *RestoreScreen) setTableStyles() {
	styles := table.DefaultStyles()
	styles.Header = styles.Header.
		BorderStyle(lipgloss.NormalBorder()).
		BorderForeground(lipgloss.Color("240")).
		BorderBottom(true).
		Bold(true)
	styles.Selected = styles.Selected.
		Foreground(lipgloss.Color("229")).
		Background(lipgloss.Color("57")).
		Bold(false)
	s.table.SetStyles(styles)
}

// performRestore performs the restore operation
func (s *RestoreScreen) performRestore() tea.Cmd {
	return func() tea.Msg {
		if s.selectedBackup == nil {
			return restoreCompletedMsg{
				err: fmt.Errorf("no backup selected"),
			}
		}

		// Get safety backup path from backup.BackupConfig
		safetyBackupPath, err := backup.BackupConfig(fmt.Sprintf("pre-restore-from-%s", s.selectedBackup.Name))
		if err != nil {
			return restoreCompletedMsg{
				err: fmt.Errorf("failed to create safety backup: %w", err),
			}
		}

		// Perform restore
		if err := backup.RestoreBackup(s.selectedBackup.Name); err != nil {
			return restoreCompletedMsg{
				err:              err,
				safetyBackupPath: safetyBackupPath,
			}
		}

		// Restore succeeded - trigger client list refresh
		return restoreCompletedMsg{
			safetyBackupPath: safetyBackupPath,
		}
	}
}

// formatBytes formats a byte count into human-readable format
func formatBytes(bytes int64) string {
	const unit = 1024
	if bytes < unit {
		return fmt.Sprintf("%d B", bytes)
	}
	div, exp := int64(unit), 0
	for n := bytes / unit; n >= unit; n /= unit {
		div *= unit
		exp++
	}
	return fmt.Sprintf("%.1f %ciB", float64(bytes)/float64(div), "KMGTPE"[exp])
}

// Messages

// backupsLoadedMsg is sent when backups are loaded
type backupsLoadedMsg struct {
	backups []backup.Backup
}

// restoreCompletedMsg is sent when a restore operation completes
type restoreCompletedMsg struct {
	err              error
	safetyBackupPath string
}