package tui

import (
	"errors"
	"tailscale-vpn/internal/pages"
	"tailscale-vpn/internal/services"

	tea "charm.land/bubbletea/v2"
)

func (m TUIInterface) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	switch msg := msg.(type) {

	case pages.HomePageMsg:
		m.Page = pageHome
		m.MenuItems = pages.HomeMenuItems(m.VPNConnected, m.HasServers)
		return m, nil

	case pages.SettingsPageMsg:
		m.Page = pageSettings
		m.SettingsEditMode = ""
		m.SettingsConfirmDelete = false
		m.SettingsSelected = 0
		return m, loadServersCmd(m.Services)

	case pages.SelectServerPageMsg:
		m.Page = pageSelectServer
		m.SelectServerServers = m.SettingsServers
		m.SelectServerSelected = 0
		for i, srv := range m.SelectServerServers {
			if m.HasSelectedServer && srv.ID == m.SelectedServer.ID {
				m.SelectServerSelected = i
				break
			}
		}
		return m, nil

	case pages.ServerSelectedMsg:
		m.SelectedServer = msg.Server
		m.HasSelectedServer = msg.Server.ID != ""
		if msg.Err != nil {
			m.VPNError = msg.Err
		}
		return m, func() tea.Msg { return pages.HomePageMsg{} }

	case pages.ServerSelectionCanceledMsg:
		return m, func() tea.Msg { return pages.HomePageMsg{} }

	case pages.ServerListLoadedMsg:
		m.SettingsServers = msg.Servers
		m.HasServers = len(msg.Servers) > 0
		if msg.Err != nil {
			m.VPNError = msg.Err
		}
		return m, nil

	case pages.ServerEditMsg:
		m.SettingsEditMode = msg.Mode
		m.SettingsConfirmDelete = false
		if msg.Mode == "edit" {
			m.SettingsEditingServer = msg.Server
			m.SettingsFormName = msg.Server.Name
			m.SettingsFormHost = msg.Server.Host
		} else {
			m.SettingsEditingServer = services.Server{}
			m.SettingsFormName = ""
			m.SettingsFormHost = ""
		}
		m.SettingsFormField = 0
		return m, nil

	case pages.ServerSaveMsg:
		m.SettingsEditMode = ""
		if msg.Err != nil {
			m.VPNError = msg.Err
		}
		return m, loadServersCmd(m.Services)

	case pages.ServerDeleteMsg:
		m.SettingsConfirmDelete = false
		if msg.Err != nil {
			m.VPNError = msg.Err
		} else {
			if m.SettingsSelected >= len(m.SettingsServers) {
				m.SettingsSelected = max(len(m.SettingsServers)-1, 0)
			}
		}
		return m, loadServersCmd(m.Services)

	case tea.WindowSizeMsg:
		m.WindowWidth = msg.Width
		m.WindowHeight = msg.Height
		return m, nil

	case tea.KeyPressMsg:
		if m.Page == pageHome {
			return m.updateHomePage(msg)
		}
		if m.Page == pageSettings {
			return m.updateSettingsPage(msg)
		}
		if m.Page == pageSelectServer {
			return m.updateSelectServerPage(msg)
		}

	case tea.PasteMsg:
		if m.Page == pageSettings && m.SettingsEditMode != "" {
			if m.SettingsFormField == 0 {
				m.SettingsFormName += msg.Content
			} else if m.SettingsFormField == 1 {
				m.SettingsFormHost += msg.Content
			}
			return m, nil
		}

	case pages.VPNStatusMsg:
		m.VPNConnected = msg.Connected
		m.VPNLoading = false
		if msg.Err != nil {
			m.VPNError = msg.Err
		} else {
			m.VPNError = nil
		}
		m.MenuItems = pages.HomeMenuItems(m.VPNConnected, m.HasServers)
		return m, nil

	case pages.VPNToggleMsg:
		m.VPNConnected = msg.Connected
		m.VPNToggleLoading = false
		if msg.Err != nil {
			m.VPNError = msg.Err
		} else {
			m.VPNError = nil
		}
		m.MenuItems = pages.HomeMenuItems(m.VPNConnected, m.HasServers)
		return m, nil
	}

	return m, nil
}

func (m TUIInterface) updateHomePage(msg tea.KeyPressMsg) (tea.Model, tea.Cmd) {
	if m.VPNLoading || m.VPNToggleLoading {
		if msg.String() == "ctrl+c" {
			m.Quitting = true
			return m, tea.Quit
		}
		return m, nil
	}

	switch msg.String() {
	case "up", "k":
		if m.Selected > 0 {
			m.Selected--
		}
		return m, nil

	case "down", "j":
		if m.Selected < len(m.MenuItems)-1 {
			m.Selected++
		}
		return m, nil

	case "enter":
		if len(m.MenuItems) > 0 {
			switch m.MenuItems[m.Selected].Key {
			case "select-server":
				return m, func() tea.Msg { return pages.SelectServerPageMsg{} }
			case "settings":
				return m, func() tea.Msg { return pages.SettingsPageMsg{} }
			case "on":
				m.VPNToggleLoading = true
				m.VPNError = nil
				return m, turnOnVPNCmd(m.Services)
			case "off":
				m.VPNToggleLoading = true
				m.VPNError = nil
				return m, turnOffVPNCmd(m.Services)
			}
		}
		return m, nil

	case "r":
		m.VPNLoading = true
		m.VPNError = nil
		return m, checkVPNStatusCmd(m.Services)

	case "ctrl+c", "esc":
		m.Quitting = true
		return m, tea.Quit
	}

	return m, nil
}

func (m TUIInterface) updateSelectServerPage(msg tea.KeyPressMsg) (tea.Model, tea.Cmd) {
	switch msg.String() {
	case "up", "k":
		if m.SelectServerSelected > 0 {
			m.SelectServerSelected--
		}
		return m, nil
	case "down", "j":
		if m.SelectServerSelected < len(m.SelectServerServers)-1 {
			m.SelectServerSelected++
		}
		return m, nil
	case "enter":
		if m.SelectServerSelected >= 0 && m.SelectServerSelected < len(m.SelectServerServers) {
			return m, selectServerCmd(m.Services, m.SelectServerServers[m.SelectServerSelected].ID)
		}
		return m, nil
	case "esc", "ctrl+c":
		return m, func() tea.Msg { return pages.ServerSelectionCanceledMsg{} }
	}
	return m, nil
}

func (m TUIInterface) updateSettingsPage(msg tea.KeyPressMsg) (tea.Model, tea.Cmd) {
	if m.SettingsEditMode != "" {
		switch msg.String() {
		case "esc":
			m.SettingsEditMode = ""
			return m, nil
		case "enter":
			if m.SettingsFormField == 2 {
				if m.SettingsFormName == "" || m.SettingsFormHost == "" {
					m.VPNError = errors.New("name and host are required")
					return m, nil
				}
				if m.SettingsEditMode == "add" {
					return m, addServerCmd(m.Services, m.SettingsFormName, m.SettingsFormHost)
				}
				return m, updateServerCmd(m.Services, m.SettingsEditingServer.ID, m.SettingsFormName, m.SettingsFormHost)
			} else if m.SettingsFormField == 3 {
				m.SettingsEditMode = ""
				return m, nil
			} else {
				m.SettingsFormField = (m.SettingsFormField + 1) % 4
				return m, nil
			}
		case "up", "k":
			m.SettingsFormField = (m.SettingsFormField - 1 + 4) % 4
			return m, nil
		case "down", "j":
			m.SettingsFormField = (m.SettingsFormField + 1) % 4
			return m, nil
		case "tab":
			m.SettingsFormField = (m.SettingsFormField + 1) % 4
			return m, nil
		case "backtab":
			m.SettingsFormField = (m.SettingsFormField - 1 + 4) % 4
			return m, nil
		case "backspace":
			if m.SettingsFormField == 0 && len(m.SettingsFormName) > 0 {
				m.SettingsFormName = m.SettingsFormName[:len(m.SettingsFormName)-1]
			} else if m.SettingsFormField == 1 && len(m.SettingsFormHost) > 0 {
				m.SettingsFormHost = m.SettingsFormHost[:len(m.SettingsFormHost)-1]
			}
			return m, nil
		case "ctrl+c":
			m.Quitting = true
			return m, tea.Quit
		default:
			if m.SettingsFormField == 0 || m.SettingsFormField == 1 {
				if msg.Text != "" {
					if m.SettingsFormField == 0 {
						m.SettingsFormName += msg.Text
					} else {
						m.SettingsFormHost += msg.Text
					}
				}
			}
			return m, nil
		}
	}

	switch msg.String() {

	case "esc":
		if m.SettingsConfirmDelete {
			m.SettingsConfirmDelete = false
			return m, nil
		}
		return m, func() tea.Msg { return pages.HomePageMsg{} }

	case "up", "k":
		if m.SettingsConfirmDelete {
			return m, nil
		}
		if m.SettingsSelected > 0 {
			m.SettingsSelected--
		}
		return m, nil

	case "down", "j":
		if m.SettingsConfirmDelete {
			return m, nil
		}
		if m.SettingsSelected < len(m.SettingsServers)-1 {
			m.SettingsSelected++
		}
		return m, nil

	case "a":
		if m.SettingsConfirmDelete {
			return m, nil
		}
		return m, func() tea.Msg { return pages.ServerEditMsg{Mode: "add"} }

	case "enter":
		if m.SettingsConfirmDelete {
			if m.SettingsSelected >= 0 && m.SettingsSelected < len(m.SettingsServers) {
				return m, deleteServerCmd(m.Services, m.SettingsServers[m.SettingsSelected].ID)
			}
			m.SettingsConfirmDelete = false
			return m, nil
		}
		if m.SettingsSelected >= 0 && m.SettingsSelected < len(m.SettingsServers) {
			return m, func() tea.Msg {
				return pages.ServerEditMsg{
					Mode:   "edit",
					Server: m.SettingsServers[m.SettingsSelected],
				}
			}
		}
		return m, nil

	case "d":
		if m.SettingsConfirmDelete {
			return m, nil
		}
		if len(m.SettingsServers) > 0 {
			m.SettingsConfirmDelete = true
		}
		return m, nil

	case "ctrl+c":
		m.Quitting = true
		return m, tea.Quit
	}

	return m, nil
}