// Package ui implements the interactive terminal UI: a single bubbletea
// Model with a small screen stack, backed by the real system/store/keymgr
// operations — every action taken here (create user, lock, edit group
// hosts, export) performs the actual privileged operation immediately, then
// records it to the audit log and (for state changes) commits it to the
// git-backed state store.
package ui

import (
	"fmt"
	"time"

	"github.com/charmbracelet/bubbles/list"
	"github.com/charmbracelet/bubbles/textinput"
	tea "github.com/charmbracelet/bubbletea"
	"github.com/charmbracelet/lipgloss"

	"ssh-access-tui/internal/audit"
	"ssh-access-tui/internal/config"
	"ssh-access-tui/internal/keymgr"
	"ssh-access-tui/internal/model"
	"ssh-access-tui/internal/store"
)

type screen int

const (
	scrMenu screen = iota
	scrUsers
	scrUserNew
	scrUserNewGroups
	scrGroups
	scrGroupHosts
	scrHostNew
	scrExportSelect
	scrExportResult
	scrAudit
)

var (
	titleStyle  = lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("212")).Padding(0, 1)
	errStyle    = lipgloss.NewStyle().Foreground(lipgloss.Color("196"))
	okStyle     = lipgloss.NewStyle().Foreground(lipgloss.Color("42"))
	helpStyle   = lipgloss.NewStyle().Foreground(lipgloss.Color("240"))
	warnStyle   = lipgloss.NewStyle().Foreground(lipgloss.Color("214"))
	borderStyle = lipgloss.NewStyle().Border(lipgloss.RoundedBorder()).BorderForeground(lipgloss.Color("240")).Padding(1, 2)
)

// Model is the root bubbletea model for the whole application.
type Model struct {
	cfg config.Config
	st  *store.Store

	screen screen
	err    string
	status string

	menu list.Model

	usersList list.Model

	userNewName        textinput.Model
	userNewComment     textinput.Model
	userNewFocus       int
	userNewGroupsSel   map[string]bool
	userNewGroupsOrder []string
	userNewCursor      int

	groupsList    list.Model
	groupNewName  textinput.Model
	awaitingGroup bool
	selectedGroup string
	hostsList     list.Model
	hostForm      [4]textinput.Model // name, address, port, description
	hostFormFocus int

	exportSel    map[string]bool
	exportOrder  []string
	exportCursor int
	exportRes    []keymgr.BuildResult
	exportPass   string
	exportErr    string

	onlineSessions []audit.OnlineSession
	recentEvents   []audit.Event

	width, height int
}

// New builds the initial Model rooted at the given config and store.
//
// All list.Model fields are initialized here via list.New (not left as the
// zero value), even for screens the user hasn't visited yet: bubbletea
// delivers a WindowSizeMsg immediately on startup, which fans out to
// SetSize on every list in Update — and list.Model.SetSize on an
// uninitialized zero-value list panics (nil pagination model).
func New(cfg config.Config, st *store.Store) Model {
	m := Model{cfg: cfg, st: st}
	m.menu = newMenuList()
	m.usersList = emptyList("Пользователи")
	m.groupsList = emptyList("Группы доступа")
	m.hostsList = emptyList("Хосты")
	return m
}

func emptyList(title string) list.Model {
	l := list.New(nil, list.NewDefaultDelegate(), 0, 0)
	l.Title = title
	l.SetShowStatusBar(false)
	return l
}

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

func (m *Model) loadState() *model.State {
	st, err := m.st.Load()
	if err != nil {
		m.err = err.Error()
		return &model.State{}
	}
	return st
}

func (m *Model) mutate(commitMsg string, fn func(st *model.State) error) {
	err := m.st.WithLock(func() error {
		st, err := m.st.Load()
		if err != nil {
			return err
		}
		if err := fn(st); err != nil {
			return err
		}
		return m.st.Save(st, commitMsg)
	})
	if err != nil {
		m.err = err.Error()
	} else {
		m.err = ""
		m.status = commitMsg
	}
}

func (m *Model) logAudit(user, action, detail string) {
	_ = audit.Append(m.cfg.AuditLog, audit.Event{Time: time.Now(), User: user, Action: action, Detail: detail})
}

func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	switch msg := msg.(type) {
	case tea.WindowSizeMsg:
		m.width, m.height = msg.Width, msg.Height
		listW, listH := msg.Width-4, msg.Height-8
		m.menu.SetSize(listW, listH)
		m.usersList.SetSize(listW, listH)
		m.groupsList.SetSize(listW, listH)
		m.hostsList.SetSize(listW, listH)
		return m, nil
	case tea.KeyMsg:
		if msg.String() == "ctrl+c" {
			return m, tea.Quit
		}
	}

	switch m.screen {
	case scrMenu:
		return m.updateMenu(msg)
	case scrUsers:
		return m.updateUsers(msg)
	case scrUserNew:
		return m.updateUserNew(msg)
	case scrUserNewGroups:
		return m.updateUserNewGroups(msg)
	case scrGroups:
		return m.updateGroups(msg)
	case scrGroupHosts:
		return m.updateGroupHosts(msg)
	case scrHostNew:
		return m.updateHostNew(msg)
	case scrExportSelect:
		return m.updateExportSelect(msg)
	case scrExportResult:
		return m.updateExportResult(msg)
	case scrAudit:
		return m.updateAudit(msg)
	}
	return m, nil
}

func (m Model) View() string {
	var body string
	switch m.screen {
	case scrMenu:
		body = m.viewMenu()
	case scrUsers:
		body = m.viewUsers()
	case scrUserNew:
		body = m.viewUserNew()
	case scrUserNewGroups:
		body = m.viewUserNewGroups()
	case scrGroups:
		body = m.viewGroups()
	case scrGroupHosts:
		body = m.viewGroupHosts()
	case scrHostNew:
		body = m.viewHostNew()
	case scrExportSelect:
		body = m.viewExportSelect()
	case scrExportResult:
		body = m.viewExportResult()
	case scrAudit:
		body = m.viewAudit()
	}

	footer := ""
	if m.err != "" {
		footer = errStyle.Render("ошибка: " + m.err)
	} else if m.status != "" {
		footer = okStyle.Render(m.status)
	}
	return fmt.Sprintf("%s\n\n%s\n", body, footer)
}