package inbox

import (
	"fmt"
	"io"
	"strings"
	"time"

	"charm.land/bubbles/v2/key"
	"charm.land/bubbles/v2/list"
	"charm.land/bubbles/v2/spinner"
	tea "charm.land/bubbletea/v2"
	"charm.land/lipgloss/v2"

	_ "charm.land/bubbles/v2/help"
)

type EmailDetail struct {
	UID       uint32
	From      string
	FromName  string
	To        string
	Cc        string
	Subject   string
	Date      time.Time
	TextBody  string
	HTMLBody  string
	Account   string
	AccountID string
}

type DetailResultMsg struct {
	Detail *EmailDetail
	Err    error
}

type EmailItem struct {
	UID       uint32
	From      string
	FromName  string
	Subject   string
	Date      time.Time
	Preview   string
	Account   string
	AccountID string
}

func (e EmailItem) FilterValue() string {
	return fmt.Sprintf("%s %s %s %s", e.Account, e.FromName, e.From, e.Subject)
}

func (e EmailItem) Title() string {
	return fmt.Sprintf("%s · %s - %s", e.Account, e.FromName, e.Subject)
}

func (e EmailItem) Description() string {
	return e.Preview
}

func formatTimeAgo(d time.Duration) string {
	if d < time.Minute {
		return "刚刚"
	}
	if d < time.Hour {
		mins := int(d.Minutes())
		return fmt.Sprintf("%d分钟前", mins)
	}
	if d < 24*time.Hour {
		hours := int(d.Hours())
		return fmt.Sprintf("%d小时前", hours)
	}
	if d < 7*24*time.Hour {
		days := int(d.Hours() / 24)
		return fmt.Sprintf("%d天前", days)
	}
	return d.Truncate(24 * time.Hour).String()
}

func truncateString(s string, maxWidth int) string {
	if maxWidth <= 0 {
		return ""
	}
	runes := []rune(s)
	if len(runes) <= maxWidth {
		return s
	}
	if maxWidth <= 3 {
		return strings.Repeat(".", maxWidth)
	}
	return string(runes[:maxWidth-3]) + "..."
}

type InboxModel struct {
	list           list.Model
	emails         []EmailItem
	loading        bool
	err            error
	selectedEmail  *EmailItem
	selectedDetail *EmailDetail
	loadingDetail  bool
	windowWidth    int
	windowHeight   int
	helpKeyMap     inboxHelpKeyMap
	spinner        spinner.Model
	detailFetcher  DetailFetcher
}

type inboxHelpKeyMap struct{}

func (i inboxHelpKeyMap) ShortHelp() []key.Binding {
	return []key.Binding{
		key.NewBinding(key.WithHelp("↑", "上移")),
		key.NewBinding(key.WithHelp("↓", "下移")),
		key.NewBinding(key.WithHelp("enter", "查看详情")),
		key.NewBinding(key.WithHelp("/", "搜索")),
		key.NewBinding(key.WithHelp("q", "退出")),
	}
}

func (i inboxHelpKeyMap) FullHelp() [][]key.Binding {
	return [][]key.Binding{
		{
			key.NewBinding(key.WithHelp("↑↓", "移动")),
			key.NewBinding(key.WithHelp("enter", "查看详情")),
			key.NewBinding(key.WithHelp("/", "搜索")),
			key.NewBinding(key.WithHelp("q", "退出")),
		},
	}
}

func NewInboxModel() *InboxModel {
	l := list.New(nil, emailDelegate{}, 40, 14)
	l.Title = "收件箱"
	l.Styles = list.DefaultStyles(true)
	l.Styles.Title = inboxTitleStyle
	l.Styles.NoItems = inboxNoItemsStyle
	l.SetShowHelp(true)
	l.SetShowPagination(false)
	l.SetFilteringEnabled(true)

	s := spinner.New()
	s.Spinner = spinner.Dot
	s.Style = spinnerStyle

	return &InboxModel{
		list:        l,
		emails:      []EmailItem{},
		windowWidth: 0,
		spinner:     s,
	}
}

func (m *InboxModel) SetEmails(emails []EmailItem) {
	m.emails = emails
	items := make([]list.Item, len(emails))
	for i, e := range emails {
		items[i] = e
	}
	m.list.SetItems(items)
	m.list.Title = fmt.Sprintf("收件箱 (%d 封新邮件)", len(items))
}

func (m InboxModel) Init() tea.Cmd {
	return tea.Batch(
		func() tea.Msg {
			return tea.WindowSizeMsg{Width: 120, Height: 30}
		},
		m.spinner.Tick,
	)
}

func fetchEmailDetail(accountID string, uid uint32, fetcher DetailFetcher) tea.Cmd {
	return func() tea.Msg {
		detail, err := fetcher(accountID, uid)
		return DetailResultMsg{Detail: detail, Err: err}
	}
}

func (m *InboxModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	var cmd tea.Cmd

	switch msg := msg.(type) {
	case tea.KeyMsg:
		if msg.String() == "ctrl+c" {
			return m, tea.Quit
		}
		if msg.String() == "enter" {
			email := m.SelectedEmail()
			if email != nil && m.detailFetcher != nil {
				m.loadingDetail = true
				m.selectedDetail = nil
				return m, fetchEmailDetail(email.AccountID, email.UID, m.detailFetcher)
			}
		}
	case tea.WindowSizeMsg:
		m.windowWidth = msg.Width
		m.windowHeight = msg.Height
		m.list.SetWidth(calculateListWidth(msg.Width))
		m.list.SetHeight(int(float64(msg.Height) * 0.8))
	case DetailResultMsg:
		m.loadingDetail = false
		if msg.Err != nil {
			m.err = msg.Err
		} else {
			m.selectedDetail = msg.Detail
		}
	case spinner.TickMsg:
		m.spinner, cmd = m.spinner.Update(msg)
		return m, cmd
	}

	m.list, cmd = m.list.Update(msg)
	return m, cmd
}

func calculateListWidth(totalWidth int) int {
	if totalWidth <= 0 {
		return 0
	}
	return int(float64(totalWidth) * 0.45)
}

func (m InboxModel) View() tea.View {
	if m.loading {
		return tea.NewView(loadingStyle.Render("正在加载邮件..."))
	}
	if m.err != nil {
		return tea.NewView(errorStyle.Render(fmt.Sprintf("错误: %v", m.err)))
	}

	listWidth := calculateListWidth(m.windowWidth)
	detailWidth := m.windowWidth - listWidth - 1

	m.list.SetWidth(listWidth)

	mainContentStyle := lipgloss.NewStyle().
		Width(m.windowWidth - 1).
		Height(m.windowHeight - 2)

	helpBarStyle := lipgloss.NewStyle().
		Width(m.windowWidth - 1).
		Foreground(lipgloss.Color("241"))

	helpView := helpBarStyle.Render(m.list.Help.View(m.helpKeyMap))

	if m.windowWidth >= 80 {
		detailView := m.renderDetailPanel(detailWidth)
		listView := m.list.View()
		mainContent := lipgloss.JoinHorizontal(lipgloss.Top, listView, detailView)
		box := mainContentStyle.Render(mainContent)
		content := lipgloss.JoinVertical(lipgloss.Bottom, box, helpView)
		v := tea.NewView(content)
		v.AltScreen = true
		return v
	}

	listView := m.list.View()
	box := mainContentStyle.Render(listView)
	content := lipgloss.JoinVertical(lipgloss.Bottom, box, helpView)
	v := tea.NewView(content)
	v.AltScreen = true
	return v
}

func (m InboxModel) renderHelpBar() string {
	helpItems := "↑↓ 移动 │ enter 查看详情 │ / 搜索 │ q 退出"
	return helpBarStyle.Render(helpItems)
}

func (m InboxModel) renderDetailPanel(listWidth int) string {
	email := m.SelectedEmail()
	if email == nil {
		return detailPanelStyle.Render("选择一封邮件查看详情")
	}

	if m.loadingDetail {
		spinnerView := m.spinner.View()
		loadingText := detailMetaStyle.Render(spinnerView + " 正在加载邮件内容...")
		return detailPanelStyle.Width(40).Render(loadingText)
	}

	if m.selectedDetail != nil {
		detail := m.selectedDetail
		subject := detailTitleStyle.Render(detail.Subject)

		from := detailMetaStyle.Render(fmt.Sprintf("发件人: %s", detail.From))

		to := detailMetaStyle.Render(fmt.Sprintf("收件人: %s", detail.To))
		if detail.Cc != "" {
			to += "\n" + detailMetaStyle.Render(fmt.Sprintf("抄送: %s", detail.Cc))
		}
		account := detailMetaStyle.Render(fmt.Sprintf("账户: %s", detail.Account))
		date := detailMetaStyle.Render(fmt.Sprintf("时间: %s", detail.Date.Format("2006-01-02 15:04")))

		var body string
		if detail.TextBody != "" {
			body = detailBodyStyle.Render(detail.TextBody)
		} else if detail.HTMLBody != "" {
			body = detailMetaStyle.Render("[HTML邮件内容]")
		} else {
			body = detailMetaStyle.Render("[无正文]")
		}

		content := fmt.Sprintf("%s\n%s\n%s\n%s\n%s\n\n%s", subject, from, to, account, date, body)

		detailWidth := 40
		if m.windowWidth > 0 {
			detailWidth = m.windowWidth - listWidth - 1
		}
		if detailWidth < 10 {
			detailWidth = 40
		}

		return detailPanelStyle.Width(detailWidth).Render(content)
	}

	subject := detailTitleStyle.Render(email.Subject)
	from := detailMetaStyle.Render(fmt.Sprintf("发件人: %s <%s>", email.FromName, email.From))
	account := detailMetaStyle.Render(fmt.Sprintf("账户: %s", email.Account))
	date := detailMetaStyle.Render(fmt.Sprintf("时间: %s", email.Date.Format("2006-01-02 15:04")))
	preview := detailPanelStyle.Render(email.Preview)

	content := fmt.Sprintf("%s\n%s\n%s\n%s\n\n%s", subject, from, account, date, preview)

	detailWidth := 40
	if m.windowWidth > 0 {
		detailWidth = m.windowWidth - listWidth - 1
	}
	if detailWidth < 10 {
		detailWidth = 40
	}

	return detailPanelStyle.Width(detailWidth).Render(content)
}

func (m *InboxModel) SetLoading(loading bool) {
	m.loading = loading
}

func (m *InboxModel) SetError(err error) {
	m.err = err
}

func (m InboxModel) SelectedEmail() *EmailItem {
	idx := m.list.Index()
	if idx >= 0 && idx < len(m.emails) {
		return &m.emails[idx]
	}
	return nil
}

var (
	inboxTitleStyle = lipgloss.NewStyle().
			Foreground(lipgloss.Color("219")).
			Bold(true)

	inboxNoItemsStyle = lipgloss.NewStyle().
				Foreground(lipgloss.Color("241")).
				Padding(1, 2)

	loadingStyle = lipgloss.NewStyle().
			Foreground(lipgloss.Color("219")).
			Padding(1, 2)

	errorStyle = lipgloss.NewStyle().
			Foreground(lipgloss.Color("196")).
			Padding(1, 2)

	emailCardSubjectStyle = lipgloss.NewStyle().
				Foreground(lipgloss.Color("255")).
				Bold(true).
				Padding(0, 2)

	emailCardMetaStyle = lipgloss.NewStyle().
				Foreground(lipgloss.Color("241")).
				Padding(0, 2)

	emailCardSubjectSelectedStyle = lipgloss.NewStyle().
					Foreground(lipgloss.Color("255")).
					Bold(true).
					Background(lipgloss.Color("99")).
					Border(lipgloss.NormalBorder()).
					BorderLeft(true).
					BorderForeground(lipgloss.Color("219")).
					Padding(0, 2)

	emailCardMetaSelectedStyle = lipgloss.NewStyle().
					Foreground(lipgloss.Color("186")).
					Background(lipgloss.Color("99")).
					Border(lipgloss.NormalBorder()).
					BorderLeft(true).
					BorderForeground(lipgloss.Color("219")).
					Padding(0, 2)

	detailPanelStyle = lipgloss.NewStyle().
				Foreground(lipgloss.Color("255")).
				Padding(1, 2)

	detailTitleStyle = lipgloss.NewStyle().
				Foreground(lipgloss.Color("219")).
				Bold(true).
				Padding(0, 1)

	detailMetaStyle = lipgloss.NewStyle().
			Foreground(lipgloss.Color("241")).
			Padding(0, 1)

	detailBodyStyle = lipgloss.NewStyle().
			Foreground(lipgloss.Color("252")).
			Padding(0, 1)

	helpBarStyle = lipgloss.NewStyle().
			Foreground(lipgloss.Color("241")).
			Padding(0, 1)

	spinnerStyle = lipgloss.NewStyle().
			Foreground(lipgloss.Color("219"))

	cardSpacing = 1
)

type DetailFetcher func(accountID string, uid uint32) (*EmailDetail, error)

func (m *InboxModel) SetDetailFetcher(fetcher DetailFetcher) {
	m.detailFetcher = fetcher
}

type emailDelegate struct{}

func (d emailDelegate) Height() int  { return 2 }
func (d emailDelegate) Spacing() int { return 0 }
func (d emailDelegate) Update(msg tea.Msg, m *list.Model) tea.Cmd {
	return nil
}
func (d emailDelegate) Render(w io.Writer, m list.Model, index int, item list.Item) {
	email, ok := item.(EmailItem)
	if !ok {
		return
	}

	isSelected := index == m.Index()

	width := m.Width() - 1
	subjectWidth := width - 2
	metaWidth := width - 2

	subject := truncateString(email.Subject, subjectWidth)
	meta := truncateString("▣ "+email.Account+" · "+formatTimeAgo(time.Since(email.Date)), metaWidth)

	if isSelected {
		subjectStyle := lipgloss.NewStyle().
			Width(width).
			Foreground(lipgloss.Color("255")).
			Background(lipgloss.Color("99")).
			Padding(1, 1, 0, 1)

		metaStyle := lipgloss.NewStyle().
			Width(width).
			Foreground(lipgloss.Color("186")).
			Background(lipgloss.Color("99")).
			Padding(0, 1, 1, 1)

		fmt.Fprintf(w, "%s\n%s",
			subjectStyle.Render(subject),
			metaStyle.Render(meta))
	} else {
		subjectStyle := lipgloss.NewStyle().
			Width(width).
			Foreground(lipgloss.Color("255")).
			Padding(1, 1, 0, 1)

		metaStyle := lipgloss.NewStyle().
			Width(width).
			Foreground(lipgloss.Color("241")).
			Padding(0, 1, 1, 1)

		fmt.Fprintf(w, "%s\n%s",
			subjectStyle.Render(subject),
			metaStyle.Render(meta))
	}
}