package tui

import (
	"context"
	"strings"

	"github.com/charmbracelet/bubbles/textarea"
	"github.com/charmbracelet/bubbletea"
	"github.com/charmbracelet/lipgloss"
	"github.com/titor/fanyi/internal/config"
	"github.com/titor/fanyi/internal/translator"
)

type model struct {
	config     *config.Config
	translator *translator.Translator
	textArea   textarea.Model
	result     string
	errMsg     string
	targetLang string
	langIndex  int
	loading    bool
	width      int
	height     int
}

type translateMsg struct {
	result string
	err    error
}

var (
	headerStyle = lipgloss.NewStyle().
			Foreground(lipgloss.Color("#00D9FF")).
			Bold(true)
	dividerStyle = lipgloss.NewStyle().
			Foreground(lipgloss.Color("#00D9FF"))
	resultStyle = lipgloss.NewStyle().
			Foreground(lipgloss.Color("#98FB98")).
			Background(lipgloss.Color("#0D1B2A"))
	errorStyle = lipgloss.NewStyle().
			Foreground(lipgloss.Color("#FF6B6B")).
			Background(lipgloss.Color("#1A1A2E"))
	helpStyle = lipgloss.NewStyle().
			Foreground(lipgloss.Color("#888888"))
	statusBarStyle = lipgloss.NewStyle().
			Foreground(lipgloss.Color("#FFFFFF")).
			Background(lipgloss.Color("#1F2937"))
	langStyle = lipgloss.NewStyle().
			Foreground(lipgloss.Color("#FBBF24")).
			Bold(true)
	loadingStyle = lipgloss.NewStyle().
			Foreground(lipgloss.Color("#60A5FA"))
)

var supportedLangs = []string{"zh-CN", "en-US", "ja", "ko", "zh-TW", "es", "fr", "de"}

func NewApp(cfg *config.Config, t *translator.Translator) *tea.Program {
	targetLang := "zh-CN"
	if cfg != nil && cfg.DefaultTargetLang != "" {
		targetLang = cfg.DefaultTargetLang
	}

	ta := textarea.New()
	ta.Placeholder = "输入要翻译的文本..."
	ta.Focus()
	ta.Prompt = ""
	ta.ShowLineNumbers = false
	ta.SetHeight(3)

	ta.FocusedStyle.Base = lipgloss.NewStyle().
		Background(lipgloss.Color("#1A1A2E")).
		Foreground(lipgloss.Color("#FAFAFA"))

	return tea.NewProgram(model{
		config:     cfg,
		translator: t,
		textArea:   ta,
		targetLang: targetLang,
	})
}

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

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

	switch msg := msg.(type) {
	case tea.WindowSizeMsg:
		m.width = msg.Width
		m.height = msg.Height
		m.updateTextAreaWidth()

	case translateMsg:
		m.loading = false
		if msg.err != nil {
			m.errMsg = msg.err.Error()
			m.result = ""
		} else {
			m.result = msg.result
			m.errMsg = ""
		}
		m.updateTextAreaHeight()
		return m, nil

	case tea.KeyMsg:
		switch msg.Type {
		case tea.KeyEnter:
			if msg.Alt {
				m.textArea.InsertString("\n")
				m.updateTextAreaHeight()
				return m, nil
			}
			if m.loading {
				return m, nil
			}
			text := m.textArea.Value()
			if text == "" {
				return m, nil
			}
			m.loading = true
			m.errMsg = ""
			return m, m.doTranslate(text, m.targetLang)

		case tea.KeyCtrlC:
			return m, tea.Quit

		case tea.KeyCtrlL:
			m.textArea.SetValue("")
			m.result = ""
			m.errMsg = ""
			return m, nil

		case tea.KeyCtrlT:
			m.langIndex = (m.langIndex + 1) % len(supportedLangs)
			m.targetLang = supportedLangs[m.langIndex]
			return m, nil

		case tea.KeyEsc:
			return m, tea.Quit
		}

		m.textArea, cmd = m.textArea.Update(msg)
		m.updateTextAreaHeight()
		return m, cmd

	default:
		m.textArea, cmd = m.textArea.Update(msg)
		m.updateTextAreaHeight()
	}
	return m, cmd
}

func (m model) updateTextAreaWidth() {
	if m.width > 0 {
		margin := 4
		width := m.width - margin
		if width < 20 {
			width = 60
		}
		m.textArea.SetWidth(width)
	}
}

func (m model) updateTextAreaHeight() {
	lines := strings.Count(m.textArea.Value(), "\n") + 1
	if lines < 1 {
		lines = 1
	}
	if lines > 7 {
		lines = 7
	}
	if lines < 3 {
		lines = 3
	}
	m.textArea.SetHeight(lines)
}

func (m model) doTranslate(text, toLang string) tea.Cmd {
	return func() tea.Msg {
		result, err := m.translator.Translate(
			context.Background(),
			text,
			&translator.TranslateOptions{
				ToLang:     toLang,
				PromptName: "simple",
			},
		)
		if err != nil {
			return translateMsg{err: err}
		}
		return translateMsg{result: result.Translated}
	}
}

func (m model) View() string {
	margin := "  "
	resultBox := m.renderResult()

	return "\n" +
		margin + headerStyle.Render("YOYO翻译") + "\n" +
		margin + dividerStyle.Render(getDivider(m.width-2)) + "\n\n" +
		margin + m.textArea.View() + "\n\n" +
		margin + resultBox +
		margin + dividerStyle.Render(getDivider(m.width-2)) + "\n" +
		m.renderStatusBar()
}

func getDivider(width int) string {
	if width < 10 {
		width = 40
	}
	result := ""
	for i := 0; i < width-4; i++ {
		result += "─"
	}
	return result
}

func (m model) renderResult() string {
	if m.loading {
		return loadingStyle.Render("正在翻译...") + "\n\n"
	}
	if m.errMsg != "" {
		return errorStyle.Render("错误: "+m.errMsg) + "\n\n"
	}
	if m.result == "" {
		return helpStyle.Render("翻译结果将显示在这里...") + "\n\n"
	}
	return resultStyle.Render(m.result) + "\n\n"
}

func (m model) renderStatusBar() string {
	width := m.width - 4
	if width < 30 {
		width = 60
	}
	langInfo := langStyle.Render("目标: " + m.targetLang)
	hint := helpStyle.Render("按 / 显示命令")

	return "  " + statusBarStyle.Render(" "+langInfo+"  ") + "  " + hint
}