package main

import (
	"context"
	"errors"
	"flag"
	"net"
	"os"
	"os/signal"
	"path/filepath"
	"slices"
	"strings"
	"syscall"
	"time"

	"github.com/charmbracelet/bubbles/list"
	"github.com/charmbracelet/bubbles/viewport"
	tea "github.com/charmbracelet/bubbletea"
	"github.com/charmbracelet/glamour"
	"github.com/charmbracelet/lipgloss"
	"github.com/charmbracelet/log"
	"github.com/charmbracelet/ssh"
	"github.com/charmbracelet/wish"
	"github.com/charmbracelet/wish/activeterm"
	"github.com/charmbracelet/wish/bubbletea"
	"github.com/charmbracelet/wish/logging"
	"github.com/charmbracelet/x/term"
)

type errMsg error

type item struct {
	title, desc string
	index       int // This is stupid but it'll work for now
}

func (i item) Title() string       { return i.title }
func (i item) Description() string { return i.desc }
func (i item) FilterValue() string { return i.title }

// TODO: this should take in a parsed object, not just a string.
// That way we don't have to handle the parsing errors here.
func getPostWithoutMetaData(post string) (string, error) {
	splitPost := strings.Split(post, "\n")

	index := slices.Index(splitPost[1:], "+++")
	if index == -1 {
		return "", errors.New("Could not find close +++")
	}

	return strings.Join(splitPost[index+2:], "\n"), nil
}

type Page int

const (
	FRONT Page = iota
	POST_LIST
	POST
)

type model struct {
	renderer     *lipgloss.Renderer
	termRenderer *glamour.TermRenderer

	list     list.Model
	allPosts []string

	width  int
	height int

	navModel navModel

	frontPageContent string
	frontPageModel   postModel
	postModel        postModel

	page Page

	viewport viewport.Model

	err error
}

func getViewPort(renderer *lipgloss.Renderer, width int, height int) viewport.Model {
	vp := viewport.New(width, height)
	vp.Style = renderer.NewStyle().
		BorderStyle(lipgloss.RoundedBorder()).
		BorderForeground(lipgloss.Color("62")).
		PaddingRight(2)

	return vp
}

func initialModel(renderer *lipgloss.Renderer, w int, h int) model {
	posts, err := getAllPosts(filepath.Join(os.Getenv("BLOG_PATH"), "content/blog"))
	if err != nil {
		panic(err)
	}

	listItems := make([]list.Item, len(posts))
	for i, post := range posts {
		postInfo, err := getPostInfo(post)
		if err != nil {
			continue
		}

		listItems[i] = item{title: postInfo.Title, desc: postInfo.Date.String(), index: i}
	}

	list := list.New(listItems, list.NewDefaultDelegate(), w, h-4)
	list.SetShowTitle(false)

	// -1 to allow for the initial height of the nav model
	vp := getViewPort(renderer, w, h-3)

	// We need to adjust the width of the glamour render from our main width
	// to account for a few things:
	//
	//  * The viewport border width
	//  * The viewport padding
	//  * The viewport margins
	//  * The gutter glamour applies to the left side of the content
	//
	const glamourGutter = 2
	glamourRenderWidth := w - vp.Style.GetHorizontalFrameSize() - glamourGutter

	termRenderer, err := glamour.NewTermRenderer(
		glamour.WithAutoStyle(),
		glamour.WithWordWrap(glamourRenderWidth),
	)
	if err != nil {
		panic(err)
	}

	frontPageContent, err := os.ReadFile(filepath.Join(os.Getenv("BLOG_PATH"), "content/_index.md"))
	if err != nil {
		panic(err)
	}

	processedFrontPage, err := processMarkdown(string(frontPageContent))
	if err != nil {
		panic(err)
	}

	frontPageModel, err := createMarkdownPostModel(processedFrontPage, termRenderer, vp)
	if err != nil {
		panic(err)
	}

	return model{
		list:             list,
		allPosts:         posts,
		page:             FRONT,
		termRenderer:     termRenderer,
		viewport:         vp,
		frontPageModel:   frontPageModel,
		frontPageContent: processedFrontPage,
		width:            w,
		height:           h,
		navModel:         createNavModel(renderer, w),
	}
}

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

func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	switch msg := msg.(type) {
	case tea.KeyMsg:
		switch msg.String() {
		case "h":
			m.page = FRONT
			return m, nil
		case "b":
			m.page = POST_LIST
			return m, nil
		}
	}

	switch m.page {
	case FRONT:
		updatedFrontPageModel, cmd := m.frontPageModel.Update(msg)
		m.frontPageModel = updatedFrontPageModel.(postModel)

		if cmd != nil {
			if _, ok := cmd().(childMessage); ok {
				return m, tea.Quit
			}
		}

		return m, cmd
	case POST_LIST:
		switch msg := msg.(type) {
		case tea.KeyMsg:
			switch msg.String() {
			case tea.KeyEnter.String():
				m.page = POST
				selectedItem := m.list.SelectedItem().(item)

				processedPost, err := processMarkdown(m.allPosts[selectedItem.index])
				if err != nil {
					panic(err)
				}

				postModel, err := createMarkdownPostModel(processedPost, m.termRenderer, m.viewport)
				if err != nil {
					panic(err)
				}

				m.postModel = postModel
				return m, nil
			}
		case tea.WindowSizeMsg:
			// h, v := m.termRenderer.GetFrameSize()
			// m.list.SetSize(msg.Width-h, msg.Height-v)
			//
			// m.height = msg.Height
			// m.width = msg.Width
		}

		list, cmd := m.list.Update(msg)
		m.list = list

		return m, cmd
	case POST:
		updatedPostModel, cmd := m.postModel.Update(msg)
		if cmd != nil {
			if _, ok := cmd().(childMessage); ok {
				m.page = POST_LIST
			}
		}

		m.postModel = updatedPostModel.(postModel)

		return m, nil
	default:
		panic("unreachable")
	}
}

func (m model) View() string {
	// TODO: better type safety would be to do this over the type.
	switch m.page {
	case FRONT:
		return m.navModel.View() + "\n" + m.frontPageModel.View()
	case POST_LIST:
		return m.navModel.View() + m.renderer.NewStyle().Margin(1, 2).Render(m.list.View())
	case POST:
		return m.navModel.View() + "\n" + m.postModel.View()
	default:
		panic("unreachable")
	}
}

const (
	host = "localhost"
	port = "23234"
)

func initServer() {
	s, err := wish.NewServer(
		wish.WithAddress(net.JoinHostPort(host, port)),
		wish.WithHostKeyPath("./.ssh/id_rsa"),
		wish.WithMiddleware(
			bubbletea.Middleware(teaHandler),
			activeterm.Middleware(), // Bubble Tea apps usually require a PTY.
			logging.Middleware(),
		),
	)
	if err != nil {
		log.Error("Could not start server", "error", err)
	}

	done := make(chan os.Signal, 1)
	signal.Notify(done, os.Interrupt, syscall.SIGINT, syscall.SIGTERM)
	log.Info("Starting SSH server", "host", host, "port", port)
	go func() {
		if err = s.ListenAndServe(); err != nil && !errors.Is(err, ssh.ErrServerClosed) {
			log.Error("Could not start server", "error", err)
			done <- nil
		}
	}()

	<-done
	log.Info("Stopping SSH server")
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer func() { cancel() }()
	if err := s.Shutdown(ctx); err != nil && !errors.Is(err, ssh.ErrServerClosed) {
		log.Error("Could not stop server", "error", err)
	}
}

func main() {
	var isSsh bool
	flag.BoolVar(&isSsh, "ssh", false, "Start an SSH server instead of the TUI application.")

	flag.Parse()

	if isSsh {
		initServer()
	} else {
		w, h, err := term.GetSize(os.Stdout.Fd())
		if err != nil {
			panic(err)
		}

		p := tea.NewProgram(initialModel(lipgloss.DefaultRenderer(), w, h))
		if _, err := p.Run(); err != nil {
			log.Fatal(err)
		}
	}
}

// You can wire any Bubble Tea model up to the middleware with a function that
// handles the incoming ssh.Session. Here we just grab the terminal info and
// pass it to the new model. You can also return tea.ProgramOptions (such as
// tea.WithAltScreen) on a session by session basis.
func teaHandler(s ssh.Session) (tea.Model, []tea.ProgramOption) {
	// This should never fail, as we are using the activeterm middleware.
	pty, _, _ := s.Pty()

	// When running a Bubble Tea app over SSH, you shouldn't use the default
	// lipgloss.NewStyle function.
	// That function will use the color profile from the os.Stdin, which is the
	// server, not the client.
	// We provide a MakeRenderer function in the bubbletea middleware package,
	// so you can easily get the correct renderer for the current session, and
	// use it to create the styles.
	// The recommended way to use these styles is to then pass them down to
	// your Bubble Tea model.
	renderer := bubbletea.MakeRenderer(s)

	m := initialModel(renderer, pty.Window.Width, pty.Window.Height)
	return m, []tea.ProgramOption{tea.WithAltScreen()}
}