package ui

import (
	"fmt"

	"codeflow.dananglin.me.uk/apollo/canal/internal/board"
	"github.com/rivo/tview"
	"github.com/gdamore/tcell/v2"
)

const (
	shiftLeft int = iota
	shiftRight
)

const (
	mainPageName string = "main"
	quitPageName string = "quit"
	addPageName  string = "add"
)

// UI does some magical stuff.
type UI struct {
	*tview.Application

	columns       []column
	flex          *tview.Flex
	pages         *tview.Pages
	focusedColumn int
	board         board.Board
	quit          *tview.Modal
}

// NewUI returns a new UI value.
func NewUI() UI {
	u := UI{
		Application:   tview.NewApplication(),
		pages:         tview.NewPages(),
		flex:          tview.NewFlex(),
		quit:          tview.NewModal(),
		focusedColumn: 0,
	}

	u.initialise()

	return u
}

// initialise the UI.
func (u *UI) initialise() {
	u.pages.AddPage(mainPageName, u.flex, true, true)

	u.initQuitModal()
	u.pages.AddPage(quitPageName, u.quit, false, false)

	u.SetInputCapture(func(event *tcell.EventKey) *tcell.EventKey {
		if event.Rune() == 'q' {
			u.pages.ShowPage(quitPageName)
			u.SetFocus(u.quit)
		} else if event.Rune() == 'o' {
			u.openBoard("")
		}

		return event
	})

	u.SetRoot(u.pages, true)
}

// initQuitModal initialises the quit modal.
func (u *UI) initQuitModal() {
	quitDoneFunc := func(_ int, buttonLabel string) {
		switch buttonLabel {
		case "Quit":
			u.shutdown()
		default:
			u.pages.SwitchToPage("main")
			u.setColumnFocus()
		}
	}

	u.quit.SetText("Do you want to quit the application?").
		AddButtons([]string{"Quit", "Cancel"}).
		SetDoneFunc(quitDoneFunc)
}

// shutdown shuts down the application.
func (u *UI) shutdown() {
	u.closeBoard()
	u.Stop()
}

// closeBoard closes the BoltDB database.
func (u *UI) closeBoard() {
	_ = u.board.Close()
}

// openBoard opens the kanban project.
func (u *UI) openBoard(path string) error {
	b, err := board.Open(path)
	if err != nil {
		return fmt.Errorf("unable to load board, %w", err)
	}

	u.board = b

	if err = u.refresh(); err != nil {
		return err
	}

	return nil
}

// refresh refreshes the UI.
func (u *UI) refresh() error {
	statusList, err := u.board.StatusList()
	if err != nil {
		return fmt.Errorf("unable to get the status list, %w", err)
	}

	u.updateBoard(statusList)

	u.setColumnFocus()

	return nil
}

func (u *UI) updateBoard(statusList []board.Status) error {
	u.flex.Clear()

	columns := make([]column, len(statusList))

	for i := range statusList {
		columns[i] = u.newColumn(statusList[i].ID, statusList[i].Name)

		if len(statusList[i].CardIds) > 0 {
			cards, err := u.board.CardList(statusList[i].CardIds)
			if err != nil {
				return fmt.Errorf("unable to get the card list. %w", err)
			}

			for _, c := range cards {
				columns[i].cards.AddItem(fmt.Sprintf("[%d] %s", c.Id(), c.Title), "", 0, nil)
			}
		}

		u.flex.AddItem(columns[i].cards, 0, 1, false)
	}

	u.columns = columns

	return nil
}

func (u *UI) shiftColumnFocus(s int) {
	switch s {
	case shiftRight:
		if u.focusedColumn == len(u.columns)-1 {
			u.focusedColumn = 0
		} else {
			u.focusedColumn++
		}
	case shiftLeft:
		if u.focusedColumn == 0 {
			u.focusedColumn = len(u.columns) - 1
		} else {
			u.focusedColumn--
		}
	}

	u.setColumnFocus()
}

func (u *UI) setColumnFocus() {
	u.SetFocus(u.columns[u.focusedColumn].cards)
}

// newCard creates a new card and saves it to the database.
func (u *UI) newCard(title, content string) error {
	args := board.CardArgs{
		NewTitle:   title,
		NewContent: content,
	}

	if err := u.board.CreateCard(args); err != nil {
		return fmt.Errorf("unable to create card, %w", err)
	}

	u.refresh()

	return nil
}

// TODO: Move 'Add' to the centre of the app
// TODO: Customize list primitive or create a new one
// TODO: If customizing existing list primitive, wrap list around a column type. Add statusID to it.
// TODO: Update card status (card ID, oldStatus, newStatus)

//func viewCard() error {
//return nil
//}