package ui

import (
	"fmt"

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

type (
	boardMovement int
	boardMode     int
)

const (
	next boardMovement = iota
	previous
)

const (
	normal boardMode = iota
	selection
)

const (
	mainPage       string = "main"
	quitPage       string = "quit"
	addPage        string = "add"
	deleteCardPage string = "delete card"
)

type UI struct {
	*tview.Application

	columns         []*column
	flex            *tview.Flex
	pages           *tview.Pages
	focusedColumn   int
	board           board.Board
	mode            boardMode
	quitModal       *tview.Modal
	addModal        *modalInput
	deleteCardModal *tview.Modal
	statusSelection statusSelection
}

// NewUI returns a new UI value.
func NewUI(path string) (UI, error) {
	kanban, err := board.Open(path)
	if err != nil {
		return UI{}, fmt.Errorf("unable to open the project's board; %w", err)
	}

	userInterface := UI{
		Application:     tview.NewApplication(),
		pages:           tview.NewPages(),
		flex:            tview.NewFlex(),
		quitModal:       tview.NewModal(),
		addModal:        NewModalInput(),
		focusedColumn:   0,
		columns:         nil,
		board:           kanban,
		deleteCardModal: tview.NewModal(),
		mode:            normal,
		statusSelection: statusSelection{0, 0, 0},
	}

	if err := userInterface.init(); err != nil {
		return UI{}, fmt.Errorf("received an error after running the initialisation; %w", err)
	}

	return userInterface, nil
}

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

// init initialises the UI.
func (u *UI) init() error {
	err := u.initColumns()
	if err != nil {
		return fmt.Errorf("error initialising the status columns; %w", err)
	}

	u.flex.SetInputCapture(func(event *tcell.EventKey) *tcell.EventKey {
		key, letter := event.Key(), event.Rune()

		switch {
		case letter == 'h' || key == tcell.KeyLeft:
			u.shiftColumnFocus(previous)
		case letter == 'l' || key == tcell.KeyRight:
			u.shiftColumnFocus(next)
		case letter == 'a':
			if u.mode == normal {
				u.pages.ShowPage(addPage)
				u.SetFocus(u.addModal)
			}
		case letter == 'm':
			if u.mode == normal {
				focusedCard := u.columns[u.focusedColumn].focusedCard
				u.statusSelection.cardID = u.columns[u.focusedColumn].cards[focusedCard].id
				u.statusSelection.currentStatusID = u.columns[u.focusedColumn].statusID
				u.mode = selection
			}
		case key == tcell.KeyCtrlD:
			if u.mode == normal {
				u.pages.ShowPage(deleteCardPage)
				u.SetFocus(u.deleteCardModal)
			}
		case key == tcell.KeyCtrlQ:
			if u.mode == normal {
				u.pages.ShowPage(quitPage)
				u.SetFocus(u.quitModal)
			}
		case key == tcell.KeyESC:
			if u.mode != normal {
				u.mode = normal
			}
		case key == tcell.KeyEnter:
			if u.mode == selection {
				u.statusSelection.nextStatusID = u.columns[u.focusedColumn].statusID
				if u.statusSelection.currentStatusID != u.statusSelection.nextStatusID {
					u.statusSelection.moveCard(u.board)
				}
				u.statusSelection = statusSelection{0, 0, 0}
				u.mode = normal
				_ = u.refresh(false)
			}
		}

		return event
	})

	u.pages.AddPage(mainPage, u.flex, true, true)

	u.initQuitModal()
	u.pages.AddPage(quitPage, u.quitModal, false, false)

	u.initAddInputModal()
	u.pages.AddPage(addPage, u.addModal, false, false)

	u.initDeleteCardModal()
	u.pages.AddPage(deleteCardPage, u.deleteCardModal, false, false)

	u.SetRoot(u.pages, true)

	if err := u.refresh(false); err != nil {
		return fmt.Errorf("error refreshing the board; %w", err)
	}

	return nil
}

// initAddInputModal initialises the add input modal.
func (u *UI) initAddInputModal() {
	doneFunc := func(text string, success bool) {
		if success {
			_ = u.newCard(text, "")
		}

		u.pages.HidePage(addPage)
		u.setColumnFocus()
	}

	u.addModal.SetDoneFunc(doneFunc)
}

// initDeleteCardModal initialises the modal for deleting cards.
func (u *UI) initDeleteCardModal() {
	doneFunc := func(_ int, buttonLabel string) {
		if buttonLabel == "Confirm" {
			u.deleteCard()
			_ = u.refresh(true)
		}

		u.pages.HidePage(deleteCardPage)
		u.setColumnFocus()
	}

	u.deleteCardModal.SetText("Do you want to delete this card?").
		AddButtons([]string{"Confirm", "Cancel"}).
		SetDoneFunc(doneFunc)
}

// deleteCard deletes a card from the board.
func (u *UI) deleteCard() {
	statusID := u.columns[u.focusedColumn].statusID
	focusedCard := u.columns[u.focusedColumn].focusedCard
	cardID := u.columns[u.focusedColumn].cards[focusedCard].id

	args := board.DeleteCardArgs{
		CardID:   cardID,
		StatusID: statusID,
	}

	_ = u.board.DeleteCard(args)
}

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

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

// newCard creates and saves a new card 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(false)

	return nil
}

func (u *UI) initColumns() error {
	u.flex.Clear()

	statusList, err := u.board.StatusList()
	if err != nil {
		return fmt.Errorf("unable to retrieve the list of statuses; %w", err)
	}

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

	for i := range statusList {
		column := newColumn(statusList[i].ID, statusList[i].Name, u.boardMode)
		u.flex.AddItem(column, 50, 1, true)
		columns[i] = column
	}

	u.columns = columns

	return nil
}

func (u *UI) updateAllColumns() error {
	for i := range u.columns {
		if err := u.updateColumn(i); err != nil {
			return err
		}
	}

	return nil
}

func (u *UI) updateColumn(index int) error {
	if err := u.columns[index].update(u.board); err != nil {
		return fmt.Errorf("unable to update column; %w", err)
	}

	return nil
}

func (u *UI) shiftColumnFocus(movement boardMovement) {
	switch movement {
	case next:
		if u.focusedColumn == len(u.columns)-1 {
			u.focusedColumn = 0
		} else {
			u.focusedColumn++
		}
	case previous:
		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])
}

// refresh refreshes the UI.
func (u *UI) refresh(updateFocusedColumnOnly bool) error {
	if updateFocusedColumnOnly {
		if err := u.updateColumn(u.focusedColumn); err != nil {
			return err
		}
	} else {
		if err := u.updateAllColumns(); err != nil {
			return err
		}
	}

	u.setColumnFocus()

	return nil
}

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

func (u *UI) boardMode() boardMode {
	return u.mode
}