package ui

import (
	"fmt"

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

type (
	boardMovement int
	boardMode     string
)

const (
	next boardMovement = iota
	previous
)

const (
	mainPage            string = "main"
	quitPage            string = "quit"
	cardFormPage        string = "card form"
	deleteCardModalPage string = "delete card modal"
	viewPage            string = "view"
	statusFormPage      string = "status form"
)

const (
	normal    boardMode = "NORMAL"
	selection boardMode = "SELECTION"
	boardEdit boardMode = "BOARD EDIT"
)

type App struct {
	*tview.Application

	columns         []*column
	grid            *tview.Grid
	columnFlex      *tview.Flex
	pages           *tview.Pages
	focusedColumn   int
	board           board.Board
	mode            boardMode
	modeView        *modeView
	quitModal       *tview.Modal
	cardForm        *cardForm
	deleteCardModal *tview.Modal
	statusSelection statusSelection
	cardView        *cardView
	statusbar       *statusbar
	statusForm      *statusForm
}

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

	app := App{
		Application:     tview.NewApplication(),
		pages:           tview.NewPages(),
		grid:            tview.NewGrid(),
		columnFlex:      tview.NewFlex(),
		quitModal:       tview.NewModal(),
		cardForm:        newCardForm(),
		focusedColumn:   0,
		columns:         nil,
		board:           kanban,
		deleteCardModal: tview.NewModal(),
		mode:            normal,
		modeView:        newModeView(),
		statusSelection: statusSelection{0, 0, 0},
		cardView:        newCardView(),
		statusbar:       newStatusbar(),
		statusForm:      newStatusForm(),
	}

	return app, nil
}

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

	a.columnFlex.SetInputCapture(a.inputCapture())

	a.initStatusbar()

	a.modeView.update(a.mode)

	a.grid.SetColumns(10, 0).SetRows(0, 1).SetBorders(false)
	a.grid.AddItem(a.columnFlex, 0, 0, 1, 2, 0, 0, true)
	a.grid.AddItem(a.modeView, 1, 0, 1, 1, 0, 0, false)
	a.grid.AddItem(a.statusbar, 1, 1, 1, 1, 0, 0, false)

	a.pages.AddPage(mainPage, a.grid, true, true)

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

	a.initCardForm()
	a.pages.AddPage(cardFormPage, a.cardForm, false, false)

	a.initDeleteCardModal()
	a.pages.AddPage(deleteCardModalPage, a.deleteCardModal, false, false)

	a.initCardView()
	a.pages.AddPage(viewPage, a.cardView, false, false)

	a.initStatusForm()
	a.pages.AddPage(statusFormPage, a.statusForm, false, false)

	a.SetRoot(a.pages, true)

	a.refresh(false)

	return nil
}

// saveCard saves a new card to the database.
func (a *App) saveCard(title, description string) {
	args := board.CardArgs{
		NewTitle:       title,
		NewDescription: description,
	}

	_, err := a.board.CreateCard(args)
	if err != nil {
		a.statusbar.displayMessage(errorLevel, fmt.Sprintf("Failed to create card: %v.", err))

		return
	}

	a.statusbar.displayMessage(infoLevel, "Card created successfully.")

	a.refresh(false)
}

// editFocusedCard saves an edited card to the database.
func (a *App) editFocusedCard(title, description string) {
	cardID := a.focusedCardID()

	args := board.UpdateCardArgs{
		CardID: cardID,
		CardArgs: board.CardArgs{
			NewTitle:       title,
			NewDescription: description,
		},
	}

	if err := a.board.UpdateCard(args); err != nil {
		a.statusbar.displayMessage(errorLevel, fmt.Sprintf("Failed to edit card: %v.", err))

		return
	}

	a.statusbar.displayMessage(infoLevel, "Card edited successfully.")

	a.refresh(true)
}

// getFocusedCard retrieves the details of the card in focus.
func (a *App) getFocusedCard() (board.Card, bool) {
	cardID := a.focusedCardID()

	card, err := a.board.Card(cardID)
	if err != nil {
		a.statusbar.displayMessage(
			errorLevel,
			fmt.Sprintf("Failed to retrieve the card with card ID %d, %v.", cardID, err),
		)

		return card, false
	}

	return card, true
}

// deleteFocusedCard deletes the card in focus from the board.
func (a *App) deleteFocusedCard() {
	args := board.DeleteCardArgs{
		CardID:   a.focusedCardID(),
		StatusID: a.focusedStatusID(),
	}

	if err := a.board.DeleteCard(args); err != nil {
		a.statusbar.displayMessage(errorLevel, fmt.Sprintf("Failed to delete card: %v.", err))

		return
	}

	a.statusbar.displayMessage(infoLevel, "Card deleted successfully.")
}

// updateAllColumns ensures that all columns are up-to-date.
func (a *App) updateAllColumns() error {
	for i := range a.columns {
		if err := a.updateColumn(i); err != nil {
			return err
		}
	}

	return nil
}

// updateColumn ensures that the column is up-to-date.
func (a *App) updateColumn(index int) error {
	if err := a.columns[index].update(a.board); err != nil {
		return fmt.Errorf("unable to update column; %w", err)
	}

	return nil
}

// shiftColumnFocus shifts the focus to the column to the left or right depending
// on the movement set by the user.
func (a *App) shiftColumnFocus(movement boardMovement) {
	switch movement {
	case next:
		if a.focusedColumn == len(a.columns)-1 {
			a.focusedColumn = 0
		} else {
			a.focusedColumn++
		}
	case previous:
		if a.focusedColumn == 0 {
			a.focusedColumn = len(a.columns) - 1
		} else {
			a.focusedColumn--
		}
	}

	a.setColumnFocus()
}

// setColumnFocus sets the focus to the column primitive as specified by focusedColumn.
func (a *App) setColumnFocus() {
	a.SetFocus(a.columns[a.focusedColumn])
}

// refresh refreshes the UI.
func (a *App) refresh(updateFocusedColumnOnly bool) {
	if updateFocusedColumnOnly {
		if err := a.updateColumn(a.focusedColumn); err != nil {
			a.statusbar.displayMessage(
				errorLevel,
				fmt.Sprintf("Failed to update status column %q: %v", a.focusedStatusName(), err),
			)

			return
		}
	} else {
		if err := a.updateAllColumns(); err != nil {
			a.statusbar.displayMessage(
				errorLevel,
				fmt.Sprintf("Failed to update status columns: %v", err),
			)

			return
		}
	}

	a.setColumnFocus()
}

// shutdown shuts down the application.
func (a *App) shutdown() {
	a.closeBoard()
	a.Stop()
}

// boardMode returns the current board mode.
func (a *App) boardMode() boardMode {
	return a.mode
}

// updateBoardMode updates the board mode.
func (a *App) updateBoardMode(mode boardMode) {
	a.mode = mode
	a.modeView.update(mode)
}

// focusedCardID returns the ID of the card in focus.
func (a *App) focusedCardID() int {
	focusedCard := a.columns[a.focusedColumn].focusedCard
	id := a.columns[a.focusedColumn].cards[focusedCard].id

	return id
}

// focusedStatusID returns the ID of the status (column) in focus.
func (a *App) focusedStatusID() int {
	return a.columns[a.focusedColumn].statusID
}

// focusedStatusName returns the name of the status (column) in focus.
func (a *App) focusedStatusName() string {
	return a.columns[a.focusedColumn].statusName
}

// closeBoard closes the board.
func (a *App) closeBoard() {
	_ = a.board.Close()
}

// editFocusedStatusColumn updates the status column in focus and saves the changes to the database.
func (a *App) editFocusedStatusColumn(newName string) {
	statusID := a.focusedStatusID()

	args := board.UpdateStatusArgs{
		StatusID: statusID,
		StatusArgs: board.StatusArgs{
			Name: newName,
		},
	}

	if err := a.board.UpdateStatus(args); err != nil {
		a.statusbar.displayMessage(errorLevel, fmt.Sprintf("Failed to edit status: %v.", err))

		return
	}

	a.statusbar.displayMessage(infoLevel, "Status updated successfully.")

	a.refresh(true)
}