package main

import (
	"errors"
	"time"

	termbox "github.com/nsf/termbox-go"
)

type Screen interface {
	handleKeyEvent(termbox.Event) int
	initialize(Bundle) error
	drawScreen()
}

const (
	ScreenMain = iota
	ScreenAbout
	ScreenExit

	DefaultBg = termbox.ColorBlack
	DefaultFg = termbox.ColorWhite
	TitleFg   = termbox.ColorWhite
	TitleBg   = termbox.ColorBlue
	CursorFg  = termbox.ColorBlack
	CursorBg  = termbox.ColorGreen
)

func (a *AppState) BuildScreens() {
	mainScreen := MainScreen{}
	aboutScreen := AboutScreen{}
	a.screens = append(a.screens, &mainScreen)
	a.screens = append(a.screens, &aboutScreen)
}

func (a *AppState) drawBackground(bg termbox.Attribute) {
	termbox.Clear(0, bg)
}

func (a *AppState) layoutAndDrawScreen(s Screen) {
	a.drawBackground(DefaultBg)
	s.drawScreen()
	termbox.Flush()
}

func readUserInput(e chan termbox.Event) {
	for {
		e <- termbox.PollEvent()
	}
}

func checkForUpdate(e chan termbox.Event) {
	for {
		time.Sleep(time.Minute)
		// Check if the on-disk tasklist has changed
		//app.LoadTasklist()
		//app.LoadDoneList()
		if false {
			e <- termbox.Event{
				Type: termbox.EventError,
				Err:  errors.New("List changed elsewhere"),
			}
		}
	}
}

/*
 * ViewPort helps keep track of what's being displayed on the screen
 */
type ViewPort struct {
	bytesPerRow  int
	numberOfRows int
	firstRow     int
}