package tui

import (
	"errors"
	"fmt"

	"git.tordarus.net/Tordarus/buf2d"
	"github.com/gdamore/tcell"
)

type Screen struct {
	scr    tcell.Screen
	buf    *ViewBuffer
	stopCh chan error
	Root   View

	// KeyPressed is called every time a key or key-combination is pressed.
	KeyPressed func(event *KeyEvent) (consumed bool)
}

func NewScreen(root View) (*Screen, error) {
	scr, err := tcell.NewScreen()
	if err != nil {
		return nil, err
	}

	s := &Screen{
		Root:   root,
		scr:    scr,
		stopCh: make(chan error, 1),
	}

	go s.eventloop()

	return s, nil
}

func (s *Screen) eventloop() {
	for evt := s.scr.PollEvent(); evt != nil; evt = s.scr.PollEvent() {
		switch event := evt.(type) {
		case *tcell.EventResize:
			go s.Redraw()
		case *tcell.EventKey:
			go s.onKeyPressed(event)
		default:
			s.StopWithError(errors.New(fmt.Sprintf("%#v", event)))
		}
	}
	s.StopWithError(errors.New("unknown error occured"))
}

func (s *Screen) Start() error {
	err := s.scr.Init()
	if err != nil {
		return err
	}
	defer s.scr.Fini()

	s.Redraw()
	return <-s.stopCh
}

func (s *Screen) Stop() {
	s.StopWithError(nil)
}

func (s *Screen) StopWithError(err error) {
	s.stopCh <- err
}

func (s *Screen) onKeyPressed(event *KeyEvent) {
	if s.KeyPressed == nil || !s.KeyPressed(event) {
		s.Root.OnKeyPressed(event)
	}
	s.Redraw()
}

func (s *Screen) Redraw() {
	w, h := s.scr.Size()

	if s.buf == nil || s.buf.Width() != w || s.buf.Height() != h {
		s.buf = buf2d.NewBuffer(w, h, DefaultRune)
	}

	rw, rh := s.Root.Layout()
	s.Root.Draw(truncateBuffer(s.buf, rw, rh))
	drawBuffer(s.scr, s.buf)
}