func CreateWatermelon(pg *playground.Playground, cxt context.Context,
) (*Watermelon, error) {
if pg == nil {
return nil, &errCreateObject{playground.ErrNilPlayground}
}
if err := cxt.Err(); err != nil {
return nil, &errCreateObject{err}
}
dots, err := pg.GetEmptyField(_WATERMELON_W, _WATERMELON_H)
if err != nil {
return nil, &errCreateObject{err}
}
wcxt, cncl := context.WithCancel(cxt)
watermelon := &Watermelon{
pg: pg,
updated: time.Now(),
cancel: cncl,
}
copy(watermelon.dots[:], dots[:_WATERMELON_AREA])
if err := pg.Locate(watermelon); err != nil {
return nil, &errCreateObject{err}
}
if err := watermelon.run(wcxt); err != nil {
pg.Delete(watermelon)
return nil, &errCreateObject{err}
}
return watermelon, nil
}
func CreateLongWall(pg *playground.Playground) (Wall, error) {
if pg == nil {
return nil, playground.ErrNilPlayground
}
var (
pgW, pgH = pg.GetSize()
err error
dots playground.DotList
)
switch playground.RandomDirection() {
case playground.DIR_NORTH, playground.DIR_SOUTH:
dots, err = pg.GetEmptyField(1, pgH)
case playground.DIR_EAST, playground.DIR_WEST:
dots, err = pg.GetEmptyField(pgW, 1)
default:
err = playground.ErrInvalidDirection
}
if err != nil {
return nil, err
}
return CreateWall(pg, dots)
}
// CreateSnake creates new snake
func CreateSnake(pg *playground.Playground, cxt context.Context,
) (*Snake, error) {
if pg == nil {
return nil, &errCreateObject{playground.ErrNilPlayground}
}
if err := cxt.Err(); err != nil {
return nil, &errCreateObject{err}
}
var (
dir = playground.RandomDirection()
dots playground.DotList
err error
)
switch dir {
case playground.DIR_NORTH, playground.DIR_SOUTH:
dots, err = pg.GetEmptyField(1, uint8(_SNAKE_START_LENGTH))
case playground.DIR_EAST, playground.DIR_WEST:
dots, err = pg.GetEmptyField(uint8(_SNAKE_START_LENGTH), 1)
}
if err != nil {
return nil, &errCreateObject{err}
}
if dir == playground.DIR_SOUTH || dir == playground.DIR_EAST {
dots = dots.Reverse()
}
// Parent context stores in snake to pass it to corpse when snake
// will be died. Snakes context are passed in run func
scxt, cncl := context.WithCancel(cxt)
snake := &Snake{pg, dots, _SNAKE_START_LENGTH, dir, time.Now(),
cxt, cncl}
if err = pg.Locate(snake); err != nil {
return nil, &errCreateObject{err}
}
if err := snake.run(scxt); err != nil {
pg.Delete(snake)
return nil, &errCreateObject{err}
}
return snake, nil
}