// FetchWebSudoku scrapes a sudoku puzzle from websudoku.com.
// A Sudoku is returned on success, nil otherwise.
func FetchWebSudoku(level, id int) *common.Sudoku {
resp, err := http.PostForm(webSudokuEndpoint,
url.Values{"level": {strconv.Itoa(level)}, "set_id": {strconv.Itoa(id)}})
if err != nil {
return nil
}
defer resp.Body.Close()
parsed, perr := html.Parse(resp.Body)
if perr != nil {
return nil
}
cheat, editMask := scrapeCheatAndEditMask(parsed)
if cheat == nil || editMask == nil {
return nil
}
if len(*cheat) != 81 || len(*editMask) != 81 {
return nil
}
sudoku := common.NewSudoku(3)
for i := 0; i < 81; i++ {
if (*editMask)[i] == '0' {
sudoku.Values[i/9][i%9] = int((*cheat)[i]) - int('0')
}
}
return sudoku
}
// Next deserializes and returns the next puzzle in the stream.
// On success, a Sudoku is returned without an error. On failure,
// an error is returned without a Sudoku and all subsequent calls
// return the same error. If the Reader has reached the end of the
// stream, Next returns nil, nil.
func (r *Reader) Next() (*common.Sudoku, error) {
// once a terminal state is reached, subsequent calls return the terminal state
if r.termOk {
return nil, nil
}
if r.termErr != nil {
return nil, r.termErr
}
// attempt to read the next puzzle
r.curSudoku = nil
r.curSudokuRow = 0
eof, size, err := r.scanSize()
if eof {
r.termOk = true
return nil, nil
}
if err != nil {
r.termErr = err
return nil, err
}
r.curSudoku = common.NewSudoku(uint8(size))
for s := r.curSudoku.Size * r.curSudoku.Size; s > 0; s-- {
eof, err := r.scanRow()
if eof {
r.termOk = true
return nil, nil
}
if err != nil {
r.termErr = err
return nil, err
}
}
return r.curSudoku, nil
}