"strings"
	"text/scanner"

	"cmd/asm/internal/flags"
	"cmd/internal/objabi"
	"cmd/internal/src"
)

// Input is the main input: a stack of readers and some macro definitions.
// It also handles #include processing (by pushing onto the input stack)
// and parses and instantiates macro definitions.
type Input struct {
	Stack
	includes        []string
	beginningOfLine bool
	ifdefStack      []bool

		fmt.Fprintln(os.Stderr, "reading input:", err)
	}
	fmt.Printf("%d\n", count)
	// Output: 15
}

// Use a Scanner with a custom split function (built by wrapping ScanWords) to validate
// 32-bit decimal input.
func ExampleScanner_custom() {
	// An artificial input source.
	const input = "1234 5678 1234567901234567890"
	scanner := bufio.NewScanner(strings.NewReader(input))

	for i, test := range exprTests {
		p.start(lex.Tokenize(test.input))
		result := int64(p.expr())
		if result != test.output {
			t.Errorf("%d: %q evaluated to %d; expected %d", i, test.input, result, test.output)
		}
		tok := p.next()
		if test.atEOF && tok.ScanToken != scanner.EOF {
			t.Errorf("%d: %q: at EOF got %s", i, test.input, tok)
		} else if !test.atEOF && tok.ScanToken == scanner.EOF {

}

// SplitFunc is the signature of the split function used to tokenize the
// input. The arguments are an initial substring of the remaining unprocessed
// data and a flag, atEOF, that reports whether the [Reader] has no more data
// to give. The return values are the number of bytes to advance the input
// and the next token to return to the user, if any, plus an error, if any.
//

		[]byte("short"),
		[]byte(strings.Repeat("a", 42)),
	}
	for _, input := range cloneTests {
		clone := Clone(input)
		if !Equal(clone, input) {
			t.Errorf("Clone(%q) = %q; want %q", input, clone, input)
		}

		if input == nil && clone != nil {
			t.Errorf("Clone(%#v) return value should be equal to nil slice.", input)
		}

		if input != nil && clone == nil {

		tokenizer := lex.NewTokenizer("", strings.NewReader(test.input+"\n"), nil)
		parser := NewParser(ctxt, arch, tokenizer)

		err := tryParse(t, func() {
			parser.Parse()
		})

		switch {
		case err == nil:
			t.Errorf("#%d: %q: want error %q; have none", i, test.input, test.error)
		case !strings.Contains(err.Error(), test.error):
			t.Errorf("#%d: %q: want error %q; have %q", i, test.input, test.error, err)
		}
	}

	if flag.NArg() == 0 {
		flag.Usage()
	}

	// Flag refinement.
	if *OutputFile == "" {
		if flag.NArg() != 1 {
			flag.Usage()
		}
		input := filepath.Base(flag.Arg(0))
		input = strings.TrimSuffix(input, ".s")
		*OutputFile = fmt.Sprintf("%s.o", input)
	}

	for i := p.inputPos; i < len(p.input); i++ {
		if p.input[i].ScanToken == token {
			return true
		}
	}
	return false
}

// at reports whether the next tokens are as requested.
func (p *Parser) at(next ...lex.ScanToken) bool {
	if len(p.input)-p.inputPos < len(next) {
		return false
	}
	for i, r := range next {
		if p.input[p.inputPos+i].ScanToken != r {
			return false

		input[i] = byte(i % 251)
		if i%101 == 0 {
			input[i] ^= byte(i / 101)
		}
	}
	return input
}

func TestReaderWriteTo(t *testing.T) {
	input := createTestInput(8192)
	r := NewReader(onlyReader{bytes.NewReader(input)})
	w := new(bytes.Buffer)
	if n, err := r.WriteTo(w); err != nil || n != int64(len(input)) {
		t.Fatalf("r.WriteTo(w) = %d, %v, want %d, nil", n, err, len(input))
	}

func drain(input *Input) string {
	var buf strings.Builder
	for {
		tok := input.Next()
		if tok == scanner.EOF {
			return buf.String()
		}
		if tok == '#' {
			continue
		}
		if buf.Len() > 0 {
			buf.WriteByte('.')
		}
		buf.WriteString(input.Text())
	}
}

type badLexTest struct {
	input string
	error string
}