import unittest
from calc.lexer import tokenize, Token, LexError


def kinds(src):
    return [t.kind for t in tokenize(src)]


def pairs(src):
    return [(t.kind, t.value) for t in tokenize(src)]


class TestNumbers(unittest.TestCase):
    def test_integer(self):
        toks = tokenize("42")
        self.assertEqual(toks, [Token('NUMBER', 42), Token('EOF', None)])
        self.assertIsInstance(toks[0].value, int)

    def test_float(self):
        toks = tokenize("3.14")
        self.assertEqual(toks[0], Token('NUMBER', 3.14))
        self.assertIsInstance(toks[0].value, float)

    def test_leading_dot(self):
        toks = tokenize(".5")
        self.assertAlmostEqual(toks[0].value, 0.5)

    def test_trailing_dot(self):
        toks = tokenize("10.")
        self.assertEqual(toks[0].value, 10.0)
        self.assertIsInstance(toks[0].value, float)


class TestOperatorsAndParens(unittest.TestCase):
    def test_all_operators(self):
        self.assertEqual(kinds("+"), ['PLUS', 'EOF'])
        self.assertEqual(kinds("-"), ['MINUS', 'EOF'])
        self.assertEqual(kinds("*"), ['STAR', 'EOF'])
        self.assertEqual(kinds("/"), ['SLASH', 'EOF'])
        self.assertEqual(kinds("("), ['LPAREN', 'EOF'])
        self.assertEqual(kinds(")"), ['RPAREN', 'EOF'])

    def test_expression_1_plus_2_star_3(self):
        self.assertEqual(kinds("1+2*3"),
                         ['NUMBER', 'PLUS', 'NUMBER', 'STAR', 'NUMBER', 'EOF'])

    def test_expression_3_5_times_paren(self):
        self.assertEqual(kinds("3.5*(1-2)"),
                         ['NUMBER', 'STAR', 'LPAREN', 'NUMBER', 'MINUS', 'NUMBER', 'RPAREN', 'EOF'])


class TestWhitespaceAndErrors(unittest.TestCase):
    def test_whitespace_between_tokens(self):
        toks = tokenize("  12  +  3 ")
        self.assertEqual([(t.kind, t.value) for t in toks],
                         [('NUMBER', 12), ('PLUS', '+'), ('NUMBER', 3), ('EOF', None)])

    def test_tabs_skipped(self):
        self.assertEqual(kinds("1\t+\t2"), ['NUMBER', 'PLUS', 'NUMBER', 'EOF'])

    def test_invalid_at_raises(self):
        with self.assertRaises(LexError) as ctx:
            tokenize("1 @ 2")
        self.assertIn('@', str(ctx.exception))

    def test_invalid_dollar_raises(self):
        with self.assertRaises(LexError):
            tokenize("$")

    def test_invalid_letter_raises(self):
        with self.assertRaises(LexError):
            tokenize("x")

    def test_error_position_reported(self):
        with self.assertRaises(LexError) as ctx:
            tokenize("1 @ 2")
        self.assertIn('2', str(ctx.exception))  # position 2

    def test_complex_expression(self):
        toks = tokenize("3.5*(1-2)")
        expected = [
            ('NUMBER', 3.5), ('STAR', '*'), ('LPAREN', '('),
            ('NUMBER', 1), ('MINUS', '-'), ('NUMBER', 2),
            ('RPAREN', ')'), ('EOF', None),
        ]
        self.assertEqual([(t.kind, t.value) for t in toks], expected)


if __name__ == '__main__':
    unittest.main()