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(len(toks), 2)
        self.assertEqual(toks[0].kind, 'NUMBER')
        self.assertEqual(toks[0].value, 42)
        self.assertIsInstance(toks[0].value, int)
        self.assertEqual(toks[1].kind, 'EOF')

    def test_float(self):
        t = tokenize("3.14")[0]
        self.assertEqual(t.kind, 'NUMBER')
        self.assertAlmostEqual(t.value, 3.14)
        self.assertIsInstance(t.value, float)

    def test_float_leading_dot(self):
        t = tokenize(".5")[0]
        self.assertEqual(t.kind, 'NUMBER')
        self.assertAlmostEqual(t.value, 0.5)

    def test_float_trailing_dot(self):
        t = tokenize("10.")[0]
        self.assertEqual(t.kind, 'NUMBER')
        self.assertAlmostEqual(t.value, 10.0)
        self.assertIsInstance(t.value, float)


class TestOperatorsAndParens(unittest.TestCase):
    def test_single_ops(self):
        for ch, kind in [('+', 'PLUS'), ('-', 'MINUS'), ('*', 'STAR'), ('/', 'SLASH'),
                         ('(', 'LPAREN'), (')', 'RPAREN')]:
            with self.subTest(ch=ch):
                toks = tokenize(ch)
                self.assertEqual(toks[0].kind, kind)
                self.assertEqual(toks[1].kind, 'EOF')

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

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


class TestWhitespaceAndErrors(unittest.TestCase):
    def test_whitespace(self):
        toks = tokenize("  12  +  3 ")
        self.assertEqual(kinds("  12  +  3 "), ['NUMBER', 'PLUS', 'NUMBER', 'EOF'])
        self.assertEqual(toks[0].value, 12)
        self.assertEqual(toks[2].value, 3)

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

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

    def test_invalid_letter(self):
        with self.assertRaises(LexError):
            tokenize("abc")

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

    def test_position_in_message(self):
        try:
            tokenize("1 @ 2")
        except LexError as e:
            msg = str(e)
            self.assertIn('@', msg)
            self.assertIn('2', msg)


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