"""Tests for calc/lexer.py — covers D1, D2, D3."""
import unittest
from calc.lexer import tokenize, Token, LexError


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


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


class TestNumbers(unittest.TestCase):
    """D1 — integers and floats tokenize to NUMBER with numeric value."""

    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_standard(self):
        toks = tokenize("3.14")
        self.assertEqual(toks[0].kind, 'NUMBER')
        self.assertAlmostEqual(toks[0].value, 3.14)
        self.assertIsInstance(toks[0].value, float)

    def test_float_leading_dot(self):
        toks = tokenize(".5")
        self.assertEqual(toks[0].kind, 'NUMBER')
        self.assertAlmostEqual(toks[0].value, 0.5)
        self.assertIsInstance(toks[0].value, float)

    def test_float_trailing_dot(self):
        toks = tokenize("10.")
        self.assertEqual(toks[0].kind, 'NUMBER')
        self.assertAlmostEqual(toks[0].value, 10.0)
        self.assertIsInstance(toks[0].value, float)


class TestOperatorsAndParens(unittest.TestCase):
    """D2 — operators and parens produce correct kinds."""

    def test_plus(self):
        self.assertIn('PLUS', kinds('+'))

    def test_minus(self):
        self.assertIn('MINUS', kinds('-'))

    def test_star(self):
        self.assertIn('STAR', kinds('*'))

    def test_slash(self):
        self.assertIn('SLASH', kinds('/'))

    def test_lparen(self):
        self.assertIn('LPAREN', kinds('('))

    def test_rparen(self):
        self.assertIn('RPAREN', kinds(')'))

    def test_expression_1plus2star3(self):
        self.assertEqual(
            kinds("1+2*3"),
            ['NUMBER', 'PLUS', 'NUMBER', 'STAR', 'NUMBER', 'EOF'],
        )


class TestWhitespaceAndErrors(unittest.TestCase):
    """D3 — whitespace skipped; invalid chars raise LexError."""

    def test_whitespace_skipped(self):
        self.assertEqual(
            kinds("  12  +  3 "),
            ['NUMBER', 'PLUS', 'NUMBER', 'EOF'],
        )

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

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

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

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

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

    def test_error_includes_position(self):
        with self.assertRaises(LexError) as ctx:
            tokenize("1 @ 2")
        # position 2 (0-indexed) is where '@' lives
        self.assertIn('2', str(ctx.exception))


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