"""Unit tests for calc.lexer — covers D1–D3."""

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


def kinds(src: str) -> list[str]:
    return [t.kind for t in tokenize(src)]


def values(src: str) -> list:
    return [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_standard(self):
        toks = tokenize("3.14")
        self.assertEqual(len(toks), 2)
        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)

    def test_zero(self):
        toks = tokenize("0")
        self.assertEqual(toks[0], Token("NUMBER", 0))


class TestOperatorsAndParens(unittest.TestCase):
    def test_plus(self):
        self.assertIn("PLUS", kinds("1+2"))

    def test_minus(self):
        self.assertIn("MINUS", kinds("1-2"))

    def test_star(self):
        self.assertIn("STAR", kinds("1*2"))

    def test_slash(self):
        self.assertIn("SLASH", kinds("1/2"))

    def test_lparen(self):
        self.assertIn("LPAREN", kinds("(1)"))

    def test_rparen(self):
        self.assertIn("RPAREN", kinds("(1)"))

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

    def test_eof_always_last(self):
        for src in ["", "1", "1+2", "()"]:
            self.assertEqual(tokenize(src)[-1].kind, "EOF")


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

    def test_tabs_skipped(self):
        self.assertEqual(kinds("\t1\t+\t2\t"), ["NUMBER", "PLUS", "NUMBER", "EOF"])

    def test_complex_expr(self):
        self.assertEqual(
            kinds("3.5*(1-2)"),
            ["NUMBER", "STAR", "LPAREN", "NUMBER", "MINUS", "NUMBER", "RPAREN", "EOF"],
        )
        toks = tokenize("3.5*(1-2)")
        self.assertAlmostEqual(toks[0].value, 3.5)
        self.assertEqual(toks[3].value, 1)
        self.assertEqual(toks[5].value, 2)

    def test_invalid_at_raises(self):
        with self.assertRaises(LexError):
            tokenize("1 @ 2")

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

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

    def test_lex_error_message_contains_char(self):
        try:
            tokenize("1 @ 2")
            self.fail("LexError not raised")
        except LexError as e:
            self.assertIn("@", str(e))

    def test_lex_error_message_contains_position(self):
        try:
            tokenize("1 @ 2")
            self.fail("LexError not raised")
        except LexError as e:
            self.assertIn("2", str(e))


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