import unittest
from calc.lexer import tokenize
from calc.parser import parse, ParseError, Num, BinOp, Unary


def p(src):
    return parse(tokenize(src))


class TestPrecedence(unittest.TestCase):
    def test_add_then_mul(self):
        # 1+2*3 => BinOp('+', Num(1), BinOp('*', Num(2), Num(3)))
        self.assertEqual(p('1+2*3'), BinOp('+', Num(1), BinOp('*', Num(2), Num(3))))

    def test_mul_then_add(self):
        # 2*3+1 => BinOp('+', BinOp('*', Num(2), Num(3)), Num(1))
        self.assertEqual(p('2*3+1'), BinOp('+', BinOp('*', Num(2), Num(3)), Num(1)))

    def test_add_then_div(self):
        # 6+10/2 => BinOp('+', Num(6), BinOp('/', Num(10), Num(2)))
        self.assertEqual(p('6+10/2'), BinOp('+', Num(6), BinOp('/', Num(10), Num(2))))

    def test_sub_then_mul(self):
        # 5-2*3 => BinOp('-', Num(5), BinOp('*', Num(2), Num(3)))
        self.assertEqual(p('5-2*3'), BinOp('-', Num(5), BinOp('*', Num(2), Num(3))))


class TestLeftAssociativity(unittest.TestCase):
    def test_subtraction(self):
        # 8-3-2 => BinOp('-', BinOp('-', Num(8), Num(3)), Num(2))
        self.assertEqual(p('8-3-2'), BinOp('-', BinOp('-', Num(8), Num(3)), Num(2)))

    def test_division(self):
        # 8/4/2 => BinOp('/', BinOp('/', Num(8), Num(4)), Num(2))
        self.assertEqual(p('8/4/2'), BinOp('/', BinOp('/', Num(8), Num(4)), Num(2)))

    def test_addition(self):
        # 1+2+3 => BinOp('+', BinOp('+', Num(1), Num(2)), Num(3))
        self.assertEqual(p('1+2+3'), BinOp('+', BinOp('+', Num(1), Num(2)), Num(3)))

    def test_multiplication(self):
        # 2*3*4 => BinOp('*', BinOp('*', Num(2), Num(3)), Num(4))
        self.assertEqual(p('2*3*4'), BinOp('*', BinOp('*', Num(2), Num(3)), Num(4)))


class TestParentheses(unittest.TestCase):
    def test_parens_override_precedence(self):
        # (1+2)*3 => BinOp('*', BinOp('+', Num(1), Num(2)), Num(3))
        self.assertEqual(p('(1+2)*3'), BinOp('*', BinOp('+', Num(1), Num(2)), Num(3)))

    def test_parens_right(self):
        # 1*(2+3) => BinOp('*', Num(1), BinOp('+', Num(2), Num(3)))
        self.assertEqual(p('1*(2+3)'), BinOp('*', Num(1), BinOp('+', Num(2), Num(3))))

    def test_nested_parens(self):
        # ((4)) => Num(4)
        self.assertEqual(p('((4))'), Num(4))

    def test_parens_with_sub_vs_mul(self):
        # 3*(4-1) => BinOp('*', Num(3), BinOp('-', Num(4), Num(1)))
        self.assertEqual(p('3*(4-1)'), BinOp('*', Num(3), BinOp('-', Num(4), Num(1))))


class TestUnaryMinus(unittest.TestCase):
    def test_simple_unary(self):
        # -5 => Unary('-', Num(5))
        self.assertEqual(p('-5'), Unary('-', Num(5)))

    def test_unary_parens(self):
        # -(1+2) => Unary('-', BinOp('+', Num(1), Num(2)))
        self.assertEqual(p('-(1+2)'), Unary('-', BinOp('+', Num(1), Num(2))))

    def test_mul_unary(self):
        # 3 * -2 => BinOp('*', Num(3), Unary('-', Num(2)))
        self.assertEqual(p('3 * -2'), BinOp('*', Num(3), Unary('-', Num(2))))

    def test_double_unary(self):
        # --5 => Unary('-', Unary('-', Num(5)))
        self.assertEqual(p('--5'), Unary('-', Unary('-', Num(5))))

    def test_unary_in_add(self):
        # 1 + -2 => BinOp('+', Num(1), Unary('-', Num(2)))
        self.assertEqual(p('1 + -2'), BinOp('+', Num(1), Unary('-', Num(2))))


class TestErrors(unittest.TestCase):
    def _raises(self, src):
        with self.assertRaises(ParseError):
            p(src)

    def test_trailing_op(self):
        self._raises('1 +')

    def test_unclosed_paren(self):
        self._raises('(1')

    def test_two_numbers(self):
        self._raises('1 2')

    def test_close_then_open(self):
        self._raises(')(')

    def test_empty(self):
        self._raises('')

    def test_op_only(self):
        self._raises('*')

    def test_mismatched_parens(self):
        self._raises('(1+2')


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