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


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


class TestD1Precedence(unittest.TestCase):
    def test_add_mul(self):
        # 1+2*3  =>  BinOp('+', Num(1), BinOp('*', Num(2), Num(3)))
        result = p("1+2*3")
        self.assertEqual(result, BinOp('+', Num(1), BinOp('*', Num(2), Num(3))))

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

    def test_sub_div(self):
        # 10-4/2  =>  BinOp('-', Num(10), BinOp('/', Num(4), Num(2)))
        result = p("10-4/2")
        self.assertEqual(result, BinOp('-', Num(10), BinOp('/', Num(4), Num(2))))


class TestD2LeftAssociativity(unittest.TestCase):
    def test_sub_left(self):
        # 8-3-2  =>  BinOp('-', BinOp('-', Num(8), Num(3)), Num(2))
        result = p("8-3-2")
        self.assertEqual(result, BinOp('-', BinOp('-', Num(8), Num(3)), Num(2)))

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

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

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


class TestD3Parentheses(unittest.TestCase):
    def test_paren_overrides_precedence(self):
        # (1+2)*3  =>  BinOp('*', BinOp('+', Num(1), Num(2)), Num(3))
        result = p("(1+2)*3")
        self.assertEqual(result, BinOp('*', BinOp('+', Num(1), Num(2)), Num(3)))

    def test_nested_parens(self):
        # ((2+3))  =>  BinOp('+', Num(2), Num(3))
        result = p("((2+3))")
        self.assertEqual(result, BinOp('+', Num(2), Num(3)))

    def test_paren_in_sub(self):
        # 10-(2+3)  =>  BinOp('-', Num(10), BinOp('+', Num(2), Num(3)))
        result = p("10-(2+3)")
        self.assertEqual(result, BinOp('-', Num(10), BinOp('+', Num(2), Num(3))))


class TestD4UnaryMinus(unittest.TestCase):
    def test_simple_unary(self):
        # -5  =>  Unary('-', Num(5))
        result = p("-5")
        self.assertEqual(result, Unary('-', Num(5)))

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

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

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


class TestD5Errors(unittest.TestCase):
    def _raises(self, src):
        with self.assertRaises(ParseError):
            p(src)

    def test_trailing_operator(self):
        self._raises("1 +")

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

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

    def test_close_before_open(self):
        self._raises(")(")

    def test_empty_string(self):
        self._raises("")


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