import itertools

import numpy as np

import unittest
from numba.core.compiler import compile_isolated, Flags
from numba import typeof, njit
from numba.core import types, lowering
from numba.tests.support import TestCase


def return_double_or_none(x):
    if x:
        ret = None
    else:
        ret = 1.2
    return ret


def return_different_statement(x):
    if x:
        return None
    else:
        return 1.2


def return_bool_optional_or_none(x, y):
    if y:
        z = False
    else:
        z = None
    if x == 2:
        # A boolean
        return True
    elif x == 1:
        # A runtime optional
        return z
    else:
        # None
        return None


def is_this_a_none(x):
    if x:
        val_or_none = None
    else:
        val_or_none = x

    if val_or_none is None:
        return x - 1

    if val_or_none is not None:
        return x + 1


def a_is_b(a, b):
    """
    Note in nopython mode, this operation does not make much sense.
    Because we don't have objects anymore.
    `a is b` is always False if not operating on None and Optional type
    """
    return a is b


def a_is_not_b(a, b):
    """
    This is `not (a is b)`
    """
    return a is not b


class TestOptional(TestCase):

    _numba_parallel_test_ = False

    def test_return_double_or_none(self):
        pyfunc = return_double_or_none
        cres = compile_isolated(pyfunc, [types.boolean])
        cfunc = cres.entry_point

        for v in [True, False]:
            self.assertPreciseEqual(pyfunc(v), cfunc(v))

    def test_return_different_statement(self):
        pyfunc = return_different_statement
        cres = compile_isolated(pyfunc, [types.boolean])
        cfunc = cres.entry_point

        for v in [True, False]:
            self.assertPreciseEqual(pyfunc(v), cfunc(v))

    def test_return_bool_optional_or_none(self):
        pyfunc = return_bool_optional_or_none
        cres = compile_isolated(pyfunc, [types.int32, types.int32])
        cfunc = cres.entry_point

        for x, y in itertools.product((0, 1, 2), (0, 1)):
            self.assertPreciseEqual(pyfunc(x, y), cfunc(x, y))

    def test_is_this_a_none(self):
        pyfunc = is_this_a_none
        cres = compile_isolated(pyfunc, [types.intp])
        cfunc = cres.entry_point

        for v in [-1, 0, 1, 2]:
            self.assertPreciseEqual(pyfunc(v), cfunc(v))

    def test_is_this_a_none_objmode(self):
        pyfunc = is_this_a_none
        flags = Flags()
        flags.set('force_pyobject')
        cres = compile_isolated(pyfunc, [types.intp], flags=flags)
        cfunc = cres.entry_point
        self.assertTrue(cres.objectmode)
        for v in [-1, 0, 1, 2]:
            self.assertPreciseEqual(pyfunc(v), cfunc(v))

    def test_a_is_b_intp(self):
        pyfunc = a_is_b
        cres = compile_isolated(pyfunc, [types.intp, types.intp])
        cfunc = cres.entry_point
        # integer identity relies on `==`
        self.assertTrue(cfunc(1, 1))
        self.assertFalse(cfunc(1, 2))

    def test_a_is_not_b_intp(self):
        pyfunc = a_is_not_b
        cres = compile_isolated(pyfunc, [types.intp, types.intp])
        cfunc = cres.entry_point
        # integer identity relies on `==`
        self.assertFalse(cfunc(1, 1))
        self.assertTrue(cfunc(1, 2))

    def test_optional_float(self):
        def pyfunc(x, y):
            if y is None:
                return x
            else:
                return x + y

        cfunc = njit("(float64, optional(float64))")(pyfunc)
        self.assertAlmostEqual(pyfunc(1., 12.3), cfunc(1., 12.3))
        self.assertAlmostEqual(pyfunc(1., None), cfunc(1., None))

    def test_optional_array(self):
        def pyfunc(x, y):
            if y is None:
                return x
            else:
                y[0] += x
                return y[0]

        cfunc = njit("(float32, optional(float32[:]))")(pyfunc)
        cy = np.array([12.3], dtype=np.float32)
        py = cy.copy()
        self.assertAlmostEqual(pyfunc(1., py), cfunc(1., cy))
        np.testing.assert_almost_equal(py, cy)
        self.assertAlmostEqual(pyfunc(1., None), cfunc(1., None))

    def test_optional_array_error(self):
        def pyfunc(y):
            return y[0]

        cfunc = njit("(optional(int32[:]),)")(pyfunc)
        with self.assertRaises(TypeError) as raised:
            cfunc(None)
        self.assertIn('expected array(int32, 1d, A), got None',
                      str(raised.exception))

        y = np.array([0xabcd], dtype=np.int32)
        self.assertEqual(cfunc(y), pyfunc(y))

    def test_optional_array_attribute(self):
        """
        Check that we can access attribute of an optional
        """
        def pyfunc(arr, do_it):
            opt = None
            if do_it:  # forces `opt` to be an optional of arr
                opt = arr
            return opt.shape[0]

        cfunc = njit(pyfunc)
        arr = np.arange(5)
        self.assertEqual(pyfunc(arr, True), cfunc(arr, True))

    def test_assign_to_optional(self):
        """
        Check that we can assign to a variable of optional type
        """
        @njit
        def make_optional(val, get_none):
            if get_none:
                ret = None
            else:
                ret = val
            return ret

        @njit
        def foo(val, run_second):
            a = make_optional(val, True)
            if run_second:
                a = make_optional(val, False)
            return a

        self.assertIsNone(foo(123, False))
        self.assertEqual(foo(231, True), 231)

    def test_optional_thru_omitted_arg(self):
        """
        Issue 1868
        """

        def pyfunc(x=None):
            if x is None:
                x = 1
            return x

        cfunc = njit(pyfunc)
        self.assertEqual(pyfunc(), cfunc())
        self.assertEqual(pyfunc(3), cfunc(3))

    def test_optional_unpack(self):
        """
        Issue 2171
        """
        def pyfunc(x):
            if x is None:
                return
            else:
                a, b = x
                return a, b

        tup = types.Tuple([types.intp] * 2)
        opt_tup = types.Optional(tup)
        sig = (opt_tup,)
        cfunc = njit(sig)(pyfunc)
        self.assertEqual(pyfunc(None), cfunc(None))
        self.assertEqual(pyfunc((1, 2)), cfunc((1, 2)))

    def test_many_optional_none_returns(self):
        """
        Issue #4058
        """
        @njit
        def foo(maybe):
            lx = None
            if maybe:
                lx = 10
            return 1, lx

        def work():
            tmp = []
            for _ in range(20000):
                maybe = False
                _ = foo(maybe)

        # this caused "Fatal Python error: deallocating None" as there was no
        # incref being made on the returned None.
        work()


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