import gc
from io import StringIO

import numpy as np

from numba import njit, vectorize
from numba import typeof
from numba.core import utils, types, typing, ir, compiler, cpu
from numba.core.compiler import Compiler, Flags
from numba.tests.support import MemoryLeakMixin, TestCase
import unittest


class Namespace(dict):
    def __getattr__(s, k):
        return s[k] if k in s else super(Namespace, s).__getattr__(k)

def axy(a, x, y):
    return a * x + y

def ax2(a, x, y):
    return a * x + y

def pos_root(As, Bs, Cs):
    return (-Bs + (((Bs ** 2.) - (4. * As * Cs)) ** 0.5)) / (2. * As)

def neg_root_common_subexpr(As, Bs, Cs):
    _2As = 2. * As
    _4AsCs = 2. * _2As * Cs
    _Bs2_4AsCs = (Bs ** 2. - _4AsCs)
    return (-Bs - (_Bs2_4AsCs ** 0.5)) / _2As

def neg_root_complex_subexpr(As, Bs, Cs):
    _2As = 2. * As
    _4AsCs = 2. * _2As * Cs
    _Bs2_4AsCs = (Bs ** 2. - _4AsCs) + 0j # Force into the complex domain.
    return (-Bs - (_Bs2_4AsCs ** 0.5)) / _2As

vaxy = vectorize(axy)

def call_stuff(a0, a1):
    return np.cos(vaxy(a0, np.sin(a1) - 1., 1.))

def are_roots_imaginary(As, Bs, Cs):
    return (Bs ** 2 - 4 * As * Cs) < 0

def div_add(As, Bs, Cs):
    return As / Bs + Cs

def cube(As):
    return As ** 3

def explicit_output(a, b, out):
    np.cos(a, out)
    return np.add(out, b, out)

def variable_name_reuse(a, b, c, d):
    u = a + b
    u = u - a * b
    u = u * c + d
    return u


# From issue #1264
def distance_matrix(vectors):
    n_vectors = vectors.shape[0]
    result = np.empty((n_vectors, n_vectors), dtype=np.float64)

    for i in range(n_vectors):
        for j in range(i, n_vectors):
            result[i,j] = result[j,i] = np.sum(
                (vectors[i] - vectors[j]) ** 2) ** 0.5

    return result


class RewritesTester(Compiler):
    @classmethod
    def mk_pipeline(cls, args, return_type=None, flags=None, locals={},
                    library=None, typing_context=None, target_context=None):
        if not flags:
            flags = Flags()
        flags.nrt = True
        if typing_context is None:
            typing_context = typing.Context()
        if target_context is None:
            target_context = cpu.CPUContext(typing_context)
        return cls(typing_context, target_context, library, args, return_type,
                   flags, locals)

    @classmethod
    def mk_no_rw_pipeline(cls, args, return_type=None, flags=None, locals={},
                          library=None, **kws):
        if not flags:
            flags = Flags()
        flags.no_rewrites = True
        return cls.mk_pipeline(args, return_type, flags, locals, library, **kws)


class TestArrayExpressions(MemoryLeakMixin, TestCase):

    def _compile_function(self, fn, arg_tys):
        """
        Compile the given function both without and with rewrites enabled.
        """
        control_pipeline = RewritesTester.mk_no_rw_pipeline(arg_tys)
        cres_0 = control_pipeline.compile_extra(fn)
        control_cfunc = cres_0.entry_point

        test_pipeline = RewritesTester.mk_pipeline(arg_tys)
        cres_1 = test_pipeline.compile_extra(fn)
        test_cfunc = cres_1.entry_point

        return control_pipeline, control_cfunc, test_pipeline, test_cfunc

    def test_simple_expr(self):
        '''
        Using a simple array expression, verify that rewriting is taking
        place, and is fusing loops.
        '''
        A = np.linspace(0,1,10)
        X = np.linspace(2,1,10)
        Y = np.linspace(1,2,10)
        arg_tys = [typeof(arg) for arg in (A, X, Y)]

        control_pipeline, nb_axy_0, test_pipeline, nb_axy_1 = \
            self._compile_function(axy, arg_tys)

        control_pipeline2 = RewritesTester.mk_no_rw_pipeline(arg_tys)
        cres_2 = control_pipeline2.compile_extra(ax2)
        nb_ctl = cres_2.entry_point

        expected = nb_axy_0(A, X, Y)
        actual = nb_axy_1(A, X, Y)
        control = nb_ctl(A, X, Y)
        np.testing.assert_array_equal(expected, actual)
        np.testing.assert_array_equal(control, actual)

        ir0 = control_pipeline.state.func_ir.blocks
        ir1 = test_pipeline.state.func_ir.blocks
        ir2 = control_pipeline2.state.func_ir.blocks
        self.assertEqual(len(ir0), len(ir1))
        self.assertEqual(len(ir0), len(ir2))
        # The rewritten IR should be smaller than the original.
        self.assertGreater(len(ir0[0].body), len(ir1[0].body))
        self.assertEqual(len(ir0[0].body), len(ir2[0].body))

    def _get_array_exprs(self, block):
        for instr in block:
            if isinstance(instr, ir.Assign):
                if isinstance(instr.value, ir.Expr):
                    if instr.value.op == 'arrayexpr':
                        yield instr

    def _array_expr_to_set(self, expr, out=None):
        '''
        Convert an array expression tree into a set of operators.
        '''
        if out is None:
            out = set()
        if not isinstance(expr, tuple):
            raise ValueError("{0} not a tuple".format(expr))
        operation, operands = expr
        processed_operands = []
        for operand in operands:
            if isinstance(operand, tuple):
                operand, _ = self._array_expr_to_set(operand, out)
            processed_operands.append(operand)
        processed_expr = operation, tuple(processed_operands)
        out.add(processed_expr)
        return processed_expr, out

    def _test_root_function(self, fn=pos_root):
        A = np.random.random(10)
        B = np.random.random(10) + 1. # Increase likelihood of real
                                      # root (could add 2 to force all
                                      # roots to be real).
        C = np.random.random(10)
        arg_tys = [typeof(arg) for arg in (A, B, C)]

        control_pipeline = RewritesTester.mk_no_rw_pipeline(arg_tys)
        control_cres = control_pipeline.compile_extra(fn)
        nb_fn_0 = control_cres.entry_point

        test_pipeline = RewritesTester.mk_pipeline(arg_tys)
        test_cres = test_pipeline.compile_extra(fn)
        nb_fn_1 = test_cres.entry_point

        np_result = fn(A, B, C)
        nb_result_0 = nb_fn_0(A, B, C)
        nb_result_1 = nb_fn_1(A, B, C)
        np.testing.assert_array_almost_equal(np_result, nb_result_0)
        np.testing.assert_array_almost_equal(nb_result_0, nb_result_1)

        return Namespace(locals())

    def _test_cube_function(self, fn=cube):
        A = np.arange(10, dtype=np.float64)
        arg_tys = (typeof(A),)

        control_pipeline = RewritesTester.mk_no_rw_pipeline(arg_tys)
        control_cres = control_pipeline.compile_extra(fn)
        nb_fn_0 = control_cres.entry_point

        test_pipeline = RewritesTester.mk_pipeline(arg_tys)
        test_cres = test_pipeline.compile_extra(fn)
        nb_fn_1 = test_cres.entry_point

        expected = A ** 3
        self.assertPreciseEqual(expected, nb_fn_0(A))
        self.assertPreciseEqual(expected, nb_fn_1(A))

        return Namespace(locals())

    def _test_explicit_output_function(self, fn):
        """
        Test function having a (a, b, out) signature where *out* is
        an output array the function writes into.
        """
        A = np.arange(10, dtype=np.float64)
        B = A + 1
        arg_tys = (typeof(A),) * 3

        control_pipeline, control_cfunc, test_pipeline, test_cfunc = \
            self._compile_function(fn, arg_tys)

        def run_func(fn):
            out = np.zeros_like(A)
            fn(A, B, out)
            return out

        expected = run_func(fn)
        self.assertPreciseEqual(expected, run_func(control_cfunc))
        self.assertPreciseEqual(expected, run_func(test_cfunc))

        return Namespace(locals())

    def _assert_array_exprs(self, block, expected_count):
        """
        Assert the *block* has the expected number of array expressions
        in it.
        """
        rewrite_count = len(list(self._get_array_exprs(block)))
        self.assertEqual(rewrite_count, expected_count)

    def _assert_total_rewrite(self, control_ir, test_ir, trivial=False):
        """
        Given two dictionaries of Numba IR blocks, check to make sure the
        control IR has no array expressions, while the test IR
        contains one and only one.
        """
        # Both IRs have the same number of blocks (presumably 1)
        self.assertEqual(len(control_ir), len(test_ir))
        control_block = control_ir[0].body
        test_block = test_ir[0].body
        self._assert_array_exprs(control_block, 0)
        self._assert_array_exprs(test_block, 1)
        if not trivial:
            # If the expression wasn't trivial, the block length should
            # have decreased (since a sequence of exprs was replaced
            # with a single nested array expr).
            self.assertGreater(len(control_block), len(test_block))

    def _assert_no_rewrite(self, control_ir, test_ir):
        """
        Given two dictionaries of Numba IR blocks, check to make sure
        the control IR and the test IR both have no array expressions.
        """
        self.assertEqual(len(control_ir), len(test_ir))
        # All blocks should be identical, and not rewritten
        for k, v in control_ir.items():
            control_block = v.body
            test_block = test_ir[k].body
            self.assertEqual(len(control_block), len(test_block))
            self._assert_array_exprs(control_block, 0)
            self._assert_array_exprs(test_block, 0)

    def test_trivial_expr(self):
        """
        Ensure even a non-nested expression is rewritten, as it can enable
        scalar optimizations such as rewriting `x ** 2`.
        """
        ns = self._test_cube_function()
        self._assert_total_rewrite(ns.control_pipeline.state.func_ir.blocks,
                                   ns.test_pipeline.state.func_ir.blocks,
                                   trivial=True)

    def test_complicated_expr(self):
        '''
        Using the polynomial root function, ensure the full expression is
        being put in the same kernel with no remnants of intermediate
        array expressions.
        '''
        ns = self._test_root_function()
        self._assert_total_rewrite(ns.control_pipeline.state.func_ir.blocks,
                                   ns.test_pipeline.state.func_ir.blocks)

    def test_common_subexpressions(self, fn=neg_root_common_subexpr):
        '''
        Attempt to verify that rewriting will incorporate user common
        subexpressions properly.
        '''
        ns = self._test_root_function(fn)
        ir0 = ns.control_pipeline.state.func_ir.blocks
        ir1 = ns.test_pipeline.state.func_ir.blocks
        self.assertEqual(len(ir0), len(ir1))
        self.assertGreater(len(ir0[0].body), len(ir1[0].body))
        self.assertEqual(len(list(self._get_array_exprs(ir0[0].body))), 0)
        # Verify that we didn't rewrite everything into a monolithic
        # array expression since we stored temporary values in
        # variables that might be used later (from the optimization's
        # point of view).
        array_expr_instrs = list(self._get_array_exprs(ir1[0].body))
        self.assertGreater(len(array_expr_instrs), 1)
        # Now check that we haven't duplicated any subexpressions in
        # the rewritten code.
        array_sets = list(self._array_expr_to_set(instr.value.expr)[1]
                          for instr in array_expr_instrs)
        for expr_set_0, expr_set_1 in zip(array_sets[:-1], array_sets[1:]):
            intersections = expr_set_0.intersection(expr_set_1)
            if intersections:
                self.fail("Common subexpressions detected in array "
                          "expressions ({0})".format(intersections))

    def test_complex_subexpression(self):
        return self.test_common_subexpressions(neg_root_complex_subexpr)

    def test_ufunc_and_dufunc_calls(self):
        '''
        Verify that ufunc and DUFunc calls are being properly included in
        array expressions.
        '''
        A = np.random.random(10)
        B = np.random.random(10)
        arg_tys = [typeof(arg) for arg in (A, B)]

        vaxy_descr = vaxy._dispatcher.targetdescr
        control_pipeline = RewritesTester.mk_no_rw_pipeline(
            arg_tys,
            typing_context=vaxy_descr.typing_context,
            target_context=vaxy_descr.target_context)
        cres_0 = control_pipeline.compile_extra(call_stuff)
        nb_call_stuff_0 = cres_0.entry_point

        test_pipeline = RewritesTester.mk_pipeline(
            arg_tys,
            typing_context=vaxy_descr.typing_context,
            target_context=vaxy_descr.target_context)
        cres_1 = test_pipeline.compile_extra(call_stuff)
        nb_call_stuff_1 = cres_1.entry_point

        expected = call_stuff(A, B)
        control = nb_call_stuff_0(A, B)
        actual = nb_call_stuff_1(A, B)
        np.testing.assert_array_almost_equal(expected, control)
        np.testing.assert_array_almost_equal(expected, actual)

        self._assert_total_rewrite(control_pipeline.state.func_ir.blocks,
                                   test_pipeline.state.func_ir.blocks)

    def test_cmp_op(self):
        '''
        Verify that comparison operators are supported by the rewriter.
        '''
        ns = self._test_root_function(are_roots_imaginary)
        self._assert_total_rewrite(ns.control_pipeline.state.func_ir.blocks,
                                   ns.test_pipeline.state.func_ir.blocks)

    def test_explicit_output(self):
        """
        Check that ufunc calls with explicit outputs are not rewritten.
        """
        ns = self._test_explicit_output_function(explicit_output)
        self._assert_no_rewrite(ns.control_pipeline.state.func_ir.blocks,
                                ns.test_pipeline.state.func_ir.blocks)


class TestRewriteIssues(MemoryLeakMixin, TestCase):

    def test_issue_1184(self):
        from numba import jit
        import numpy as np

        @jit(nopython=True)
        def foo(arr):
            return arr

        @jit(nopython=True)
        def bar(arr):
            c = foo(arr)
            d = foo(arr)   # two calls to trigger rewrite
            return c, d

        arr = np.arange(10)
        out_c, out_d = bar(arr)
        self.assertIs(out_c, out_d)
        self.assertIs(out_c, arr)

    def test_issue_1264(self):
        n = 100
        x = np.random.uniform(size=n*3).reshape((n,3))
        expected = distance_matrix(x)
        actual = njit(distance_matrix)(x)
        np.testing.assert_array_almost_equal(expected, actual)
        # Avoid sporadic failures in MemoryLeakMixin.tearDown()
        gc.collect()

    def test_issue_1372(self):
        """Test array expression with duplicated term"""
        from numba import njit

        @njit
        def foo(a, b):
            b = np.sin(b)
            return b + b + a

        a = np.random.uniform(10)
        b = np.random.uniform(10)
        expect = foo.py_func(a, b)
        got = foo(a, b)
        np.testing.assert_allclose(got, expect)

    def test_unary_arrayexpr(self):
        """
        Typing of unary array expression (np.negate) can be incorrect.
        """
        @njit
        def foo(a, b):
            return b - a + -a

        b = 1.5
        a = np.arange(10, dtype=np.int32)

        expect = foo.py_func(a, b)
        got = foo(a, b)
        self.assertPreciseEqual(got, expect)

    def test_bitwise_arrayexpr(self):
        """
        Typing of bitwise boolean array expression can be incorrect
        (issue #1813).
        """
        @njit
        def foo(a, b):
            return ~(a & (~b))

        a = np.array([True, True, False, False])
        b = np.array([False, True, False, True])

        expect = foo.py_func(a, b)
        got = foo(a, b)
        self.assertPreciseEqual(got, expect)

    def test_annotations(self):
        """
        Type annotation of array expressions with disambiguated
        variable names (issue #1466).
        """
        cfunc = njit(variable_name_reuse)

        a = np.linspace(0, 1, 10)
        cfunc(a, a, a, a)

        buf = StringIO()
        cfunc.inspect_types(buf)
        res = buf.getvalue()
        self.assertIn("#   u.1 = ", res)
        self.assertIn("#   u.2 = ", res)

    def test_issue_5599_name_collision(self):
        # The original error will fail in lowering of the array_expr
        @njit
        def f(x):
            arr = np.ones(x)

            for _ in range(2):
                val =  arr * arr
                arr = arr.copy()
            return arr

        got = f(5)
        expect = f.py_func(5)
        np.testing.assert_array_equal(got, expect)


class TestSemantics(MemoryLeakMixin, unittest.TestCase):

    def test_division_by_zero(self):
        # Array expressions should follow the Numpy error model
        # i.e. 1./0. returns +inf instead of raising ZeroDivisionError
        pyfunc = div_add
        cfunc = njit(pyfunc)

        a = np.float64([0.0, 1.0, float('inf')])
        b = np.float64([0.0, 0.0, 1.0])
        c = np.ones_like(a)

        expect = pyfunc(a, b, c)
        got = cfunc(a, b, c)
        np.testing.assert_array_equal(expect, got)


class TestOptionals(MemoryLeakMixin, unittest.TestCase):
    """ Tests the arrival and correct lowering of Optional types at a arrayexpr
    derived ufunc, see #3972"""

    def test_optional_scalar_type(self):

        @njit
        def arr_expr(x, y):
            return x + y

        @njit
        def do_call(x, y):
            if y > 0:
                z = None
            else:
                z = y
            return arr_expr(x, z)

        args = (np.arange(5), -1.2)

        # check result
        res = do_call(*args)
        expected = do_call.py_func(*args)
        np.testing.assert_allclose(res, expected)

        # check type
        s = arr_expr.signatures
        oty = s[0][1]
        self.assertTrue(isinstance(oty, types.Optional))
        self.assertTrue(isinstance(oty.type, types.Float))

    def test_optional_array_type(self):

        @njit
        def arr_expr(x, y):
            return x + y

        @njit
        def do_call(x, y):
            if y[0] > 0:
                z = None
            else:
                z = y
            return arr_expr(x, z)

        args = (np.arange(5), np.arange(5.))

        # check result
        res = do_call(*args)
        expected = do_call.py_func(*args)
        np.testing.assert_allclose(res, expected)

        # check type
        s = arr_expr.signatures
        oty = s[0][1]
        self.assertTrue(isinstance(oty, types.Optional))
        self.assertTrue(isinstance(oty.type, types.Array))
        self.assertTrue(isinstance(oty.type.dtype, types.Float))


class TestOptionalsExceptions(MemoryLeakMixin, unittest.TestCase):
    # same as above, but the Optional resolves to None and TypeError's

    def test_optional_scalar_type_exception_on_none(self):

        self.disable_leak_check()

        @njit
        def arr_expr(x, y):
            return x + y

        @njit
        def do_call(x, y):
            if y > 0:
                z = None
            else:
                z = y
            return arr_expr(x, z)

        args = (np.arange(5), 1.0)

        # check result
        with self.assertRaises(TypeError) as raises:
            do_call(*args)

        self.assertIn("expected float64, got None", str(raises.exception))

        # check type
        s = arr_expr.signatures
        oty = s[0][1]
        self.assertTrue(isinstance(oty, types.Optional))
        self.assertTrue(isinstance(oty.type, types.Float))

    def test_optional_array_type_exception_on_none(self):

        self.disable_leak_check()

        @njit
        def arr_expr(x, y):
            return x + y

        @njit
        def do_call(x, y):
            if y[0] > 0:
                z = None
            else:
                z = y
            return arr_expr(x, z)

        args = (np.arange(5), np.arange(1., 5.))

        # check result
        with self.assertRaises(TypeError) as raises:
            do_call(*args)

        excstr = str(raises.exception)
        self.assertIn("expected array(float64,", excstr)
        self.assertIn("got None", excstr)

        # check type
        s = arr_expr.signatures
        oty = s[0][1]
        self.assertTrue(isinstance(oty, types.Optional))
        self.assertTrue(isinstance(oty.type, types.Array))
        self.assertTrue(isinstance(oty.type.dtype, types.Float))


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