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# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.
import tvm

class CanonicalChecker:
    def __init__(self):
        self.analyzer = tvm.arith.Analyzer()

    def verify(self, data, expected):
        res = self.analyzer.canonical_simplify(data)
        assert tvm.ir_pass.Equal(res, expected), "data={}, res={}, expected={}".format(data, res, expected)


def test_mul_sum_simplify():
    ck = CanonicalChecker()
    x, y, z = tvm.var("x"), tvm.var("y"), tvm.var("z")
    ck.verify(2 + (3 * x + z + y + 1) * 4 + x,
              x * 13 + z * 4 + y * 4 +6)
    ck.verify((x + y + x + y * 3) / 2, y * 2 + x)
    ck.verify((x + y + x + y * 3) % 2, 0)
    ck.verify(x * 3 - 4 * x + 1, 1 - x)
    ck.verify(y + x * 3 - 5 * x + 1 + y, y * 2 + 1 - x * 2)


def test_split_index_simplify():
    ck = CanonicalChecker()
    x, y, z = tvm.var("x"), tvm.var("y"), tvm.var("z")
    ck.verify((x/3) *3 + x % 3, x)
    ck.verify((x/6) * 6 + ((x/3) % 2) * 3 + x % 3, x)

    # split div const
    ck.verify(((x % 16) / 2) * 2 / 4, (x % 16) / 4)
    ck.verify((x % 2) / 8, 0)
    ck.verify((x % 2) / 7, 0)
    ck.verify(((x % 16) / 2) * 2 / 6, (x % 16) / 6)

    # split mod const
    ck.verify((x * 8) % 16, (x % 2) * 8)
    ck.verify((x * 8) % 2, 0)

    # simplify then fold
    ck.analyzer.update(x, tvm.arith.ConstIntBound(0, 1000))
    ck.analyzer.update(y, tvm.arith.ConstIntBound(0, 1000))
    ck.verify((x * 4 + y) / 2 * 2 + (x * 4 + y) % 2, x * 4 + y)
    # complex fold
    ck.verify((z * 9 + y) / 2 * 2 + (z * 9 + y) % 2, z * 9 + y)



def test_div_simplify():
    ck = CanonicalChecker()
    x = tvm.var("x")
    ck.verify((16+48*x)/16, x*3 + 1)
    # (17+48*x)/16 is not simplifiable for arbitrary x because when 17+48*x<0
    # (17+48*x)/16 != 1+3*x
    ck.verify((17+48*x)/16, (x * 48 + 17) / 16)
    # However, when x >= 0, then 17+48*x >= 0 and (17+48*x)/16 can be simplified
    ck.analyzer.update(x, tvm.arith.ConstIntBound(0, 10))
    ck.verify((17+48*x)/16, x * 3 + 1)
    # Trying expressions that are not simplifiable for any values of the variables
    ck.verify((17+47*x)/16, (x * 47 + 17) / 16)


def test_canonical_mixed():
    ck = CanonicalChecker()
    x = tvm.var("x")
    z = tvm.const(3, "int32")
    ck.verify(x / (z*z) - x / (z*z), 0)
    ck.verify(x / (z+z) - x / (z+z), 0)


def test_reduce_combiner_simplify():
    ck = CanonicalChecker()
    dummy = tvm.var('dummy')
    comm_reducer = tvm.comm_reducer
    prod = comm_reducer(lambda x, y: x*y, lambda t0: tvm.const(1, t0))

    sum_or_prod = comm_reducer(
        lambda x, y: tvm.expr.Select(dummy < 0,
                                     x + y, x*y),
        lambda t0: tvm.expr.Select(dummy < 0,
                                   tvm.const(0, t0), tvm.const(1, t0)))
    sum_and_prod = comm_reducer(
        lambda x, y: (x[0] + y[0],
                      x[1]*y[1]),
        lambda t0, t1: (tvm.const(0, t0),
                        tvm.const(5, t0) - tvm.const(4, t0)))
    some_reducer1 = comm_reducer(
        lambda x, y: (x[0] + y[0],
                      x[0] + y[0] + x[1] + y[1],
                      x[0]*y[2] + y[0]*x[2],
                      x[1] + y[2],
                    4.0),
        lambda t0, t1, t2, t3, t4: (tvm.const(0, t0),
                                    tvm.const(1, t1),
                                    tvm.const(2, t2),
                                    tvm.const(3, t3),
                                    tvm.const(4, t4)))

    k = tvm.reduce_axis((0, 10), name="k")
    A = tvm.placeholder((10,), name='A')
    # Test that SimplifyCombiner makes use of vranges
    ck.analyzer.update(dummy, tvm.arith.ConstIntBound(-10, -4))
    ck.verify(sum_or_prod(A[k], k), tvm.sum(A[k], k))
    ck.analyzer.update(dummy, tvm.arith.ConstIntBound(5, 9), True)
    ck.verify(sum_or_prod(A[k], k), prod(A[k], k))
    ck.analyzer.update(dummy, tvm.arith.ConstIntBound(-10, 100), True)
    ck.verify(sum_and_prod((A[k], A[10-k]), k)[0], tvm.sum(A[k], k))
    ck.verify(sum_and_prod((A[k], A[10-k]), k)[1], prod(A[10-k], k))

    reference_simplified_sources = [[A[0]],
                                    [A[0], A[1]],
                                    [A[0], A[2]],
                                    [A[0], A[1], A[2], A[3]],
                                    [A[4]]]
    for j in range(5):
        # Here we use the j-th component of the result, so only it and the components it
        # depends on are left.
        simplified = ck.analyzer.canonical_simplify(
            some_reducer1((A[0], A[1], A[2], A[3], A[4]), k)[j])

        # Check that the remaining components are the expected ones.
        for lhs, rhs in zip(simplified.source, reference_simplified_sources[j]):
            assert tvm.ir_pass.Equal(lhs, rhs)

    # Test that components with side effects are not removed
    side_effect = lambda *xs: tvm.make.Call("int32", "dummy", xs, tvm.expr.Call.Intrinsic, None, 0)
    ck.verify(sum_and_prod((A[k], side_effect(A[10-k])), k)[0],
             sum_and_prod((A[k], side_effect(A[10-k])), k)[0])
    ck.verify(sum_and_prod((side_effect(A[k]), A[10-k]), k)[0],
              tvm.sum(side_effect(A[k]), k))


def test_reduce_simplify():
    ck = CanonicalChecker()
    k = tvm.reduce_axis((0, 10), name="k")
    j = tvm.reduce_axis((-5, 3), name="j")
    A = tvm.placeholder((10,), name='A')
    ck.verify(tvm.sum(tvm.expr.Select(k + j < 12, k + j, 0), [k, j]),
              tvm.sum(k + j, [k, j]))
    ck.verify(tvm.sum(A[3], []), A[3])
    # The rule below is not typical, removed for now
    ck.verify(tvm.sum(k / 10, k), tvm.sum(tvm.const(0, "int32"), k))


if __name__ == "__main__":
    test_div_simplify()
    test_reduce_simplify()
    test_reduce_combiner_simplify()
    test_mul_sum_simplify()
    test_split_index_simplify()
    test_canonical_mixed()
