import asyncio
import functools
import threading
import numpy as np
from numba import cuda
from numba.core import utils
from numba.cuda.testing import unittest, CUDATestCase, skip_on_cudasim


def with_asyncio_loop(f):
    @functools.wraps(f)
    def runner(*args, **kwds):
        loop = asyncio.new_event_loop()
        loop.set_debug(True)
        try:
            return loop.run_until_complete(f(*args, **kwds))
        finally:
            loop.close()
    return runner


asyncio_create_task = asyncio.create_task if utils.PYVERSION >= (3, 7) \
    else asyncio.ensure_future


@skip_on_cudasim('CUDA Driver API unsupported in the simulator')
class TestCudaStream(CUDATestCase):
    def test_add_callback(self):
        def callback(stream, status, event):
            event.set()

        stream = cuda.stream()
        callback_event = threading.Event()
        stream.add_callback(callback, callback_event)
        self.assertTrue(callback_event.wait(1.0))

    @with_asyncio_loop
    async def test_async_done(self):
        stream = cuda.stream()
        await stream.async_done()

    @with_asyncio_loop
    async def test_parallel_tasks(self):
        async def async_cuda_fn(value_in: float) -> float:
            stream = cuda.stream()
            h_src, h_dst = cuda.pinned_array(8), cuda.pinned_array(8)
            h_src[:] = value_in
            d_ary = cuda.to_device(h_src, stream=stream)
            d_ary.copy_to_host(h_dst, stream=stream)
            await stream.async_done()
            return h_dst.mean()

        values_in = [1, 2, 3, 4]
        tasks = [asyncio_create_task(async_cuda_fn(v)) for v in values_in]
        values_out = await asyncio.gather(*tasks)
        self.assertTrue(np.allclose(values_in, values_out))

    @with_asyncio_loop
    async def test_multiple_async_done(self):
        stream = cuda.stream()
        done_aws = [stream.async_done() for _ in range(4)]
        await asyncio.gather(*done_aws)

    @with_asyncio_loop
    async def test_cancelled_future(self):
        stream = cuda.stream()
        done1, done2 = stream.async_done(), stream.async_done()
        done1.cancel()
        await done2
        self.assertTrue(done1.cancelled())
        self.assertTrue(done2.done())


@skip_on_cudasim('CUDA Driver API unsupported in the simulator')
class TestFailingStream(CUDATestCase):
    # This test can only be run in isolation because it corrupts the CUDA
    # context, which cannot be recovered from within the same process. It is
    # left here so that it can be run manually for debugging / testing purposes
    # - or may be re-enabled if in future there is infrastructure added for
    # running tests in a separate process (a subprocess cannot be used because
    # CUDA will have been initialized before the fork, so it cannot be used in
    # the child process).
    @unittest.skip
    @with_asyncio_loop
    async def test_failed_stream(self):
        ctx = cuda.current_context()
        module = ctx.create_module_ptx("""
            .version 6.5
            .target sm_30
            .address_size 64
            .visible .entry failing_kernel() { trap; }
        """)
        failing_kernel = module.get_function("failing_kernel")

        stream = cuda.stream()
        failing_kernel.configure((1,), (1,), stream=stream).__call__()
        done = stream.async_done()
        with self.assertRaises(Exception):
            await done
        self.assertIsNotNone(done.exception())


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