import asyncio
import logging
import random
from datetime import timedelta
from time import monotonic, sleep

import pytest

from distributed import Client, Nanny, TimeoutError, Variable, wait, worker_client
from distributed.compatibility import WINDOWS
from distributed.metrics import time
from distributed.utils_test import captured_logger, div, gen_cluster, inc, popen


@gen_cluster(client=True)
async def test_variable(c, s, a, b):
    x = Variable("x")
    xx = Variable("x")
    assert x.client is c

    future = c.submit(inc, 1)

    await x.set(future)
    future2 = await xx.get()
    assert future.key == future2.key

    del future, future2

    await asyncio.sleep(0.1)
    assert s.tasks  # future still present

    x.delete()

    start = time()
    while s.tasks:
        await asyncio.sleep(0.01)
        assert time() < start + 5


def test_variable_in_task(loop):
    # Ensure that we can create a Variable inside a task on a
    # worker in a separate Python process than the client
    with popen(["dask-scheduler", "--no-dashboard"]):
        with popen(["dask-worker", "127.0.0.1:8786"]):
            with Client("tcp://127.0.0.1:8786", loop=loop) as c:
                c.wait_for_workers(1)

                x = Variable("x")
                x.set(123)

                def foo():
                    y = Variable("x")
                    return y.get()

                result = c.submit(foo).result()
                assert result == 123


@gen_cluster(client=True)
async def test_delete_unset_variable(c, s, a, b):
    x = Variable()
    assert x.client is c
    with captured_logger(logging.getLogger("distributed.utils")) as logger:
        x.delete()
        await c.close()
    text = logger.getvalue()
    assert "KeyError" not in text


@gen_cluster(client=True)
async def test_queue_with_data(c, s, a, b):
    x = Variable("x")
    xx = Variable("x")
    assert x.client is c

    await x.set((1, "hello"))
    data = await xx.get()

    assert data == (1, "hello")


def test_sync(client):
    future = client.submit(lambda x: x + 1, 10)
    x = Variable("x")
    xx = Variable("x")
    x.set(future)
    future2 = xx.get()

    assert future2.result() == 11


@gen_cluster()
async def test_hold_futures(s, a, b):
    c1 = await Client(s.address, asynchronous=True)
    future = c1.submit(lambda x: x + 1, 10)
    x1 = Variable("x")
    await x1.set(future)
    del x1
    await c1.close()

    await asyncio.sleep(0.1)

    c2 = await Client(s.address, asynchronous=True)
    x2 = Variable("x")
    future2 = await x2.get()
    result = await future2

    assert result == 11
    await c2.close()


@gen_cluster(client=True)
async def test_timeout(c, s, a, b):
    v = Variable("v")

    start = monotonic()
    with pytest.raises(TimeoutError):
        await v.get(timeout="200ms")
    stop = monotonic()

    if WINDOWS:  # timing is weird with asyncio and Windows
        assert 0.1 < stop - start < 2.0
    else:
        assert 0.2 < stop - start < 2.0

    with pytest.raises(TimeoutError):
        await v.get(timeout=timedelta(milliseconds=10))


def test_timeout_sync(client):
    v = Variable("v")
    start = time()
    with pytest.raises(TimeoutError):
        v.get(timeout=0.2)
    stop = time()

    if WINDOWS:
        assert 0.1 < stop - start < 2.0
    else:
        assert 0.2 < stop - start < 2.0

    with pytest.raises(TimeoutError):
        v.get(timeout=0.01)


@gen_cluster(client=True)
async def test_cleanup(c, s, a, b):
    v = Variable("v")
    vv = Variable("v")

    x = c.submit(lambda x: x + 1, 10)
    y = c.submit(lambda x: x + 1, 20)
    x_key = x.key

    await v.set(x)
    del x
    await asyncio.sleep(0.1)

    t_future = xx = asyncio.ensure_future(vv._get())
    await asyncio.sleep(0)
    asyncio.ensure_future(v.set(y))

    future = await t_future
    assert future.key == x_key
    result = await future
    assert result == 11


def test_pickleable(client):
    v = Variable("v")

    def f(x):
        v.set(x + 1)

    client.submit(f, 10).result()
    assert v.get() == 11


@gen_cluster(client=True)
async def test_timeout_get(c, s, a, b):
    v = Variable("v")

    tornado_future = v.get()

    vv = Variable("v")
    await vv.set(1)

    result = await tornado_future
    assert result == 1


@pytest.mark.slow
@gen_cluster(client=True, nthreads=[("127.0.0.1", 2)] * 5, Worker=Nanny, timeout=60)
async def test_race(c, s, *workers):
    NITERS = 50

    def f(i):
        with worker_client() as c:
            v = Variable("x", client=c)
            for _ in range(NITERS):
                future = v.get()
                x = future.result()
                y = c.submit(inc, x)
                v.set(y)
                sleep(0.01 * random.random())
            result = v.get().result()
            sleep(0.1)  # allow fire-and-forget messages to clear
            return result

    v = Variable("x", client=c)
    x = await c.scatter(1)
    await v.set(x)

    futures = c.map(f, range(15))
    results = await c.gather(futures)
    assert all(r > NITERS * 0.8 for r in results)

    while len(s.wants_what["variable-x"]) != 1:
        await asyncio.sleep(0.01)


@gen_cluster(client=True)
async def test_Future_knows_status_immediately(c, s, a, b):
    x = await c.scatter(123)
    v = Variable("x")
    await v.set(x)

    c2 = await Client(s.address, asynchronous=True)
    v2 = Variable("x", client=c2)
    future = await v2.get()
    assert future.status == "finished"

    x = c.submit(div, 1, 0)
    await wait(x)
    await v.set(x)

    future2 = await v2.get()
    assert future2.status == "error"
    with pytest.raises(Exception):
        await future2

    start = time()
    while True:  # we learn about the true error eventually
        try:
            await future2
        except ZeroDivisionError:
            break
        except Exception:
            assert time() < start + 5
            await asyncio.sleep(0.05)

    await c2.close()


@gen_cluster(client=True)
async def test_erred_future(c, s, a, b):
    future = c.submit(div, 1, 0)
    var = Variable()
    await var.set(future)
    await asyncio.sleep(0.1)
    future2 = await var.get()
    with pytest.raises(ZeroDivisionError):
        await future2.result()

    exc = await future2.exception()
    assert isinstance(exc, ZeroDivisionError)


def test_future_erred_sync(client):
    future = client.submit(div, 1, 0)
    var = Variable()
    var.set(future)

    sleep(0.1)

    future2 = var.get()

    with pytest.raises(ZeroDivisionError):
        future2.result()


@gen_cluster(client=True)
async def test_variables_do_not_leak_client(c, s, a, b):
    # https://github.com/dask/distributed/issues/3899
    clients_pre = set(s.clients)

    # setup variable with future
    x = Variable("x")
    future = c.submit(inc, 1)
    await x.set(future)

    # complete teardown
    x.delete()

    start = time()
    while set(s.clients) != clients_pre:
        await asyncio.sleep(0.01)
        assert time() < start + 5
