import click
import json
import os
import ray
import ray._private.test_utils as test_utils
import time
import tqdm

sleep_time = 300


def test_max_running_tasks(num_tasks):
    cpus_per_task = 0.25

    @ray.remote(num_cpus=cpus_per_task)
    def task():
        time.sleep(sleep_time)

    refs = [
        task.remote() for _ in tqdm.trange(num_tasks, desc="Launching tasks")
    ]

    max_cpus = ray.cluster_resources()["CPU"]
    min_cpus_available = max_cpus
    for _ in tqdm.trange(int(sleep_time / 0.1), desc="Waiting"):
        try:
            cur_cpus = ray.available_resources().get("CPU", 0)
            min_cpus_available = min(min_cpus_available, cur_cpus)
        except Exception:
            # There are race conditions `.get` can fail if a new heartbeat
            # comes at the same time.
            pass
        time.sleep(0.1)

    # There are some relevant magic numbers in this check. 10k tasks each
    # require 1/4 cpus. Therefore, ideally 2.5k cpus will be used.
    err_str = f"Only {max_cpus - min_cpus_available}/{max_cpus} cpus used."
    threshold = num_tasks * cpus_per_task * 0.75
    assert max_cpus - min_cpus_available > threshold, err_str

    for _ in tqdm.trange(num_tasks, desc="Ensuring all tasks have finished"):
        done, refs = ray.wait(refs)
        assert ray.get(done[0]) is None


def no_resource_leaks():
    return ray.available_resources() == ray.cluster_resources()


@click.command()
@click.option(
    "--num-tasks", required=True, type=int, help="Number of tasks to launch.")
def test(num_tasks):
    ray.init(address="auto")

    test_utils.wait_for_condition(no_resource_leaks)
    start_time = time.time()
    test_max_running_tasks(num_tasks)
    end_time = time.time()
    test_utils.wait_for_condition(no_resource_leaks)

    rate = num_tasks / (end_time - start_time - sleep_time)

    print(f"Success! Started {num_tasks} tasks in {end_time - start_time}s. "
          f"({rate} tasks/s)")

    if "TEST_OUTPUT_JSON" in os.environ:
        out_file = open(os.environ["TEST_OUTPUT_JSON"], "w")
        results = {
            "tasks_per_second": rate,
            "num_tasks": num_tasks,
            "time": end_time - start_time,
            "success": "1"
        }
        json.dump(results, out_file)


if __name__ == "__main__":
    test()