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import os
import sys
from pathlib import Path
import logging
import hashlib
import random

import pytest
import torch
import numpy as np


project_root = Path(__file__).resolve().parent.parent.parent.parent

cute_example_path = project_root / "examples" / "python" / "CuTeDSL" / "cute"
example_path = project_root / "examples" / "python" / "CuTeDSL"
utils_path = project_root / "test" / "utils"

# Import cutlass *before* adding example_path to sys.path.
# The examples directory contains a `jax/` subdirectory that Python 3 treats
# as a namespace package.  If that directory is on sys.path first, cutlass's
# JAX-availability check (which does a bare `import jax`) incorrectly returns
# True, and the subsequent `import jax.numpy` fails with ModuleNotFoundError.
# Importing cutlass here, while sys.path is still clean, avoids that race.
import cutlass  # noqa: E402  (intentional early import)

sys.path.append(str(cute_example_path))
sys.path.append(str(example_path))
sys.path.append(str(utils_path))


# The helper class to prevent modification of sys.path from test files
# Only allow modification of sys.path from pytest monkeypatch API calls
class ImmutableSysPath(list):
    mutating_methods = {
        "append",
        "extend",
        "insert",
        "remove",
        "pop",
        "clear",
        "reverse",
        "sort",
        "__setitem__",
        "__delitem__",
    }

    for mtd in mutating_methods:

        def mutating_method(self, *args, mtd=mtd, **kwargs):
            frame = sys._getframe().f_back
            if (
                frame
                and hasattr(frame, "f_locals")
                and "__file__" in frame.f_locals
                and frame.f_locals["__file__"].startswith(str(project_root))
            ):
                err_msg = (
                    "Modification of sys.path is forbidden in test file! "
                    "Please use pytest monkeypatch.syspath_prepend(...) instead."
                )
                raise RuntimeError(err_msg)
            else:
                return getattr(super(), mtd)(*args, **kwargs)

        locals()[mtd] = mutating_method

    def __init__(self, initial=None):
        if initial is None:
            initial = []
        super().__init__(initial)


sys.path = ImmutableSysPath(list(sys.path))

pytest_plugins = ["test_sharding"]


def pytest_addoption(parser):
    parser.addoption(
        "--sample-interval",
        action="store",
        type=int,
        default=4,
        help="If value x is provided, then 1 / x of random picked tests will be run",
    )


@pytest.fixture
def sample_interval(request):
    return request.config.getoption("--sample-interval")


# Removes all StreamHandlers from loggers at the end of test session
# This prevents errors when atexit-registered functions try to use loggers
# whose handlers have already been closed during pytest teardown
@pytest.fixture(scope="session", autouse=True)
def cleanup_logging_handlers():
    try:
        yield
    finally:
        loggers = [logging.getLogger()] + list(
            logging.Logger.manager.loggerDict.values()
        )
        for logger in loggers:
            handlers = getattr(logger, "handlers", [])
            for handler in handlers:
                if isinstance(handler, logging.StreamHandler):
                    logger.removeHandler(handler)


@pytest.fixture(autouse=True, scope="module")
def torch_sanity_check():
    if not torch.cuda.is_available():
        raise RuntimeError("GPU is required to run example tests!")


@pytest.fixture(autouse=True)
def torch_empty_cache():
    """
    Automatically empty the torch CUDA cache at the end of each test, to reduce risk of OOM errors.
    """
    yield
    if torch.cuda.is_available():
        torch.cuda.empty_cache()


@pytest.fixture(autouse=True)
def random_seed(request):
    test_case = request.node.nodeid.split(os.sep)[-1]
    seed = int(hashlib.md5(test_case.encode("utf-8")).hexdigest(), 16) % (2**32)
    random.seed(seed)
    np.random.seed(seed)
    if torch.cuda.is_available():
        torch.manual_seed(seed)