r"""
This package adds support for CUDA tensor types, that implement the same
function as CPU tensors, but they utilize GPUs for computation.

It is lazily initialized, so you can always import it, and use
:func:`is_available()` to determine if your system supports CUDA.

:ref:`cuda-semantics` has more details about working with CUDA.
"""

import contextlib
import os
import torch
import traceback
import warnings
import threading
from typing import List, Optional, Tuple, Union
from ._utils import _get_device_index, _dummy_type
from .streams import Stream, Event, _Graph
from .. import device as _device
import torch._C

try:
    from torch._C import _cudart  # type: ignore
except ImportError:
    _cudart = None

_initialized = False
_tls = threading.local()
_initialization_lock = threading.Lock()
_queued_calls = []  # don't invoke these until initialization occurs
_is_in_bad_fork = getattr(torch._C, "_cuda_isInBadFork", lambda: False)
_device_t = Union[_device, str, int, None]

# Define dummy _CudaDeviceProperties type if PyTorch was compiled without CUDA
if hasattr(torch._C, '_CudaDeviceProperties'):
    _CudaDeviceProperties = torch._C._CudaDeviceProperties
else:
    _CudaDeviceProperties = _dummy_type('_CudaDeviceProperties')  # type: ignore

# Global variables dynamically populated by native code
has_magma: bool = False
has_half: bool = False
default_generators: Tuple[torch._C.Generator] = ()  # type: ignore[assignment]

def is_available() -> bool:
    r"""Returns a bool indicating if CUDA is currently available."""
    if not hasattr(torch._C, '_cuda_getDeviceCount'):
        return False
    # This function never throws and returns 0 if driver is missing or can't
    # be initialized
    return torch._C._cuda_getDeviceCount() > 0


def _sleep(cycles):
    torch._C._cuda_sleep(cycles)


def _check_capability():
    incorrect_binary_warn = """
    Found GPU%d %s which requires CUDA_VERSION >= %d to
     work properly, but your PyTorch was compiled
     with CUDA_VERSION %d. Please install the correct PyTorch binary
     using instructions from https://pytorch.org
    """

    old_gpu_warn = """
    Found GPU%d %s which is of cuda capability %d.%d.
    PyTorch no longer supports this GPU because it is too old.
    The minimum cuda capability that we support is 3.5.
    """

    if torch.version.cuda is not None:  # on ROCm we don't want this check
        CUDA_VERSION = torch._C._cuda_getCompiledVersion()
        for d in range(device_count()):
            capability = get_device_capability(d)
            major = capability[0]
            minor = capability[1]
            name = get_device_name(d)
            if capability == (3, 0) or major < 3:
                warnings.warn(old_gpu_warn % (d, name, major, capability[1]))
            elif CUDA_VERSION <= 9000 and major >= 7 and minor >= 5:
                warnings.warn(incorrect_binary_warn % (d, name, 10000, CUDA_VERSION))

def _check_cubins():
    incompatible_device_warn = """
{} with CUDA capability sm_{} is not compatible with the current PyTorch installation.
The current PyTorch install supports CUDA capabilities {}.
If you want to use the {} GPU with PyTorch, please check the instructions at https://pytorch.org/get-started/locally/
"""
    if torch.version.cuda is None:  # on ROCm we don't want this check
        return
    arch_list = get_arch_list()
    if len(arch_list) == 0:
        return
    supported_sm = [int(arch.split('_')[1]) for arch in arch_list if 'sm_' in arch]
    for idx in range(device_count()):
        cap_major, cap_minor = get_device_capability(idx)
        # NVIDIA GPU compute architectures are backward compatible within major version
        supported = any([sm // 10 == cap_major for sm in supported_sm])
        if not supported:
            device_name = get_device_name(idx)
            capability = cap_major * 10 + cap_minor
            warnings.warn(incompatible_device_warn.format(device_name, capability, " ".join(arch_list), device_name))


def is_initialized():
    r"""Returns whether PyTorch's CUDA state has been initialized."""
    return _initialized and not _is_in_bad_fork()


def _lazy_call(callable):
    if is_initialized():
        callable()
    else:
        # TODO(torch_deploy): this accesses linecache, which attempts to read the
        # file system to get traceback info. Patch linecache or do something
        # else here if this ends up being important.

        # Don't store the actual traceback to avoid memory cycle
        _queued_calls.append((callable, traceback.format_stack()))

_lazy_call(_check_capability)
_lazy_call(_check_cubins)


class DeferredCudaCallError(Exception):
    pass


def init():
    r"""Initialize PyTorch's CUDA state.  You may need to call
    this explicitly if you are interacting with PyTorch via
    its C API, as Python bindings for CUDA functionality will not
    be available until this initialization takes place.  Ordinary users
    should not need this, as all of PyTorch's CUDA methods
    automatically initialize CUDA state on-demand.

    Does nothing if the CUDA state is already initialized.
    """
    _lazy_init()


def _lazy_init():
    global _initialized, _queued_calls
    if is_initialized() or hasattr(_tls, 'is_initializing'):
        return
    with _initialization_lock:
        # We be double-checked locking, boys!  This is OK because
        # the above test was GIL protected anyway.  The inner test
        # is for when a thread blocked on some other thread which was
        # doing the initialization; when they get the lock, they will
        # find there is nothing left to do.
        if is_initialized():
            return
        # It is important to prevent other threads from entering _lazy_init
        # immediately, while we are still guaranteed to have the GIL, because some
        # of the C calls we make below will release the GIL
        if _is_in_bad_fork():
            raise RuntimeError(
                "Cannot re-initialize CUDA in forked subprocess. To use CUDA with "
                "multiprocessing, you must use the 'spawn' start method")
        if not hasattr(torch._C, '_cuda_getDeviceCount'):
            raise AssertionError("Torch not compiled with CUDA enabled")
        if _cudart is None:
            raise AssertionError(
                "libcudart functions unavailable. It looks like you have a broken build?")
        # This function throws if there's a driver initialization error, no GPUs
        # are found or any other error occurs
        torch._C._cuda_init()
        # Some of the queued calls may reentrantly call _lazy_init();
        # we need to just return without initializing in that case.
        # However, we must not let any *other* threads in!
        _tls.is_initializing = True
        try:
            for queued_call, orig_traceback in _queued_calls:
                try:
                    queued_call()
                except Exception as e:
                    msg = (f"CUDA call failed lazily at initialization with error: {str(e)}\n\n"
                           f"CUDA call was originally invoked at:\n\n{orig_traceback}")
                    raise DeferredCudaCallError(msg) from e
        finally:
            delattr(_tls, 'is_initializing')
        _initialized = True


def cudart():
    _lazy_init()
    return _cudart


class cudaStatus(object):
    SUCCESS: int = 0
    ERROR_NOT_READY: int = 34

class CudaError(RuntimeError):
    def __init__(self, code: int) -> None:
        msg = _cudart.cudaGetErrorString(_cudart.cudaError(code))
        super(CudaError, self).__init__('{0} ({1})'.format(msg, code))


def check_error(res: int) -> None:
    if res != _cudart.cudaError.success:
        raise CudaError(res)


class device(object):
    r"""Context-manager that changes the selected device.

    Args:
        device (torch.device or int): device index to select. It's a no-op if
            this argument is a negative integer or ``None``.
    """

    def __init__(self, device):
        self.idx = _get_device_index(device, optional=True)
        self.prev_idx = -1

    def __enter__(self):
        if self.idx == -1:
            return
        self.prev_idx = torch._C._cuda_getDevice()
        if self.prev_idx != self.idx:
            torch._C._cuda_setDevice(self.idx)
        _lazy_init()

    def __exit__(self, *args):
        if self.prev_idx != self.idx:
            torch._C._cuda_setDevice(self.prev_idx)
        return False


class device_of(device):
    r"""Context-manager that changes the current device to that of given object.

    You can use both tensors and storages as arguments. If a given object is
    not allocated on a GPU, this is a no-op.

    Args:
        obj (Tensor or Storage): object allocated on the selected device.
    """

    def __init__(self, obj):
        idx = obj.get_device() if obj.is_cuda else -1
        super(device_of, self).__init__(idx)


def set_device(device: _device_t) -> None:
    r"""Sets the current device.

    Usage of this function is discouraged in favor of :any:`device`. In most
    cases it's better to use ``CUDA_VISIBLE_DEVICES`` environmental variable.

    Args:
        device (torch.device or int): selected device. This function is a no-op
            if this argument is negative.
    """
    device = _get_device_index(device)
    if device >= 0:
        torch._C._cuda_setDevice(device)


def get_device_name(device: Optional[_device_t] = None) -> str:
    r"""Gets the name of a device.

    Args:
        device (torch.device or int, optional): device for which to return the
            name. This function is a no-op if this argument is a negative
            integer. It uses the current device, given by :func:`~torch.cuda.current_device`,
            if :attr:`device` is ``None`` (default).

    Returns:
        str: the name of the device
    """
    return get_device_properties(device).name


def get_device_capability(device: Optional[_device_t] = None) -> Tuple[int, int]:
    r"""Gets the cuda capability of a device.

    Args:
        device (torch.device or int, optional): device for which to return the
            device capability. This function is a no-op if this argument is
            a negative integer. It uses the current device, given by
            :func:`~torch.cuda.current_device`, if :attr:`device` is ``None``
            (default).

    Returns:
        tuple(int, int): the major and minor cuda capability of the device
    """
    prop = get_device_properties(device)
    return prop.major, prop.minor


def get_device_properties(device: _device_t) -> _CudaDeviceProperties:
    r"""Gets the properties of a device.

    Args:
        device (torch.device or int or str): device for which to return the
            properties of the device.

    Returns:
        _CudaDeviceProperties: the properties of the device
    """
    _lazy_init()  # will define _get_device_properties
    device = _get_device_index(device, optional=True)
    if device < 0 or device >= device_count():
        raise AssertionError("Invalid device id")
    return _get_device_properties(device)  # type: ignore[name-defined]

def can_device_access_peer(device: _device_t, peer_device: _device_t) -> bool:
    r"""Checks if peer access between two devices is possible.
    """
    _lazy_init()
    device = _get_device_index(device, optional=True)
    peer_device = _get_device_index(peer_device)
    if device < 0 or device >= device_count():
        raise AssertionError("Invalid device id")
    if peer_device < 0 or peer_device >= device_count():
        raise AssertionError("Invalid peer device id")
    return torch._C._cuda_canDeviceAccessPeer(device, peer_device)


@contextlib.contextmanager
def stream(stream):
    r"""Context-manager that selects a given stream.

    All CUDA kernels queued within its context will be enqueued on a selected
    stream.

    Args:
        stream (Stream): selected stream. This manager is a no-op if it's
            ``None``.

    .. note:: Streams are per-device. If the selected stream is not on the
        current device, this function will also change the current device to
        match the stream.
    """
    if stream is None:
        yield
        return
    src_prev_stream = current_stream()

    if src_prev_stream.device != stream.device: