# SPDX-FileCopyrightText: Copyright (c) 2025-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
# SPDX-License-Identifier: Apache-2.0

import contextlib
import ctypes
import ctypes.util
import os
import sys

import pytest

from cuda.bindings import runtime as cudart


@contextlib.contextmanager
def _gl_context():
    """
    Yield a (tex_id, tex_target) with a current GL context.
    Tries:
      1) Windows: hidden WGL window (no EGL)
      2) Linux with DISPLAY/wayland: hidden window
      3) Linux headless: EGL headless if available
    Skips if none work.
    """
    pyglet = pytest.importorskip("pyglet")

    # Prefer non-headless when a display is available; it's more portable and avoids EGL.
    if sys.platform.startswith("linux") and not (os.environ.get("DISPLAY") or os.environ.get("WAYLAND_DISPLAY")):
        if ctypes.util.find_library("EGL") is None:
            pytest.skip("No DISPLAY and no EGL runtime available for headless context.")
        pyglet.options["headless"] = True

    # Create a minimal offscreen/hidden context
    win = None
    try:
        if not pyglet.options.get("headless"):
            # Hidden window path (WGL on Windows, GLX/WLS on Linux)
            from pyglet import gl

            config = gl.Config(double_buffer=False)
            win = pyglet.window.Window(visible=False, config=config)
            win.switch_to()
        else:
            # Headless EGL path; pyglet will arrange a pbuffer-like headless context
            from pyglet.gl import headless  # noqa: F401

        # Make a tiny texture so we have a real GL object to register
        from pyglet.gl import gl as _gl

        tex_id = _gl.GLuint(0)
        _gl.glGenTextures(1, ctypes.byref(tex_id))
        target = _gl.GL_TEXTURE_2D
        _gl.glBindTexture(target, tex_id.value)
        _gl.glTexParameteri(target, _gl.GL_TEXTURE_MIN_FILTER, _gl.GL_NEAREST)
        _gl.glTexParameteri(target, _gl.GL_TEXTURE_MAG_FILTER, _gl.GL_NEAREST)
        width, height = 16, 16
        _gl.glTexImage2D(target, 0, _gl.GL_RGBA8, width, height, 0, _gl.GL_RGBA, _gl.GL_UNSIGNED_BYTE, None)

        yield int(tex_id.value), int(target)

    except Exception as e:
        # Convert any pyglet/GL creation failure into a clean skip
        pytest.skip(f"Could not create GL context/texture: {type(e).__name__}: {e}")
    finally:
        # Best-effort cleanup
        try:
            from pyglet.gl import gl as _gl

            if tex_id.value:
                _gl.glDeleteTextures(1, ctypes.byref(tex_id))
        except Exception:  # noqa: S110
            pass
        try:
            if win is not None:
                win.close()
        except Exception:  # noqa: S110
            pass


@pytest.mark.parametrize(
    "flags",
    [
        cudart.cudaGraphicsRegisterFlags.cudaGraphicsRegisterFlagsNone,
        cudart.cudaGraphicsRegisterFlags.cudaGraphicsRegisterFlagsWriteDiscard,
    ],
)
def test_cuda_gl_register_image_smoketest(flags):
    with _gl_context() as (tex_id, tex_target):
        # Register
        err, resource = cudart.cudaGraphicsGLRegisterImage(tex_id, tex_target, flags)
        name = cudart.cudaGetErrorName(err)[1].decode()

        # Map error expectations by environment:
        # - success: we actually exercised the API
        # - operating-system: typical when the driver/runtime refuses interop (e.g., no GPU/driver in CI container)
        acceptable = {"cudaSuccess", "cudaErrorOperatingSystem"}

        assert name in acceptable, f"cudaGraphicsGLRegisterImage returned {name}"
        if name == "cudaSuccess":
            assert int(resource) != 0
            # Unregister to be tidy
            cudart.cudaGraphicsUnregisterResource(resource)


def test_cuda_register_image_invalid():
    """Exercise cudaGraphicsGLRegisterImage with dummy handle only using CUDA runtime API."""
    fake_gl_texture_id = 1
    fake_gl_target = 0x0DE1
    flags = cudart.cudaGraphicsRegisterFlags.cudaGraphicsRegisterFlagsWriteDiscard

    err, resource = cudart.cudaGraphicsGLRegisterImage(fake_gl_texture_id, fake_gl_target, flags)
    err_name = cudart.cudaGetErrorName(err)[1].decode()
    err_str = cudart.cudaGetErrorString(err)[1].decode()

    if err == 0:
        cudart.cudaGraphicsUnregisterResource(resource)
        raise AssertionError("Expected error from invalid GL texture ID")
