import os
import sys
from pathlib import Path

import pytest

REPO_ROOT = Path(__file__).resolve().parents[1]
SRC_ROOT = REPO_ROOT / "src"
if str(SRC_ROOT) not in sys.path:
    sys.path.insert(0, str(SRC_ROOT))

from orisys import Sensor
from orisys import configs as orisys_configs
from orisys.backend_availability import check_cupy_available, check_opencl_available


def _resolve_test_video() -> Path:
    env_video = os.getenv("ORISYS_TEST_VIDEO")
    if env_video:
        raw = Path(env_video)
        candidates = [
            raw,                # as provided (absolute or cwd-relative)
            REPO_ROOT / raw,    # repo-relative
        ]
        # Common typo fallback: "test/..." -> "tests/..."
        if env_video.startswith("test/") or env_video.startswith("test\\"):
            fixed = Path("tests", *Path(env_video).parts[1:])
            candidates.append(REPO_ROOT / fixed)

        for candidate in candidates:
            if candidate.exists():
                return candidate
        return raw

    # Prefer tests/ fixture clip; fallback kept by caller exists check.
    return REPO_ROOT / "tests" / "idle_1min.mp4"


@pytest.fixture(scope="session")
def test_video_path() -> Path:
    path = _resolve_test_video()
    if not path.exists():
        pytest.skip(
            "Test video not found. Set ORISYS_TEST_VIDEO to a valid video path."
        )
    return path


@pytest.fixture(scope="session")
def test_config_name() -> str:
    requested = os.getenv("ORISYS_TEST_CONFIG")

    def _is_usable_config(name: str) -> bool:
        cfg = orisys_configs.load_config(name)
        return "box_size" in cfg.get("stitcher", {})

    if requested:
        if not _is_usable_config(requested):
            raise RuntimeError(
                f"ORISYS_TEST_CONFIG='{requested}' is missing required key "
                "'stitcher.box_size'. Use a config like 'ddjx01' or provide a full path."
            )
        return requested

    # Auto-pick a stable config for tests (avoid prototype variants missing keys).
    for name in orisys_configs.list_config():
        try:
            if _is_usable_config(name):
                return name
        except Exception:
            continue

    raise RuntimeError(
        "No usable config found for tests (missing 'stitcher.box_size'). "
        "Set ORISYS_TEST_CONFIG to a valid config JSON/path."
    )


@pytest.fixture(scope="session")
def available_backends() -> list[str]:
    backends = ["cpu"]
    if check_cupy_available():
        backends.append("cupy")
    if check_opencl_available():
        backends.append("opencl")
    return backends


def make_sensor(
    video_path: Path,
    config_name: str = "prototype",
    backend: str = "cpu",
    verbose: bool = False,
) -> Sensor:
    use_cuda = backend in ("cupy", "opencl")
    return Sensor(
        vid_src=str(video_path),
        cuda=use_cuda,
        isstitch=True,
        verbose=verbose,
        config_name=config_name,
        backend=backend,
    )


@pytest.fixture
def sensor_factory(test_video_path, test_config_name):
    def _factory(backend: str = "cpu", verbose: bool = False):
        return make_sensor(
            test_video_path,
            config_name=test_config_name,
            backend=backend,
            verbose=verbose,
        )

    return _factory