"""Tests for OpenCV preprocessing — runs without GPU."""

import numpy as np
import pytest

try:
    import cv2
    HAS_CV2 = True
except ImportError:
    HAS_CV2 = False

requires_cv2 = pytest.mark.skipif(not HAS_CV2, reason="opencv-python-headless not installed")

# Add gpu/ to path so imports resolve (gpu modules use relative imports)
import sys
from pathlib import Path
sys.path.insert(0, str(Path(__file__).resolve().parents[2] / "gpu"))


def _make_image(w: int = 200, h: int = 60) -> np.ndarray:
    """White image with black text-like region."""
    img = np.ones((h, w, 3), dtype=np.uint8) * 255
    img[15:45, 20:180] = 30  # dark band simulating text
    return img


@requires_cv2
def test_binarize():
    from core.gpu.models.preprocess import binarize

    img = _make_image()
    result = binarize(img)

    assert result.shape == img.shape
    assert result.dtype == np.uint8
    # Should be mostly black and white (no grays)
    unique_values = np.unique(result)
    assert len(unique_values) <= 3  # 0, 255, maybe one more from anti-aliasing


@requires_cv2
def test_enhance_contrast():
    from core.gpu.models.preprocess import enhance_contrast

    img = _make_image()
    result = enhance_contrast(img)

    assert result.shape == img.shape
    assert result.dtype == np.uint8


@requires_cv2
def test_deskew_no_rotation():
    from core.gpu.models.preprocess import deskew

    img = _make_image()
    result = deskew(img)

    assert result.shape == img.shape
    # Straight image should be unchanged (angle < 0.5 deg)
    assert np.allclose(result, img, atol=5)


@requires_cv2
def test_preprocess_pipeline():
    from core.gpu.models.preprocess import preprocess

    img = _make_image()

    result = preprocess(img, do_binarize=False, do_deskew=False, do_contrast=True)
    assert result.shape == img.shape

    result = preprocess(img, do_binarize=True, do_deskew=True, do_contrast=True)
    assert result.shape[:2] == img.shape[:2]  # h, w same; channels may differ then get converted back


@requires_cv2
def test_preprocess_all_disabled():
    from core.gpu.models.preprocess import preprocess

    img = _make_image()
    result = preprocess(img, do_binarize=False, do_deskew=False, do_contrast=False)

    assert np.array_equal(result, img)