"""Shared fixtures for LiDAR pipeline tests."""

import numpy as np
import rasterio
from rasterio.transform import from_bounds
import pytest
from pathlib import Path


@pytest.fixture
def tmp_output_dir(tmp_path):
    """Create a temporary output directory."""
    out = tmp_path / "output"
    out.mkdir()
    return out


@pytest.fixture
def synthetic_dem(tmp_path):
    """Create a small synthetic DEM GeoTIFF with realistic terrain features.

    Includes:
    - A gaussian hill (tumulus)
    - A linear ridge (wall)
    - A depression (ditch)
    - Background noise
    """
    size = 200
    x = np.linspace(0, 1000, size)
    y = np.linspace(0, 1000, size)
    X, Y = np.meshgrid(x, y)

    # Base terrain with gentle slope
    dem = 100.0 + 0.01 * X + 0.005 * Y

    # Gaussian hill (tumulus) at center
    dem += 5.0 * np.exp(-((X - 500)**2 + (Y - 500)**2) / (2 * 80**2))

    # Linear ridge (wall) running SW-NE
    dist_to_wall = np.abs((X - 200) * 0.707 + (Y - 300) * 0.707) / np.sqrt(2)
    dem += 1.5 * np.exp(-dist_to_wall**2 / (2 * 10**2))

    # Depression (ditch)
    dist_to_ditch = np.abs(X - 800)
    dem -= 2.0 * np.exp(-dist_to_ditch**2 / (2 * 15**2)) * (Y > 300) * (Y < 700)

    # Small random noise
    rng = np.random.default_rng(42)
    dem += rng.normal(0, 0.05, dem.shape)

    # Save as GeoTIFF (Lambert 93)
    dem_file = tmp_path / "test_dem.tif"
    transform = from_bounds(660000, 6700000, 661000, 6701000, size, size)

    with rasterio.open(
        dem_file, 'w',
        driver='GTiff', height=size, width=size,
        count=1, dtype='float32',
        crs='EPSG:2154', transform=transform,
        compress='lzw'
    ) as dst:
        dst.write(dem.astype('float32'), 1)

    return dem_file


@pytest.fixture
def synthetic_dem_data(synthetic_dem):
    """Return (array, transform, crs) from the synthetic DEM."""
    with rasterio.open(synthetic_dem) as src:
        return src.read(1), src.transform, src.crs