"""Shared pytest fixtures: builds a minimal fake KITTI raw date/drive tree."""

from __future__ import annotations

from pathlib import Path

import numpy as np
import pytest
from PIL import Image

IMAGE_SIZE = (32, 32)  # (width, height)


def make_fake_kitti_date(
    date_dir: Path,
    drive: str = "0001",
    num_frames: int = 4,
    baseline_shift_units: float = -40.0,
    focal_length: float = 700.0,
) -> Path:
    """Builds a minimal fake KITTI raw <date>/ directory: per-date calib files + one drive.

    `baseline_shift_units` is P_rect_02[0, 3] in KITTI's raw projection-matrix
    units (not meters) -- nonzero by default so tests can catch a dropped
    stereo-baseline correction (see kitti_calib.py's docstring). Passing 0.0
    reproduces the (buggy, cam0-only-correct) behavior for comparison tests.
    """
    date_dir.mkdir(parents=True, exist_ok=True)
    drive_name = f"{date_dir.name}_drive_{drive}_sync"
    drive_dir = date_dir / drive_name
    image_dir = drive_dir / "image_02" / "data"
    lidar_dir = drive_dir / "velodyne_points" / "data"
    image_dir.mkdir(parents=True, exist_ok=True)
    lidar_dir.mkdir(parents=True, exist_ok=True)

    rng = np.random.default_rng(0)
    width, height = IMAGE_SIZE
    for frame in range(num_frames):
        image = rng.integers(0, 255, size=(height, width, 3), dtype=np.uint8)
        Image.fromarray(image).save(image_dir / f"{frame:010d}.png")

        num_points = 32
        points = rng.uniform(-5.0, 5.0, size=(num_points, 3)).astype(np.float32)
        points[:, 2] = rng.uniform(2.0, 20.0, size=num_points).astype(np.float32)  # plausible forward depth
        reflectance = rng.uniform(0.0, 1.0, size=(num_points, 1)).astype(np.float32)
        scan = np.concatenate([points, reflectance], axis=1)
        scan.tofile(lidar_dir / f"{frame:010d}.bin")

    (date_dir / "calib_imu_to_velo.txt").write_text(
        "calib_time: 15-Mar-2012 11:37:16\n"
        "R: 1.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.0\n"
        "T: 0.8 0.0 0.3\n"
    )
    (date_dir / "calib_velo_to_cam.txt").write_text(
        "calib_time: 15-Mar-2012 11:37:16\n"
        "R: 7.533745e-03 -9.999714e-01 -6.166020e-04 "
        "1.480249e-02 7.280733e-04 -9.998902e-01 "
        "9.998621e-01 7.523790e-03 1.480755e-02\n"
        "T: -4.069766e-03 -7.631618e-02 -2.717806e-01\n"
    )
    p_rect_00 = f"{focal_length} 0.0 16.0 0.0 0.0 {focal_length} 16.0 0.0 0.0 0.0 1.0 0.0"
    p_rect_02 = f"{focal_length} 0.0 16.0 {baseline_shift_units} 0.0 {focal_length} 16.0 0.0 0.0 0.0 1.0 0.0"
    (date_dir / "calib_cam_to_cam.txt").write_text(
        "calib_time: 15-Mar-2012 11:37:16\n"
        "R_rect_00: 1.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.0\n"
        f"S_rect_00: {float(width)} {float(height)}\n"
        f"P_rect_00: {p_rect_00}\n"
        f"S_rect_02: {float(width)} {float(height)}\n"
        f"P_rect_02: {p_rect_02}\n"
    )
    return date_dir


@pytest.fixture
def fake_kitti_root(tmp_path: Path) -> Path:
    """A fake KITTI raw root with one date (`2011_09_30`) and one drive (`0016`), 4 frames."""
    make_fake_kitti_date(tmp_path / "2011_09_30", drive="0016", num_frames=4)
    return tmp_path