"""StereoConfig 校验与 JSON 加载测试（规格 §9：配置外置、fail-fast）。"""

import json
from pathlib import Path

import pytest

from stereo_ranger import StereoConfig, load_from_json

CONFIG_PATH = Path(__file__).resolve().parents[2] / "config" / "stereo_ranger.json"


def _config_dict() -> dict:
    return json.loads(CONFIG_PATH.read_text(encoding="utf-8"))


def _write(tmp_path: Path, data: dict) -> str:
    path = tmp_path / "stereo.json"
    path.write_text(json.dumps(data, ensure_ascii=False), encoding="utf-8")
    return str(path)


def test_defaults_are_valid_and_domains_are_consistent():
    cfg = StereoConfig()
    assert cfg.focal_baseline_px_m == pytest.approx(cfg.fx_px * cfg.baseline_m)
    assert cfg.z_min_m == pytest.approx(cfg.focal_baseline_px_m / cfg.disparity_max_px)
    assert cfg.z_max_m == pytest.approx(cfg.focal_baseline_px_m / cfg.disparity_min_px)
    assert cfg.z_error_budget_max_m == pytest.approx((cfg.max_delta_z_m * cfg.focal_baseline_px_m) ** 0.5)


def test_load_from_json_matches_defaults():
    assert load_from_json(str(CONFIG_PATH)) == StereoConfig()


def test_missing_field_rejected(tmp_path):
    data = _config_dict()
    data.pop("baseline_m")
    with pytest.raises(ValueError, match="缺少配置字段"):
        load_from_json(_write(tmp_path, data))


def test_unknown_field_rejected(tmp_path):
    data = _config_dict()
    data["radar_fallback"] = True
    with pytest.raises(ValueError, match="未知配置字段"):
        load_from_json(_write(tmp_path, data))


@pytest.mark.parametrize(
    "field,value",
    [
        ("fx_px", "960"),
        ("consistency_N_frames", 3.5),
        ("smooth_alpha", True),
    ],
)
def test_type_error_rejected(tmp_path, field, value):
    data = _config_dict()
    data[field] = value
    with pytest.raises(ValueError, match="配置类型非法"):
        load_from_json(_write(tmp_path, data))


@pytest.mark.parametrize(
    "field,value",
    [
        ("fx_px", 0.0),
        ("fy_px", -1.0),
        ("cx_px", -0.5),
        ("cy_px", -0.5),
        ("baseline_m", 0.0),
        ("tau_y_px", 0.0),
        ("tau_h_ratio", 0.0),
        ("disparity_min_px", 0.0),
        ("disparity_min_px", 60.0),
        ("max_delta_z_m", 0.0),
        ("consistency_N_frames", 0),
        ("consistency_M_frames", 2),
        ("consistency_jump_px", 0.0),
        ("smooth_alpha", 0.0),
        ("smooth_alpha", 1.5),
        ("jump_reset_m", 0.0),
        ("filter_reset_frames", 0),
        ("isolation_gate_px", 0.0),
    ],
)
def test_invalid_values_rejected(field, value):
    with pytest.raises(ValueError, match="配置非法"):
        StereoConfig(**{field: value})


def test_boundary_values_accepted():
    cfg = StereoConfig(disparity_min_px=3.0, disparity_max_px=3.0 + 1e-9, smooth_alpha=1.0, consistency_M_frames=3)
    assert cfg.z_max_m > cfg.z_min_m