"""StereoConfig 默认值、派生区间与 JSON 加载测试（规格 §2：参数全部外置）。"""

import json

import pytest

from stereo_ranger.config import StereoConfig, load_from_json

VALID = {
    "fx_px": 1663.0, "fy_px": 1663.0, "cx_px": 960.0, "cy_px": 540.0,
    "baseline_m": 0.12, "z_min_m": 2.0, "z_max_m": 40.0,
    "vertical_tau_px": 3.0, "height_ratio_tau": 0.3,
    "disparity_min_px": 4.0, "range_tol_m": 3.0, "disp_noise_px": 1.5,
    "use_center_fallback": False, "filter_enabled": True,
    "filter_alpha": 0.5, "filter_jump_ratio": 0.1, "warn_interval_s": 1.0,
}


def test_defaults_and_disparity_window():
    cfg = StereoConfig()
    assert cfg.baseline_m == 0.06 and cfg.fx_px == 960.0
    # FB = 57.6，z 窗口 [1, 50] m -> D 窗口 [57.6/50, 57.6/1]
    lo, hi = cfg.disparity_bounds_px()
    assert lo == pytest.approx(1.152)
    assert hi == pytest.approx(57.6)


@pytest.mark.parametrize("kwargs", [
    {"baseline_m": 0.0},
    {"fx_px": -1.0},
    {"fy_px": 0.0},
    {"cx_px": -1.0},
    {"z_min_m": 0.0},
    {"z_max_m": 10.0, "z_min_m": 20.0},
    {"vertical_tau_px": 0.0},
    {"height_ratio_tau": 0.0},
    {"disparity_min_px": 0.0},
    {"range_tol_m": 0.0},
    {"disp_noise_px": 0.0},
    {"filter_alpha": 0.0},
    {"filter_alpha": 1.5},
    {"filter_jump_ratio": -0.1},
    {"warn_interval_s": -1.0},
])
def test_invalid_config_raises(kwargs):
    with pytest.raises(ValueError):
        StereoConfig(**kwargs)


def test_load_from_json_roundtrip(tmp_path):
    p = tmp_path / "stereo.json"
    p.write_text(json.dumps(VALID), encoding="utf-8")
    cfg = load_from_json(str(p))
    for field, value in VALID.items():
        assert getattr(cfg, field) == value
    lo, hi = cfg.disparity_bounds_px()
    assert hi == pytest.approx(1663.0 * 0.12 / 2.0)  # FB / z_min
    assert lo == pytest.approx(1663.0 * 0.12 / 40.0)  # FB / z_max


def test_load_from_json_missing_field_reports_name(tmp_path):
    p = tmp_path / "stereo.json"
    data = dict(VALID)
    del data["baseline_m"]
    p.write_text(json.dumps(data), encoding="utf-8")
    with pytest.raises(ValueError, match="baseline_m"):
        load_from_json(str(p))


def test_load_from_json_unknown_field_rejected(tmp_path):
    p = tmp_path / "stereo.json"
    data = dict(VALID)
    data["magic_extra"] = 1
    p.write_text(json.dumps(data), encoding="utf-8")
    with pytest.raises(ValueError, match="magic_extra"):
        load_from_json(str(p))