"""vtc_config_test.py —— TrackingConfig::load_from_json 单元测试。

移植自 reference-c++/visual_track_control/tests/vtc_config_test.cpp。
覆盖（物理追踪思路 §8、需求分析 NFR-007）：真实配置文件加载成功与取值
正确（含 A1/A2 修改后的字段结构）、缺字段 / 缺分组 / 非法枚举 / 非法数值 /
文件缺失均抛带字段名的 ValueError。

C++ 版用字符串替换构造非法变体；Python 版改为 dict 变异（更稳健），
临时文件经 pytest 的 tmp_path 提供。
"""

import json
from pathlib import Path

import pytest

from visual_track_control.config import (HeadingMode, NoDistanceAction,
                                         load_from_json)

_REPO_ROOT = Path(__file__).resolve().parents[3]
REAL_CONFIG = _REPO_ROOT / "reference-c++" / "visual_track_control" / "config" / "track_control.json"


def full_config() -> dict:
    """与真实配置同构的完整合法配置（用于派生各非法变体）。"""
    return {
        "control": {
            "frequency_hz": 20.0,
            "visual_stale_ms": 200,
            "radar_stale_ms": 500,
            "attitude_stale_ms": 300,
        },
        "camera": {
            "image_width": 1920,
            "image_height": 1080,
            "fov_h_deg": 60.0,
            "fov_v_deg": 35.0,
        },
        "heading": {
            "mode": "rate",
            "gain": 1.0,
            "yaw_rate_limit_dps": 30.0,
            "yaw_slew_limit_dps2": 60.0,
        },
        "vertical": {
            "vz_gain_mps_per_deg": 0.1,
            "vz_limit_mps": 2.0,
        },
        "distance": {
            "d_exp_m": 10.0,
            "kp": 0.5,
            "ki": 0.05,
            "kd": 0.1,
            "integral_limit": 2.0,
            "derivative_filter_coef": 0.2,
            "approach_velocity_limit_mps": 3.0,
            "retreat_velocity_limit_mps": 1.0,
            "no_distance_action": "hold",
            "no_distance_approach_limit_mps": 0.5,
        },
        "accel_limit": {
            "ax_mps2": 2.0,
            "ay_mps2": 2.0,
            "az_mps2": 1.5,
        },
    }


def write_temp_json(tmp_path: Path, config: dict, name: str) -> str:
    path = tmp_path / name
    path.write_text(json.dumps(config), encoding="utf-8")
    return str(path)


def test_load_real_config_succeeds():
    cfg = load_from_json(str(REAL_CONFIG))
    assert cfg.control.frequency_hz == 20.0
    assert cfg.control.visual_stale_ms == 200
    assert cfg.camera.image_width == 1920
    assert cfg.camera.image_height == 1080
    assert cfg.camera.fov_h_deg == 60.0
    assert cfg.heading.mode is HeadingMode.RATE  # A2：默认速率式
    assert cfg.heading.yaw_rate_limit_dps == 30.0
    assert cfg.vertical.vz_gain_mps_per_deg == 0.1
    assert cfg.vertical.vz_limit_mps == 2.0
    assert cfg.distance.d_exp_m == 10.0
    assert cfg.distance.no_distance_action is NoDistanceAction.HOLD
    assert cfg.accel_limit.ax_mps2 == 2.0


def test_full_json_round_trip_matches_expected(tmp_path):
    # 内嵌合法配置与真实配置文件行为一致
    path = write_temp_json(tmp_path, full_config(), "vtc_cfg_full.json")
    cfg = load_from_json(path)
    assert cfg.heading.mode is HeadingMode.RATE
    assert cfg.distance.kp == 0.5


def test_position_mode_accepted(tmp_path):
    config = full_config()
    config["heading"]["mode"] = "position"
    path = write_temp_json(tmp_path, config, "vtc_cfg_position.json")
    cfg = load_from_json(path)
    assert cfg.heading.mode is HeadingMode.POSITION


def test_missing_file_throws_with_path():
    with pytest.raises(ValueError) as exc_info:
        load_from_json("/nonexistent/vtc_no_such_file.json")
    assert "vtc_no_such_file.json" in str(exc_info.value)


def test_malformed_json_throws(tmp_path):
    path = tmp_path / "vtc_cfg_bad.json"
    path.write_text("{ this is not json", encoding="utf-8")
    with pytest.raises(ValueError):
        load_from_json(str(path))


def test_missing_field_throws_with_field_name(tmp_path):
    config = full_config()
    del config["heading"]["gain"]
    path = write_temp_json(tmp_path, config, "vtc_cfg_missing.json")
    with pytest.raises(ValueError) as exc_info:
        load_from_json(path)
    assert "heading.gain" in str(exc_info.value)


def test_missing_section_throws(tmp_path):
    config = full_config()
    del config["accel_limit"]
    path = write_temp_json(tmp_path, config, "vtc_cfg_nosection.json")
    with pytest.raises(ValueError) as exc_info:
        load_from_json(path)
    assert "accel_limit" in str(exc_info.value)


def test_invalid_heading_mode_throws(tmp_path):
    config = full_config()
    config["heading"]["mode"] = "magic"
    path = write_temp_json(tmp_path, config, "vtc_cfg_badmode.json")
    with pytest.raises(ValueError) as exc_info:
        load_from_json(path)
    assert "heading.mode" in str(exc_info.value)


def test_invalid_no_distance_action_throws(tmp_path):
    config = full_config()
    config["distance"]["no_distance_action"] = "zoom"
    path = write_temp_json(tmp_path, config, "vtc_cfg_badaction.json")
    with pytest.raises(ValueError) as exc_info:
        load_from_json(path)
    assert "no_distance_action" in str(exc_info.value)


def test_negative_frequency_throws(tmp_path):
    config = full_config()
    config["control"]["frequency_hz"] = -1.0
    path = write_temp_json(tmp_path, config, "vtc_cfg_negfreq.json")
    with pytest.raises(ValueError) as exc_info:
        load_from_json(path)
    assert "control.frequency_hz" in str(exc_info.value)


def test_fov_out_of_range_throws(tmp_path):
    config = full_config()
    config["camera"]["fov_h_deg"] = 200.0
    path = write_temp_json(tmp_path, config, "vtc_cfg_badfov.json")
    with pytest.raises(ValueError) as exc_info:
        load_from_json(path)
    assert "camera.fov_h_deg" in str(exc_info.value)