"""ground_link_test.py —— 地面坐标注入通道单元测试。

覆盖：parse_payload 解析（合法/缺字段/非法 JSON/非对象/类型错误）、
is_valid 新鲜度判定（未注入/新鲜/超龄边界）。
"""

import pytest

from pod_bridge.ground_link import GroundInjectConfig, GroundLink, GroundTarget


# --- parse_payload ----------------------------------------------------------
def test_parse_valid_payload():
    t = GroundLink.parse_payload(
        b'{"lat": 39.9042, "lon": 116.4074, "alt": 50.0}')
    assert t is not None
    assert t.latitude_deg == pytest.approx(39.9042)
    assert t.longitude_deg == pytest.approx(116.4074)
    assert t.abs_alt_m == pytest.approx(50.0)
    assert t.time_ms == 0  # 打戳由接收方（run）负责


def test_parse_default_alt_is_zero():
    t = GroundLink.parse_payload(b'{"lat": 1.0, "lon": 2.0}')
    assert t is not None
    assert t.abs_alt_m == 0.0


def test_parse_missing_lat_returns_none():
    assert GroundLink.parse_payload(b'{"lon": 2.0}') is None


def test_parse_missing_lon_returns_none():
    assert GroundLink.parse_payload(b'{"lat": 1.0}') is None


def test_parse_invalid_json_returns_none():
    assert GroundLink.parse_payload(b'not json') is None


def test_parse_non_object_returns_none():
    assert GroundLink.parse_payload(b'[1, 2, 3]') is None


def test_parse_string_coords_returns_none():
    assert GroundLink.parse_payload(b'{"lat": "x", "lon": 2.0}') is None


def test_parse_bool_coords_returns_none():
    # True 是 bool 不是数值 → 拒绝
    assert GroundLink.parse_payload(b'{"lat": true, "lon": 2.0}') is None


def test_parse_ignores_ts_field():
    """ts 字段仅诊断，不参与解析（新鲜度用本地接收时刻）。"""
    t = GroundLink.parse_payload(b'{"lat": 1.0, "lon": 2.0, "ts": 999}')
    assert t is not None
    assert t.latitude_deg == pytest.approx(1.0)


# --- is_valid ---------------------------------------------------------------
def _link(timeout_ms=5000):
    return GroundLink(GroundInjectConfig(timeout_ms=timeout_ms),
                      now_ms_fn=lambda: 0)


def _inject(link, time_ms):
    link._target = GroundTarget(latitude_deg=1.0, longitude_deg=2.0,
                                time_ms=time_ms)


def test_is_valid_false_when_never_injected():
    assert _link().is_valid(1000) is False


def test_is_valid_true_when_fresh():
    link = _link(timeout_ms=5000)
    _inject(link, 1000)
    assert link.is_valid(1000) is True
    assert link.is_valid(4000) is True


def test_is_valid_timeout_boundary():
    link = _link(timeout_ms=5000)
    _inject(link, 1000)
    assert link.is_valid(6000) is True   # 恰好 5000ms，未超龄
    assert link.is_valid(6001) is False  # 5001ms，超龄


def test_latest_returns_injected_target():
    link = _link()
    _inject(link, 1000)
    assert link.latest().latitude_deg == pytest.approx(1.0)
    assert link.latest().time_ms == 1000