"""tracklet_test.py —— Tracklet 与几何工具单元测试。

移植自 reference-c++/target_tracker/tests/tracklet_test.cpp。
覆盖（视觉追踪技术路线 §3.2/§5.2/§6.1/§7）：框互转、IoU 边界、
IsDead/IsCoasting 判定（严格大于）、Predict/Update/MarkMiss 计数语义。
"""

import pytest

from target_tracker.tracklet import (BoxXYXY, BoxCXCYWH, Tracklet, compute_iou,
                                     to_center_size, to_xyxy)


# ---- 框表示互转（§7） ----

def test_round_trip_preserves_values():
    box = BoxXYXY(10.0, 20.0, 50.0, 80.0)
    c = to_center_size(box)
    assert c.cx == 30.0   # (10+50)/2
    assert c.cy == 50.0   # (20+80)/2
    assert c.w == 40.0    # 50−10
    assert c.h == 60.0    # 80−20

    back = to_xyxy(c)
    assert back.x1 == box.x1
    assert back.y1 == box.y1
    assert back.x2 == box.x2
    assert back.y2 == box.y2


# ---- IoU 边界（§5.2） ----

def test_identical_boxes_return_one():
    a = BoxXYXY(10.0, 10.0, 30.0, 30.0)
    assert compute_iou(a, a) == pytest.approx(1.0, abs=1e-12)  # 完全重合 = 1


def test_disjoint_boxes_return_zero():
    a = BoxXYXY(0.0, 0.0, 10.0, 10.0)
    b = BoxXYXY(20.0, 20.0, 30.0, 30.0)
    assert compute_iou(a, b) == 0.0  # 零交集


def test_touching_edges_return_zero():
    # 仅边/角相接：交集宽高为 0 → 交集面积 ≤ 0 返回 0（§5.2）
    a = BoxXYXY(0.0, 0.0, 10.0, 10.0)
    b = BoxXYXY(10.0, 0.0, 20.0, 10.0)   # 右边缘相接
    assert compute_iou(a, b) == 0.0
    c = BoxXYXY(10.0, 10.0, 20.0, 20.0)  # 角点相接
    assert compute_iou(a, c) == 0.0


def test_empty_box_returns_zero():
    normal = BoxXYXY(0.0, 0.0, 10.0, 10.0)
    zero_area = BoxXYXY(5.0, 5.0, 5.0, 5.0)    # 零面积
    inverted = BoxXYXY(10.0, 10.0, 0.0, 0.0)   # 反向（负宽高）
    assert compute_iou(normal, zero_area) == 0.0
    assert compute_iou(zero_area, normal) == 0.0
    assert compute_iou(normal, inverted) == 0.0
    assert compute_iou(zero_area, zero_area) == 0.0


def test_partial_overlap_is_correct():
    # A = [0,0,10,10]（面积 100），B = [5,5,15,15]（面积 100），交集 25
    a = BoxXYXY(0.0, 0.0, 10.0, 10.0)
    b = BoxXYXY(5.0, 5.0, 15.0, 15.0)
    assert compute_iou(a, b) == pytest.approx(25.0 / 175.0, abs=1e-12)
    assert compute_iou(b, a) == pytest.approx(25.0 / 175.0, abs=1e-12)  # 对称性


# ---- 构造与派生状态（§3.2 / §6.1） ----

def test_construction_initial_fields():
    t = Tracklet(7, BoxCXCYWH(100.0, 100.0, 20.0, 20.0), 0.9, 1, 8)

    assert t.track_id == 7
    assert t.lost_count == 0
    assert t.max_lost == 8
    assert t.confidence == 0.9
    assert t.cls_id == 1
    assert t.age == 1   # 创建时为 1（§3.2）
    assert t.hits == 1  # 创建时为 1（§3.2）
    assert t.last_center == (100.0, 100.0)
    assert t.last_box is not None  # 创建当帧即赋 last_box（§7 步骤 5）
    assert t.last_box.x1 == 90.0
    assert t.last_box.y1 == 90.0
    assert t.last_box.x2 == 110.0
    assert t.last_box.y2 == 110.0
    assert not t.is_dead
    assert not t.is_coasting


def test_is_dead_uses_strictly_greater():
    # IsDead 使用严格大于：lost_count == max_lost 仍存活（§6.1 注记 2）
    t = Tracklet(0, BoxCXCYWH(100.0, 100.0, 20.0, 20.0), 0.9, 0, 8)
    for _ in range(8):
        t.mark_miss()
        assert not t.is_dead, f"lost_count={t.lost_count} 未超过 max_lost 不应判死"
    assert t.lost_count == 8
    t.mark_miss()  # lost_count = 9 > 8
    assert t.is_dead


def test_is_coasting_when_lost_positive():
    t = Tracklet(0, BoxCXCYWH(100.0, 100.0, 20.0, 20.0), 0.9, 0, 8)
    assert not t.is_coasting
    t.mark_miss()
    assert t.is_coasting  # lost_count > 0 即 Coast（§3.2）


# ---- 生命周期方法计数语义（§7） ----

def test_predict_advances_age_and_updates_last_state():
    t = Tracklet(0, BoxCXCYWH(100.0, 100.0, 20.0, 20.0), 0.9, 0, 8)
    age_before = t.age
    t.predict()  # 速度为零：位置不变，但 age+1、last_box 更新为预测框
    assert t.age == age_before + 1
    assert t.last_box is not None
    assert t.last_center[0] == pytest.approx(100.0, abs=1e-9)
    assert t.last_center[1] == pytest.approx(100.0, abs=1e-9)
    # hits / lost_count / confidence 不受预测影响
    assert t.hits == 1
    assert t.lost_count == 0
    assert t.confidence == 0.9


def test_update_resets_lost_and_increments_hits():
    t = Tracklet(0, BoxCXCYWH(100.0, 100.0, 20.0, 20.0), 0.9, 0, 8)
    t.mark_miss()
    t.mark_miss()
    assert t.lost_count == 2
    assert t.is_coasting

    age_before = t.age
    box = BoxXYXY(150.0, 160.0, 170.0, 180.0)
    t.update(box, 0.75, 2)

    assert t.lost_count == 0   # 匹配成功清零（§7）
    assert t.hits == 2         # hits+1
    assert t.age == age_before + 1  # age+1
    assert t.confidence == 0.75
    assert t.cls_id == 2
    assert t.last_center == (160.0, 170.0)  # ((150+170)/2, (160+180)/2)
    assert t.last_box is not None
    assert t.last_box.x1 == box.x1
    assert t.last_raw_box is not None  # 实测框同步记录
    assert t.last_raw_box.x2 == box.x2
    assert not t.is_coasting


def test_mark_miss_increments_lost_and_age():
    t = Tracklet(0, BoxCXCYWH(100.0, 100.0, 20.0, 20.0), 0.9, 0, 8)
    age_before = t.age
    t.mark_miss()
    assert t.lost_count == 1
    assert t.age == age_before + 1
    # MarkMiss 不影响 hits / confidence
    assert t.hits == 1
    assert t.confidence == 0.9