"""Unit tests for core engine components.

Run with: pytest tests/test_core.py -v
No ONNX model or GPU required — detector is mocked.
"""
from __future__ import annotations

import numpy as np
import pytest

from core.analytics import AnalyticsEngine, CountingLine, AnomalyDetector
from core.detector import Detection
from core.tracker import Track


# ── Fixtures ──────────────────────────────────────────────────────────────────

def make_track(track_id: int, x1: float, y1: float, x2: float, y2: float, class_id: int = 0) -> Track:
    return Track(track_id=track_id, bbox=(x1, y1, x2, y2), confidence=0.9, class_id=class_id)


def make_detection(x1: float, y1: float, x2: float, y2: float, class_id: int = 0) -> Detection:
    return Detection(bbox=(x1, y1, x2, y2), confidence=0.9, class_id=class_id)


# ── Detection tests ───────────────────────────────────────────────────────────

class TestDetection:
    def test_class_name_assigned(self):
        d = make_detection(0, 0, 100, 100, class_id=0)
        assert d.class_name == "car"

    def test_class_name_bus(self):
        d = make_detection(0, 0, 100, 100, class_id=1)
        assert d.class_name == "bus"

    def test_xywh(self):
        d = make_detection(10, 20, 110, 70, class_id=0)
        x, y, w, h = d.xywh
        assert x == 10 and y == 20 and w == 100 and h == 50

    def test_area(self):
        d = make_detection(0, 0, 50, 100, class_id=0)
        assert d.area == pytest.approx(5000.0)


# ── Track tests ───────────────────────────────────────────────────────────────

class TestTrack:
    def test_center(self):
        t = make_track(1, 0, 0, 100, 100)
        cx, cy = t.center
        assert cx == pytest.approx(50.0)
        assert cy == pytest.approx(50.0)

    def test_class_name(self):
        t = make_track(1, 0, 0, 100, 100, class_id=2)
        assert t.class_name == "motorcycle"


# ── CountingLine tests ────────────────────────────────────────────────────────

class TestCountingLine:
    def test_no_crossing_on_first_frame(self):
        line = CountingLine((0, 100), (1280, 100))
        track = make_track(1, 0, 50, 100, 90)   # center y=70, above line
        crossed = line.update([track])
        assert crossed == []
        assert line.total_count == 0

    def test_crossing_detected(self):
        """Track moves from above line (y<100) to below (y>100)."""
        line = CountingLine((0, 100), (1280, 100))

        # Frame 1: track above line
        track_above = make_track(1, 0, 0, 100, 80, class_id=0)   # center y=40
        line.update([track_above])

        # Frame 2: track below line
        track_below = make_track(1, 0, 120, 100, 200, class_id=0)  # center y=160
        crossed = line.update([track_below])

        assert len(crossed) == 1
        assert line.total_count == 1
        assert line.count_per_class["car"] == 1

    def test_no_false_crossing_same_side(self):
        """Track stays on same side — no count."""
        line = CountingLine((0, 100), (1280, 100))
        for y_top in [0, 20, 40, 60]:
            track = make_track(1, 0, y_top, 100, y_top + 80)
            line.update([track])
        assert line.total_count == 0

    def test_multiple_tracks(self):
        line = CountingLine((0, 100), (1280, 100))

        # Both tracks above
        line.update([
            make_track(1, 0, 0, 100, 80),
            make_track(2, 200, 0, 300, 80),
        ])

        # Both cross
        crossed = line.update([
            make_track(1, 0, 120, 100, 200),
            make_track(2, 200, 120, 300, 200),
        ])
        assert len(crossed) == 2
        assert line.total_count == 2


# ── AnalyticsEngine tests ─────────────────────────────────────────────────────

class TestAnalyticsEngine:
    def test_empty_frame(self):
        engine = AnalyticsEngine()
        metrics = engine.update([])
        assert metrics.vehicles_in_frame == 0
        assert metrics.total_count == 0
        assert metrics.avg_speed_kmh == 0.0

    def test_vehicles_in_frame_count(self):
        engine = AnalyticsEngine()
        tracks = [make_track(i, i * 100, 0, i * 100 + 80, 80) for i in range(5)]
        metrics = engine.update(tracks)
        assert metrics.vehicles_in_frame == 5

    def test_count_increments_on_crossing(self):
        from core.analytics import CountingLineSpec
        engine = AnalyticsEngine(counting_lines=[CountingLineSpec("line", (0, 100), (1280, 100))])

        # Frame 1: above
        engine.update([make_track(1, 0, 0, 100, 80)])
        # Frame 2: below (crossing)
        metrics = engine.update([make_track(1, 0, 120, 100, 200)])

        assert metrics.total_count == 1

    def test_tracks_in_metrics(self):
        engine = AnalyticsEngine()
        tracks = [make_track(42, 0, 0, 100, 100, class_id=1)]
        metrics = engine.update(tracks)
        assert len(metrics.tracks) == 1
        assert metrics.tracks[0]["id"] == 42
        assert metrics.tracks[0]["class_name"] == "bus"

    def test_frame_index_increments(self):
        engine = AnalyticsEngine()
        m1 = engine.update([])
        m2 = engine.update([])
        assert m2.frame_index == m1.frame_index + 1


# ── AnomalyDetector tests ─────────────────────────────────────────────────────

class TestAnomalyDetector:
    def test_no_alert_on_small_history(self):
        detector = AnomalyDetector()
        # Fill with 10 frames — not enough for spike detection (needs 60)
        for _ in range(10):
            alerts = detector.update([make_track(1, 0, 0, 100, 100)])
        assert not any("surge" in a.message for a in alerts)

    def test_stopped_vehicle_alert(self):
        detector = AnomalyDetector()
        detector.STOPPED_MIN_FRAMES = 3   # speed up test

        # Same position for 3+ frames
        track = make_track(99, 50, 50, 150, 150)
        alerts = []
        for _ in range(4):
            alerts = detector.update([track])

        assert any("Stopped" in a.message for a in alerts)