"""Tests der geglätteten Wurfgeschwindigkeit."""

import random

import pytest

from sandbox.interaction import VelocityTracker
from sandbox.physics import Vector2

WINDOW = 0.1
SMOOTHING = 0.05


def _track(velocity: Vector2, fps: float, seconds: float) -> VelocityTracker:
    """Bewegt einen Zeiger mit konstanter Geschwindigkeit und liefert den Tracker."""
    tracker = VelocityTracker(WINDOW, SMOOTHING)
    tracker.reset(0.0, Vector2(0, 0))
    frames = round(seconds * fps)
    for frame in range(1, frames + 1):
        t = frame / fps
        tracker.add_sample(t, velocity * t)
    return tracker


def test_constant_motion_is_measured_exactly() -> None:
    tracker = _track(Vector2(600, -200), fps=60, seconds=0.5)
    assert tracker.velocity.is_close(Vector2(600, -200), tolerance=1.0)


def test_result_does_not_depend_on_the_frame_rate() -> None:
    slow = _track(Vector2(500, 0), fps=30, seconds=0.5)
    fast = _track(Vector2(500, 0), fps=144, seconds=0.5)
    assert slow.velocity.x == pytest.approx(fast.velocity.x, rel=0.01)


def test_velocity_decays_when_the_pointer_stops() -> None:
    tracker = _track(Vector2(800, 0), fps=60, seconds=0.3)
    resting = Vector2(800 * 0.3, 0)
    for frame in range(1, 31):  # eine halbe Sekunde stillhalten
        tracker.add_sample(0.3 + frame / 60, resting)
        if frame == 12:  # nach 0,2 s ist der Schwung auf wenige Prozent abgeklungen
            assert tracker.velocity.length() < 0.1 * 800
    assert tracker.velocity.length() < 1.0


def test_jitter_is_smoothed() -> None:
    rng = random.Random(0)
    tracker = VelocityTracker(WINDOW, SMOOTHING)
    tracker.reset(0.0, Vector2(0, 0))
    for frame in range(1, 61):
        t = frame / 60
        noise = Vector2(rng.uniform(-3, 3), rng.uniform(-3, 3))  # zittrige Hand
        tracker.add_sample(t, Vector2(400 * t, 0) + noise)
    assert tracker.velocity.x == pytest.approx(400, rel=0.1)
    assert abs(tracker.velocity.y) < 60


def test_samples_with_the_same_timestamp_replace_each_other() -> None:
    tracker = VelocityTracker(WINDOW, SMOOTHING)
    tracker.reset(0.0, Vector2(0, 0))
    tracker.add_sample(0.0, Vector2(50, 0))  # gleicher Frame: keine Division durch 0
    assert tracker.velocity == Vector2(0, 0)
    tracker.add_sample(0.1, Vector2(50, 0))
    assert tracker.velocity.x == 0  # die ersetzte Position ist der neue Bezugspunkt


def test_first_sample_without_reset_starts_a_measurement() -> None:
    tracker = VelocityTracker(WINDOW, SMOOTHING)
    tracker.add_sample(1.0, Vector2(5, 5))
    assert tracker.velocity == Vector2(0, 0)


def test_invalid_parameters_are_rejected() -> None:
    with pytest.raises(ValueError, match="positiv"):
        VelocityTracker(0, SMOOTHING)