import importlib.util
from pathlib import Path


def _load_patterns_module():
    repo_root = Path(__file__).resolve().parents[1]
    # Canonical home for shipped demos — `workspace/` is gitignored.
    module_path = repo_root / "src" / "static" / "bundled-demos" / "led_patterns.py"
    spec = importlib.util.spec_from_file_location("led_patterns", module_path)
    module = importlib.util.module_from_spec(spec)
    assert spec is not None and spec.loader is not None
    spec.loader.exec_module(module)
    return module


def test_rainbow_frame_shape_and_bounds():
    patterns = _load_patterns_module()
    frame = patterns.rainbow_frame(12, 3)
    assert len(frame) == 12
    for color in frame:
        assert len(color) == 3
        assert all(0 <= c <= 255 for c in color)


def test_chase_frame_has_head_and_tail():
    patterns = _load_patterns_module()
    frame = patterns.chase_frame(8, 5, color=(10, 20, 30), tail=(1, 2, 3))
    assert len(frame) == 8
    assert frame[5] == (10, 20, 30)
    assert frame[4] == (1, 2, 3)
    assert sum(1 for c in frame if c != (0, 0, 0)) == 2


def test_bounce_head_pingpongs_off_ends():
    patterns = _load_patterns_module()
    bounce = patterns._bounce_head_index
    assert bounce(5, 0) == 0 and bounce(5, 4) == 4
    assert bounce(5, 5) == 3 and bounce(5, 8) == 1 and bounce(5, 16) == bounce(5, 0)


def test_scanner_bounce_has_head_and_fading_tail():
    patterns = _load_patterns_module()
    frame = patterns.scanner_bounce_frame(
        8, 20, head_color=(80, 10, 10), tail_color=(20, 50, 90), tail_len=4
    )
    assert len(frame) == 8
    bright = max(range(8), key=lambda i: sum(frame[i]))
    assert sum(frame[bright]) >= 80


def test_knight_rider_tail_falls_off():
    patterns = _load_patterns_module()
    fr = patterns.knight_rider_scanner_frame(16, 55, tail_len=8, falloff_gamma=3.0)
    assert len(fr) == 16
    reds_sorted = sorted(fr[i][0] for i in range(16) if sum(fr[i]) > 0)
    assert len(reds_sorted) >= 2
    assert reds_sorted[-1] >= 200
    assert reds_sorted[0] < reds_sorted[-1] * 0.5


def test_twinkle_frame_is_deterministic_for_same_inputs():
    patterns = _load_patterns_module()
    a = patterns.twinkle_frame(20, frame=9, seed=777, sparkles=4)
    b = patterns.twinkle_frame(20, frame=9, seed=777, sparkles=4)
    assert a == b


def test_twinkle_frame_varies_between_frames():
    patterns = _load_patterns_module()
    a = patterns.twinkle_frame(20, frame=1, seed=777, sparkles=4)
    b = patterns.twinkle_frame(20, frame=2, seed=777, sparkles=4)
    assert a != b