from lyra_worker.adapters._streamrip import _ProgressAggregator


def _record():
    seen: list[float] = []
    return seen, seen.append


def test_equal_size_tracks_aggregate_monotonically_to_near_one():
    # 4 tracks of 100 bytes each, all started up front (concurrency covers the album), then
    # each downloaded in 25-byte chunks. Fraction must climb monotonically 0→~1.
    seen, cb = _record()
    agg = _ProgressAggregator(4, cb)
    for _ in range(4):
        agg.start_track(100)
    for _ in range(16):  # 16 chunks * 25 bytes = 400 bytes = full album
        agg.advance(25)

    assert seen == sorted(seen)                 # monotonic non-decreasing
    assert all(0.0 <= f <= 0.99 for f in seen)  # never negative, capped at 0.99
    assert seen[-1] == 0.99                      # reaches the cap when all bytes are in
    assert seen[len(seen) // 2] > 0.3           # genuinely climbs mid-download (no 0→100 jump)


def test_estimate_uses_track_count_before_all_tracks_start():
    # Only the first of 4 tracks has started; with a known track count the estimate already
    # spans the whole album, so finishing track 1 reports ~1/4, not ~1/1.
    seen, cb = _record()
    agg = _ProgressAggregator(4, cb)
    agg.start_track(100)
    agg.advance(100)  # track 1 fully downloaded
    assert abs(seen[-1] - 0.25) < 0.01


def test_zero_or_missing_sizes_never_emit_and_never_divide_by_zero():
    seen, cb = _record()
    agg = _ProgressAggregator(0, cb)
    agg.advance(50)          # no track started yet -> no emit
    agg.start_track(0)       # a track with unknown size
    agg.advance(50)          # est_total still 0 -> still no emit, no crash
    assert seen == []