"""
Tests for data/latency.py — latency tracking.
"""
import time

from data.latency import LatencyTracker


def test_empty_stats():
    lt = LatencyTracker()
    s = lt.stats()
    for key in ("transport_ms", "signal_ms", "order_ms", "roundtrip_ms"):
        assert s[key]["count"] == 0


def test_record_transport():
    lt = LatencyTracker()
    lt.record_transport(1705312800000, 1705312800.100)  # 100ms
    s = lt.stats()
    assert s["transport_ms"]["p50"] == 100.0
    assert s["transport_ms"]["count"] == 1


def test_record_signal():
    lt = LatencyTracker()
    lt.record_signal(5.2)
    lt.record_signal(3.1)
    s = lt.stats()
    assert s["signal_ms"]["p50"] == 4.15  # interpolated median of [3.1, 5.2]
    assert s["signal_ms"]["count"] == 2


def test_record_order():
    lt = LatencyTracker()
    lt.record_order(12.5)
    s = lt.stats()
    assert s["order_ms"]["p50"] == 12.5


def test_record_roundtrip():
    lt = LatencyTracker()
    lt.record_roundtrip(150.0)
    s = lt.stats()
    assert s["roundtrip_ms"]["p50"] == 150.0


def test_negative_latency_ignored():
    lt = LatencyTracker()
    lt.record_transport(1705312800100, 1705312800.000)  # local before exchange
    s = lt.stats()
    assert s["transport_ms"]["count"] == 0


def test_summary_compact():
    lt = LatencyTracker()
    lt.record_transport(1705312800000, 1705312800.100)
    lt.record_signal(5.0)
    summary = lt.summary()
    assert "transport_ms" in summary
    assert "signal_ms" in summary
    assert "p50" in summary["transport_ms"]


def test_percentiles_multiple_values():
    lt = LatencyTracker()
    for lat in [10, 20, 30, 40, 50, 60, 70, 80, 90, 100]:
        lt.record_signal(float(lat))
    s = lt.stats()
    assert s["signal_ms"]["p50"] == 55.0  # interpolated median of 10 values
    assert s["signal_ms"]["p90"] == 91.0  # (10-1)*90/100=8.1, lo=8, vals[8]=90, vals[9]=100, frac=0.1, result=91


def test_window_pruning_approx():
    """Old records should be pruned after window expires."""
    lt = LatencyTracker(window_seconds=0.1)
    lt.record_signal(10.0)
    time.sleep(0.15)
    lt.record_signal(20.0)
    s = lt.stats()
    assert s["signal_ms"]["p50"] == 20.0  # only the recent one