"""The event-report PDF must draw the three geo channels on ONE shared Y scale
(max |sample| across Long/Vert/Tran, floored), not each trace auto-zoomed to its
own peak — so relative amplitudes are honest and a small channel doesn't fill its
lane looking as big as a large one.  Mirrors the event-modal waveform behaviour.
"""
import matplotlib
matplotlib.use("Agg")
import matplotlib.pyplot as plt
import pytest

from sfm.report_pdf import ReportData, _draw_waveform_subplot


def _draw(channels):
    rd = ReportData(
        channels=channels,
        sample_rate_sps=1024,
        dt_ms=1000.0 / 1024,
        t0_ms=0.0,
    )
    fig = plt.figure()
    cell = fig.add_gridspec(1, 1)[0, 0]
    _draw_waveform_subplot(fig, cell, rd)
    by_label = {ax.get_ylabel(): ax for ax in fig.axes}
    try:
        yield_ = {k: by_label[k].get_ylim() for k in ("Long", "Vert", "Tran", "MicL")}
    finally:
        plt.close(fig)
    return yield_


def test_geo_traces_share_one_y_scale():
    # Tran is the biggest geo channel (0.35); Long 0.10, Vert 0.02.
    ylims = _draw({
        "Long": [0.10, -0.10, 0.0],
        "Vert": [0.02, -0.02, 0.0],
        "Tran": [0.35, -0.35, 0.0],
        "MicL": [0.0005, -0.0005, 0.0],
    })
    # Shared scale = max(0.35 * 1.10, floor 0.05) = 0.385, symmetric.
    expected = pytest.approx(0.385, rel=1e-6)
    for ch in ("Long", "Vert", "Tran"):
        lo, hi = ylims[ch]
        assert hi == expected, f"{ch} top ylim {hi} != shared 0.385"
        assert lo == pytest.approx(-0.385, rel=1e-6), f"{ch} bottom ylim {lo}"
    # All three geo lanes identical.
    assert ylims["Long"] == ylims["Vert"] == ylims["Tran"]
    # Mic keeps its own (much smaller) scale — not lumped into the geo max.
    assert ylims["MicL"][1] < 0.01


def test_geo_shared_scale_has_floor():
    # A tiny event (all geo well under the floor) clamps to the 0.05 floor.
    ylims = _draw({
        "Long": [0.008, -0.008, 0.0],
        "Vert": [0.006, -0.006, 0.0],
        "Tran": [0.010, -0.010, 0.0],
        "MicL": [0.0001, -0.0001, 0.0],
    })
    for ch in ("Long", "Vert", "Tran"):
        assert ylims[ch][1] == pytest.approx(0.05, rel=1e-6), f"{ch} not floored"