"""core.sras_analysis + the viewer's LoadedScan/compute path, run headlessly
over the golden fixtures."""
from pathlib import Path

import numpy as np
import pytest

from core.sras_analysis import (
    CH1_IDX, CH4_IDX, ChannelCalibration, FALLBACK_YMULT_MV,
    SawPipeline, compute_dc_image, compute_rf_image, power_spectrum,
)

GOLDEN = Path(__file__).parent / "golden"


def _loaded_scan(name="complete.sras"):
    # Imported lazily: sras_viewer pulls in PyQt6/matplotlib.
    from sras_viewer import LoadedScan
    return LoadedScan(str(GOLDEN / name))


def test_loaded_scan_basics():
    scan = _loaded_scan()
    assert scan.rows_available == [3, 3]
    assert scan.background is not None and len(scan.background) == 8
    assert len(scan.calib.ymult_mv) == 3
    view = scan.angle_view(0)
    assert view.shape == (3, 3, 4, 8)
    scan.close()


def test_loaded_scan_truncated_rows():
    scan = _loaded_scan("trunc_rowboundary_a1.sras")
    assert scan.rows_available == [3, 2]
    assert scan.angle_view(1).shape[0] == 2
    scan = _loaded_scan("header_only.sras")
    assert scan.rows_available == [0, 0]
    assert scan.angle_view(0).shape[0] == 0


def test_compute_dc_image_matches_manual():
    scan = _loaded_scan()
    view = scan.angle_view(0)
    img = compute_dc_image(view, CH4_IDX)
    manual = view[:, CH4_IDX].astype(np.float64).mean(axis=-1)
    assert img.shape == (3, 4)
    assert img.dtype == np.float32
    np.testing.assert_allclose(img, manual, rtol=1e-6)


def test_compute_rf_image_mask_and_values():
    scan = _loaded_scan()
    view = scan.angle_view(0)
    sras = scan.sras
    f_mhz = sras.freq_axis_mhz(sras.header.samples_per_frame)

    # Threshold below everything: all pixels valid, values from the freq axis
    img_all = compute_rf_image(view, scan.calib, f_mhz, dc_threshold_mv=-1e9)
    assert img_all.shape == (3, 4)
    assert set(np.unique(img_all)).issubset(set(f_mhz))

    # Threshold above everything: fully masked, zero image, no FFT work
    img_none = compute_rf_image(view, scan.calib, f_mhz, dc_threshold_mv=1e9)
    assert not img_none.any()


def test_compute_rf_image_gate_zeroes_samples():
    scan = _loaded_scan()
    view = scan.angle_view(0)
    sras = scan.sras
    f_mhz = sras.freq_axis_mhz(sras.header.samples_per_frame)
    t_ns = sras.time_axis_ns()
    img = compute_rf_image(view, scan.calib, f_mhz, dc_threshold_mv=-1e9,
                           gate_start_ns=float(t_ns[2]), gate_end_ns=float(t_ns[5]),
                           time_axis_ns=t_ns)
    assert img.shape == (3, 4)


def test_calibration_roundtrip_and_fallback():
    cal = ChannelCalibration.from_preambles(["", "", ""])
    assert cal.ymult_mv == [FALLBACK_YMULT_MV] * 3
    assert cal.mv_to_adc(cal.adc_to_mv(42.0, 0), 0) == pytest.approx(42.0)

    cal2 = ChannelCalibration.from_preambles(
        ["YMULT 1.0E-3;YOFF -10.0;YZERO 2.0E-3"])
    assert cal2.ymult_mv[0] == pytest.approx(1.0)
    assert cal2.yoff_adc[0] == pytest.approx(-10.0)
    assert cal2.yzero_mv[0] == pytest.approx(2.0)


def test_power_spectrum_dc_suppressed():
    x = np.ones(64, dtype=np.float32) * 5.0
    p = power_spectrum(x)
    assert p[0] == 0.0
    assert not p[1:].any()


def test_saw_pipeline_finds_injected_packet():
    sr = 6.25e9
    n = 1250
    t = np.arange(n) / sr
    rng = np.random.default_rng(42)

    def make_shot(delay_ns=200.0):
        sig = rng.normal(0, 0.05, n).astype(np.float32)
        packet = np.exp(-((t * 1e9 - delay_ns) / 25.0) ** 2) \
            * np.sin(2 * np.pi * 140e6 * t)
        return sig + 3.0 * packet.astype(np.float32)

    pipe = SawPipeline(sr, emi_gate_ns=50.0, bp_lo_mhz=85.0, bp_hi_mhz=200.0,
                       saw_window_ns=(80.0, 350.0))
    pipe.build_template(np.stack([make_shot() for _ in range(10)]))
    assert pipe.template is not None

    metrics = pipe.process_shot_metrics(make_shot())
    assert metrics["peak_time_ns"] == pytest.approx(200.0, abs=15.0)
    assert metrics["snr"] > 3.0

    # process_shot returns the same metrics plus the stage arrays
    full = pipe.process_shot(make_shot())
    for key in ("raw", "gated", "filtered", "mf_output", "envelope"):
        assert isinstance(full[key], np.ndarray)


def test_compute_saw_image_scalars_only():
    # Synthetic angle view: golden frames (8 samples) are too short for the
    # 6th-order zero-phase bandpass; real records are >1000 samples.
    from core.sras_analysis import compute_saw_image
    rng = np.random.default_rng(1)
    view = rng.integers(-40, 40, size=(3, 3, 4, 512), dtype=np.int8)
    view[:, CH4_IDX] = 100   # every pixel passes the DC mask
    calib = ChannelCalibration.from_preambles(["", "", ""])

    pipe = SawPipeline(6.25e9, saw_window_ns=(10.0, 70.0))
    pipe.build_template(view[0, CH1_IDX, :4].astype(np.float32))
    img = compute_saw_image(view, calib, -1e9, pipe, "amplitude")
    assert img.shape == (3, 4)
    assert img.dtype == np.float32
    assert (img > 0).all()

    tof = compute_saw_image(view, calib, -1e9, pipe, "tof")
    assert tof.shape == (3, 4)