from __future__ import annotations

from pathlib import Path

import pytest

from scripts.measure_gpio_status import MeasurementError, percentile_95, validate_samples


def sample(frames: int, *, misses: int = 0, fault: int = 0, performance: bool = True):
    return {
        "screen": {
            "driver_status": {
                "actual_refresh_rate_hz": 97.4,
                "panel_scan_rate_hz": 97.4,
                "scans_per_frame": 1,
                "completed_frames": frames,
                "completed_scans": frames,
                "deadline_misses": misses,
                "oe_pulse_faults": fault,
                "oe_forced_blanks": 0,
                "driver_error": None,
                "oe_timing_error": None,
                "safeoff_error": None,
                "cpu_affinity": 3,
                "cpu_affinity_active": True,
                "realtime_priority": 50,
                "realtime_priority_active": True,
                "memory_locked": True,
            }
        },
        "system": {
            "performance_mode": {
                "requested": performance,
                "effective": performance,
                "current_governors": {"policy0": "performance" if performance else "schedutil"},
                "restore_governors": {"policy0": "schedutil"},
            }
        },
    }


def test_gpio_measurement_accepts_equal_progress_and_fixed_rgb_frame():
    result = validate_samples(
        [sample(100), sample(198), sample(295)],
        performance="on",
        frame_before="same",
        frame_after="same",
    )
    assert result["completed_frames_delta"] == 195
    assert result["deadline_miss_rate"] == 0
    assert percentile_95([1, 2, 3, 100]) == 100


def test_gpio_measurement_rejects_fault_growth_and_changed_frame():
    with pytest.raises(MeasurementError, match="oe_pulse_faults"):
        validate_samples(
            [sample(100), sample(198, fault=1)],
            performance="on",
            frame_before="same",
            frame_after="same",
        )
    with pytest.raises(MeasurementError, match="RGB frame changed"):
        validate_samples(
            [sample(100), sample(198)],
            performance="on",
            frame_before="before",
            frame_after="after",
        )


def test_gpio_measurement_requires_governor_restore_when_off():
    off = [sample(100, performance=False), sample(198, performance=False)]
    validate_samples(off, performance="off", frame_before="same", frame_after="same")
    off[-1]["system"]["performance_mode"]["current_governors"] = {"policy0": "powersave"}
    with pytest.raises(MeasurementError, match="not restored"):
        validate_samples(off, performance="off", frame_before="same", frame_after="same")


def test_preview_performance_unit_is_isolated_and_preserves_realtime_contract():
    source_root = Path(__file__).resolve().parents[1]
    unit = (source_root / "systemd/matrix-screen-controller-preview-perf.service").read_text(
        encoding="utf-8"
    )
    assert "Conflicts=matrix-screen-controller.service" in unit
    assert "MATRIX_DATA_DIR=/var/tmp/matrix-screen-controller-preview-perf-20260824" in unit
    assert "MATRIX_RUNTIME_DIR=/run/matrix-screen-controller-preview-perf-20260824" in unit
    assert "/var/lib/matrix-screen-controller" not in unit
    assert "CPUAffinity=0 1 2" in unit
    assert "LimitRTPRIO=50" in unit
    assert "LimitMEMLOCK=infinity" in unit
    assert unit.count("hub75_safeoff") == 2
    assert "app.system.performance restore" in unit