from __future__ import annotations

import hashlib
import importlib.util
import json
import sys
from pathlib import Path

import pytest


def _module(name: str, relative: str):
    path = Path(__file__).resolve().parents[1] / relative
    spec = importlib.util.spec_from_file_location(name, path)
    assert spec is not None and spec.loader is not None
    module = importlib.util.module_from_spec(spec)
    sys.modules[spec.name] = module
    spec.loader.exec_module(module)
    return module


def test_camera_replay_loads_segments_lazily_and_checks_each_digest(tmp_path: Path) -> None:
    module = _module(
        "e21_source_replay_test",
        "experiments/perception/run_e12_shadow_transport_replay.py",
    )
    epoch = tmp_path / "epoch-1"
    segments = epoch / "segments"
    segments.mkdir(parents=True)
    (epoch / "init.mp4").write_bytes(b"init")
    rows = []
    for sequence, payload in ((1, b"one"), (2, b"two")):
        path = segments / f"{sequence}.m4s"
        path.write_bytes(payload)
        rows.append(
            {
                "host_epoch_ns": sequence * 100_000_000,
                "host_monotonic_ns": sequence * 100_000_000,
                "length": len(payload),
                "path": f"segments/{sequence}.m4s",
                "sequence": sequence,
                "sha256": hashlib.sha256(payload).hexdigest(),
            }
        )
    (epoch / "index.jsonl").write_text(
        "".join(json.dumps(row) + "\n" for row in rows),
        encoding="utf-8",
    )

    events = module._camera_events(epoch, 1.0)
    assert next(events).modality == "camera-init"
    assert next(events).payload == b"one"
    (segments / "2.m4s").write_bytes(b"changed-after-generator-start")
    with pytest.raises(RuntimeError, match="length differs"):
        next(events)


def test_e21_trend_reports_accumulating_age_and_stable_memory() -> None:
    module = _module(
        "e21_analyzer_test",
        "experiments/perception/analyze_e21_realtime_envelope.py",
    )
    growing = module._trend([(float(index), float(index) * 2) for index in range(20)])
    stable = module._trend([(float(index), 100.0) for index in range(20)])

    assert growing["slope_per_second"] == pytest.approx(2.0)
    assert growing["late_vs_early_p95"] > 0
    assert stable["slope_per_second"] == pytest.approx(0.0)
    assert stable["late_vs_early_p95"] == pytest.approx(0.0)


def test_e21_profile_keeps_diagnostic_authority_and_long_1x_gate() -> None:
    root = Path(__file__).resolve().parents[1]
    profile = json.loads(
        (
            root
            / "experiments"
            / "perception"
            / "e21_realtime_envelope_profile.json"
        ).read_text()
    )

    assert profile["source"]["speed"] == 1.0
    assert profile["source"]["minimum_span_seconds"] >= 55.0
    assert profile["worker"]["minimum_detector_fps"] >= 9.5
    assert profile["worker"]["maximum_detector_drop_fraction"] <= 0.02
    assert profile["worker"]["maximum_p95_world_state_age_ms"] == 200.0
    assert profile["authority"] == {
        "commands_enabled": False,
        "navigation_or_safety_accepted": False,
    }