"""Unit tests for `e2e/runner/helpers/fc_proxy_runtime.py` (AZ-596)."""

from __future__ import annotations

import json
from pathlib import Path

import pytest

from e2e.runner.helpers import fc_proxy_runtime as fpr


def _schedule_payload(
    *,
    window_start_ms: int = 10_000,
    window_end_ms: int = 25_000,
    spoof_frame_count: int = 5,
) -> dict:
    """Build a minimally valid `schedule.json` payload that `BlackoutSpoofProxy.from_schedule_file` accepts."""
    return {
        "window_start_ms": window_start_ms,
        "window_end_ms": window_end_ms,
        "max_alignment_err_ms": 40.0,
        "spoof_gps": [
            {
                "monotonic_ms": window_start_ms + (i * 200),
                "lat_deg": 50.0 + (i * 0.0001),
                "lon_deg": 36.2 + (i * 0.0001),
                "alt_m": 200.0,
                "fix_type": 3,
                "hdop": 1.0,
            }
            for i in range(spoof_frame_count)
        ],
    }


def _write_schedule(path: Path, payload: dict) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)
    path.write_text(json.dumps(payload))


# AC-1: schedule load + error branches


def test_missing_schedule_raises_file_not_found(tmp_path: Path):
    # Assert
    with pytest.raises(FileNotFoundError, match="schedule.json not found"):
        fpr.drive_fc_proxy(tmp_path / "nope.json")


def test_malformed_json_raises_value_error(tmp_path: Path):
    # Arrange
    bad = tmp_path / "schedule.json"
    bad.write_text("{not valid json")

    # Assert
    with pytest.raises(ValueError, match="malformed schedule JSON"):
        fpr.drive_fc_proxy(bad)


def test_happy_path_returns_well_formed_report(tmp_path: Path):
    # Arrange
    schedule = tmp_path / "schedule.json"
    _write_schedule(schedule, _schedule_payload(spoof_frame_count=7))

    # Act
    report = fpr.drive_fc_proxy(schedule)

    # Assert
    assert report.schedule_path == str(schedule)
    assert report.window_start_ms == 10_000
    assert report.window_end_ms == 25_000
    assert report.spoof_frame_count == 7
    assert report.alignment_err_ms == 0
    assert report.was_replay_mode is True


# AC-2: now_ms_provider activation + alignment_err_ms


def test_now_ms_provider_activates_proxy_and_reports_alignment(tmp_path: Path):
    # Arrange
    schedule = tmp_path / "schedule.json"
    _write_schedule(schedule, _schedule_payload(window_start_ms=5_000))

    def clock() -> int:
        return 5_002  # 2 ms drift from window_start_ms

    # Act
    report = fpr.drive_fc_proxy(schedule, now_ms_provider=clock)

    # Assert
    assert report.alignment_err_ms == 0  # `activate(...)` with no first_blackout_ms anchors at `now`
    assert report.was_replay_mode is False


def test_now_ms_provider_with_replay_mode_false_distinguishes_from_default(tmp_path: Path):
    # Arrange
    schedule = tmp_path / "schedule.json"
    _write_schedule(schedule, _schedule_payload())

    # Act
    replay_report = fpr.drive_fc_proxy(schedule)
    live_report = fpr.drive_fc_proxy(schedule, now_ms_provider=lambda: 12_345)

    # Assert
    assert replay_report.was_replay_mode is True
    assert live_report.was_replay_mode is False


# AC-3: replay_dir / E2E_SITL_REPLAY_DIR JSON write


def test_writes_report_when_replay_dir_supplied(tmp_path: Path):
    # Arrange
    schedule = tmp_path / "schedule.json"
    _write_schedule(schedule, _schedule_payload(spoof_frame_count=3))
    replay_dir = tmp_path / "replay"

    # Act
    fpr.drive_fc_proxy(schedule, replay_dir=replay_dir)

    # Assert
    report_path = replay_dir / "proxy_drive_report.json"
    assert report_path.is_file()
    written = json.loads(report_path.read_text())
    assert written["spoof_frame_count"] == 3
    assert written["was_replay_mode"] is True


def test_writes_report_when_env_var_set(
    tmp_path: Path, monkeypatch: pytest.MonkeyPatch
):
    # Arrange
    schedule = tmp_path / "schedule.json"
    _write_schedule(schedule, _schedule_payload())
    env_dir = tmp_path / "from-env"
    monkeypatch.setenv("E2E_SITL_REPLAY_DIR", str(env_dir))

    # Act
    fpr.drive_fc_proxy(schedule)

    # Assert
    assert (env_dir / "proxy_drive_report.json").is_file()


def test_explicit_replay_dir_overrides_env_var(
    tmp_path: Path, monkeypatch: pytest.MonkeyPatch
):
    # Arrange
    schedule = tmp_path / "schedule.json"
    _write_schedule(schedule, _schedule_payload())
    env_dir = tmp_path / "from-env"
    explicit_dir = tmp_path / "explicit"
    monkeypatch.setenv("E2E_SITL_REPLAY_DIR", str(env_dir))

    # Act
    fpr.drive_fc_proxy(schedule, replay_dir=explicit_dir)

    # Assert
    assert (explicit_dir / "proxy_drive_report.json").is_file()
    assert not (env_dir / "proxy_drive_report.json").exists()


def test_no_file_written_when_neither_supplied(
    tmp_path: Path, monkeypatch: pytest.MonkeyPatch
):
    # Arrange
    schedule = tmp_path / "schedule.json"
    _write_schedule(schedule, _schedule_payload())
    monkeypatch.delenv("E2E_SITL_REPLAY_DIR", raising=False)

    # Act
    fpr.drive_fc_proxy(schedule)

    # Assert: nothing written next to the schedule (the only writable dir)
    assert list(tmp_path.iterdir()) == [schedule]


def test_no_file_written_when_env_var_empty(
    tmp_path: Path, monkeypatch: pytest.MonkeyPatch
):
    # Arrange
    schedule = tmp_path / "schedule.json"
    _write_schedule(schedule, _schedule_payload())
    monkeypatch.setenv("E2E_SITL_REPLAY_DIR", "   ")

    # Act
    fpr.drive_fc_proxy(schedule)

    # Assert
    assert list(tmp_path.iterdir()) == [schedule]


def test_replay_dir_is_created_when_missing(tmp_path: Path):
    # Arrange
    schedule = tmp_path / "schedule.json"
    _write_schedule(schedule, _schedule_payload())
    replay_dir = tmp_path / "deep" / "nested" / "replay"

    # Act
    fpr.drive_fc_proxy(schedule, replay_dir=replay_dir)

    # Assert
    assert (replay_dir / "proxy_drive_report.json").is_file()