"""Unit tests for `e2e/runner/helpers/replay_mode.py` (AZ-597)."""

from __future__ import annotations

import json
from pathlib import Path

import pytest

from e2e.runner.helpers import replay_mode as rm


@pytest.fixture
def replay_dir(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> Path:
    monkeypatch.setenv("E2E_SITL_REPLAY_DIR", str(tmp_path))
    return tmp_path


@pytest.fixture
def unset_replay_dir(monkeypatch: pytest.MonkeyPatch) -> None:
    monkeypatch.delenv("E2E_SITL_REPLAY_DIR", raising=False)


# NullFrameSink


def test_null_frame_sink_counts_writes():
    # Arrange
    sink = rm.NullFrameSink()

    # Act
    sink.write_frame(b"jpeg-bytes-1", timestamp_ms=100)
    sink.write_frame(b"jpeg-bytes-2", timestamp_ms=200)
    sink.write_frame(b"jpeg-bytes-3", timestamp_ms=300)

    # Assert
    assert sink.frames_written == 3


def test_null_frame_sink_starts_at_zero():
    # Assert
    assert rm.NullFrameSink().frames_written == 0


# NullFcInboundEmitter


def test_null_emitter_counts_emits():
    # Arrange
    emitter = rm.NullFcInboundEmitter()

    # Act
    emitter.emit(object())
    emitter.emit(object())

    # Assert
    assert emitter.samples_emitted == 2


def test_null_emitter_starts_at_zero():
    # Assert
    assert rm.NullFcInboundEmitter().samples_emitted == 0


# default_frame_period_ms


def test_default_frame_period_ms_is_30_fps():
    # Assert
    assert rm.default_frame_period_ms() == 33
    assert rm.DEFAULT_FRAME_PERIOD_MS == 33


# imu_replay_noop


def test_imu_replay_noop_returns_none(tmp_path: Path):
    # Assert
    assert rm.imu_replay_noop(tmp_path / "any.csv") is None


def test_imu_replay_noop_does_not_touch_disk(tmp_path: Path):
    # Arrange
    csv = tmp_path / "does-not-exist.csv"

    # Act
    rm.imu_replay_noop(csv)

    # Assert
    assert not csv.exists()


# load_replay_json


def test_load_replay_json_raises_when_env_unset(unset_replay_dir):
    # Assert
    with pytest.raises(FileNotFoundError, match="E2E_SITL_REPLAY_DIR.*not set"):
        rm.load_replay_json("any.json")


def test_load_replay_json_raises_when_env_empty(monkeypatch: pytest.MonkeyPatch):
    # Arrange
    monkeypatch.setenv("E2E_SITL_REPLAY_DIR", "   ")

    # Assert
    with pytest.raises(FileNotFoundError, match="not set or empty"):
        rm.load_replay_json("any.json")


def test_load_replay_json_raises_when_file_missing(replay_dir: Path):
    # Assert
    with pytest.raises(FileNotFoundError, match="replay fixture 'gone.json' not found"):
        rm.load_replay_json("gone.json")


def test_load_replay_json_raises_on_malformed_json(replay_dir: Path):
    # Arrange
    (replay_dir / "bad.json").write_text("{not valid")

    # Assert
    with pytest.raises(ValueError, match="malformed replay fixture JSON"):
        rm.load_replay_json("bad.json")


def test_load_replay_json_round_trips_dict(replay_dir: Path):
    # Arrange
    payload = {"key": "value", "nested": {"a": 1}}
    (replay_dir / "ok.json").write_text(json.dumps(payload))

    # Act
    result = rm.load_replay_json("ok.json")

    # Assert
    assert result == payload


def test_load_replay_json_round_trips_list(replay_dir: Path):
    # Arrange
    payload = [{"frame_idx": i} for i in range(3)]
    (replay_dir / "list.json").write_text(json.dumps(payload))

    # Act
    result = rm.load_replay_json("list.json")

    # Assert
    assert result == payload


# resolve_replay_subdir


def test_resolve_replay_subdir_raises_when_env_unset(unset_replay_dir):
    # Assert
    with pytest.raises(FileNotFoundError, match="E2E_SITL_REPLAY_DIR.*not set"):
        rm.resolve_replay_subdir("frames")


def test_resolve_replay_subdir_raises_when_subdir_missing(replay_dir: Path):
    # Assert
    with pytest.raises(FileNotFoundError, match="replay fixture subdir 'frames' not found"):
        rm.resolve_replay_subdir("frames")


def test_resolve_replay_subdir_returns_path_when_exists(replay_dir: Path):
    # Arrange
    target = replay_dir / "frames"
    target.mkdir()

    # Act
    result = rm.resolve_replay_subdir("frames")

    # Assert
    assert result == target
    assert result.is_dir()


def test_resolve_replay_subdir_rejects_file_at_path(replay_dir: Path):
    # Arrange
    (replay_dir / "actually-a-file").write_text("oops")

    # Assert
    with pytest.raises(FileNotFoundError, match="subdir 'actually-a-file' not found"):
        rm.resolve_replay_subdir("actually-a-file")