"""Unit-level tests for the AZ-404 e2e helpers.

Runs unconditionally in the regular regression suite (NOT gated by
``RUN_REPLAY_E2E``) — the helpers are pure / deterministic and test
themselves cheaply. Covers AC-9 (Helper L2 computation correct) and
ancillary helper invariants.
"""

from __future__ import annotations

from pathlib import Path

import pytest

from tests.e2e.replay._helpers import (
    CapturingMavlinkTransport,
    GroundTruthRow,
    l2_horizontal_m,
    match_percentage,
    parse_jsonl,
)


# ----------------------------------------------------------------------
# AC-9: L2 helper correctness


def test_ac9_l2_zero_at_same_point() -> None:
    # Arrange / Act
    d = l2_horizontal_m(50.08, 36.11, 50.08, 36.11)

    # Assert
    assert d == pytest.approx(0.0, abs=1e-6)


def test_ac9_l2_north_one_degree_111km() -> None:
    """One degree of latitude ≈ 111 km on the WGS84 spherical model."""
    # Act
    d = l2_horizontal_m(50.08, 36.11, 51.08, 36.11)

    # Assert
    assert d == pytest.approx(111_195.0, rel=0.001)


def test_ac9_l2_known_pair_kharkiv_kyiv() -> None:
    """Hand-checked Derkachi (~Kharkiv) to Kyiv center: 411 km ± 1 km."""
    # Arrange
    kharkiv_lat, kharkiv_lon = 49.9935, 36.2304
    kyiv_lat, kyiv_lon = 50.4501, 30.5234

    # Act
    d = l2_horizontal_m(kharkiv_lat, kharkiv_lon, kyiv_lat, kyiv_lon)

    # Assert — externally known reference distance is 411 km.
    assert d == pytest.approx(411_000.0, rel=0.005)


def test_ac9_l2_symmetric() -> None:
    # Arrange
    a = (49.991, 36.221)
    b = (50.080, 36.111)

    # Act
    d_ab = l2_horizontal_m(*a, *b)
    d_ba = l2_horizontal_m(*b, *a)

    # Assert
    assert d_ab == pytest.approx(d_ba, rel=1e-12)


# ----------------------------------------------------------------------
# match_percentage


def test_match_percentage_all_within_threshold() -> None:
    # Arrange
    gt = [GroundTruthRow(t_s=0.0, lat_deg=50.0, lon_deg=36.0, alt_m=100.0)]
    emissions = [
        {
            "emitted_at": 0,
            "position_wgs84": {"lat_deg": 50.0, "lon_deg": 36.0, "alt_m": 100.0},
        }
    ]

    # Act
    pct = match_percentage(emissions, gt, threshold_m=100.0)

    # Assert
    assert pct == 1.0


def test_match_percentage_none_within_threshold() -> None:
    # Arrange
    gt = [GroundTruthRow(t_s=0.0, lat_deg=50.0, lon_deg=36.0, alt_m=100.0)]
    emissions = [
        {
            "emitted_at": 0,
            # ~111 km north of the GT row.
            "position_wgs84": {"lat_deg": 51.0, "lon_deg": 36.0, "alt_m": 100.0},
        }
    ]

    # Act
    pct = match_percentage(emissions, gt, threshold_m=100.0)

    # Assert
    assert pct == 0.0


def test_match_percentage_empty_emissions_zero() -> None:
    # Arrange
    gt = [GroundTruthRow(t_s=0.0, lat_deg=50.0, lon_deg=36.0, alt_m=100.0)]

    # Act
    pct = match_percentage([], gt, threshold_m=100.0)

    # Assert
    assert pct == 0.0


def test_match_percentage_empty_ground_truth_raises() -> None:
    # Act / Assert
    with pytest.raises(AssertionError, match="ground_truth must be non-empty"):
        match_percentage(
            [{"emitted_at": 0, "position_wgs84": {"lat_deg": 50, "lon_deg": 36}}],
            [],
            threshold_m=100.0,
        )


# ----------------------------------------------------------------------
# parse_jsonl


def test_parse_jsonl_round_trip(tmp_path: Path) -> None:
    # Arrange
    path = tmp_path / "out.jsonl"
    path.write_text('{"a": 1}\n{"b": 2}\n')

    # Act
    rows = parse_jsonl(path)

    # Assert
    assert rows == [{"a": 1}, {"b": 2}]


def test_parse_jsonl_skips_trailing_blank(tmp_path: Path) -> None:
    # Arrange
    path = tmp_path / "out.jsonl"
    path.write_text('{"a": 1}\n\n')

    # Act
    rows = parse_jsonl(path)

    # Assert — the trailing blank line is tolerated
    assert rows == [{"a": 1}]


def test_parse_jsonl_invalid_line_raises(tmp_path: Path) -> None:
    # Arrange
    path = tmp_path / "out.jsonl"
    path.write_text("not json\n")

    # Act / Assert
    with pytest.raises(AssertionError, match="not valid JSON"):
        parse_jsonl(path)


# ----------------------------------------------------------------------
# CapturingMavlinkTransport (ready for AZ-558 unblock)


def test_capturing_transport_records_writes() -> None:
    # Arrange
    t = CapturingMavlinkTransport()

    # Act
    t.write(b"abc")
    t.write(b"def")

    # Assert
    assert t.captured_payloads == (b"abc", b"def")
    assert t.captured_concat == b"abcdef"
    assert t.bytes_written() == 6


def test_capturing_transport_close_then_write_raises() -> None:
    # Arrange
    t = CapturingMavlinkTransport()
    t.close()

    # Act / Assert
    with pytest.raises(RuntimeError, match="after close"):
        t.write(b"x")


def test_capturing_transport_implements_protocol() -> None:
    # Arrange
    from gps_denied_onboard.components.c8_fc_adapter.interface import MavlinkTransport

    # Act
    t = CapturingMavlinkTransport()

    # Assert — runtime_checkable Protocol acceptance
    assert isinstance(t, MavlinkTransport)