"""AZ-528 — c1_vio facade orchestration-spine consolidation tests.

Covers AC-1..AC-8 of
``_docs/02_tasks/todo/AZ-528_hygiene_c1_vio_facade_spine_consolidation.md``:

- AC-1: helper module exposes the documented surface.
- AC-2: ``now_iso()`` returns an aware UTC ISO-8601 timestamp with
  ``+00:00`` offset (NOT the ``Z``-suffix variant — that is
  ``iso_ts_from_clock`` in AZ-526).
- AC-3: ``bias_norm`` matches the L2 formula on a hand-checked vector.
- AC-4: ``se3_from_4x4`` builds a ``gtsam.Pose3`` with the expected
  identity rotation + zero translation when fed ``np.eye(4)``.
- AC-5: ``FacadeSpine._classify_state`` returns INIT during warm-up,
  TRACKING above the threshold, DEGRADED below it.
- AC-6: ``FacadeSpine._tick_lost`` demotes TRACKING → DEGRADED on the
  first lost frame and escalates to LOST at the threshold.
- AC-7: ``FacadeSpine._emit_transition`` emits exactly one
  ``vio.health`` FDR record per state change (no record on
  steady-state).
- AC-8: AST-walk regression guard — zero module-level definitions of
  the consolidated free functions remain in any of the three strategy
  modules. Mirrors the AZ-508 / AZ-526 / AZ-527 pattern.

AC-9 (existing AZ-332 / AZ-333 / AZ-334 AC tests pass unmodified) and
AC-10 (AZ-270 layer lint) ride the existing test files; this module
does not re-stage them.
"""

from __future__ import annotations

import ast
from datetime import datetime
from pathlib import Path
from typing import Final

import gtsam
import numpy as np
import pytest

from gps_denied_onboard._types.nav import FeatureQuality, ImuBias, VioState
from gps_denied_onboard.components.c1_vio._facade_spine import (
    FacadeSpine,
    bias_norm,
    frame_image,
    frame_ts_ns,
    now_iso,
    se3_from_4x4,
)
from gps_denied_onboard.fdr_client.fakes import FakeFdrSink

_C1_VIO_SRC: Final[Path] = (
    Path(__file__).resolve().parents[3]
    / "src"
    / "gps_denied_onboard"
    / "components"
    / "c1_vio"
)
_STRATEGY_MODULES: Final[tuple[str, ...]] = (
    "okvis2.py",
    "vins_mono.py",
    "klt_ransac.py",
)
_FORBIDDEN_FREE_FUNCS: Final[frozenset[str]] = frozenset(
    {"_now_iso", "_bias_norm", "_se3_from_4x4", "_frame_ts_ns", "_frame_image"}
)


# ---------------------------------------------------------------------------
# AC-1 — surface.


def test_ac1_helper_module_exposes_documented_surface() -> None:
    # Assert
    assert callable(now_iso)
    assert callable(bias_norm)
    assert callable(se3_from_4x4)
    assert callable(frame_ts_ns)
    assert callable(frame_image)
    assert isinstance(FacadeSpine, type)
    for method_name in ("_classify_state", "_tick_lost", "_emit_transition"):
        assert callable(getattr(FacadeSpine, method_name)), method_name


# ---------------------------------------------------------------------------
# AC-2 — now_iso ISO-8601 UTC with +00:00 offset.


def test_ac2_now_iso_returns_aware_utc_with_plus_offset() -> None:
    # Act
    stamp = now_iso()

    # Assert
    parsed = datetime.fromisoformat(stamp)
    assert parsed.utcoffset() is not None, "expected aware datetime"
    assert parsed.utcoffset().total_seconds() == 0.0  # type: ignore[union-attr]
    assert stamp.endswith("+00:00"), (
        f"expected '+00:00' offset suffix, not 'Z'; got {stamp!r}"
    )


# ---------------------------------------------------------------------------
# AC-3 — bias_norm matches the L2 formula.


def test_ac3_bias_norm_matches_l2_formula() -> None:
    # Arrange
    bias = ImuBias(accel_bias=(1.0, 2.0, 2.0), gyro_bias=(0.0, 0.0, 0.0))

    # Act
    result = bias_norm(bias)

    # Assert
    assert result == pytest.approx(3.0)


def test_ac3_bias_norm_includes_gyro_component() -> None:
    # Arrange
    bias = ImuBias(accel_bias=(0.0, 0.0, 0.0), gyro_bias=(0.0, 4.0, 3.0))

    # Act
    result = bias_norm(bias)

    # Assert
    assert result == pytest.approx(5.0)


# ---------------------------------------------------------------------------
# AC-4 — se3_from_4x4 returns gtsam.Pose3.


def test_ac4_se3_from_4x4_builds_identity_pose() -> None:
    # Act
    pose = se3_from_4x4(np.eye(4, dtype=np.float64))

    # Assert
    assert isinstance(pose, gtsam.Pose3)
    translation = np.asarray(pose.translation())
    assert translation.shape == (3,)
    assert np.allclose(translation, np.zeros(3))
    rotation = np.asarray(pose.rotation().matrix())
    assert np.allclose(rotation, np.eye(3))


# ---------------------------------------------------------------------------
# Helpers for AC-5..AC-7 — minimal test-only mixin subclass that
# only sets the attributes the mixin reads. No native binding, no
# config DTO, no real fdr client wiring.


class _SpineHarness(FacadeSpine):
    def __init__(
        self,
        *,
        fdr: FakeFdrSink,
        producer_id: str = "c1_vio.test",
        strategy_label: str = "test_strategy",
        warm_start_max_frames: int = 5,
        feature_threshold: int = 50,
        lost_frame_threshold: int = 3,
        reported_state: VioState = VioState.INIT,
        last_emitted_state: VioState | None = None,
        frames_since_warmup: int = 0,
        consecutive_lost: int = 0,
        latest_bias: ImuBias | None = None,
    ) -> None:
        self._fdr = fdr  # type: ignore[assignment]
        self._producer_id = producer_id
        self._strategy_label = strategy_label
        self._warm_start_max_frames = warm_start_max_frames
        self._feature_threshold = feature_threshold
        self._lost_frame_threshold = lost_frame_threshold
        self._reported_state = reported_state
        self._last_emitted_state = last_emitted_state
        self._frames_since_warmup = frames_since_warmup
        self._consecutive_lost = consecutive_lost
        self._latest_bias = latest_bias or ImuBias(
            accel_bias=(0.0, 0.0, 0.0), gyro_bias=(0.0, 0.0, 0.0)
        )


def _fq(tracked: int) -> FeatureQuality:
    return FeatureQuality(
        tracked=tracked, new=0, lost=0, mean_parallax=1.0, mre_px=0.5
    )


def _fdr() -> FakeFdrSink:
    return FakeFdrSink(producer_id="c1_vio.test", capacity=64)


# ---------------------------------------------------------------------------
# AC-5 — _classify_state mirrors the existing logic across all strategies.


def test_ac5_classify_state_returns_init_during_warmup() -> None:
    # Arrange
    spine = _SpineHarness(
        fdr=_fdr(),
        warm_start_max_frames=5,
        feature_threshold=50,
        frames_since_warmup=0,
        reported_state=VioState.INIT,
    )

    # Act
    state = spine._classify_state(_fq(tracked=80))

    # Assert
    assert state == VioState.INIT


def test_ac5_classify_state_returns_tracking_after_warmup() -> None:
    # Arrange
    spine = _SpineHarness(
        fdr=_fdr(),
        warm_start_max_frames=5,
        feature_threshold=50,
        frames_since_warmup=5,
        reported_state=VioState.INIT,
    )

    # Act
    state = spine._classify_state(_fq(tracked=80))

    # Assert
    assert state == VioState.TRACKING


def test_ac5_classify_state_returns_degraded_below_threshold() -> None:
    # Arrange
    spine = _SpineHarness(
        fdr=_fdr(),
        warm_start_max_frames=5,
        feature_threshold=50,
        frames_since_warmup=10,
        reported_state=VioState.TRACKING,
    )

    # Act
    state = spine._classify_state(_fq(tracked=10))

    # Assert
    assert state == VioState.DEGRADED


# ---------------------------------------------------------------------------
# AC-6 — _tick_lost transitions correctly.


def test_ac6_tick_lost_demotes_tracking_to_degraded_first_call() -> None:
    # Arrange
    spine = _SpineHarness(
        fdr=_fdr(),
        lost_frame_threshold=3,
        reported_state=VioState.TRACKING,
        consecutive_lost=0,
    )

    # Act
    spine._tick_lost("frame_42")

    # Assert
    assert spine._reported_state == VioState.DEGRADED
    assert spine._consecutive_lost == 1


def test_ac6_tick_lost_escalates_to_lost_at_threshold() -> None:
    # Arrange
    spine = _SpineHarness(
        fdr=_fdr(),
        lost_frame_threshold=3,
        reported_state=VioState.TRACKING,
        consecutive_lost=0,
    )

    # Act
    spine._tick_lost("frame_42")
    spine._tick_lost("frame_43")
    spine._tick_lost("frame_44")

    # Assert
    assert spine._reported_state == VioState.LOST
    assert spine._consecutive_lost == 3


# ---------------------------------------------------------------------------
# AC-7 — _emit_transition emits exactly one FDR record per state change.


def test_ac7_emit_transition_no_record_on_steady_state() -> None:
    # Arrange
    fdr = _fdr()
    spine = _SpineHarness(
        fdr=fdr,
        reported_state=VioState.TRACKING,
        last_emitted_state=VioState.TRACKING,
    )

    # Act
    spine._emit_transition(VioState.TRACKING, "frame_42")

    # Assert
    assert fdr.records == []
    assert spine._last_emitted_state == VioState.TRACKING


def test_ac7_emit_transition_one_record_per_state_change() -> None:
    # Arrange
    fdr = _fdr()
    spine = _SpineHarness(
        fdr=fdr,
        producer_id="c1_vio.test",
        strategy_label="test_strategy",
        reported_state=VioState.TRACKING,
        last_emitted_state=VioState.TRACKING,
        consecutive_lost=2,
        latest_bias=ImuBias(accel_bias=(1.0, 0.0, 0.0), gyro_bias=(0.0, 0.0, 0.0)),
    )

    # Act
    spine._emit_transition(VioState.DEGRADED, "frame_42")

    # Assert
    assert len(fdr.records) == 1
    record = fdr.records[0]
    assert record.kind == "vio.health"
    assert record.producer_id == "c1_vio.test"
    assert set(record.payload.keys()) == {
        "state",
        "consecutive_lost",
        "bias_norm",
        "strategy_label",
        "frame_id",
    }
    assert record.payload["state"] == VioState.DEGRADED.value
    assert record.payload["consecutive_lost"] == 2
    assert record.payload["bias_norm"] == pytest.approx(1.0)
    assert record.payload["strategy_label"] == "test_strategy"
    assert record.payload["frame_id"] == "frame_42"
    assert spine._last_emitted_state == VioState.DEGRADED


def test_ac7_emit_transition_idempotent_for_repeated_state() -> None:
    # Arrange
    fdr = _fdr()
    spine = _SpineHarness(
        fdr=fdr,
        reported_state=VioState.TRACKING,
        last_emitted_state=VioState.TRACKING,
    )

    # Act
    spine._emit_transition(VioState.DEGRADED, "frame_42")
    spine._emit_transition(VioState.DEGRADED, "frame_43")
    spine._emit_transition(VioState.DEGRADED, "frame_44")

    # Assert
    assert len(fdr.records) == 1


# ---------------------------------------------------------------------------
# AC-8 — AST regression guard: no duplicated free-function definitions
# remain in any strategy module. Mirrors the AZ-508 / AZ-526 / AZ-527
# precedent of AST-based source-asserts so a future strategy author
# cannot silently re-introduce a 4th local copy.


@pytest.mark.parametrize("strategy_module", _STRATEGY_MODULES)
def test_ac8_no_duplicated_free_functions_remain_in_strategy_module(
    strategy_module: str,
) -> None:
    # Arrange
    src = (_C1_VIO_SRC / strategy_module).read_text(encoding="utf-8")
    tree = ast.parse(src)

    # Act
    offenders = sorted(
        {
            node.name
            for node in tree.body
            if isinstance(node, ast.FunctionDef) and node.name in _FORBIDDEN_FREE_FUNCS
        }
    )

    # Assert
    assert offenders == [], (
        f"{strategy_module} re-introduced consolidated free functions: "
        f"{offenders}. They live in _facade_spine.py — import them from "
        f"there instead of re-declaring."
    )


# ---------------------------------------------------------------------------
# Risk-1 mitigation — strategies set every attribute the mixin reads.
# AST-based check: each strategy's __init__ writes every required attr
# before any mixin method could be called externally. This is the
# spec's "verify all required attributes set after construction"
# pattern, executed statically so it does not require booting a fake
# native binding for the assertion.


_REQUIRED_SPINE_ATTRS: Final[frozenset[str]] = frozenset(
    {
        "_reported_state",
        "_frames_since_warmup",
        "_warm_start_max_frames",
        "_feature_threshold",
        "_consecutive_lost",
        "_lost_frame_threshold",
        "_last_emitted_state",
        "_producer_id",
        "_strategy_label",
        "_latest_bias",
        "_fdr",
    }
)


@pytest.mark.parametrize("strategy_module", _STRATEGY_MODULES)
def test_strategy_init_sets_all_required_spine_attributes(
    strategy_module: str,
) -> None:
    # Arrange
    src = (_C1_VIO_SRC / strategy_module).read_text(encoding="utf-8")
    tree = ast.parse(src)
    strategy_class = next(
        node
        for node in ast.walk(tree)
        if isinstance(node, ast.ClassDef) and node.name.endswith("Strategy")
    )
    init_method = next(
        node
        for node in strategy_class.body
        if isinstance(node, ast.FunctionDef) and node.name == "__init__"
    )

    # Act
    assigned_attrs: set[str] = set()
    for stmt in ast.walk(init_method):
        if not isinstance(stmt, (ast.Assign, ast.AnnAssign)):
            continue
        targets = stmt.targets if isinstance(stmt, ast.Assign) else [stmt.target]
        for target in targets:
            if (
                isinstance(target, ast.Attribute)
                and isinstance(target.value, ast.Name)
                and target.value.id == "self"
            ):
                assigned_attrs.add(target.attr)

    # Assert
    missing = _REQUIRED_SPINE_ATTRS - assigned_attrs
    assert not missing, (
        f"{strategy_module}.__init__ does not set {sorted(missing)}; "
        f"the FacadeSpine mixin needs every one before any state-machine "
        f"method runs."
    )