"""AZ-382 — GtsamIsam2StateEstimator + ISam2GraphHandleImpl real-body tests.

Ten ACs from ``_docs/02_tasks/done/AZ-382_c5_isam2_smoother_wiring.md``
(authored todo, archived here once the task transitions to Done):

- AC-1  Construction succeeds; ``_isam2`` / ``_smoother`` / ``_graph``
        / ``_values`` / ``_key_for_frame`` initialised.
- AC-2  Key-management policy assigns unique GTSAM keys via
        ``gtsam.symbol('x', counter)``; repeat lookups return the same
        key.
- AC-3  ``IncrementalFixedLagSmoother`` instantiated with
        ``K * frame_period_s``.
- AC-4  ``keyframe_window_size = 5`` rejected at config-load
        (delegates to the AZ-381 ``C5StateConfig.__post_init__``).
- AC-5  ``ISam2GraphHandleImpl.add_factor`` real body — appends to
        ``estimator._graph``; failure raises
        :class:`EstimatorDegradedError` AND logs the failure record.
- AC-6  ``ISam2GraphHandleImpl.update`` real body — iSAM2 +
        smoother advance; failure raises
        :class:`EstimatorFatalError`.
- AC-7  ``ISam2GraphHandleImpl.compute_marginals`` returns a real
        ``gtsam.Marginals`` instance.
- AC-8  ``ISam2GraphHandleImpl.last_anchor_age_ms`` returns a very
        large number until an anchor lands.
- AC-9  Defensive logging emitted on every mutation (success + failure).
- AC-10 ``StateEstimator`` Protocol methods on the estimator still
        raise ``NotImplementedError`` naming AZ-383 / AZ-384.
"""

from __future__ import annotations

import logging
from unittest import mock
from uuid import uuid4

import gtsam
import gtsam_unstable
import pytest

from gps_denied_onboard.components.c5_state._isam2_handle import (
    ISam2GraphHandle,
    ISam2GraphHandleImpl,
)
from gps_denied_onboard.components.c5_state.config import C5StateConfig
from gps_denied_onboard.components.c5_state.errors import (
    EstimatorDegradedError,
    EstimatorFatalError,
)
from gps_denied_onboard.components.c5_state.gtsam_isam2_estimator import (
    _FRAME_PERIOD_S,
    GtsamIsam2StateEstimator,
    create,
    register,
)
from gps_denied_onboard.components.c5_state.interface import StateEstimator
from gps_denied_onboard.config.schema import ConfigError
from gps_denied_onboard.runtime_root.state_factory import (
    build_state_estimator,
    clear_state_registry,
)


@pytest.fixture(autouse=True)
def _registry_isolation():
    # Arrange
    clear_state_registry()
    yield
    clear_state_registry()


def _build_config(*, strategy: str = "gtsam_isam2", keyframe_window_size: int = 15):
    block = C5StateConfig(strategy=strategy, keyframe_window_size=keyframe_window_size)
    cfg = mock.MagicMock()
    cfg.components = {"c5_state": block}
    return cfg


def _build_estimator(*, keyframe_window_size: int = 15) -> GtsamIsam2StateEstimator:
    cfg = _build_config(keyframe_window_size=keyframe_window_size)
    return GtsamIsam2StateEstimator(
        cfg,
        imu_preintegrator=mock.MagicMock(),
        se3_utils=mock.MagicMock(),
        wgs_converter=mock.MagicMock(),
        fdr_client=mock.MagicMock(),
    )


# ---------------------------------------------------------------------
# AC-1: construction


def test_ac1_construction_initialises_substrate() -> None:
    estimator = _build_estimator(keyframe_window_size=15)

    assert isinstance(estimator._isam2, gtsam.ISAM2)
    assert isinstance(estimator._smoother, gtsam_unstable.IncrementalFixedLagSmoother)
    assert isinstance(estimator._graph, gtsam.NonlinearFactorGraph)
    assert isinstance(estimator._values, gtsam.Values)
    assert estimator._key_for_frame == {}
    assert estimator._next_key_counter == 0
    assert estimator._last_anchor_ns == 0
    assert estimator._graph.size() == 0
    assert isinstance(estimator, StateEstimator)


def test_ac1_construction_emits_debug_log(caplog: pytest.LogCaptureFixture) -> None:
    # ``get_logger`` resets the named logger to NOTSET, which masks
    # ``caplog.at_level(DEBUG, logger=...)``. Bump the root level
    # instead so the DEBUG record propagates to caplog's handler.
    with caplog.at_level(logging.DEBUG):
        _build_estimator(keyframe_window_size=12)

    records = [r for r in caplog.records if r.kind == "c5.state.isam2_initialised"]
    assert len(records) == 1
    assert records[0].kv["keyframe_window_size"] == 12
    assert records[0].kv["total_factors_initial"] == 0


# ---------------------------------------------------------------------
# AC-2: key-management policy


def test_ac2_key_for_frame_assigns_unique_keys() -> None:
    estimator = _build_estimator()
    u1, u2, u3 = uuid4(), uuid4(), uuid4()

    k1 = estimator.key_for_frame(u1)
    k2 = estimator.key_for_frame(u2)
    k3 = estimator.key_for_frame(u3)

    assert k1 != k2 != k3
    assert estimator._next_key_counter == 3
    assert estimator._key_for_frame == {u1: k1, u2: k2, u3: k3}


def test_ac2_key_for_frame_is_idempotent() -> None:
    estimator = _build_estimator()
    u1 = uuid4()

    first = estimator.key_for_frame(u1)
    second = estimator.key_for_frame(u1)

    assert first == second
    assert estimator._next_key_counter == 1


def test_ac2_keys_use_x_namespace() -> None:
    estimator = _build_estimator()
    u1 = uuid4()

    key = estimator.key_for_frame(u1)
    expected_first_x_key = gtsam.symbol("x", 0)

    assert key == expected_first_x_key


# ---------------------------------------------------------------------
# AC-3: window size respected


def test_ac3_smoother_window_is_k_times_frame_period() -> None:
    # Arrange / Act
    estimator = _build_estimator(keyframe_window_size=15)

    expected_window_seconds = 15 * _FRAME_PERIOD_S

    # Hit the smoother through a controlled smoke path to be sure the
    # window is honored — direct introspection is C++-private. We use
    # the smoother's ``smootherLag()`` getter (FixedLagSmoother base).
    assert estimator._smoother.smootherLag() == pytest.approx(expected_window_seconds, rel=1e-6)


# ---------------------------------------------------------------------
# AC-4: window size validation


def test_ac4_window_below_min_rejected_by_config() -> None:
    with pytest.raises(ConfigError, match=r"\[10, 20\]"):
        C5StateConfig(keyframe_window_size=5)


def test_ac4_window_above_max_rejected_by_config() -> None:
    with pytest.raises(ConfigError, match=r"\[10, 20\]"):
        C5StateConfig(keyframe_window_size=21)


# ---------------------------------------------------------------------
# AC-5: ISam2GraphHandleImpl.add_factor real body


def test_ac5_add_factor_appends_to_graph(caplog: pytest.LogCaptureFixture) -> None:
    estimator = _build_estimator()
    handle = ISam2GraphHandleImpl(estimator)
    key = estimator.key_for_frame(uuid4())
    factor = gtsam.PriorFactorPose3(key, gtsam.Pose3(), gtsam.noiseModel.Isotropic.Sigma(6, 0.1))

    with caplog.at_level(logging.DEBUG, logger="c5_state.isam2_handle"):
        handle.add_factor(factor)

    assert estimator._graph.size() == 1
    ok_records = [r for r in caplog.records if r.kind == "c5.state.add_factor_ok"]
    assert len(ok_records) == 1
    assert ok_records[0].kv["factor_type"] == "PriorFactorPose3"
    assert ok_records[0].kv["graph_size"] == 1


def test_ac5_add_factor_failure_raises_degraded_and_logs(
    caplog: pytest.LogCaptureFixture,
) -> None:
    estimator = _build_estimator()
    handle = ISam2GraphHandleImpl(estimator)
    # Replace the graph with a stub whose ``add`` raises so we can test
    # the failure path without depending on a specific GTSAM exception.
    failing_graph = mock.MagicMock()
    failing_graph.add.side_effect = RuntimeError("synthetic graph failure")
    estimator._graph = failing_graph

    with caplog.at_level(logging.ERROR, logger="c5_state.isam2_handle"):
        with pytest.raises(EstimatorDegradedError, match="synthetic graph failure"):
            handle.add_factor(mock.MagicMock())

    err_records = [r for r in caplog.records if r.kind == "c5.state.add_factor_failed"]
    assert len(err_records) == 1
    assert "synthetic graph failure" in err_records[0].kv["error"]


# ---------------------------------------------------------------------
# AC-6: ISam2GraphHandleImpl.update real body


def _build_unit_update_payload() -> tuple[
    gtsam.NonlinearFactorGraph, gtsam.Values, gtsam_unstable.FixedLagSmootherKeyTimestampMap
]:
    key = gtsam.symbol("x", 0)
    graph = gtsam.NonlinearFactorGraph()
    graph.add(gtsam.PriorFactorPose3(key, gtsam.Pose3(), gtsam.noiseModel.Isotropic.Sigma(6, 0.1)))
    values = gtsam.Values()
    values.insert(key, gtsam.Pose3())
    timestamps = gtsam_unstable.FixedLagSmootherKeyTimestampMap()
    timestamps.insert((key, 0.0))
    return graph, values, timestamps


def test_ac6_update_advances_isam2_and_smoother(caplog: pytest.LogCaptureFixture) -> None:
    estimator = _build_estimator()
    handle = ISam2GraphHandleImpl(estimator)
    graph, values, timestamps = _build_unit_update_payload()

    with caplog.at_level(logging.DEBUG, logger="c5_state.isam2_handle"):
        handle.update(graph, values, timestamps)

    # iSAM2 should now hold the prior factor; calculateEstimate() ⇒ non-empty Values.
    assert estimator._isam2.calculateEstimate().size() == 1
    ok_records = [r for r in caplog.records if r.kind == "c5.state.update_ok"]
    assert len(ok_records) == 1


def test_ac6_update_with_none_timestamps_substitutes_empty_map() -> None:
    estimator = _build_estimator()
    handle = ISam2GraphHandleImpl(estimator)
    graph, values, _ = _build_unit_update_payload()

    handle.update(graph, values, None)

    assert estimator._isam2.calculateEstimate().size() == 1


def test_ac6_isam2_failure_raises_fatal(caplog: pytest.LogCaptureFixture) -> None:
    estimator = _build_estimator()
    handle = ISam2GraphHandleImpl(estimator)
    failing_isam2 = mock.MagicMock()
    failing_isam2.update.side_effect = RuntimeError("synthetic isam2 failure")
    estimator._isam2 = failing_isam2

    with caplog.at_level(logging.ERROR, logger="c5_state.isam2_handle"):
        with pytest.raises(EstimatorFatalError, match="synthetic isam2 failure"):
            handle.update(mock.MagicMock(), mock.MagicMock())

    err_records = [r for r in caplog.records if r.kind == "c5.state.isam2_update_failed"]
    assert len(err_records) == 1


def test_ac6_smoother_failure_raises_fatal(caplog: pytest.LogCaptureFixture) -> None:
    estimator = _build_estimator()
    handle = ISam2GraphHandleImpl(estimator)
    failing_smoother = mock.MagicMock()
    failing_smoother.update.side_effect = RuntimeError("synthetic smoother failure")
    estimator._smoother = failing_smoother
    graph, values, timestamps = _build_unit_update_payload()

    with caplog.at_level(logging.ERROR, logger="c5_state.isam2_handle"):
        with pytest.raises(EstimatorFatalError, match="synthetic smoother failure"):
            handle.update(graph, values, timestamps)

    err_records = [r for r in caplog.records if r.kind == "c5.state.smoother_update_failed"]
    assert len(err_records) == 1


# ---------------------------------------------------------------------
# AC-7: compute_marginals real body


def test_ac7_compute_marginals_returns_real_instance() -> None:
    estimator = _build_estimator()
    handle = ISam2GraphHandleImpl(estimator)
    graph, values, timestamps = _build_unit_update_payload()
    handle.update(graph, values, timestamps)

    marginals = handle.compute_marginals()

    assert isinstance(marginals, gtsam.Marginals)


# ---------------------------------------------------------------------
# AC-8: last_anchor_age_ms real body


def test_ac8_last_anchor_age_ms_huge_when_no_anchor() -> None:
    estimator = _build_estimator()
    handle = ISam2GraphHandleImpl(estimator)

    age_ms = handle.last_anchor_age_ms()

    # _last_anchor_ns=0 ⇒ age = monotonic_ns()/1e6 (typically 1e9 ms+)
    assert age_ms > 1_000_000


def test_ac8_last_anchor_age_ms_small_after_anchor_set() -> None:
    import time as _time

    estimator = _build_estimator()
    handle = ISam2GraphHandleImpl(estimator)
    estimator._last_anchor_ns = _time.monotonic_ns()

    age_ms = handle.last_anchor_age_ms()

    assert 0 <= age_ms < 100


# ---------------------------------------------------------------------
# AC-9: defensive logging on every mutation (success and failure)


def test_ac9_add_factor_emits_success_log(caplog: pytest.LogCaptureFixture) -> None:
    estimator = _build_estimator()
    handle = ISam2GraphHandleImpl(estimator)
    key = estimator.key_for_frame(uuid4())
    factor = gtsam.PriorFactorPose3(key, gtsam.Pose3(), gtsam.noiseModel.Isotropic.Sigma(6, 0.1))

    with caplog.at_level(logging.DEBUG, logger="c5_state.isam2_handle"):
        handle.add_factor(factor)

    success_records = [r for r in caplog.records if r.kind == "c5.state.add_factor_ok"]
    assert len(success_records) == 1


def test_ac9_update_emits_success_log(caplog: pytest.LogCaptureFixture) -> None:
    estimator = _build_estimator()
    handle = ISam2GraphHandleImpl(estimator)
    graph, values, timestamps = _build_unit_update_payload()

    with caplog.at_level(logging.DEBUG, logger="c5_state.isam2_handle"):
        handle.update(graph, values, timestamps)

    success_records = [r for r in caplog.records if r.kind == "c5.state.update_ok"]
    assert len(success_records) == 1


# ---------------------------------------------------------------------
# AC-10 NOTE: All six ``StateEstimator`` Protocol methods originally
# raised ``NotImplementedError`` in AZ-382's scope. They have all
# landed:
#
# - ``add_vio`` / ``add_pose_anchor`` / ``add_fc_imu`` → tested in
#   ``tests/unit/c5_state/test_az383_factor_adds.py``.
# - ``current_estimate`` / ``smoothed_history`` / ``health_snapshot``
#   → tested in ``tests/unit/c5_state/test_az384_marginals_outputs.py``.


# ---------------------------------------------------------------------
# Factory integration: register() + build_state_estimator returns the tuple


def test_register_makes_strategy_available_to_factory() -> None:
    register()
    cfg = _build_config(strategy="gtsam_isam2")

    estimator, handle = build_state_estimator(
        cfg,
        imu_preintegrator=mock.MagicMock(),
        se3_utils=mock.MagicMock(),
        wgs_converter=mock.MagicMock(),
        fdr_client=mock.MagicMock(),
    )

    assert isinstance(estimator, GtsamIsam2StateEstimator)
    assert isinstance(handle, ISam2GraphHandle)
    assert isinstance(handle, ISam2GraphHandleImpl)


def test_create_returns_handle_bound_to_returned_estimator() -> None:
    cfg = _build_config(strategy="gtsam_isam2")

    estimator, handle = create(
        config=cfg,
        imu_preintegrator=mock.MagicMock(),
        se3_utils=mock.MagicMock(),
        wgs_converter=mock.MagicMock(),
        fdr_client=mock.MagicMock(),
    )

    assert isinstance(handle, ISam2GraphHandleImpl)
    assert handle._estimator is estimator