"""AZ-331 — C1 VioStrategy Protocol + DTO + error + factory conformance.

Covers all 9 ACs of AZ-331 plus NFR-perf-factory and
NFR-reliability-error-family. The factory ACs (AC-4 / AC-5) substitute
fake strategy modules at ``sys.modules`` boundaries so the test never
touches OKVIS2 / VINS-Mono / OpenCV native libraries.
"""

from __future__ import annotations

import dataclasses
import re
import sys
import time
import types
from pathlib import Path

import gtsam
import numpy as np
import pytest

from gps_denied_onboard._types.nav import (
    FeatureQuality,
    ImuBias,
    VioHealth,
    VioOutput,
    VioState,
    WarmStartPose,
)
from gps_denied_onboard.components.c1_vio import (
    C1VioConfig,
    VioDegradedError,
    VioError,
    VioFatalError,
    VioInitializingError,
    VioStrategy,
)
from gps_denied_onboard.components.c1_vio.config import KNOWN_STRATEGIES
from gps_denied_onboard.config.schema import Config, ConfigError
from gps_denied_onboard.runtime_root.errors import StrategyNotAvailableError
from gps_denied_onboard.runtime_root.vio_factory import build_vio_strategy

_CONTRACT_PATH = (
    Path(__file__).resolve().parents[3]
    / "_docs/02_document/contracts/c1_vio/vio_strategy_protocol.md"
)
_STRATEGY_MODULES: dict[str, tuple[str, str, str]] = {
    "okvis2": (
        "gps_denied_onboard.components.c1_vio.okvis2",
        "Okvis2Strategy",
        "BUILD_OKVIS2",
    ),
    "vins_mono": (
        "gps_denied_onboard.components.c1_vio.vins_mono",
        "VinsMonoStrategy",
        "BUILD_VINS_MONO",
    ),
    "klt_ransac": (
        "gps_denied_onboard.components.c1_vio.klt_ransac",
        "KltRansacStrategy",
        "BUILD_KLT_RANSAC",
    ),
}


# ----------------------------------------------------------------------
# Fakes that structurally satisfy the VioStrategy Protocol.


class _FullVioStrategy:
    def __init__(self, config: Config, *, fdr_client) -> None:
        self.config = config
        self.fdr_client = fdr_client
        self._label = config.components["c1_vio"].strategy

    def process_frame(self, frame, imu, calibration):
        raise NotImplementedError

    def reset_to_warm_start(self, hint):
        return None

    def health_snapshot(self):
        return VioHealth(state=VioState.INIT, consecutive_lost=0, bias_norm=0.0)

    def current_strategy_label(self):
        return self._label


class _PartialVioStrategy:
    def process_frame(self, frame, imu, calibration):
        raise NotImplementedError

    def reset_to_warm_start(self, hint):
        return None


def _config_with_strategy(strategy: str) -> Config:
    return Config.with_blocks(c1_vio=C1VioConfig(strategy=strategy))


def _install_fake_strategy(strategy_label: str) -> type:
    module_name, class_name, _flag = _STRATEGY_MODULES[strategy_label]

    class _FakeStrategy(_FullVioStrategy):
        pass

    _FakeStrategy.__name__ = class_name
    module = types.ModuleType(module_name)
    setattr(module, class_name, _FakeStrategy)
    sys.modules[module_name] = module
    return _FakeStrategy


@pytest.fixture
def strategy_module_cleanup():
    """Pop every fake strategy module before/after each factory test."""
    for module_name, _, _ in _STRATEGY_MODULES.values():
        sys.modules.pop(module_name, None)
    yield
    for module_name, _, _ in _STRATEGY_MODULES.values():
        sys.modules.pop(module_name, None)


def _zero_bias() -> ImuBias:
    return ImuBias(accel_bias=(0.0, 0.0, 0.0), gyro_bias=(0.0, 0.0, 0.0))


def _neutral_feature_quality() -> FeatureQuality:
    return FeatureQuality(tracked=20, new=2, lost=1, mean_parallax=5.0, mre_px=1.0)


def _make_vio_output(frame_id: str = "frame-0001") -> VioOutput:
    return VioOutput(
        frame_id=frame_id,
        relative_pose_T=gtsam.Pose3(np.eye(4)),
        pose_covariance_6x6=np.eye(6) * 0.01,
        imu_bias=_zero_bias(),
        feature_quality=_neutral_feature_quality(),
        emitted_at_ns=1_000_000_000,
    )


# ----------------------------------------------------------------------
# AC-1: Protocol is conformance-checkable.


def test_ac1_vio_strategy_conformance_full() -> None:
    instance = _FullVioStrategy(_config_with_strategy("klt_ransac"), fdr_client=None)
    assert isinstance(instance, VioStrategy)


def test_ac1_vio_strategy_conformance_partial_missing_methods() -> None:
    assert not isinstance(_PartialVioStrategy(), VioStrategy)


# ----------------------------------------------------------------------
# AC-2: frozen DTOs reject mutation.


@pytest.mark.parametrize(
    "dto, field_name, new_value",
    [
        (_make_vio_output(), "frame_id", "renamed"),
        (
            VioHealth(state=VioState.TRACKING, consecutive_lost=0, bias_norm=0.0),
            "state",
            VioState.LOST,
        ),
        (
            WarmStartPose(
                body_T_world=gtsam.Pose3(np.eye(4)),
                velocity_b=(0.0, 0.0, 0.0),
                bias=_zero_bias(),
                captured_at_ns=1_000_000_000,
            ),
            "captured_at_ns",
            0,
        ),
        (_neutral_feature_quality(), "tracked", 0),
    ],
)
def test_ac2_frozen_dtos_reject_mutation(dto, field_name: str, new_value) -> None:
    original_value = getattr(dto, field_name)
    with pytest.raises(dataclasses.FrozenInstanceError):
        setattr(dto, field_name, new_value)
    assert getattr(dto, field_name) == original_value


# ----------------------------------------------------------------------
# AC-3: error hierarchy catchable as a single family.


@pytest.mark.parametrize(
    "exc_factory",
    [VioInitializingError, VioDegradedError, VioFatalError],
)
def test_ac3_all_vio_errors_caught_as_family(exc_factory) -> None:
    with pytest.raises(VioError):
        raise exc_factory("boom")


def test_ac3_unrelated_exception_not_caught_as_family() -> None:
    with pytest.raises(ValueError):
        try:
            raise ValueError("not us")
        except VioError:
            pytest.fail("ValueError must not be caught as VioError")


def test_ac3_strategy_not_available_outside_family() -> None:
    with pytest.raises(StrategyNotAvailableError):
        try:
            raise StrategyNotAvailableError("composition-time")
        except VioError:
            pytest.fail(
                "StrategyNotAvailableError is a composition-root error "
                "and MUST NOT be in the c1 VioError family"
            )


# ----------------------------------------------------------------------
# AC-4 + AC-5: factory honours config + BUILD flag gate.


@pytest.mark.parametrize("strategy", sorted(_STRATEGY_MODULES))
def test_ac4_build_vio_strategy_returns_protocol_impl(
    monkeypatch, strategy_module_cleanup, strategy
) -> None:
    _, _, flag = _STRATEGY_MODULES[strategy]
    monkeypatch.setenv(flag, "ON")
    fake_cls = _install_fake_strategy(strategy)
    config = _config_with_strategy(strategy)
    instance = build_vio_strategy(config, fdr_client=object())
    assert isinstance(instance, fake_cls)
    assert isinstance(instance, VioStrategy)


@pytest.mark.parametrize("strategy", sorted(_STRATEGY_MODULES))
def test_ac5_build_vio_strategy_flag_off_no_import(
    monkeypatch, strategy_module_cleanup, strategy
) -> None:
    module_name, _, flag = _STRATEGY_MODULES[strategy]
    monkeypatch.delenv(flag, raising=False)
    config = _config_with_strategy(strategy)
    with pytest.raises(StrategyNotAvailableError) as exc_info:
        build_vio_strategy(config, fdr_client=object())
    assert strategy in str(exc_info.value)
    assert flag in str(exc_info.value)
    assert module_name not in sys.modules


# Which strategies still have NO concrete Python module on disk?
# Once an AZ-332 / AZ-333 / AZ-334 implementation lands, the
# `flag_on_but_module_missing` semantic shifts: the factory's import
# succeeds, the constructor fails on missing native binding or other
# prerequisite. We assert the meaningful-error-before-first-frame
# property holds for BOTH cases — the exception class differs by
# strategy.
_STRATEGIES_WITHOUT_PY_MODULE: tuple[str, ...] = ("vins_mono", "klt_ransac")


@pytest.mark.parametrize("strategy", sorted(_STRATEGY_MODULES))
def test_ac5_build_vio_strategy_flag_on_but_module_missing(
    monkeypatch, strategy_module_cleanup, strategy
) -> None:
    _, _, flag = _STRATEGY_MODULES[strategy]
    monkeypatch.setenv(flag, "ON")
    config = _config_with_strategy(strategy)
    if strategy in _STRATEGIES_WITHOUT_PY_MODULE:
        # Module not yet implemented — factory's __import__ raises
        # ModuleNotFoundError, rewrapped into StrategyNotAvailableError.
        with pytest.raises(StrategyNotAvailableError) as exc_info:
            build_vio_strategy(config, fdr_client=object())
        assert strategy in str(exc_info.value)
    else:
        # Module IS implemented (AZ-332). Factory import succeeds, then
        # the strategy constructor fails on missing native binding —
        # which the strategy MUST surface as VioFatalError BEFORE any
        # frame is processed (the AC-5 spirit: no silent fall-through).
        with pytest.raises(VioFatalError) as exc_info:
            build_vio_strategy(config, fdr_client=object())
        assert "native binding" in str(exc_info.value)


# ----------------------------------------------------------------------
# AC-6: unknown strategy label rejected at config load.


@pytest.mark.parametrize(
    "bad_label",
    ["openvslam", "orbslam3", "OKVIS2", "okvis", ""],
)
def test_ac6_unknown_strategy_rejected_at_config_load(bad_label: str) -> None:
    with pytest.raises(ConfigError) as exc_info:
        C1VioConfig(strategy=bad_label)
    msg = str(exc_info.value)
    for valid in KNOWN_STRATEGIES:
        assert valid in msg


# ----------------------------------------------------------------------
# AC-7: current_strategy_label() matches config exactly.


@pytest.mark.parametrize("strategy", sorted(_STRATEGY_MODULES))
def test_ac7_current_strategy_label_matches_config(
    monkeypatch, strategy_module_cleanup, strategy
) -> None:
    _, _, flag = _STRATEGY_MODULES[strategy]
    monkeypatch.setenv(flag, "ON")
    _install_fake_strategy(strategy)
    config = _config_with_strategy(strategy)
    instance = build_vio_strategy(config, fdr_client=object())
    assert instance.current_strategy_label() == strategy
    assert instance.current_strategy_label() == config.components["c1_vio"].strategy


# ----------------------------------------------------------------------
# AC-8: contract file matches Protocol shape.


_METHOD_TABLE_RE = re.compile(r"^\|\s*`(?P<name>[a-z_][a-z0-9_]*)`\s*\|", re.MULTILINE)


def _methods_from_contract() -> set[str]:
    text = _CONTRACT_PATH.read_text(encoding="utf-8")
    surface_start = text.index("### Protocol surface")
    next_section = text.find("\n### ", surface_start + len("### Protocol surface"))
    section = text[surface_start:next_section] if next_section != -1 else text[surface_start:]
    return {m.group("name") for m in _METHOD_TABLE_RE.finditer(section)}


def _protocol_methods(proto: type) -> set[str]:
    return {
        name for name in dir(proto) if not name.startswith("_") and callable(getattr(proto, name))
    }


def test_ac8_contract_methods_match_protocol() -> None:
    contract_methods = _methods_from_contract()
    protocol_methods = _protocol_methods(VioStrategy)
    missing_in_protocol = contract_methods - protocol_methods
    missing_in_contract = protocol_methods - contract_methods
    assert not missing_in_protocol, (
        "Methods declared in vio_strategy_protocol.md Shape section but "
        f"missing from the Protocol: {sorted(missing_in_protocol)}"
    )
    assert not missing_in_contract, (
        "Methods present on the Protocol but missing from the contract "
        f"Shape section: {sorted(missing_in_contract)}"
    )


def test_ac8_contract_lists_all_three_error_subtypes() -> None:
    text = _CONTRACT_PATH.read_text(encoding="utf-8")
    for name in {"VioInitializingError", "VioDegradedError", "VioFatalError"}:
        assert name in text, f"Contract file is missing the documented error subtype {name!r}"


# ----------------------------------------------------------------------
# AC-9: VioOutput.frame_id echo invariant is typed.


def test_ac9_vio_output_frame_id_is_typed_str() -> None:
    """``VioOutput.frame_id`` annotation is ``str`` per AZ-331 AC-9.

    With ``from __future__ import annotations`` PEP-563 stringifies
    every annotation at module load, so ``__annotations__`` returns
    the literal ``'str'``. Compare against the string to avoid the
    full ``get_type_hints`` forward-ref resolution path (which would
    try to resolve neighbouring TYPE_CHECKING-only names like
    :class:`SE3`).
    """
    annotation = VioOutput.__annotations__["frame_id"]
    assert annotation == "str", f"frame_id annotation should be 'str'; got {annotation!r}"


def test_ac9_vio_output_docstring_documents_echo_invariant() -> None:
    docstring = VioOutput.__doc__ or ""
    assert "echo" in docstring.lower(), (
        "VioOutput docstring must document the frame_id echo invariant "
        "(MUST equal NavCameraFrame.frame_id from the input frame)"
    )
    assert "frame_id" in docstring.lower()


# ----------------------------------------------------------------------
# NFRs.


@pytest.mark.parametrize(
    "exc_type",
    [VioInitializingError, VioDegradedError, VioFatalError],
)
def test_nfr_reliability_all_vio_errors_subclass_family(exc_type) -> None:
    assert issubclass(exc_type, VioError)


def test_nfr_reliability_strategy_not_available_not_in_family() -> None:
    assert not issubclass(StrategyNotAvailableError, VioError)


def test_nfr_perf_factory_under_200ms_p99(monkeypatch, strategy_module_cleanup) -> None:
    """Factory p99 ≤ 200 ms across 1000 calls (NFR-perf-factory)."""
    strategy = "klt_ransac"
    _, _, flag = _STRATEGY_MODULES[strategy]
    monkeypatch.setenv(flag, "ON")
    _install_fake_strategy(strategy)
    config = _config_with_strategy(strategy)

    durations_ms: list[float] = []
    for _ in range(1000):
        t0 = time.perf_counter()
        build_vio_strategy(config, fdr_client=object())
        durations_ms.append((time.perf_counter() - t0) * 1000.0)

    durations_ms.sort()
    p99 = durations_ms[int(0.99 * len(durations_ms))]
    assert p99 <= 200.0, f"build_vio_strategy() p99={p99:.3f} ms exceeds 200 ms NFR"


# ----------------------------------------------------------------------
# Surface coverage.


def test_vio_state_enum_surface() -> None:
    assert {v.value for v in VioState} == {"init", "tracking", "degraded", "lost"}


def test_c1_config_lost_frame_threshold_validation() -> None:
    with pytest.raises(ConfigError):
        C1VioConfig(lost_frame_threshold=0)
    with pytest.raises(ConfigError):
        C1VioConfig(lost_frame_threshold=-1)


def test_c1_config_warm_start_max_frames_validation() -> None:
    with pytest.raises(ConfigError):
        C1VioConfig(warm_start_max_frames=0)


def test_feature_quality_dto_constructs_and_freezes() -> None:
    fq = _neutral_feature_quality()
    with pytest.raises(dataclasses.FrozenInstanceError):
        fq.mre_px = 99.0  # type: ignore[misc]


def test_warm_start_pose_constructs_with_zero_bias() -> None:
    hint = WarmStartPose(
        body_T_world=gtsam.Pose3(np.eye(4)),
        velocity_b=(0.0, 0.0, 0.0),
        bias=_zero_bias(),
        captured_at_ns=1_000_000_000,
    )
    assert hint.captured_at_ns == 1_000_000_000
    assert hint.bias.accel_bias == (0.0, 0.0, 0.0)