"""AZ-922 — cheirality / rotation-plausibility gate in KLT/RANSAC.

Covers AC-1 (axis-angle helper math), AC-2/AC-3 (gate threshold + routing
through `_pose_recovery_failed`), and AC-4 (boundary + AC-7 lost-frame
escalation). AC-5 (Jetson e2e Derkachi past frame 5) is gated separately
via the Tier-2 harness — not in unit scope.
"""

from __future__ import annotations

import math
from datetime import datetime, timezone
from typing import Any

import numpy as np
import pytest

from gps_denied_onboard._types.calibration import CameraCalibration
from gps_denied_onboard._types.nav import (
    ImuSample,
    ImuWindow,
    NavCameraFrame,
)
from gps_denied_onboard.components.c1_vio import C1VioConfig, KltRansacConfig
from gps_denied_onboard.components.c1_vio import klt_ransac as klt_ransac_module
from gps_denied_onboard.components.c1_vio.errors import (
    VioFatalError,
    VioInitializingError,
)
from gps_denied_onboard.components.c1_vio.klt_ransac import (
    KltRansacStrategy,
    _rotation_angle_rad,
)
from gps_denied_onboard.config.schema import Config, RuntimeConfig
from gps_denied_onboard.fdr_client.client import FdrClient
from gps_denied_onboard.helpers.ransac_filter import RansacResult

# ----------------------------------------------------------------------
# AC-1 — pure helper math
# ----------------------------------------------------------------------


def test_rotation_angle_identity_is_zero() -> None:
    # Assert
    assert _rotation_angle_rad(np.eye(3, dtype=np.float64)) == pytest.approx(0.0, abs=1e-12)


def test_rotation_angle_180_about_x_is_pi() -> None:
    # Arrange — R rotates 180° about the body-X axis: trace = 1 + (-1) + (-1) = -1.
    R = np.array(
        [
            [1.0, 0.0, 0.0],
            [0.0, -1.0, 0.0],
            [0.0, 0.0, -1.0],
        ],
        dtype=np.float64,
    )

    # Assert
    assert _rotation_angle_rad(R) == pytest.approx(math.pi, abs=1e-9)


def test_rotation_angle_general_diagonal_recovers_axis_angle_magnitude() -> None:
    # Arrange — 30° rotation about body-Z: trace = cos(30)+cos(30)+1.
    theta = math.radians(30.0)
    R = np.array(
        [
            [math.cos(theta), -math.sin(theta), 0.0],
            [math.sin(theta), math.cos(theta), 0.0],
            [0.0, 0.0, 1.0],
        ],
        dtype=np.float64,
    )

    # Assert
    assert _rotation_angle_rad(R) == pytest.approx(theta, abs=1e-9)


def test_rotation_angle_arccos_argument_clipped_against_float_drift() -> None:
    # Arrange — synthesise an R whose trace is *just* above 3.0 (impossible
    # in exact arithmetic but achievable via float drift). Without the
    # arccos clip this would yield NaN; with the clip it must return 0.
    R = np.eye(3, dtype=np.float64) + np.full((3, 3), 1e-15, dtype=np.float64)

    # Assert
    assert _rotation_angle_rad(R) == pytest.approx(0.0, abs=1e-6)
    assert math.isfinite(_rotation_angle_rad(R))


def test_rotation_angle_uses_jetson_frame_5_diagonal_signature() -> None:
    # Arrange — exact R diagonal observed at Derkachi frame 5 (the
    # divergence point). Trace = -0.848 - 0.639 + 0.487 = -1.0.
    R = np.diag([-0.848, -0.639, 0.487]).astype(np.float64)

    # Assert — recover the 180° rotation the ESKF traceback implied.
    assert _rotation_angle_rad(R) == pytest.approx(math.pi, abs=1e-9)


# ----------------------------------------------------------------------
# Strategy-level scaffolding (mirrors test_az920_klt_ransac_scale_integration.py)
# ----------------------------------------------------------------------


def _calibration() -> CameraCalibration:
    return CameraCalibration(
        camera_id="khp20s30-test",
        intrinsics_3x3=np.array(
            [
                [1680.0, 0.0, 960.0],
                [0.0, 1680.0, 540.0],
                [0.0, 0.0, 1.0],
            ],
            dtype=np.float64,
        ),
        distortion=np.zeros(5, dtype=np.float64),
        body_to_camera_se3=np.eye(4, dtype=np.float64),
        acquisition_method="test_az922",
    )


def _frame(idx: int) -> NavCameraFrame:
    rng = np.random.default_rng(seed=idx)
    image = (rng.integers(0, 255, size=(240, 240), dtype=np.int16)).astype(np.uint8)
    return NavCameraFrame(
        frame_id=idx,
        timestamp=datetime.fromtimestamp(idx * 0.1, tz=timezone.utc),
        image=image,
        camera_calibration_id="khp20s30-test",
    )


def _imu_window(frame_idx: int) -> ImuWindow:
    ts_start_ns = 1_000_000_000 + frame_idx * 100_000_000
    samples = tuple(
        ImuSample(
            ts_ns=ts_start_ns + i * 5_000_000,
            accel_xyz=(0.0, 0.0, 9.81),
            gyro_xyz=(0.0, 0.0, 0.0),
        )
        for i in range(3)
    )
    return ImuWindow(
        samples=samples,
        ts_start_ns=samples[0].ts_ns,
        ts_end_ns=samples[-1].ts_ns,
    )


def _config(lost_frame_threshold: int = 3) -> Config:
    return Config.with_blocks(
        c1_vio=C1VioConfig(
            strategy="klt_ransac",
            klt_ransac=KltRansacConfig(),
            lost_frame_threshold=lost_frame_threshold,
        ),
        runtime=RuntimeConfig(),
    )


def _patch_pose_recovery_with_rotation(
    monkeypatch: pytest.MonkeyPatch,
    *,
    R_3x3: np.ndarray,
    inlier_count: int = 40,
) -> None:
    """Force the geometry stack to a controlled path with a chosen R.

    Mirrors the AZ-920 test helper but takes the rotation matrix as a
    parameter so AZ-922 can exercise the cheirality gate directly.
    """
    rng = np.random.default_rng(seed=271828)
    base = rng.uniform(50.0, 1800.0, size=(inlier_count, 2))
    inliers = np.column_stack([base, base + np.array([5.0, 0.0])])
    mask = np.ones((inlier_count, 1), dtype=np.uint8)

    def _fake_filter(_corr: np.ndarray, _thresh: float, _min: int) -> RansacResult:
        return RansacResult(
            inlier_correspondences=inliers,
            inlier_count=inlier_count,
            outlier_count=0,
            median_residual_px=0.5,
        )

    def _fake_find_essential(*_a: Any, **_k: Any) -> tuple[np.ndarray, np.ndarray]:
        return np.eye(3, dtype=np.float64), mask

    def _fake_recover_pose(*_a: Any, **_k: Any) -> tuple[int, np.ndarray, np.ndarray, np.ndarray]:
        t_col = np.array([[1.0], [0.0], [0.0]], dtype=np.float64)
        return inlier_count, R_3x3.astype(np.float64), t_col, mask

    monkeypatch.setattr(
        klt_ransac_module.RansacFilter,
        "filter_correspondences",
        staticmethod(_fake_filter),
    )
    monkeypatch.setattr(klt_ransac_module.cv2, "findEssentialMat", _fake_find_essential)
    monkeypatch.setattr(klt_ransac_module.cv2, "recoverPose", _fake_recover_pose)


def _fdr_client() -> FdrClient:
    return FdrClient(producer_id="test.az922", capacity=16, _emit_diag_log=False)


def _r_about_z(theta_rad: float) -> np.ndarray:
    return np.array(
        [
            [math.cos(theta_rad), -math.sin(theta_rad), 0.0],
            [math.sin(theta_rad), math.cos(theta_rad), 0.0],
            [0.0, 0.0, 1.0],
        ],
        dtype=np.float64,
    )


# ----------------------------------------------------------------------
# AC-2/AC-3 — gate threshold + routing through _pose_recovery_failed
# ----------------------------------------------------------------------


def test_identity_rotation_passes_gate(monkeypatch: pytest.MonkeyPatch) -> None:
    # Arrange
    _patch_pose_recovery_with_rotation(monkeypatch, R_3x3=np.eye(3))
    strategy = KltRansacStrategy(_config(), fdr_client=_fdr_client())
    calibration = _calibration()

    # Act
    strategy.process_frame(_frame(idx=1), _imu_window(1), calibration)
    second = strategy.process_frame(_frame(idx=2), _imu_window(2), calibration)

    # Assert
    assert second is not None
    assert second.frame_id == "2"


def test_five_degree_rotation_passes_gate(monkeypatch: pytest.MonkeyPatch) -> None:
    # Arrange — 5° rotation, well below the 30° default threshold.
    _patch_pose_recovery_with_rotation(monkeypatch, R_3x3=_r_about_z(math.radians(5.0)))
    strategy = KltRansacStrategy(_config(), fdr_client=_fdr_client())
    calibration = _calibration()

    # Act
    strategy.process_frame(_frame(idx=1), _imu_window(1), calibration)
    second = strategy.process_frame(_frame(idx=2), _imu_window(2), calibration)

    # Assert
    assert second is not None


def test_sixty_degree_rotation_rejected_by_gate(monkeypatch: pytest.MonkeyPatch) -> None:
    # Arrange — 60° rotation exceeds the 30° default threshold.
    _patch_pose_recovery_with_rotation(monkeypatch, R_3x3=_r_about_z(math.radians(60.0)))
    strategy = KltRansacStrategy(_config(), fdr_client=_fdr_client())
    calibration = _calibration()

    # Act + Assert
    strategy.process_frame(_frame(idx=1), _imu_window(1), calibration)
    with pytest.raises(VioInitializingError, match="implausible_rotation_angle"):
        strategy.process_frame(_frame(idx=2), _imu_window(2), calibration)


def test_180_degree_rotation_rejected_by_gate(monkeypatch: pytest.MonkeyPatch) -> None:
    # Arrange — synthesise the Jetson-observed frame-5 R signature.
    R_180 = np.diag([-0.848, -0.639, 0.487]).astype(np.float64)
    _patch_pose_recovery_with_rotation(monkeypatch, R_3x3=R_180)
    strategy = KltRansacStrategy(_config(), fdr_client=_fdr_client())
    calibration = _calibration()

    # Act + Assert
    strategy.process_frame(_frame(idx=1), _imu_window(1), calibration)
    with pytest.raises(VioInitializingError, match="implausible_rotation_angle"):
        strategy.process_frame(_frame(idx=2), _imu_window(2), calibration)


def test_threshold_boundary_just_above_rejects(monkeypatch: pytest.MonkeyPatch) -> None:
    # Arrange — 30.1° vs 30° threshold.
    _patch_pose_recovery_with_rotation(
        monkeypatch, R_3x3=_r_about_z(math.radians(30.1))
    )
    strategy = KltRansacStrategy(_config(), fdr_client=_fdr_client())
    calibration = _calibration()

    # Act + Assert
    strategy.process_frame(_frame(idx=1), _imu_window(1), calibration)
    with pytest.raises(VioInitializingError, match="implausible_rotation_angle"):
        strategy.process_frame(_frame(idx=2), _imu_window(2), calibration)


def test_threshold_boundary_just_below_passes(monkeypatch: pytest.MonkeyPatch) -> None:
    # Arrange — 29.9° just below 30° threshold.
    _patch_pose_recovery_with_rotation(
        monkeypatch, R_3x3=_r_about_z(math.radians(29.9))
    )
    strategy = KltRansacStrategy(_config(), fdr_client=_fdr_client())
    calibration = _calibration()

    # Act
    strategy.process_frame(_frame(idx=1), _imu_window(1), calibration)
    second = strategy.process_frame(_frame(idx=2), _imu_window(2), calibration)

    # Assert
    assert second is not None


# ----------------------------------------------------------------------
# AC-4 (AC-7 path) — consecutive rejections escalate to VioFatalError
# ----------------------------------------------------------------------


def test_consecutive_rejections_eventually_raise_vio_fatal(
    monkeypatch: pytest.MonkeyPatch,
) -> None:
    # Arrange — every frame yields a 180° flip; lost_frame_threshold=3
    # means the 4th frame in this stream (the 3rd consecutive failure)
    # crosses the LOST gate.
    R_180 = np.diag([-1.0, -1.0, 1.0]).astype(np.float64)  # 180° about Z
    _patch_pose_recovery_with_rotation(monkeypatch, R_3x3=R_180)
    strategy = KltRansacStrategy(
        _config(lost_frame_threshold=3), fdr_client=_fdr_client()
    )
    calibration = _calibration()

    # Act — frame 1 seeds INIT; frames 2-4 hit the gate and tick lost.
    strategy.process_frame(_frame(idx=1), _imu_window(1), calibration)
    for idx in range(2, 4):
        with pytest.raises(VioInitializingError, match="implausible_rotation_angle"):
            strategy.process_frame(_frame(idx=idx), _imu_window(idx), calibration)
    # The 4th consecutive failed frame trips the LOST/VioFatalError gate.
    with pytest.raises(VioFatalError, match="exhausted lost-frame budget"):
        strategy.process_frame(_frame(idx=4), _imu_window(4), calibration)


# ----------------------------------------------------------------------
# Config validation — defends the (0, π] range
# ----------------------------------------------------------------------


def test_config_rejects_zero_or_negative_threshold() -> None:
    # Act + Assert
    with pytest.raises(Exception, match="max_frame_rotation_rad must be in"):
        KltRansacConfig(max_frame_rotation_rad=0.0)


def test_config_rejects_threshold_above_pi() -> None:
    # Act + Assert
    with pytest.raises(Exception, match="max_frame_rotation_rad must be in"):
        KltRansacConfig(max_frame_rotation_rad=math.pi + 0.01)


def test_config_accepts_pi_exactly() -> None:
    # Act — the inclusive upper bound. No rotation can exceed π anyway.
    cfg = KltRansacConfig(max_frame_rotation_rad=math.pi)

    # Assert
    assert cfg.max_frame_rotation_rad == pytest.approx(math.pi)