"""AZ-921 AC-4 — VioOutput.scale_quality DTO contract."""

from __future__ import annotations

import typing
from dataclasses import fields

import numpy as np

from gps_denied_onboard._types.nav import (
    FeatureQuality,
    ImuBias,
    ScaleQuality,
    VioOutput,
)
from gps_denied_onboard.helpers.se3_utils import SE3, matrix_to_se3


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


def _feature_quality() -> FeatureQuality:
    return FeatureQuality(
        tracked=10,
        new=2,
        lost=1,
        mean_parallax=1.0,
        mre_px=0.5,
    )


def _identity_se3() -> SE3:
    return matrix_to_se3(np.eye(4, dtype=np.float64))


def test_vio_output_default_scale_quality_is_unknown_for_back_compat() -> None:
    # Arrange / Act — constructor MUST work without scale_quality so
    # legacy strategies (OKVIS2, VINS-Mono) that have not been updated
    # for AZ-921 stay bug-for-bug compatible.
    vio = VioOutput(
        frame_id="frame-0",
        relative_pose_T=_identity_se3(),
        pose_covariance_6x6=np.eye(6, dtype=np.float64),
        imu_bias=_imu_bias(),
        feature_quality=_feature_quality(),
        emitted_at_ns=1_000_000_000,
    )

    # Assert
    assert vio.scale_quality == "unknown"


def test_vio_output_accepts_each_scale_quality_value() -> None:
    # Arrange
    accepted_values = ("metric", "direction_only", "unknown")

    # Act / Assert
    for value in accepted_values:
        vio = VioOutput(
            frame_id="frame-0",
            relative_pose_T=_identity_se3(),
            pose_covariance_6x6=np.eye(6, dtype=np.float64),
            imu_bias=_imu_bias(),
            feature_quality=_feature_quality(),
            emitted_at_ns=1_000_000_000,
            scale_quality=value,
        )
        assert vio.scale_quality == value


def test_scale_quality_literal_pins_the_three_documented_values() -> None:
    # Arrange / Act — the Literal type from the typing module exposes
    # its parameters via __args__, which lets the contract test pin
    # the exact accepted-string set rather than relying on a string
    # comparison alone.
    args = typing.get_args(ScaleQuality)

    # Assert
    assert set(args) == {"metric", "direction_only", "unknown"}


def test_vio_output_dataclass_exposes_scale_quality_field() -> None:
    # Arrange / Act
    field_names = {f.name for f in fields(VioOutput)}

    # Assert
    assert "scale_quality" in field_names