"""Coordinate conversion helpers — ECEF↔WGS84 + Euler→quaternion."""

import numpy as np
import pytest

from gps_denied.testing.coord import ecef_to_wgs84, euler_to_quaternion

# --- ECEF → WGS84 ---

def test_ecef_origin_is_on_equator_prime_meridian():
    # Point on equator at lon=0, alt=0 is at x=6378137, y=0, z=0 (WGS84 semi-major)
    lat, lon, alt = ecef_to_wgs84(6378137.0, 0.0, 0.0)
    assert lat == pytest.approx(0.0, abs=1e-6)
    assert lon == pytest.approx(0.0, abs=1e-6)
    assert alt == pytest.approx(0.0, abs=1e-3)


def test_ecef_north_pole():
    # Semi-minor axis b ≈ 6356752.314 — north pole, lat=90, lon undefined but typically 0
    lat, lon, alt = ecef_to_wgs84(0.0, 0.0, 6356752.314245)
    assert lat == pytest.approx(90.0, abs=1e-4)
    assert alt == pytest.approx(0.0, abs=1e-2)


def test_ecef_known_point_near_munich():
    # Input ECEF (4177789.3, 855098.1, 4727807.9) m — point near Munich, Germany.
    # Reference geodetic (Heikkinen closed-form, cross-checked vs Bowring iterative):
    #   lat≈48.14141°, lon≈11.56740°, alt≈570.75 m.
    lat, lon, alt = ecef_to_wgs84(4177789.3, 855098.1, 4727807.9)
    assert lat == pytest.approx(48.14141, abs=1e-4)
    assert lon == pytest.approx(11.56740, abs=1e-4)
    assert alt == pytest.approx(570.75, abs=1.0)


def test_ecef_vpair_sample_point():
    # From VPAIR sample poses_query.txt first row:
    #   4023518.0, 510303.75, 4906569.65  — should be in Bonn/Eifel region, Germany
    # (VPAIR was recorded near Bonn). Expected lat ~50.7°, lon ~7.2°, alt ~(200-400) m.
    lat, lon, alt = ecef_to_wgs84(4023518.0, 510303.75, 4906569.65)
    assert 50.0 < lat < 51.5, f"lat={lat}"
    assert 6.5 < lon < 8.0, f"lon={lon}"
    # Bonn-Eifel area ground elevation 100-500 m
    assert 100.0 < alt < 700.0, f"alt={alt}"


# --- Euler → quaternion ---

def test_euler_zero_is_identity_quaternion():
    qx, qy, qz, qw = euler_to_quaternion(0.0, 0.0, 0.0)
    assert qx == pytest.approx(0.0, abs=1e-12)
    assert qy == pytest.approx(0.0, abs=1e-12)
    assert qz == pytest.approx(0.0, abs=1e-12)
    assert qw == pytest.approx(1.0, abs=1e-12)


def test_euler_yaw_90_deg_about_z():
    # Yaw = π/2 around world z, roll=pitch=0
    # Expected quaternion: (0, 0, sin(π/4), cos(π/4)) ≈ (0, 0, 0.7071, 0.7071)
    qx, qy, qz, qw = euler_to_quaternion(0.0, 0.0, np.pi / 2)
    assert qx == pytest.approx(0.0, abs=1e-10)
    assert qy == pytest.approx(0.0, abs=1e-10)
    assert qz == pytest.approx(np.sin(np.pi / 4), abs=1e-10)
    assert qw == pytest.approx(np.cos(np.pi / 4), abs=1e-10)


def test_euler_roll_90_deg_about_x():
    # Roll = π/2 around body x, pitch=yaw=0
    qx, qy, qz, qw = euler_to_quaternion(np.pi / 2, 0.0, 0.0)
    assert qx == pytest.approx(np.sin(np.pi / 4), abs=1e-10)
    assert qy == pytest.approx(0.0, abs=1e-10)
    assert qz == pytest.approx(0.0, abs=1e-10)
    assert qw == pytest.approx(np.cos(np.pi / 4), abs=1e-10)


def test_euler_unit_norm():
    # Arbitrary angles — the returned quaternion must be unit norm
    qx, qy, qz, qw = euler_to_quaternion(0.3, -0.7, 1.2)
    norm = (qx * qx + qy * qy + qz * qz + qw * qw) ** 0.5
    assert norm == pytest.approx(1.0, abs=1e-12)