import numpy as np
import pytest

from he11lib.data import validate_planes
from he11lib.fitting import ModalFitter, generate_mode_shells
from he11lib.modes import LGBasis
from he11lib.synthetic import SyntheticBeamGenerator

W0 = 5e-3
Z0 = 0.5
WAVELENGTH = 1.76e-3
PIXEL_SCALE = 4e-4
IMAGE_SHAPE = (61, 61)
Z_LIST = [0.35, 0.5, 0.65, 0.8]


def make_basis():
    return LGBasis(w0=W0, z0=Z0, wavelength=WAVELENGTH)


def make_generator(basis):
    return SyntheticBeamGenerator(basis=basis, image_shape=IMAGE_SHAPE, pixel_scale=PIXEL_SCALE)


def test_generate_mode_shells_orders_by_2p_plus_abs_l():
    shells = generate_mode_shells(max_order=2)
    assert shells[0] == [(0, 0)]
    assert set(shells[1]) == {(0, 1), (0, -1)}
    assert set(shells[2]) == {(0, 2), (0, -2), (1, 0)}


def test_fit_recovers_pure_fundamental_mode():
    basis = make_basis()
    gen = make_generator(basis)
    planes = gen.generate(
        coefficients={(0, 0): 1.0 + 0j}, z_list=Z_LIST, noise_std=1e-4, seed=0
    )

    fitter = ModalFitter(basis)
    result = fitter.fit(planes, modes=[(0, 0)])

    power_fraction, _ = result.purity[(0, 0)]
    assert power_fraction == pytest.approx(1.0, abs=1e-6)
    for cx, cy in result.centers:
        assert cx == pytest.approx(0.0, abs=2 * PIXEL_SCALE)
        assert cy == pytest.approx(0.0, abs=2 * PIXEL_SCALE)


def test_fit_recovers_two_mode_purity_ratio():
    basis = make_basis()
    gen = make_generator(basis)
    true_coeffs = {(0, 0): 0.9 + 0j, (1, 0): 0.3 + 0.1j}
    planes = gen.generate(coefficients=true_coeffs, z_list=Z_LIST, noise_std=1e-4, seed=1)

    fitter = ModalFitter(basis)
    result = fitter.fit(planes, modes=list(true_coeffs.keys()))

    true_total = sum(abs(c) ** 2 for c in true_coeffs.values())
    for mode, c in true_coeffs.items():
        expected_fraction = abs(c) ** 2 / true_total
        recovered_fraction, _ = result.purity[mode]
        assert recovered_fraction == pytest.approx(expected_fraction, abs=0.03)


def test_fit_recovers_center_offset():
    basis = make_basis()
    gen = make_generator(basis)
    true_center = (10 * PIXEL_SCALE, -5 * PIXEL_SCALE)
    planes = gen.generate(
        coefficients={(0, 0): 1.0 + 0j},
        z_list=Z_LIST,
        center=true_center,
        noise_std=1e-4,
        seed=2,
    )

    fitter = ModalFitter(basis)
    result = fitter.fit(planes, modes=[(0, 0)], initial_center=true_center)

    for cx, cy in result.centers:
        assert cx == pytest.approx(true_center[0], abs=2 * PIXEL_SCALE)
        assert cy == pytest.approx(true_center[1], abs=2 * PIXEL_SCALE)


def test_fit_recovers_unknown_pixel_scale():
    # Use a coarser pixel scale so the (much wider, far-field) beam at the
    # outer z distances still fits within the frame -- otherwise pixel scale
    # becomes unobservable from clipped images.
    basis = make_basis()
    local_pixel_scale = 1.5e-3
    gen = SyntheticBeamGenerator(basis=basis, image_shape=IMAGE_SHAPE, pixel_scale=local_pixel_scale)
    planes = gen.generate(coefficients={(0, 0): 1.0 + 0j}, z_list=Z_LIST, noise_std=1e-4, seed=3)

    # hide the known calibration to force the fitter to solve for it
    for plane in planes:
        plane.pixel_scale = None
        plane.viewing_angle_deg = None

    fitter = ModalFitter(basis)
    result = fitter.fit(
        planes,
        modes=[(0, 0)],
        initial_pixel_scale=local_pixel_scale * 1.1,
        initial_viewing_angle_deg=0.0,
    )

    fitted_scales = [result.geometry[f"pixel_scale_{i}"] for i in range(len(planes))]
    for scale in fitted_scales:
        assert scale == pytest.approx(local_pixel_scale, rel=0.05)


def test_fit_auto_does_not_add_modes_for_pure_fundamental():
    basis = make_basis()
    gen = make_generator(basis)
    planes = gen.generate(
        coefficients={(0, 0): 1.0 + 0j}, z_list=Z_LIST, noise_std=1e-4, seed=4
    )

    fitter = ModalFitter(basis)
    result = fitter.fit_auto(planes, max_order=2)

    assert set(result.purity.keys()) == {(0, 0)}


def test_fit_auto_grows_to_include_second_mode():
    basis = make_basis()
    gen = make_generator(basis)
    true_coeffs = {(0, 0): 0.9 + 0j, (0, 1): 0.4 + 0j}
    planes = gen.generate(coefficients=true_coeffs, z_list=Z_LIST, noise_std=1e-4, seed=5)

    fitter = ModalFitter(basis)
    result = fitter.fit_auto(planes, max_order=2)

    assert (0, 1) in result.purity or (0, -1) in result.purity