# Copyright 2021 The NetKet Authors - All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import pytest

import jax
import jax.flatten_util
import numpy as np
from flax import serialization
from jax.nn.initializers import normal

import tarfile
from io import BytesIO

from netket import experimental as nkx

import netket as nk

from .. import common

pytestmark = common.skipif_mpi

SEED = 111


@pytest.fixture()
def vstate(request):
    N = 8
    hi = nk.hilbert.Spin(1 / 2, N)

    ma = nk.models.RBM(
        alpha=1,
        param_dtype=float,
        hidden_bias_init=normal(),
        visible_bias_init=normal(),
    )

    return nk.vqs.MCState(
        nk.sampler.MetropolisLocal(hi),
        ma,
    )


def test_variables_from_file(vstate, tmp_path):
    fname = str(tmp_path) + "/file.mpack"

    with open(fname, "wb") as f:
        f.write(serialization.to_bytes(vstate.variables))

    for name in [fname, fname[:-6]]:
        vstate2 = nk.vqs.MCState(
            vstate.sampler, vstate.model, n_samples=10, seed=SEED + 100
        )

        vstate2.variables = nkx.vqs.variables_from_file(name, vstate2.variables)

        # check
        jax.tree_map(np.testing.assert_allclose, vstate.parameters, vstate2.parameters)


def test_variables_from_tar(vstate, tmp_path):
    fname = str(tmp_path) + "/file.tar"

    with tarfile.TarFile(fname, "w") as f:
        for i in range(10):
            save_binary_to_tar(
                f, serialization.to_bytes(vstate.variables), f"{i}.mpack"
            )

    for name in [fname, fname[:-4]]:
        vstate2 = nk.vqs.MCState(
            vstate.sampler, vstate.model, n_samples=10, seed=SEED + 100
        )

        for j in [0, 3, 8]:
            vstate2.variables = nkx.vqs.variables_from_tar(name, vstate2.variables, j)

            # check
            jax.tree_map(
                np.testing.assert_allclose, vstate.parameters, vstate2.parameters
            )

        with pytest.raises(KeyError):
            nkx.vqs.variables_from_tar(name, vstate2.variables, 15)


def test_deprecated_names():
    with pytest.warns(FutureWarning):
        assert nkx.vqs.variables_from_file == nk.vqs.experimental.variables_from_file

    with pytest.warns(FutureWarning):
        assert nkx.vqs.variables_from_tar == nk.vqs.experimental.variables_from_tar


def save_binary_to_tar(tar_file, byte_data, name):
    abuf = BytesIO(byte_data)

    # Contruct the info object with the correct length
    info = tarfile.TarInfo(name=name)
    info.size = len(abuf.getbuffer())

    # actually save the data to the tar file
    tar_file.addfile(tarinfo=info, fileobj=abuf)
