# Copyright (C) 2017 Michal Habera
#
# This file is part of DOLFIN.
#
# DOLFIN is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# DOLFIN is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with DOLFIN. If not, see <http://www.gnu.org/licenses/>.

import pytest
import numpy as np

import os

from dolfin import *
from dolfin_utils.test import skip_in_parallel, fixture, tempdir


@skip_in_parallel
def test_save_2d_scalar(tempdir):

    mesh = UnitSquareMesh(16, 16)
    filename = os.path.join(tempdir, "scalar2D.xyz")
    file = File(filename)
    V = FunctionSpace(mesh, "Lagrange", 1)
    u = Function(V)
    u.interpolate(Constant(1.0))

    # Save results multiple times for append test case
    N = 10
    for i in range(N):
        file << u

    # Load name of datafile, stored in main file (usually scalar2D******.xyz)
    with open(filename, 'r') as fl:
        data_filenames = fl.readlines()

    # Check if there are really N lines in main file
    assert len(data_filenames) == N

    for data_filename in data_filenames:

        # Load saved file as np array
        data_filename = data_filename.replace('\n', '')
        loaded_file = np.loadtxt(os.path.join(tempdir, data_filename))

        # Check if the loaded function is everywhere == 1.
        assert (loaded_file[:, 2] == 1.).all()