# coding=utf-8
# Copyright (c) 2015-2016, 2019 Intel Corporation

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"""Tests for compression in file backends."""

import itertools
import os
import subprocess
from unittest import mock

import pytest

from framework import core
from framework.backends import abstract
from framework.backends import compression

from .. import skip

# pylint: disable=no-self-use,redefined-outer-name

# Helpers


def _has_lzma():
    """Try to import backports.lzma, and return True if it exists, False if it
    doesn't.
    """
    try:
        import backports.lzma  # pylint: disable=unused-variable
    except ImportError:
        return False
    return True


def _has_xz_bin():
    """Check for an xz binary."""
    try:
        subprocess.check_call(['xz', '--help'])
    except subprocess.CalledProcessError:
        return False
    except OSError as e:  # pylint: disable=undefined-variable
        if e.errno != 2:
            raise
        return False
    return True


@pytest.fixture
def env():
    with mock.patch.dict('os.environ'):
        yield os.environ

@pytest.fixture
def config():
    with mock.patch('framework.core.PIGLIT_CONFIG',
                    new_callable=core.PiglitConfig) as conf:
        conf.add_section('core')
        yield conf

@pytest.fixture
def compressor():
    """Workaround for yield_fixture not working with classes."""
    class Compressor(object):
        """Fixture to control the compressor/decompressor objects."""

        def __init__(self):
            self._mock_c = mock.patch.dict(
                'framework.backends.compression.COMPRESSORS', clear=False)
            self._mock_d = mock.patch.dict(
                'framework.backends.compression.DECOMPRESSORS', clear=False)

        def __enter__(self):
            self._mock_c.start()
            self._mock_d.start()
            return self

        def __exit__(self, type_, value, traceback):
            self._mock_c.stop()
            self._mock_d.stop()

        def add(self, name, func):
            assert name not in compression.COMPRESSORS
            assert name not in compression.DECOMPRESSORS
            compression.COMPRESSORS[name] = func
            compression.DECOMPRESSORS[name] = func

        def rm(self, name):  # pylint: disable=invalid-name
            assert name in compression.COMPRESSORS
            assert name in compression.DECOMPRESSORS
            del compression.COMPRESSORS[name]
            del compression.DECOMPRESSORS[name]

    with Compressor() as c:
        yield c


# Tests


@pytest.mark.parametrize("mode", ['none', 'bz2', 'gz', 'xz'])
def test_compress(mode, tmpdir):
    """Test that each compressor that we want works.

    These only check using modules, that means on python2 this test will skip
    unless backports.lzma is available, and it will not test the the xz binary
    path.
    """
    func = compression.COMPRESSORS[mode]
    testfile = tmpdir.join('test')
    with func(str(testfile)) as f:
        f.write('foo')


@pytest.mark.parametrize("mode", ['none', 'bz2', 'gz', 'xz'])
def test_decompress(mode, tmpdir):
    """Test that each supported decompressor works.

    See the docstring in test_compress.
    """
    comp = compression.COMPRESSORS[mode]
    dec = compression.DECOMPRESSORS[mode]
    testfile = tmpdir.join('test')

    with comp(str(testfile)) as f:
        f.write('foo')

    with dec(str(testfile)) as f:
        actual = f.read()

    assert actual == 'foo'


@skip.posix
class TestXZBin(object):
    """Tests for the xz bin path on python2.x."""

    def test_compress_xz_bin(self, tmpdir):
        """Test python2 xz compression using the xz binary."""
        func = compression.COMPRESSORS['xz']
        testfile = tmpdir.join('test')
        with func(str(testfile)) as f:
            f.write('foo')

    def test_decompress_xz_bin(self, tmpdir):
        """Test python2 xz decompression using the xz binary."""
        comp = compression.COMPRESSORS['xz']
        dec = compression.DECOMPRESSORS['xz']
        testfile = tmpdir.join('test')

        with comp(str(testfile)) as f:
            f.write('foo')

        with dec(str(testfile)) as f:
            actual = f.read()

        assert actual == 'foo'


class TestGetMode(object):
    """Tests for the compression.get_mode function."""

    def test_default(self, env, config):  # pylint: disable=unused-argument
        """When neither the config file nor the environment sets a value for
        compression the default value should be used.
        """
        env.clear()

        assert compression.get_mode() == compression.DEFAULT

    def test_env(self, env, config, compressor):
        """Test that when env doesn't have a PIGLIT_COMPRESSION environment
        variable set, but the configuration has a compression method set that
        it is used.
        """
        compressor.add('foo', None)
        compressor.add('bar', None)
        config.set('core', 'compression', 'foo')
        env['PIGLIT_COMPRESSION'] = 'bar'

        assert compression.get_mode() == 'bar'

    def test_piglit_conf(self, env, config, compressor):
        """Test that when env doesn't have a PIGLIT_COMPRESSION environment
        variable set, but the configuration has a compression method set that
        it is used.
        """
        compressor.add('foobar', None)
        config.set('core', 'compression', 'foobar')
        env.clear()

        assert compression.get_mode() == 'foobar'


@pytest.mark.parametrize("extension", ['bz2', 'gz', 'xz'])
def test_duplicate_extensions(extension, tmpdir, config):
    """Tests that exercises a bug that caused the compressed extension to be
    duplicated in some cases.
    """
    tmpdir.chdir()
    config.set('core', 'compression', extension)
    expected = 'results.txt.' + extension

    with abstract.write_compressed(expected) as f:
        f.write('foo')

    assert expected in os.listdir('.')


@pytest.mark.parametrize("orig,new", itertools.permutations(
    ['bz2', 'gz', 'xz'], 2))
def test_changed_extension(orig, new, tmpdir, config):
    """Tests that exercises a bug that caused two extensions to be present if
    the compression method changed.
    """
    tmpdir.chdir()
    config.set('core', 'compression', str(new))

    with abstract.write_compressed('results.txt.' + orig) as f:
        f.write('foo')

    assert 'results.txt.' + new in os.listdir('.')
    assert 'results.txt.' + orig not in os.listdir('.')
    assert 'results.txt.{}.{}'.format(orig, new) not in os.listdir('.')
