#
#  Copyright (C) 2018 Codethink Limited
#
#  This program 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 2 of the License, or (at your option) any later version.
#
#  This library 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 this library. If not, see <http://www.gnu.org/licenses/>.
#
#  Authors: Tristan Maat <tristan.maat@codethink.co.uk>
#

# Pylint doesn't play well with fixtures and dependency injection from pytest
# pylint: disable=redefined-outer-name

import os
import time

import pytest

from buildstream._cas import CASCache
from buildstream.exceptions import ErrorDomain, LoadErrorReason
from buildstream.testing import cli  # pylint: disable=unused-import
from buildstream.testing._utils.site import have_subsecond_mtime

from tests.testutils import create_element_size, wait_for_cache_granularity


DATA_DIR = os.path.join(os.path.dirname(os.path.realpath(__file__)), "expiry")


def get_cache_usage(directory):
    cas_cache = CASCache(directory, log_directory=os.path.dirname(directory))
    try:
        wait = 0.1
        for _ in range(0, int(5 / wait)):
            used_size = cas_cache.get_cache_usage().used_size
            if used_size is not None:
                return used_size
            time.sleep(wait)

        assert False, "Unable to retrieve cache usage"
        return None
    finally:
        cas_cache.release_resources()


# Ensure that the cache successfully removes an old artifact if we do
# not have enough space left.
@pytest.mark.datafiles(DATA_DIR)
def test_artifact_expires(cli, datafiles):
    project = str(datafiles)
    element_path = "elements"

    # Skip this test if we do not have support for subsecond precision mtimes
    #
    # The artifact expiry logic relies on mtime changes, in real life second precision
    # should be enough for this to work almost all the time, but test cases happen very
    # quickly, resulting in all artifacts having the same mtime.
    #
    # This test requires subsecond mtime to be reliable.
    #
    if not have_subsecond_mtime(project):
        pytest.skip("Filesystem does not support subsecond mtime precision: {}".format(project))

    cli.configure({"cache": {"quota": 10000000,}})

    # Create an element that uses almost the entire cache (an empty
    # ostree cache starts at about ~10KiB, so we need a bit of a
    # buffer)
    create_element_size("target.bst", project, element_path, [], 6000000)
    res = cli.run(project=project, args=["build", "target.bst"])
    res.assert_success()

    assert cli.get_element_state(project, "target.bst") == "cached"

    # Our cache should now be almost full. Let's create another
    # artifact and see if we can cause buildstream to delete the old
    # one.
    create_element_size("target2.bst", project, element_path, [], 6000000)
    res = cli.run(project=project, args=["build", "target2.bst"])
    res.assert_success()

    # Check that the correct element remains in the cache
    states = cli.get_element_states(project, ["target.bst", "target2.bst"])
    assert states["target.bst"] != "cached"
    assert states["target2.bst"] == "cached"


# Ensure that we don't end up deleting the whole cache (or worse) if
# we try to store an artifact that is too large to fit in the quota.
@pytest.mark.parametrize(
    "size",
    [
        # Test an artifact that is obviously too large
        (500000),
        # Test an artifact that might be too large due to slight overhead
        # of storing stuff in ostree
        (399999),
    ],
)
@pytest.mark.datafiles(DATA_DIR)
def test_artifact_too_large(cli, datafiles, size):
    project = str(datafiles)
    element_path = "elements"

    # Skip this test if we do not have support for subsecond precision mtimes
    #
    # The artifact expiry logic relies on mtime changes, in real life second precision
    # should be enough for this to work almost all the time, but test cases happen very
    # quickly, resulting in all artifacts having the same mtime.
    #
    # This test requires subsecond mtime to be reliable.
    #
    if not have_subsecond_mtime(project):
        pytest.skip("Filesystem does not support subsecond mtime precision: {}".format(project))

    cli.configure({"cache": {"quota": 400000}})

    # Create an element whose artifact is too large
    create_element_size("target.bst", project, element_path, [], size)
    res = cli.run(project=project, args=["build", "target.bst"])
    res.assert_main_error(ErrorDomain.STREAM, None)
    res.assert_task_error(ErrorDomain.CAS, "cache-too-full")


@pytest.mark.datafiles(DATA_DIR)
def test_expiry_order(cli, datafiles):
    project = str(datafiles)
    element_path = "elements"
    checkout = os.path.join(project, "workspace")

    cli.configure({"cache": {"quota": 9000000}})

    # Create an artifact
    create_element_size("dep.bst", project, element_path, [], 2000000)
    res = cli.run(project=project, args=["build", "dep.bst"])
    res.assert_success()

    # Create another artifact
    create_element_size("unrelated.bst", project, element_path, [], 2000000)
    res = cli.run(project=project, args=["build", "unrelated.bst"])
    res.assert_success()

    # And build something else
    create_element_size("target.bst", project, element_path, [], 2000000)
    res = cli.run(project=project, args=["build", "target.bst"])
    res.assert_success()

    create_element_size("target2.bst", project, element_path, [], 2000000)
    res = cli.run(project=project, args=["build", "target2.bst"])
    res.assert_success()

    wait_for_cache_granularity()

    # Now extract dep.bst
    res = cli.run(project=project, args=["artifact", "checkout", "dep.bst", "--directory", checkout])
    res.assert_success()

    # Finally, build something that will cause the cache to overflow
    create_element_size("expire.bst", project, element_path, [], 2000000)
    res = cli.run(project=project, args=["build", "expire.bst"])
    res.assert_success()

    # While dep.bst was the first element to be created, it should not
    # have been removed.
    # Note that buildstream will reduce the cache to 50% of the
    # original size - we therefore remove multiple elements.
    check_elements = ["unrelated.bst", "target.bst", "target2.bst", "dep.bst", "expire.bst"]
    states = cli.get_element_states(project, check_elements)
    assert tuple(states[element] for element in check_elements) == (
        "buildable",
        "buildable",
        "buildable",
        "cached",
        "cached",
    )


# Ensure that we don't accidentally remove an artifact from something
# in the current build pipeline, because that would be embarassing,
# wouldn't it?
@pytest.mark.datafiles(DATA_DIR)
def test_keep_dependencies(cli, datafiles):
    project = str(datafiles)
    element_path = "elements"

    # Skip this test if we do not have support for subsecond precision mtimes
    #
    # The artifact expiry logic relies on mtime changes, in real life second precision
    # should be enough for this to work almost all the time, but test cases happen very
    # quickly, resulting in all artifacts having the same mtime.
    #
    # This test requires subsecond mtime to be reliable.
    #
    if not have_subsecond_mtime(project):
        pytest.skip("Filesystem does not support subsecond mtime precision: {}".format(project))

    cli.configure({"cache": {"quota": 10000000}})

    # Create a pretty big dependency
    create_element_size("dependency.bst", project, element_path, [], 5000000)
    res = cli.run(project=project, args=["build", "dependency.bst"])
    res.assert_success()

    # Now create some other unrelated artifact
    create_element_size("unrelated.bst", project, element_path, [], 4000000)
    res = cli.run(project=project, args=["build", "unrelated.bst"])
    res.assert_success()

    # Check that the correct element remains in the cache
    states = cli.get_element_states(project, ["dependency.bst", "unrelated.bst"])
    assert states["dependency.bst"] == "cached"
    assert states["unrelated.bst"] == "cached"

    # We try to build an element which depends on the LRU artifact,
    # and could therefore fail if we didn't make sure dependencies
    # aren't removed.
    #
    # Since some artifact caches may implement weak cache keys by
    # duplicating artifacts (bad!) we need to make this equal in size
    # or smaller than half the size of its dependencies.
    #
    create_element_size("target.bst", project, element_path, ["dependency.bst"], 2000000)
    res = cli.run(project=project, args=["build", "target.bst"])
    res.assert_success()

    states = cli.get_element_states(project, ["target.bst", "unrelated.bst"])
    assert states["target.bst"] == "cached"
    assert states["dependency.bst"] == "cached"
    assert states["unrelated.bst"] != "cached"


# Assert that we never delete a dependency required for a build tree
@pytest.mark.datafiles(DATA_DIR)
def test_never_delete_required(cli, datafiles):
    project = str(datafiles)
    element_path = "elements"

    # Skip this test if we do not have support for subsecond precision mtimes
    #
    # The artifact expiry logic relies on mtime changes, in real life second precision
    # should be enough for this to work almost all the time, but test cases happen very
    # quickly, resulting in all artifacts having the same mtime.
    #
    # This test requires subsecond mtime to be reliable.
    #
    if not have_subsecond_mtime(project):
        pytest.skip("Filesystem does not support subsecond mtime precision: {}".format(project))

    cli.configure({"cache": {"quota": 10000000}, "scheduler": {"fetchers": 1, "builders": 1}})

    # Create a linear build tree
    create_element_size("dep1.bst", project, element_path, [], 8000000)
    create_element_size("dep2.bst", project, element_path, ["dep1.bst"], 8000000)
    create_element_size("dep3.bst", project, element_path, ["dep2.bst"], 8000000)
    create_element_size("target.bst", project, element_path, ["dep3.bst"], 8000000)

    # Build dep1.bst, which should fit into the cache.
    res = cli.run(project=project, args=["build", "dep1.bst"])
    res.assert_success()

    # We try to build this pipeline, but it's too big for the
    # cache. Since all elements are required, the build should fail.
    res = cli.run(project=project, args=["build", "target.bst"])
    res.assert_main_error(ErrorDomain.STREAM, None)
    res.assert_task_error(ErrorDomain.CAS, "cache-too-full")

    states = cli.get_element_states(project, ["target.bst"])
    assert states["dep1.bst"] == "cached"
    assert states["dep2.bst"] != "cached"
    assert states["dep3.bst"] != "cached"
    assert states["target.bst"] != "cached"


# Ensure that only valid cache quotas make it through the loading
# process.
#
# Parameters:
#    quota (str): A quota size configuration for the config file
#    err_domain (str): An ErrorDomain, or 'success' or 'warning'
#    err_reason (str): A reson to compare with an error domain
#
# If err_domain is 'success', then err_reason is unused.
#
@pytest.mark.parametrize(
    "quota,err_domain,err_reason",
    [
        # Valid configurations
        ("1", "success", None),
        ("1K", "success", None),
        ("50%", "success", None),
        ("infinity", "success", None),
        ("0", "success", None),
        # Invalid configurations
        ("-1", ErrorDomain.LOAD, LoadErrorReason.INVALID_DATA),
        ("pony", ErrorDomain.LOAD, LoadErrorReason.INVALID_DATA),
        ("200%", ErrorDomain.LOAD, LoadErrorReason.INVALID_DATA),
    ],
)
@pytest.mark.datafiles(DATA_DIR)
def test_invalid_cache_quota(cli, datafiles, quota, err_domain, err_reason):
    project = str(datafiles)
    os.makedirs(os.path.join(project, "elements"))

    cli.configure(
        {"cache": {"quota": quota,},}
    )

    res = cli.run(project=project, args=["workspace", "list"])

    if err_domain == "success":
        res.assert_success()
    else:
        res.assert_main_error(err_domain, err_reason)


# Ensures that when launching BuildStream with a full artifact cache,
# the cache size and cleanup jobs are run before any other jobs.
#
@pytest.mark.datafiles(DATA_DIR)
def test_cleanup_first(cli, datafiles):
    project = str(datafiles)
    element_path = "elements"

    cli.configure({"cache": {"quota": 10000000,}})

    # Create an element that uses almost the entire cache (an empty
    # ostree cache starts at about ~10KiB, so we need a bit of a
    # buffer)
    create_element_size("target.bst", project, element_path, [], 8000000)
    res = cli.run(project=project, args=["build", "target.bst"])
    res.assert_success()

    assert cli.get_element_state(project, "target.bst") == "cached"

    # Now configure with a smaller quota, create a situation
    # where the cache must be cleaned up before building anything else.
    #
    # Fix the fetchers and builders just to ensure a predictable
    # sequence of events (although it does not effect this test)
    cli.configure({"cache": {"quota": 5000000,}, "scheduler": {"fetchers": 1, "builders": 1}})

    # Our cache is now more than full, BuildStream
    create_element_size("target2.bst", project, element_path, [], 4000000)
    res = cli.run(project=project, args=["build", "target2.bst"])
    res.assert_success()

    # Check that the correct element remains in the cache
    states = cli.get_element_states(project, ["target.bst", "target2.bst"])
    assert states["target.bst"] != "cached"
    assert states["target2.bst"] == "cached"


@pytest.mark.datafiles(DATA_DIR)
def test_cache_usage_monitor(cli, tmpdir, datafiles):
    project = str(datafiles)
    element_path = "elements"

    assert get_cache_usage(cli.directory) == 0

    ELEMENT_SIZE = 1000000
    create_element_size("target.bst", project, element_path, [], ELEMENT_SIZE)
    res = cli.run(project=project, args=["build", "target.bst"])
    res.assert_success()

    assert get_cache_usage(cli.directory) >= ELEMENT_SIZE