# vim: tabstop=4 shiftwidth=4 softtabstop=4

# Copyright 2011 OpenStack, LLC
# 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.

"""Tests the filesystem backend store"""

import errno
import hashlib
import StringIO

from glance.common import exception
from glance.common import utils
from glance.store.filesystem import Store, ChunkedFile
from glance.store.location import get_location_from_uri
from glance.tests.unit import base


class TestStore(base.IsolatedUnitTest):

    def setUp(self):
        """Establish a clean test environment"""
        super(TestStore, self).setUp()
        self.orig_chunksize = ChunkedFile.CHUNKSIZE
        ChunkedFile.CHUNKSIZE = 10
        self.store = Store()

    def tearDown(self):
        """Clear the test environment"""
        super(TestStore, self).tearDown()
        ChunkedFile.CHUNKSIZE = self.orig_chunksize

    def test_get(self):
        """Test a "normal" retrieval of an image in chunks"""
        # First add an image...
        image_id = utils.generate_uuid()
        file_contents = "chunk00000remainder"
        location = "file://%s/%s" % (self.test_dir, image_id)
        image_file = StringIO.StringIO(file_contents)

        location, size, checksum = self.store.add(image_id,
                                                  image_file,
                                                  len(file_contents))

        # Now read it back...
        uri = "file:///%s/%s" % (self.test_dir, image_id)
        loc = get_location_from_uri(uri)
        (image_file, image_size) = self.store.get(loc)

        expected_data = "chunk00000remainder"
        expected_num_chunks = 2
        data = ""
        num_chunks = 0

        for chunk in image_file:
            num_chunks += 1
            data += chunk
        self.assertEqual(expected_data, data)
        self.assertEqual(expected_num_chunks, num_chunks)

    def test_get_non_existing(self):
        """
        Test that trying to retrieve a file that doesn't exist
        raises an error
        """
        loc = get_location_from_uri("file:///%s/non-existing" % self.test_dir)
        self.assertRaises(exception.NotFound,
                          self.store.get,
                          loc)

    def test_add(self):
        """Test that we can add an image via the filesystem backend"""
        ChunkedFile.CHUNKSIZE = 1024
        expected_image_id = utils.generate_uuid()
        expected_file_size = 1024 * 5  # 5K
        expected_file_contents = "*" * expected_file_size
        expected_checksum = hashlib.md5(expected_file_contents).hexdigest()
        expected_location = "file://%s/%s" % (self.test_dir,
                                              expected_image_id)
        image_file = StringIO.StringIO(expected_file_contents)

        location, size, checksum = self.store.add(expected_image_id,
                                                  image_file,
                                                  expected_file_size)

        self.assertEquals(expected_location, location)
        self.assertEquals(expected_file_size, size)
        self.assertEquals(expected_checksum, checksum)

        uri = "file:///%s/%s" % (self.test_dir, expected_image_id)
        loc = get_location_from_uri(uri)
        (new_image_file, new_image_size) = self.store.get(loc)
        new_image_contents = ""
        new_image_file_size = 0

        for chunk in new_image_file:
            new_image_file_size += len(chunk)
            new_image_contents += chunk

        self.assertEquals(expected_file_contents, new_image_contents)
        self.assertEquals(expected_file_size, new_image_file_size)

    def test_add_already_existing(self):
        """
        Tests that adding an image with an existing identifier
        raises an appropriate exception
        """
        ChunkedFile.CHUNKSIZE = 1024
        image_id = utils.generate_uuid()
        file_size = 1024 * 5  # 5K
        file_contents = "*" * file_size
        location = "file://%s/%s" % (self.test_dir, image_id)
        image_file = StringIO.StringIO(file_contents)

        location, size, checksum = self.store.add(image_id,
                                                  image_file,
                                                  file_size)
        image_file = StringIO.StringIO("nevergonnamakeit")
        self.assertRaises(exception.Duplicate,
                          self.store.add,
                          image_id, image_file, 0)

    def _do_test_add_failure(self, errno, exception):
        ChunkedFile.CHUNKSIZE = 1024
        image_id = utils.generate_uuid()
        file_size = 1024 * 5  # 5K
        file_contents = "*" * file_size
        location = "file://%s/%s" % (self.test_dir, image_id)
        image_file = StringIO.StringIO(file_contents)

        def fake_IO_Error(size):
            e = IOError()
            e.errno = errno
            raise e

        self.stubs.Set(image_file, 'read', fake_IO_Error)
        self.assertRaises(exception,
                          self.store.add,
                          image_id, image_file, 0)

    def test_add_storage_full(self):
        """
        Tests that adding an image without enough space on disk
        raises an appropriate exception
        """
        self._do_test_add_failure(errno.ENOSPC, exception.StorageFull)

    def test_add_file_too_big(self):
        """
        Tests that adding an excessively large image file
        raises an appropriate exception
        """
        self._do_test_add_failure(errno.EFBIG, exception.StorageFull)

    def test_add_storage_write_denied(self):
        """
        Tests that adding an image with insufficient filestore permissions
        raises an appropriate exception
        """
        self._do_test_add_failure(errno.EACCES, exception.StorageWriteDenied)

    def test_add_other_failure(self):
        """
        Tests that a non-space-related IOError does not raise a
        StorageFull exception.
        """
        self._do_test_add_failure(errno.ENOTDIR, IOError)

    def test_delete(self):
        """
        Test we can delete an existing image in the filesystem store
        """
        # First add an image
        image_id = utils.generate_uuid()
        file_size = 1024 * 5  # 5K
        file_contents = "*" * file_size
        location = "file://%s/%s" % (self.test_dir, image_id)
        image_file = StringIO.StringIO(file_contents)

        location, size, checksum = self.store.add(image_id,
                                                  image_file,
                                                  file_size)

        # Now check that we can delete it
        uri = "file:///%s/%s" % (self.test_dir, image_id)
        loc = get_location_from_uri(uri)
        self.store.delete(loc)

        self.assertRaises(exception.NotFound, self.store.get, loc)

    def test_delete_non_existing(self):
        """
        Test that trying to delete a file that doesn't exist
        raises an error
        """
        loc = get_location_from_uri("file:///tmp/glance-tests/non-existing")
        self.assertRaises(exception.NotFound,
                          self.store.delete,
                          loc)
