# Copyright 2017 Google Inc. 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 abc
import datetime
import tarfile
import logging
import httplib2

from containerregistry.client import docker_creds
from containerregistry.client import docker_name
from containerregistry.client.v2_2 import docker_image
from containerregistry.client.v2_2 import docker_session
from containerregistry.client.v2_2 import save
from containerregistry.transport import transport_pool

from ftl.common import cache
from ftl.common import constants
from ftl.common import ftl_util

# Do not Remove. Fix for strptime not being thread safe.
# Initialize datetime in the base class RuntimeBase. The Build calls
# datetime.datetime.strptime in threads.
# See http://bugs.python.org/issue7980
datetime.datetime.strptime('', '')


class Base(object):
    """Base is an abstract base class representing a container builder.
    It provides methods for generating runtime layers and an application
    layer.
    """

    __metaclass__ = abc.ABCMeta  # For enforcing that methods are overriden.

    def __init__(self, ctx):
        self._ctx = ctx

    @abc.abstractmethod
    def Build(self):
        """Build method encapsulates all layer building and image creation.
        """


class JustApp(Base):
    """JustApp is an implementation of a builder that has logic to build an
    application layer.
    """

    def __init__(self, ctx):
        super(JustApp, self).__init__(ctx)

    def Build(self):
        """Override."""
        # this can't be abstract as it is instantiated in tests
        return


class RuntimeBase(JustApp):
    """RuntimeBase is an abstract base class representing a container builder
    for runtime applications with dependencies.

    It provides methods for generating appending layers and caching images
    """

    def __init__(self, ctx, cache_namespace, args, descriptor_files):
        super(RuntimeBase, self).__init__(ctx)
        self._cache_namespace = cache_namespace
        if args.entrypoint:
            args.entrypoint = args.entrypoint.split(" ")
            if args.sh_c_prefix:
                args.entrypoint = ['bash', '-c', " ".join(args.entrypoint)]
        if args.exposed_ports:
            args.exposed_ports = args.exposed_ports.split(",")
        args.cache_key_version = "%s %s" % (args.cache_key_version,
                                            args.cache_salt)
        self._args = args
        self._base_name = docker_name.Tag(self._args.base, strict=False)
        self._base_creds = docker_creds.DefaultKeychain.Resolve(
            self._base_name)
        self._target_image = docker_name.Tag(self._args.name, strict=False)
        self._target_creds = docker_creds.DefaultKeychain.Resolve(
            self._target_image)
        self._transport = transport_pool.Http(
            httplib2.Http, size=constants.THREADS)
        if args.tar_base_image_path:
            self._base_image = docker_image.FromTarball(
                args.tar_base_image_path)
        else:
            self._base_image = docker_image.FromRegistry(
                self._base_name, self._base_creds, self._transport)
        self._base_image.__enter__()
        cache_repo = args.cache_repository
        if not cache_repo:
            cache_repo = self._target_image.as_repository()
        if args.ttl:
            ttl = args.ttl
        else:
            ttl = ftl_util.get_ttl(descriptor_files, ctx)
        self._cache = cache.Registry(
            repo=cache_repo,
            namespace=self._cache_namespace,
            creds=self._target_creds,
            transport=self._transport,
            ttl=ttl,
            threads=constants.THREADS,
            mount=[self._base_name],
            use_global=args.global_cache,
            export_stats=args.export_cache_stats,
            export_location=args.builder_output_path,
            should_cache=args.cache,
            should_upload=args.upload)
        self._descriptor_files = descriptor_files

    def Build(self):
        return

    def StoreImage(self, result_image):
        with ftl_util.Timing('Uploading final image'):
            if self._args.output_path:
                with ftl_util.Timing('Saving tarball image'):
                    with tarfile.open(
                            name=self._args.output_path, mode='w') as tar:
                        save.tarball(self._target_image, result_image, tar)
                    logging.info('{0} tarball located at {1}'.format(
                        str(self._target_image), self._args.output_path))
                return
            if self._args.upload:
                with ftl_util.Timing('Pushing image to Docker registry'):
                    with docker_session.Push(
                            self._target_image,
                            self._target_creds,
                            self._transport,
                            threads=constants.THREADS,
                            mount=[self._base_name]) as session:
                        logging.info('Pushing final image...')
                        session.upload(result_image)
                    return