# -*- coding: utf-8 -*- #
# Copyright 2017 Google 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.
"""Utility library for working with docker clients."""

from __future__ import absolute_import
from __future__ import division
from __future__ import unicode_literals

import errno
import json
import os
import subprocess
import sys

from distutils import version as distutils_version

from googlecloudsdk.core import exceptions
from googlecloudsdk.core.util import encoding
from googlecloudsdk.core.util import files
from googlecloudsdk.core.util import platforms

import six
from six.moves import urllib


DOCKER_NOT_FOUND_ERROR = 'Docker is not installed.'


class DockerError(exceptions.Error):
  """Base class for docker errors."""


class DockerConfigUpdateError(DockerError):
  """There was an error updating the docker configuration file."""


class InvalidDockerConfigError(DockerError):
  """The docker configuration file could not be read."""


def _GetUserHomeDir():
  if platforms.OperatingSystem.Current() == platforms.OperatingSystem.WINDOWS:
    # %HOME% has precedence over %USERPROFILE% for files.GetHomeDir().
    # The Docker config resides under %USERPROFILE% on Windows
    return encoding.Decode(os.path.expandvars('%USERPROFILE%'))
  else:
    return files.GetHomeDir()


def _GetNewConfigDirectory():
  # Return the value of $DOCKER_CONFIG, if it exists, otherwise ~/.docker
  # see https://github.com/docker/docker/blob/master/cliconfig/config.go
  docker_config = encoding.GetEncodedValue(os.environ, 'DOCKER_CONFIG')
  if docker_config is not None:
    return docker_config
  else:
    return os.path.join(_GetUserHomeDir(), '.docker')


# Other tools like the python docker library (used by gcloud app)
# also rely on Docker's authorization configuration (in addition
# to the docker CLI client)
# NOTE: Lazy for manipulation of HOME / mocking.
def GetDockerConfigPath(force_new=False):
  """Retrieve the path to Docker's configuration file, noting its format.

  Args:
    force_new: bool, whether to force usage of the new config file regardless
               of whether it exists (for testing).

  Returns:
    A tuple containing:
    -The path to Docker's configuration file, and
    -A boolean indicating whether it is in the new (1.7.0+) configuration format
  """
  # Starting in Docker 1.7.0, the Docker client moved where it writes
  # credentials to ~/.docker/config.json.  It is half backwards-compatible,
  # if the new file doesn't exist, it falls back on the old file.
  # if the new file exists, it IGNORES the old file.
  # This is a problem when a user has logged into another registry on 1.7.0
  # and then uses 'gcloud docker'.
  # This must remain compatible with: https://github.com/docker/docker-py
  new_path = os.path.join(_GetNewConfigDirectory(), 'config.json')
  if os.path.exists(new_path) or force_new:
    return new_path, True

  # Only one location will be probed to locate the new config.
  # This is consistent with the Docker client's behavior:
  # https://github.com/docker/docker/blob/master/cliconfig/config.go#L83
  old_path = os.path.join(_GetUserHomeDir(), '.dockercfg')
  return old_path, False


def EnsureDocker(func):
  """Wraps a function that uses subprocess to invoke docker.

  Rewrites OS Exceptions when not installed.

  Args:
    func: A function that uses subprocess to invoke docker.

  Returns:
    The decorated function.

  Raises:
    DockerError: Docker cannot be run.
  """

  def DockerFunc(*args, **kwargs):
    try:
      return func(*args, **kwargs)
    except OSError as e:
      if e.errno == errno.ENOENT:
        raise DockerError(DOCKER_NOT_FOUND_ERROR)
      else:
        raise

  return DockerFunc


@EnsureDocker
def Execute(args):
  """Wraps an invocation of the docker client with the specified CLI arguments.

  Args:
    args: The list of command-line arguments to docker.

  Returns:
    The exit code from Docker.
  """
  return subprocess.call(
      ['docker'] + args, stdin=sys.stdin, stdout=sys.stdout, stderr=sys.stderr)


@EnsureDocker
def GetDockerProcess(docker_args, stdin_file, stdout_file, stderr_file):
  # Wraps the construction of a docker subprocess object with the specified
  # arguments and I/O files.
  return subprocess.Popen(
      ['docker'] + docker_args,
      stdin=stdin_file,
      stdout=stdout_file,
      stderr=stderr_file)


def GetDockerVersion():
  """Returns the installed Docker client version.

  Returns:
    The installed Docker client version.

  Raises:
    DockerError: Docker cannot be run or does not accept 'docker version
    --format '{{.Client.Version}}''.
  """
  docker_args = "version --format '{{.Client.Version}}'".split()

  docker_p = GetDockerProcess(
      docker_args,
      stdin_file=sys.stdin,
      stdout_file=subprocess.PIPE,
      stderr_file=subprocess.PIPE)

  # Wait for docker to finished executing and retrieve its stdout/stderr.
  stdoutdata, _ = docker_p.communicate()

  if docker_p.returncode != 0 or not stdoutdata:
    raise DockerError('could not retrieve Docker client version')

  # Remove ' from beginning and end of line.
  return distutils_version.LooseVersion(stdoutdata.strip("'"))


def GetNormalizedURL(server):
  """Sanitize and normalize the server input."""
  parsed_url = urllib.parse.urlparse(server)
  # Work around the fact that Python 2.6 does not properly
  # look for :// and simply splits on colon, so something
  # like 'gcr.io:1234' returns the scheme 'gcr.io'.
  if '://' not in server:
    # Server doesn't have a scheme, set it to HTTPS.
    parsed_url = urllib.parse.urlparse('https://' + server)
    if parsed_url.hostname == 'localhost':
      # Now that it parses, if the hostname is localhost switch to HTTP.
      parsed_url = urllib.parse.urlparse('http://' + server)

  return parsed_url


def ReadConfigurationFile(path):
  """Retrieve the full contents of the Docker configuration file.

  Args:
    path: string, path to configuration file

  Returns:
    The full contents of the configuration file as parsed JSON dict.

  Raises:
    ValueError: path is not set.
    InvalidDockerConfigError: config file could not be read as JSON.
  """
  if not path:
    raise ValueError('Docker configuration file path is empty')

  # In many cases file might not exist even though Docker is installed,
  # so do not treat that as an error, just return empty contents.
  if not os.path.exists(path):
    return {}

  contents = files.ReadFileContents(path)
  # If the file is empty, return empty JSON.
  # This helps if someone 'touched' the file or manually
  # deleted the contents.
  if not contents or contents.isspace():
    return {}

  try:
    return json.loads(contents)
  except ValueError as err:
    raise InvalidDockerConfigError(
        ('Docker configuration file [{}] could not be read as JSON: '
         '{}').format(path, six.text_type(err)))
