# -*- coding: utf-8 -*-
# Copyright 2015 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Library to use the androidbuild API to list and fetch builds."""

from __future__ import print_function

import os
import pwd

import googleapiclient.discovery
import googleapiclient.http
import httplib2
import oauth2client.client
from six.moves import urllib


# Locations where to look for credentials JSON files, relative to the user's
# home directory.
HOMEDIR_JSON_CREDENTIALS_PATH = '.ab_creds.json'

# Scope URL on which we need authorization.
DEFAULT_SCOPE_URL = 'https://www.googleapis.com/auth/androidbuild.internal'

# Default service name and version to connect to.
DEFAULT_API_SERVICE_NAME = 'androidbuildinternal'
DEFAULT_API_VERSION = 'v2beta1'

# Default chunk size to use when downloading files through androidbuild API.
DEFAULT_MEDIA_IO_CHUNKSIZE = 20 * 1024 * 1024  # 20MiB


class Error(Exception):
  """Base exception on the androidbuild module."""


class CredentialsNotFoundError(Error):
  """Credentials file not found."""


def FindCredentialsFile(override_json_credentials_path=None,
                        homedir_json_credentials_path=None):
  """Find the path to an existing credentials file.

  Returns the path of the first one that is found.

  Args:
    override_json_credentials_path: Path to always use, whenever specified.
        This is meant for a file specified on a --json-key-file argument on the
        command line. Whenever present, always use this value.
    homedir_json_credentials_path: Optional override for the file to be looked
        for in the user's home directory. Defaults to '.ab_creds.json'.

  Returns:
    The resolved path to the file that was found.

  Raises:
    CredentialsNotFoundError: If none of the files exist.
  """
  if override_json_credentials_path is not None:
    return override_json_credentials_path

  if homedir_json_credentials_path is None:
    homedir_json_credentials_path = HOMEDIR_JSON_CREDENTIALS_PATH

  # Check for the file in the user's homedir:
  user_homedir = os.path.expanduser('~')
  if user_homedir:
    json_path = os.path.join(user_homedir, homedir_json_credentials_path)
    if os.path.exists(json_path):
      return json_path

  # If not found, check at ~$PORTAGE_USERNAME. That might be the case if the
  # tool is being used from within an ebuild script.
  portage_username = os.environ.get('PORTAGE_USERNAME')
  if portage_username:
    try:
      portage_homedir = pwd.getpwnam(portage_username).pw_dir
    except KeyError:
      # User $PORTAGE_USERNAME does not exist.
      pass
    else:
      json_path = os.path.join(portage_homedir, homedir_json_credentials_path)
      if os.path.exists(json_path):
        return json_path

  raise CredentialsNotFoundError(
      'Could not find the JSON credentials at [%s] and no JSON file was '
      'specified in command line arguments.' % homedir_json_credentials_path)


def LoadCredentials(json_credentials_path=None, scope_url=None):
  """Load the credentials from a local file.

  Returns a scoped credentials object which can be used to .authorize() an
  httlib2.Http() instance used by a googleapiclient.

  This method works both with service accounts (JSON generated from Pantheon's
  API manager under Credentials section), or with authenticated users (using a
  scheme similar to the one used by `gcloud auth login`.)

  Args:
    json_credentials_path: Path to a JSON file with credentials for a service
        account or for authenticated user. Defaults to looking for one using
        FindCredentialsFile().
    scope_url: URL in which the credentials should be scoped.

  Returns:
    A scoped oauth2client.client.Credentials object that can be used to
    authorize an Http instance used by a googleapiclient object.
  """
  json_credentials_path = FindCredentialsFile(json_credentials_path)

  # This is the way to support both service account credentials (JSON generated
  # from Pantheon) or authenticated users (similar to `gcloud auth login`).
  google_creds = oauth2client.client.GoogleCredentials.from_stream(
      json_credentials_path)

  if scope_url is None:
    scope_url = DEFAULT_SCOPE_URL

  # We need to rescope the credentials which are currently unscoped.
  scoped_creds = google_creds.create_scoped(scope_url)
  return scoped_creds


def GetApiClient(creds, api_service_name=None, api_version=None):
  """Build an API client for androidbuild and authorize it.

  Args:
    creds: The scoped oauth2client.client.Credentials to use for authorization.
    api_service_name: Optional override for the API service name.
        Defaults to 'androidbuildinternal' (from DEFAULT_API_SERVICE_NAME.)
    api_version: Optional override for the API version.
        Defaults to 'v2beta1' (from DEFAULT_API_VERSION.)

  Returns:
    A googleapiclient.discovery.Resource that supports the androidbuild API
    methods.
  """
  if api_service_name is None:
    api_service_name = DEFAULT_API_SERVICE_NAME
  if api_version is None:
    api_version = DEFAULT_API_VERSION

  base_http_client = httplib2.Http()
  auth_http_client = creds.authorize(base_http_client)
  ab_client = googleapiclient.discovery.build(api_service_name, api_version,
                                              http=auth_http_client)
  return ab_client


def FetchArtifact(ab_client, branch, target, build_id, filepath, output=None):
  """Fetches an artifact using the API client.

  Args:
    ab_client: The androidbuild API client.
    branch: The name of the git branch. (Currently UNUSED!)
    target: The name of the build target.
    build_id: The id of the build.
    filepath: Path to the file to download.
    output: Path where to store the artifact. Defaults to filepath.

  Raises:
    googleapiclient.errors.HttpError: If the requested artifact does not exist.
  """
  # The "branch" is unused, so silent pylint warnings about it:
  _ = branch

  # Get the media id to download.
  # NOTE: For some reason the git branch is not needed here, which looks weird.
  # That means in the ab:// URL the branch name will be essentially ignored.
  media_id = ab_client.buildartifact().get_media(
      target=target,
      buildId=build_id,
      attemptId='latest',
      resourceId=filepath)

  if output is None:
    output = filepath

  # Create directory structure, if needed.
  outdir = os.path.dirname(output)
  if outdir and not os.path.isdir(outdir):
    os.makedirs(outdir)

  with open(output, 'wb') as f:
    downloader = googleapiclient.http.MediaIoBaseDownload(
        f, media_id, chunksize=DEFAULT_MEDIA_IO_CHUNKSIZE)
    done = False
    while not done:
      _, done = downloader.next_chunk()


def FindRecentBuilds(ab_client, branch, target,
                     build_type='submitted',
                     build_attempt_status=None,
                     build_successful=None):
  """Queries for the latest build_ids from androidbuild.

  Args:
    ab_client: The androidbuild API client.
    branch: The name of the git branch.
    target: The name of the build target.
    build_type: (Optional) The type of the build, defaults to 'submitted'.
    build_attempt_status: (Optional) Status of attempt, use 'complete' to look
      for completed builds only.
    build_successful: (Optional) Whether to only return successful builds.

  Returns:
    A list of numeric build_ids, sorted from most recent to oldest (in reverse
    numerical order.)
  """
  kwargs = {
      'branch': branch,
      'target': target,
  }
  if build_type is not None:
    kwargs['buildType'] = build_type
  if build_attempt_status is not None:
    kwargs['buildAttemptStatus'] = build_attempt_status
  if build_successful is not None:
    kwargs['successful'] = build_successful
  builds = ab_client.build().list(**kwargs).execute().get('builds')

  # Extract the build_ids, convert to int, arrange newest to oldest.
  return sorted((int(build['buildId']) for build in builds), reverse=True)


def FindLatestGreenBuildId(ab_client, branch, target):
  """Finds the latest build_id that has a green build.

  Args:
    ab_client: The androidbuild API client.
    branch: The name of the git branch.
    target: The name of the build target.

  Returns:
    A numeric build_id for the latest green build.
    Returns None if no green builds were found for this branch and target.
  """
  build_ids = FindRecentBuilds(ab_client, branch, target,
                               build_successful=True)
  if build_ids:
    return build_ids[0]
  else:
    return None


def SplitAbUrl(ab_url):
  """Splits an ab://... URL into its fields.

  The URL has the following format:
    ab://android-build/<branch>/<target>/<build_id>/<filepath>

  The "android-build" part is the <host> or <bucket> and for now is required to
  be the literal "android-build" (we reserve it to extend the URL format in the
  future.)

  <branch> is the git branch and <target> is the board name plus one of -user
  or -userdebug or -eng or such. <build_id> is the numeric identifier of the
  build. Finally, <filepath> is the path to the artifact itself.

  The two last components (<build_id> and <filepath>) may be absent from the
  URL. An ab:// URL without a <branch> or <target> is invalid (for now.)

  Args:
    ab_url: An ab://... URL.

  Returns:
    A 4-tuple: branch, target, build_id, filepath. The two last components will
    be set to None if they are absent from the URL. The returned <build_id>
    component will be an integer, all others will be strings.

  Raises:
    ValueError: If the URL is not a valid ab://... URL.
  """
  o = urllib.parse.urlparse(ab_url)

  if o.scheme != 'ab':
    raise ValueError('URL [%s] must start with ab:// protocol.' % ab_url)

  if o.hostname != 'android-build':
    raise ValueError('URL [%s] must use "android-build" bucket.' % ab_url)

  # Split the remaining fields of the path.
  parts = o.path.split('/', 4)

  if len(parts) < 3:
    raise ValueError(
        'URL [%s] is too short and does not specify a target.' % ab_url)

  # First field will be empty.
  assert parts[0] == ''
  branch = urllib.parse.unquote(parts[1])
  target = urllib.parse.unquote(parts[2])

  if not branch:
    raise ValueError('URL [%s] has an empty branch.' % ab_url)

  if not target:
    raise ValueError('URL [%s] has an empty target.' % ab_url)

  # Check if build_id is present. If present, it must be numeric.
  if len(parts) > 3:
    build_id_str = urllib.parse.unquote(parts[3])
    if not build_id_str.isdigit():
      raise ValueError('URL [%s] has a non-numeric build_id component [%s].' %
                       (ab_url, build_id_str))
    build_id = int(build_id_str)
  else:
    build_id = None

  # Last, use the remainder of the URL as the filepath.
  if len(parts) > 4:
    filepath = urllib.parse.unquote(parts[4])
  else:
    filepath = None

  return (branch, target, build_id, filepath)