#!/usr/bin/env python

# Copyright 2015 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.

# Retrieved from https://github.com/Google/oauth2client
"""Fetch the most recent GAE SDK and decompress it in the current directory.

Usage:
    fetch_gae_sdk.py [<dest_dir>]

Current releases are listed here:
    https://www.googleapis.com/storage/v1/b/appengine-sdks/o?prefix=featured
"""

import json
import os
import StringIO
import sys
import urllib2
import zipfile

_SDK_URL = (
    'https://www.googleapis.com/storage/v1/b/appengine-sdks/o?prefix=featured')


def get_gae_versions():
    try:
        version_info_json = urllib2.urlopen(_SDK_URL).read()
    except:
        return {}
    try:
        version_info = json.loads(version_info_json)
    except:
        return {}
    return version_info.get('items', {})


def _version_tuple(v):
    version_string = os.path.splitext(v['name'])[0].rpartition('_')[2]
    return tuple(int(x) for x in version_string.split('.'))


def get_sdk_urls(sdk_versions):
    python_releases = [
        v for v in sdk_versions
        if v['name'].startswith('featured/google_appengine')]
    current_releases = sorted(
        python_releases, key=_version_tuple, reverse=True)
    return [release['mediaLink'] for release in current_releases]


def main(argv):
    if len(argv) > 2:
        print('Usage: {} [<destination_dir>]'.format(argv[0]))
        return 1
    dest_dir = argv[1] if len(argv) > 1 else '.'
    if not os.path.exists(dest_dir):
        os.makedirs(dest_dir)

    if os.path.exists(os.path.join(dest_dir, 'google_appengine')):
        print('GAE SDK already installed at {}, exiting.'.format(dest_dir))
        return 0

    sdk_versions = get_gae_versions()
    if not sdk_versions:
        print('Error fetching GAE SDK version info')
        return 1
    sdk_urls = get_sdk_urls(sdk_versions)
    for sdk_url in sdk_urls:
        try:
            sdk_contents = StringIO.StringIO(urllib2.urlopen(sdk_url).read())
            break
        except:
            pass
    else:
        print('Could not read SDK from any of {}'.format(sdk_urls))
        return 1
    sdk_contents.seek(0)
    try:
        zip_contents = zipfile.ZipFile(sdk_contents)
        zip_contents.extractall(dest_dir)
        print('GAE SDK Installed to {}.'.format(dest_dir))
    except:
        print('Error extracting SDK contents')
        return 1

if __name__ == '__main__':
    sys.exit(main(sys.argv[:]))