#!/usr/bin/env python3
#
# Copyright 2018 The Bazel Authors. 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 argparse
import os
import queue
import sys
import threading
import urllib.error
import urllib.request
import yaml

import gcloud


CONFIG_URL = 'https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/instances.yml'
LOCAL_CONFIG_FILE_NAME = 'instances.yml'

WORK_QUEUE = queue.Queue()


def worker():
    while True:
        item = WORK_QUEUE.get()
        if not item:
            break
        try:
            # We take three keys out of the config item. The rest is passed
            # as-is to create_instance_template() and thus to the gcloud
            # command line tool.
            count = item.pop('count')
            instance_group_name = item.pop('name')
            zone = item.pop('zone')

            template_name = instance_group_name + '-template'

            if gcloud.delete_instance_group(instance_group_name, zone=zone).returncode == 0:
                print('Deleted existing instance group: {}'.format(instance_group_name))

            if gcloud.delete_instance_template(template_name).returncode == 0:
                print('Deleted existing VM template: {}'.format(template_name))

            gcloud.create_instance_template(template_name, **item)

            gcloud.create_instance_group(instance_group_name, zone=zone,
                                         base_instance_name=instance_group_name,
                                         template=template_name, size=count)
        finally:
            WORK_QUEUE.task_done()


def read_config_file(use_local_config):
    content = None
    if use_local_config:
        path = os.path.join(os.getcwd(), LOCAL_CONFIG_FILE_NAME)
        with open(path, "rb") as fd:
            content = fd.read().decode('utf-8')
    else:
        with urllib.request.urlopen(CONFIG_URL) as resp:
            content = resp.read().decode('utf-8')
    return yaml.safe_load(content)


def main(argv=None):
    if argv is None:
        argv = sys.argv[1:]

    parser = argparse.ArgumentParser(description="Bazel CI Instance Creation")
    parser.add_argument('names', type=str, nargs='*',
                        help='List of instance (group) names that should be created. '
                             'These values must correspond to "name" entries in the '
                             'Yaml configuration, e.g. "bk-pipeline-ubuntu1804-java8".')
    parser.add_argument('--local_config', action="store_true",
                        help='Whether to read the configuration from CWD/%s' % LOCAL_CONFIG_FILE_NAME)

    args = parser.parse_args(argv)
    config = read_config_file(args.local_config)

    # Verify names passed on the command-line.
    valid_names = [item['name'] for item in config['instance_groups']]
    for name in args.names:
        if name not in valid_names:
            print("Unknown instance name: {}!".format(name))
            print("\nValid instance names are: {}".format(' '.join(valid_names)))
            return 1
    if not args.names:
        parser.print_help()
        print("\nValid instance names are: {}".format(' '.join(valid_names)))
        return 1

    # Put VM creation instructions into the work queue.
    for instance in config['instance_groups']:
        if instance['name'] not in args.names:
            continue
        WORK_QUEUE.put({
            **config['default_vm'],
            **instance
        })

    # Spawn worker threads that will create the VMs.
    threads = []
    for _ in range(WORK_QUEUE.qsize()):
        t = threading.Thread(target=worker)
        t.start()
        threads.append(t)

    # Wait for all VMs to be created.
    WORK_QUEUE.join()

    # Signal worker threads to exit.
    for _ in range(len(threads)):
        WORK_QUEUE.put(None)

    # Wait for worker threads to exit.
    for t in threads:
        t.join()

    return 0


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