#!/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
from concurrent import futures
from datetime import datetime
import multiprocessing
import os
import sys
import yaml

import gcloud


def create_instance_group(config):
    try:
        # We take a few keys out of the config. The rest is passed
        # as-is to create_instance_template() and thus to the gcloud
        # command line tool.
        count = config.pop("count")
        instance_group_name = config.pop("name")
        project = config.pop("project")
        zone = config.pop("zone", None)
        region = config.pop("region", None)
        health_check = config.pop("health_check", None)
        initial_delay = config.pop("initial_delay", None)

        if not project:
            raise Exception("Invalid instance config, no project name set")

        if not zone and not region:
            raise Exception("Invalid instance config, either zone or region must be specified")

        timestamp = datetime.now().strftime("%Y%m%dt%H%M%S")
        template_name = "{}-{}".format(instance_group_name, timestamp)

        if zone is not None:
            if (
                gcloud.delete_instance_group(
                    instance_group_name, project=project, zone=zone
                ).returncode
                == 0
            ):
                print(f"Deleted existing instance group: {instance_group_name}")
        elif region is not None:
            if (
                gcloud.delete_instance_group(
                    instance_group_name, project=project, region=region
                ).returncode
                == 0
            ):
                print(f"Deleted existing instance group: {instance_group_name}")

        # Create the new instance template.
        gcloud.create_instance_template(template_name, project=project, **config)
        print(f"Created instance template {template_name}")

        # Create instance groups with the new template.
        kwargs = {
            "project": project,
            "base_instance_name": instance_group_name,
            "size": count,
            "template": template_name,
        }
        if zone:
            kwargs["zone"] = zone
        elif region:
            kwargs["region"] = region
        if health_check:
            kwargs["health_check"] = health_check
        if initial_delay:
            kwargs["initial_delay"] = initial_delay
        gcloud.create_instance_group(instance_group_name, **kwargs)
        print(f"Created instance group {instance_group_name}")
        return 0
    except Exception as ex:
        print(f"Failed to create {instance_group_name}: {ex}", file=sys.stderr)
        return 1


def read_config_file():
    path = os.path.join(os.getcwd(), "instances.yml")
    with open(path, "rb") as fd:
        content = fd.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-docker".',
    )

    args = parser.parse_args(argv)

    config = read_config_file()
    valid_names = [item["name"] for item in config["instance_groups"]]

    if not args.names:
        parser.print_help()
        print("\nValid instance names are: {}".format(" ".join(valid_names)))
        return 1

    # Handle multiple args as well as a single-arg comma-delimited list.
    names = args.names if len(args.names) > 1 else args.names[0].split(",")

    # Verify names passed on the command-line.
    for name in names:
        if name not in valid_names:
            print("Unknown instance name: {}!".format(name))
            print("\nValid instance names are: {}".format(" ".join(valid_names)))
            return 1

    selected_instances = [i for i in config["instance_groups"] if i["name"] in names]

    # Mimic v3.5 default of
    # https://docs.python.org/3/library/concurrent.futures.html#threadpoolexecutor
    max_workers = multiprocessing.cpu_count() * 5
    with futures.ThreadPoolExecutor(max_workers=max_workers) as pool:
        tasks = [
            pool.submit(create_instance_group, config={**config["default_vm"], **i})
            for i in selected_instances
        ]
        return max(list(t.result() for t in futures.as_completed(tasks)))


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