#!/usr/bin/env python
#
# 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 os
import sys

import yaml


def os_family(distro):
    "Given a distribution, returns a operating system family."
    family = None
    if distro in ['centos', 'centos7', 'fedora', 'rhel', 'rhel7']:
        family = 'redhat'
    elif distro in ['debian', 'ubuntu']:
        family = 'debian'
    elif distro == 'opensuse':
        family = 'suse'
    return family


def merge_data(source, destination, distro):
    """Merges two dictionaries and filters on distro.

    Merges two dictionaries and filters on distro family, or default (in order)
    """
    result = dict()
    result.update(destination)
    family = os_family(distro)
    for servicename, mapping in source.iteritems():
        if servicename in result:
            raise Exception("%s already found in services list" % servicename)
        if distro in mapping:
            result[servicename] = mapping.get(distro)
        elif family in mapping:
            result[servicename] = mapping.get(family)
        elif 'default' in mapping:
            result[servicename] = mapping.get('default')
        else:
            result[servicename] = servicename

    return result


def write_data_to_file(data, service_file_path):
    """Writes yaml data to a specified path."""
    with open(service_file_path, 'w') as destination:
        yaml.dump(data, destination, default_flow_style=False)


def main():
    elements = os.environ.get("IMAGE_ELEMENT").split(' ')
    element_paths = os.environ.get("ELEMENTS_PATH").split(':')
    service_names = dict()
    for element in elements:
        if not element.strip():
            continue
        for element_path in element_paths:
            data_path = os.path.join(element_path, element, "svc-map")
            if os.path.exists(data_path):
                with open(data_path, 'r') as dataFile:
                    data = yaml.load(dataFile.read())
                    try:
                        service_names = merge_data(
                            data,
                            service_names,
                            os.environ.get("DISTRO_NAME"))
                    except Exception as err:
                        print("%s.  Check %s for duplicate"
                              " service name." % (err, element))
                        sys.exit(1)

    write_data_to_file(service_names, os.path.join("/tmp", 'svc-map-services'))


if __name__ == "__main__":
    main()