#!/usr/bin/env python
"""
Create CoreOS user-data by merging contric/coreos/user-data and gce-user-data

Usage: create-gce-user-data.py <discovery_url>

Arguments:
    <discovery_url> This is the CoreOS etcd discovery URL. You should generate
    a new URL at https://discovery.etcd.io/new and pass it as the argument.
"""

import sys
import os
import re
import yaml
import collections


def combine_dicts(orig_dict, new_dict):
    for key, val in new_dict.iteritems():
        if isinstance(val, collections.Mapping):
            tmp = combine_dicts(orig_dict.get(key, {}), val)
            orig_dict[key] = tmp
        elif isinstance(val, list):
            orig_dict[key] = (orig_dict[key] + val)
        else:
            orig_dict[key] = new_dict[key]
    return orig_dict


def get_file(name, mode="r", abspath=False):
    current_dir = os.path.dirname(__file__)

    if abspath:
        return file(os.path.abspath(os.path.join(current_dir, name)), mode)
    else:
        return file(os.path.join(current_dir, name), mode)


def main():
    try:
        url = sys.argv[1]
    except (NameError, IndexError):
        print __doc__
        return 1

    url_pattern = 'http[|s]\:[\/]{2}discovery\.etcd\.io\/[0-9a-f]{32}'

    m = re.match(url_pattern, url)

    if not m:
        print "Discovery URL invalid."
        return 1

    gce_user_data = get_file("gce-user-data", "w", True)
    gce_template = get_file("gce-user-data-template")
    coreos_template = get_file("../coreos/user-data.example")

    configuration_coreos_template = yaml.safe_load(coreos_template)
    configuration_gce_template = yaml.safe_load(gce_template)

    configuration = combine_dicts(configuration_coreos_template,
                                  configuration_gce_template)

    configuration["coreos"]["etcd"]["discovery"] = url

    with gce_user_data as outfile:
        try:
            outfile.write("#cloud-config\n\n" +
                          yaml.safe_dump(configuration,
                                         default_flow_style=False,
                                         default_style='|'))
        except (IOError, ValueError):
            print "There was an issue writing to file " + gce_user_data.name
            return 1
        else:
            print "Wrote file \"%s\" with url \"%s\"" %\
                (gce_user_data.name, url)

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