#!/bin/env python3

import argparse
from sys import stdout
from yaml import load, dump
try:
    from yaml import CLoader as Loader, CDumper as Dumper
except ImportError:
    from yaml import Loader, Dumper

def deepmerge(source, destination):
    for key, value in source.items():
        if isinstance(value, dict):
            merge(value, destination.setdefault(key, {}))
        else:
            destination[key] = value
    return destination

def deepsort(dictionary):
    result = {}
    for k, v in sorted(dictionary.items()):
        if isinstance(v, dict):
            result[k] = deepsort(v)
        else:
            result[k] = v
    return result

parser = argparse.ArgumentParser(
  prog='yamerge',
  description='Merges all YAML files listed on the CLI and outputs the resulting YAML to stdout.')
parser.add_argument('files', metavar='filename', type=str, nargs='+')
args = parser.parse_args()

y = {}
for file in args.files:
  f = open(file)
  data = load(f, Loader=Loader)
  f.close()
  merged = deepmerge(y, data)
  y = merged

y = deepsort(y)
print(dump(y, Dumper=Dumper))