#!/usr/bin/python3

import os
import sys
import getopt
import json

outfile = "merged.json"

try:
    opts, args = getopt.getopt(sys.argv[1:], "o:")

except getopt.GetoptError as err:
    print(str(err)) # will print something like "option -a not recognized"
    sys.exit(2)
for o, a in opts:
    if o == "-o":
        outfile = a

merged = dict()
for f in args:
    if not os.path.exists(f):
        print("WARN: %s does not exist", f)

    fp = open(f, "r")
    d = json.load(fp)
    fp.close()

    for key in d:
        print(key, end=' ')
        if key in merged:
            print("WARNING: merged already has key", key)
            merged[key].update(d[key])
        else:
            merged[key] = d[key]

    print(merged)
    print()

fp = open(outfile, "w")
json.dump(merged, fp, indent=4, sort_keys=True)
fp.close()