#! /usr/bin/python3
# -*- coding: utf-8 -*-

from __future__ import print_function

import sys
import os.path
import json
import jsonpointer
import argparse


parser = argparse.ArgumentParser(
    description='Resolve a JSON pointer on JSON files')

# Accept pointer as argument or as file
ptr_group = parser.add_mutually_exclusive_group(required=True)

ptr_group.add_argument('-f', '--pointer-file', type=argparse.FileType('r'),
                       nargs='?',
                       help='File containing a JSON pointer expression')

ptr_group.add_argument('POINTER',  type=str, nargs='?',
                       help='A JSON pointer expression')

parser.add_argument('FILE', type=argparse.FileType('r'), nargs='+',
                    help='Files for which the pointer should be resolved')
parser.add_argument('--indent', type=int, default=None,
                    help='Indent output by n spaces')
parser.add_argument('-v', '--version', action='version',
                    version='%(prog)s ' + jsonpointer.__version__)


def main():
    try:
        resolve_files()
    except KeyboardInterrupt:
        sys.exit(1)


def parse_pointer(args):
    if args.POINTER:
        ptr = args.POINTER
    elif args.pointer_file:
        ptr = args.pointer_file.read().strip()
    else:
        parser.print_usage()
        sys.exit(1)

    return ptr


def resolve_files():
    """ Resolve a JSON pointer on JSON files """
    args = parser.parse_args()

    ptr = parse_pointer(args)

    for f in args.FILE:
        doc = json.load(f)
        try:
            result = jsonpointer.resolve_pointer(doc, ptr)
            print(json.dumps(result, indent=args.indent))
        except jsonpointer.JsonPointerException as e:
            print('Could not resolve pointer: %s' % str(e), file=sys.stderr)


if __name__ == "__main__":
    main()