bson2json

#!/usr/bin/env python
# vim: set ts=8 sw=4 sts=4 et ai:
"""
Simple utility to display BSON files.

Adapted from http://bson-lazy.readthedocs.org/en/latest/_modules/bson2json.html
to work without bson_lazy.

Walter Doekes, OSSO B.V., 2014.
"""

import errno
import sys
from bson import ObjectId, decode_all
from datetime import datetime
from json import JSONEncoder, dumps

usage = '''
Usage: %s FILE... [OPTIONS]

Options:
  --pretty  Pretty print JSON
  --help    Print this help message
'''.strip() % sys.argv[0]


class CustomEncoder(JSONEncoder):
    def default(self, obj):
        if isinstance(obj, ObjectId):
            return str(obj)  # or.. what?
        if isinstance(obj, datetime):
            if obj.utcoffset().seconds:
                return obj.strftime('%Y-%m-%dT%H:%M:%S%z')  # iso8601
            else:
                return obj.strftime('%Y-%m-%dT%H:%M:%SZ')  # iso8601
        # Raise the typeerror through the superclass.
        return JSONEncoder.default(self, obj)


def main():
    args = sys.argv[1:]
    kwargs = {'cls': CustomEncoder}
    if '--pretty' in args:
        args.remove('--pretty')
        kwargs.update({'sort_keys': True,
                       'indent': 4,
                       'separators': (',', ': ')})

    if len(args) == 0 or '--help' in args:
        sys.stderr.write(usage + '\n')
        sys.exit()

    for path in args:
        try:
            with open(path, 'rb') as f:
                data = f.read()
                decoded = decode_all(data)
                sys.stdout.write(dumps(decoded, **kwargs) + '\n')

        except IOError, e:
            if e.errno != errno.EPIPE:
                sys.stderr.write('ERROR: %s\n' % e)

        except KeyboardInterrupt:
            return


if __name__ == '__main__':
    main()