pre_commit_hooks/pretty_format_json.py

from __future__ import print_function

import argparse
import io
import json
import sys
from collections import OrderedDict
from difflib import unified_diff
from typing import List
from typing import Mapping
from typing import Optional
from typing import Sequence
from typing import Tuple
from typing import Union

from six import text_type


def _get_pretty_format(
        contents, indent, ensure_ascii=True, sort_keys=True, top_keys=(),
):  # type: (str, str, bool, bool, Sequence[str]) -> str
    def pairs_first(pairs):
        # type: (Sequence[Tuple[str, str]]) -> Mapping[str, str]
        before = [pair for pair in pairs if pair[0] in top_keys]
        before = sorted(before, key=lambda x: top_keys.index(x[0]))
        after = [pair for pair in pairs if pair[0] not in top_keys]
        if sort_keys:
            after = sorted(after, key=lambda x: x[0])
        return OrderedDict(before + after)
    json_pretty = json.dumps(
        json.loads(contents, object_pairs_hook=pairs_first),
        indent=indent,
        ensure_ascii=ensure_ascii,
        # Workaround for https://bugs.python.org/issue16333
        separators=(',', ': '),
    )
    # Ensure unicode (Py2) and add the newline that dumps does not end with.
    return text_type(json_pretty) + '\n'


def _autofix(filename, new_contents):  # type: (str, str) -> None
    print('Fixing file {}'.format(filename))
    with io.open(filename, 'w', encoding='UTF-8') as f:
        f.write(new_contents)


def parse_num_to_int(s):  # type: (str) -> Union[int, str]
    """Convert string numbers to int, leaving strings as is."""
    try:
        return int(s)
    except ValueError:
        return s


def parse_topkeys(s):  # type: (str) -> List[str]
    return s.split(',')


def get_diff(source, target, file):  # type: (str, str, str) -> str
    source_lines = source.splitlines(True)
    target_lines = target.splitlines(True)
    diff = unified_diff(source_lines, target_lines, fromfile=file, tofile=file)
    return ''.join(diff)


def main(argv=None):  # type: (Optional[Sequence[str]]) -> int
    parser = argparse.ArgumentParser()
    parser.add_argument(
        '--autofix',
        action='store_true',
        dest='autofix',
        help='Automatically fixes encountered not-pretty-formatted files',
    )
    parser.add_argument(
        '--indent',
        type=parse_num_to_int,
        default='2',
        help=(
            'The number of indent spaces or a string to be used as delimiter'
            ' for indentation level e.g. 4 or "\t" (Default: 2)'
        ),
    )
    parser.add_argument(
        '--no-ensure-ascii',
        action='store_true',
        dest='no_ensure_ascii',
        default=False,
        help=(
            'Do NOT convert non-ASCII characters to Unicode escape sequences '
            '(\\uXXXX)'
        ),
    )
    parser.add_argument(
        '--no-sort-keys',
        action='store_true',
        dest='no_sort_keys',
        default=False,
        help='Keep JSON nodes in the same order',
    )
    parser.add_argument(
        '--top-keys',
        type=parse_topkeys,
        dest='top_keys',
        default=[],
        help='Ordered list of keys to keep at the top of JSON hashes',
    )
    parser.add_argument('filenames', nargs='*', help='Filenames to fix')
    args = parser.parse_args(argv)

    status = 0

    for json_file in args.filenames:
        with io.open(json_file, encoding='UTF-8') as f:
            contents = f.read()

        try:
            pretty_contents = _get_pretty_format(
                contents, args.indent, ensure_ascii=not args.no_ensure_ascii,
                sort_keys=not args.no_sort_keys, top_keys=args.top_keys,
            )

            if contents != pretty_contents:
                if args.autofix:
                    _autofix(json_file, pretty_contents)
                else:
                    print(
                        get_diff(contents, pretty_contents, json_file),
                        end='',
                    )

                status = 1
        except ValueError:
            print(
                'Input File {} is not a valid JSON, consider using check-json'
                .format(json_file),
            )
            return 1

    return status


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