json-to-nestedtext

#!/usr/bin/env python3
"""
Read a JSON file and convert it to NestedText.

usage:
    json-to-nestedtext [options] [<filename>]

options:
    -f, --force            force overwrite of output file
    -i <n>, --indent <n>   number of spaces per indent [default: 4]

If <filename> is not given, json input is taken from stdin and NestedText output 
is written to stdout.
"""

from docopt import docopt
from inform import fatal, full_stop, os_error
from pathlib import Path
import json
import nestedtext as nt
import sys
sys.stdin.reconfigure(encoding='utf-8')
sys.stdout.reconfigure(encoding='utf-8')

cmdline = docopt(__doc__)
input_filename = cmdline['<filename>']
try:
    indent = int(cmdline['--indent'])
except Exception:
    warn('indent garbled.', culprit=cmdline['--indent'])
    indent = 4

try:
    # read JSON content; from file or from stdin
    if input_filename:
        input_path = Path(input_filename)
        json_content = input_path.read_text(encoding='utf-8')
    else:
        json_content = sys.stdin.read()
    data = json.loads(json_content)

    # convert to NestedText
    nestedtext_content = nt.dumps(data, indent=indent) + "\n"

    # output NestedText content; to file or to stdout
    if input_filename:
        output_path = input_path.with_suffix('.nt')
        if output_path.exists():
            if not cmdline['--force']:
                fatal('file exists, use -f to force over-write.', culprit=output_path)
        output_path.write_text(nestedtext_content, encoding='utf-8')
    else:
        sys.stdout.write(nestedtext_content)
except OSError as e:
    fatal(os_error(e))
except nt.NestedTextError as e:
    e.terminate(culprit=input_filename)
except json.JSONDecodeError as e:
    # create a nice error message with surrounding context
    msg = e.msg
    culprit = input_filename
    codicil = None
    try:
        lineno = e.lineno
        culprit = (culprit, lineno)
        colno = e.colno
        lines_before = e.doc.split('\n')[lineno-2:lineno]
        lines = []
        for i, l in zip(range(lineno-len(lines_before), lineno), lines_before):
            lines.append(f'{i+1:>4}> {l}')
        lines_before = '\n'.join(lines)
        lines_after = e.doc.split('\n')[lineno:lineno+1]
        lines = []
        for i, l in zip(range(lineno, lineno + len(lines_after)), lines_after):
            lines.append(f'{i+1:>4}> {l}')
        lines_after = '\n'.join(lines)
        codicil = f"{lines_before}\n     {colno*' '}▲\n{lines_after}"
    except Exception:
        pass
    fatal(full_stop(msg), culprit=culprit, codicil=codicil)