Prettify and nest comments from yt-dlp's info.json file and write it to a new json file

ytdlp_nest_comments.py

#!/usr/bin/env python3

"""
SPDX-License-Identifier: MIT https://opensource.org/licenses/MIT
Copyright © 2021 pukkandan.ytdlp@gmail.com


* Input file is an info.json (with comments) that yt-dlp (https://github.com/yt-dlp/yt-dlp) wrote
* Change FIELDS according to your needs

The output file will be in the format:
[{
  'text': 'comment 1',
  ...
  'replies': [{
    'text': 'reply 1',
    ...
    'replies': [...],
  }, ...],
}, ...]
"""


import json
import argparse
from datetime import datetime


def get_fields(dct):
    for name, fn in FIELDS.items():
        val = fn(dct, name)
        if val is not None:
            yield name, val

def filter_func(comments):
    return [dict(get_fields(c)) for c in comments]


FIELDS = {
    'text': dict.get,
    'author': dict.get,
    'timestamp': lambda dct, name: dct.get(name) and datetime.strftime(
        datetime.utcfromtimestamp(dct.get(name)), '%Y/%m/%d'),
    'replies': lambda dct, name: filter_func(dct.get(name, [])) or None
}


parser = argparse.ArgumentParser()
parser.add_argument(
    '--input-file', '-i',
    dest='inputfile', metavar='FILE', required=True,
    help='File to read info_dict from')
parser.add_argument(
    '--output-file', '-o',
    dest='outputfile', metavar='FILE', required=True,
    help='File to write comments to')
args = parser.parse_args()

print('Reading file')
with open(args.inputfile) as f:
    info_dict = json.load(f)

comment_data = {c['id']: c for c in sorted(
    info_dict['comments'], key=lambda c: c.get('timestamp') or 0)}
count = len(info_dict['comments'])
del info_dict
nested_comments = []
for i, (cid, c) in enumerate(comment_data.items(), 1):
    print(f'Processing comment {i}/{count}', end='\r')
    parent = nested_comments if c['parent'] == 'root' else comment_data[c['parent']].setdefault('replies', [])
    parent.append(c)

print('\nWriting file')
with open(args.outputfile, 'w', encoding='utf-8') as f:
    json.dump(filter_func(nested_comments), f, indent=4, ensure_ascii=False)

print('Done')