"""Tiny JSON pretty-printer.

Examples:
>>> pretty_json('{"name":"Ada","active":true}')
'{\\n  "name": "Ada",\\n  "active": true\\n}'
>>> pretty_json("[1, 2]") == "[\\n  1,\\n  2\\n]"
True
"""

import argparse
import json
import sys
from pathlib import Path
from typing import Sequence


def pretty_json(source: str) -> str:
    """Parse and format a JSON string."""
    value: object = json.loads(source)
    return json.dumps(value, indent=2, ensure_ascii=False)


def main(argv: Sequence[str] | None = None) -> int:
    parser = argparse.ArgumentParser(description="Pretty-print JSON.")
    parser.add_argument(
        "file",
        nargs="?",
        type=Path,
        help="JSON file to read; defaults to standard input",
    )
    args = parser.parse_args(argv)

    try:
        # A positional file is convenient, while stdin supports pipelines.
        source = args.file.read_text(encoding="utf-8") if args.file else sys.stdin.read()
        print(pretty_json(source))
    except (OSError, json.JSONDecodeError) as error:
        print(f"error: {error}", file=sys.stderr)
        return 1

    return 0


if __name__ == "__main__":
    raise SystemExit(main())