#!/usr/bin/env python3
"""A tiny JSON pretty-printer."""

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


def pretty_json(text: str, indent: int = 2) -> str:
    """Parse JSON text and return a consistently formatted version."""
    value: Any = json.loads(text)
    return json.dumps(value, indent=indent, ensure_ascii=False) + "\n"


def _run_tests() -> None:
    assert pretty_json('{"name":"Ada","active":true}') == (
        '{\n  "name": "Ada",\n  "active": true\n}\n'
    )
    assert pretty_json("[1,[2,3]]", indent=4) == (
        "[\n    1,\n    [\n        2,\n        3\n    ]\n]\n"
    )


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; defaults to stdin")
    parser.add_argument("-i", "--indent", type=int, default=2, help="indent width")
    parser.add_argument("--test", action="store_true", help="run built-in tests")
    args = parser.parse_args(argv)

    if args.test:
        _run_tests()
        return 0

    if args.indent < 0:
        parser.error("--indent must be non-negative")

    try:
        text = args.file.read_text(encoding="utf-8") if args.file else sys.stdin.read()
        sys.stdout.write(pretty_json(text, args.indent))
    except (OSError, UnicodeError, json.JSONDecodeError) as error:
        print(f"error: {error}", file=sys.stderr)
        return 1

    return 0


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