JSON Formatter — Python source

#!/usr/bin/env python3
"""JSON formatter — parse, pretty-print (2-space indent), and minify.

Language: Python
CosmoDev polyglot showcase port of the `json-formatter` tool.
Ported from src/tools/JsonFormatter.tsx — display source, part of CosmoDev's
polyglot tool pages.

Parses JSON with json.loads, then re-emits it compact for "minify"
(separators with no whitespace) or indented for "beautify" (indent=2 by
default, matching the island's JSON.stringify(parsed, null, 2)).
ensure_ascii=False matches JavaScript's habit of leaving non-ASCII characters
unescaped. Parse errors raise json.JSONDecodeError, whose string form carries
the message and the line/column position.

Parity caveats versus the TypeScript port: Python preserves float notation
("1.0", "1e3") where JSON.stringify normalizes ("1", "1000"); Python ints are
arbitrary-precision where JS Numbers cap at 2^53, so large integer literals
round-trip unchanged rather than snapping to the nearest double. Object key
order is preserved (dict insertion order, same as JS).
"""

from __future__ import annotations

import json
from dataclasses import dataclass
from typing import Literal, Optional

Mode = Literal["beautify", "minify"]


@dataclass
class FormatResult:
    """Mirrors the TypeScript { output, error } shape."""

    output: str
    error: Optional[str] = None


def format_json(input: str, mode: Mode = "beautify", indent: int = 2) -> FormatResult:
    """Format a JSON document the way the live island does.

    - empty / whitespace-only input -> empty output, no error
    - valid JSON + 'minify'   -> compact JSON (no whitespace)
    - valid JSON + 'beautify' -> indent-space-indented JSON
    - invalid JSON            -> empty output, error message
    """
    raw = input.strip()
    if not raw:
        return FormatResult(output="", error=None)

    try:
        parsed = json.loads(raw)
    except json.JSONDecodeError as exc:
        # str(exc) includes line/column, matching the engine-message feel of
        # the island's e.message.
        return FormatResult(output="", error=str(exc))

    if mode == "minify":
        out = json.dumps(parsed, ensure_ascii=False, separators=(",", ":"))
    else:
        out = json.dumps(parsed, ensure_ascii=False, indent=indent)

    return FormatResult(output=out, error=None)


if __name__ == "__main__":
    sample = '{"name":"CosmoDev","tools":["json","base64"],"free":true,"nested":{"ok":1}}'
    result = format_json(sample, "beautify")
    print(result.error if result.error else result.output)