#!/usr/bin/env python3
"""Simple JSON prettifier for command-line use."""

import json
import sys
import argparse


def main():
    parser = argparse.ArgumentParser(
        description="Pretty-print JSON from file or stdin",
        epilog="Examples:\n"
               "  json-pretty input.json\n"
               "  cat data.json | json-pretty\n"
               "  json-pretty input.json -o output.json\n"
               "  echo '{\"a\":1}' | json-pretty --indent 4",
        formatter_class=argparse.RawDescriptionHelpFormatter
    )
    parser.add_argument(
        'input',
        nargs='?',
        help='Input JSON file (omit or use - for stdin)'
    )
    parser.add_argument(
        '-o', '--output',
        help='Output file (default: stdout)'
    )
    parser.add_argument(
        '-i', '--indent',
        type=int,
        default=2,
        help='Indentation spaces (default: 2)'
    )
    parser.add_argument(
        '-s', '--sort-keys',
        action='store_true',
        help='Sort object keys alphabetically'
    )
    parser.add_argument(
        '-c', '--compact',
        action='store_true',
        help='Compact output (no extra whitespace)'
    )

    args = parser.parse_args()

    # Read input
    try:
        if args.input and args.input != '-':
            with open(args.input, 'r') as f:
                input_text = f.read()
        else:
            input_text = sys.stdin.read()
    except FileNotFoundError:
        print(f"Error: File '{args.input}' not found", file=sys.stderr)
        sys.exit(1)
    except Exception as e:
        print(f"Error reading input: {e}", file=sys.stderr)
        sys.exit(1)

    # Parse and format JSON
    try:
        data = json.loads(input_text)

        if args.compact:
            output = json.dumps(data, sort_keys=args.sort_keys, separators=(',', ':'))
        else:
            output = json.dumps(data, indent=args.indent, sort_keys=args.sort_keys)

    except json.JSONDecodeError as e:
        print(f"Error: Invalid JSON - {e}", file=sys.stderr)
        sys.exit(1)

    # Write output
    try:
        if args.output:
            with open(args.output, 'w') as f:
                f.write(output)
                f.write('\n')
        else:
            print(output)
    except Exception as e:
        print(f"Error writing output: {e}", file=sys.stderr)
        sys.exit(1)


if __name__ == '__main__':
    main()