#!/usr/bin/env python3
"""
JSON Key Counter Utility
Recursively counts all keys in a JSON file, including nested keys.
"""
import json
import sys
from pathlib import Path


def count_keys(obj, prefix=""):
    """Recursively count all keys in a JSON structure."""
    count = 0
    if isinstance(obj, dict):
        for key, value in obj.items():
            full_key = f"{prefix}.{key}" if prefix else key
            count += 1  # Count this key
            count += count_keys(value, full_key)  # Recurse into value
    elif isinstance(obj, list):
        for i, item in enumerate(obj):
            count += count_keys(item, f"{prefix}[{i}]")
    return count


def main():
    if len(sys.argv) < 2:
        print("Usage: json_key_counter.py <json_file>")
        sys.exit(1)
    
    filepath = Path(sys.argv[1])
    
    try:
        content = filepath.read_text().strip()
        if not content:
            print(f"Error: Empty file {filepath}")
            sys.exit(1)
        
        data = json.loads(content)
        key_count = count_keys(data)
        print(f"{filepath}: {key_count} keys")
    except json.JSONDecodeError as e:
        print(f"Invalid JSON in {filepath}: {e}")
        sys.exit(1)
    except FileNotFoundError:
        print(f"File not found: {filepath}")
        sys.exit(1)


if __name__ == "__main__":
    main()