#!/usr/bin/env python3
"""
json_syntax_checker.py - Minimal JSON syntax validator.

Verifies JSON files are syntactically correct.
Exit 0 = valid JSON, Exit 1 = invalid JSON
"""

import json
import sys
from pathlib import Path


def check_json_syntax(file_path: str) -> tuple[bool, str]:
    """Check if file contains valid JSON.
    
    Returns: (is_valid, message)
    """
    path = Path(file_path)
    
    if not path.exists():
        return False, f"File not found: {file_path}"
    
    try:
        content = path.read_text().strip()
        
        if not content:
            return False, "Empty file"
        
        json.loads(content)
        return True, "Valid JSON"
        
    except json.JSONDecodeError as e:
        return False, f"JSON error at line {e.lineno}, col {e.colno}: {e.msg}"
    except Exception as e:
        return False, f"Error: {e}"


def main():
    if len(sys.argv) < 2:
        print("Usage: json_syntax_checker.py <json_file>")
        sys.exit(1)
    
    file_path = sys.argv[1]
    is_valid, message = check_json_syntax(file_path)
    
    print(f"{message}")
    sys.exit(0 if is_valid else 1)


if __name__ == "__main__":
    main()