#!/usr/bin/env python3
"""
json_dir_validator.py - Validate all JSON files in a directory.

Usage: python json_dir_validator.py <directory>

Exits 0 if all JSON files are valid, 1 if any are invalid or missing.
Outputs each file's status: "filename: VALID" or "filename: INVALID - error"
"""

import json
import sys
from pathlib import Path


def validate_json_file(filepath):
    """Validate a JSON file. Returns (is_valid, error_message)."""
    try:
        with open(filepath, 'r') as f:
            content = f.read().strip()
        
        if not content:
            return False, "Empty file"
        
        json.loads(content)
        return True, None
    except json.JSONDecodeError as e:
        return False, str(e)
    except Exception as e:
        return False, str(e)


def main():
    if len(sys.argv) < 2:
        print("Usage: json_dir_validator.py <directory>", file=sys.stderr)
        sys.exit(1)
    
    directory = Path(sys.argv[1])
    
    if not directory.exists():
        print(f"Error: Directory '{directory}' does not exist", file=sys.stderr)
        sys.exit(1)
    
    if not directory.is_dir():
        print(f"Error: '{directory}' is not a directory", file=sys.stderr)
        sys.exit(1)
    
    json_files = sorted(directory.glob('*.json'))
    
    if not json_files:
        print(f"Warning: No JSON files found in {directory}")
        sys.exit(0)
    
    all_valid = True
    results = []
    
    for json_file in json_files:
        is_valid, error = validate_json_file(json_file)
        results.append((json_file, is_valid, error))
        if not is_valid:
            all_valid = False
    
    # Output results
    for filepath, is_valid, error in results:
        if is_valid:
            print(f"{filepath.name}: VALID")
        else:
            print(f"{filepath.name}: INVALID - {error}")
    
    sys.exit(0 if all_valid else 1)


if __name__ == '__main__':
    main()