#!/usr/bin/env python3
"""List files in a directory sorted by size, output as JSON."""
import os
import sys
import json
from pathlib import Path

def generate_report(directory: str) -> dict:
    """Generate a file size report for a directory."""
    path = Path(directory)
    if not path.exists():
        return {"error": f"Directory does not exist: {directory}", "files": []}
    if not path.is_dir():
        return {"error": f"Path is not a directory: {directory}", "files": []}
    
    files = []
    for item in path.iterdir():
        if item.is_file():
            files.append({
                "name": item.name,
                "size": item.stat().st_size,
                "path": str(item)
            })
    
    files.sort(key=lambda x: x["size"], reverse=True)
    return {"files": files, "total": len(files), "directory": directory}

if __name__ == "__main__":
    if len(sys.argv) != 2:
        print(json.dumps({"error": "Usage: fs-report.py <directory>"}))
        sys.exit(1)
    
    report = generate_report(sys.argv[1])
    print(json.dumps(report, indent=2))