import json


def read_excel(file_path: str, sheet: str = None) -> str:
    """Read an Excel file and return its contents as a formatted table.

    Args:
        file_path: Path to the Excel file (.xlsx)
        sheet: Sheet name or index to read (default: first sheet)

    Returns:
        JSON string with sheet names and formatted table data
    """
    try:
        import pandas as pd

        # Read the Excel file
        if sheet is not None:
            df = pd.read_excel(file_path, sheet_name=sheet, engine='openpyxl')
        else:
            df = pd.read_excel(file_path, sheet_name=0, engine='openpyxl')

        # Convert to formatted text
        table_text = df.to_string(index=False)

        result = {
            'sheet': sheet if sheet else 0,
            'columns': list(df.columns),
            'rows': len(df),
            'data': table_text,
        }

        return json.dumps(result, indent=2)

    except Exception as e:
        return json.dumps({'error': str(e)}, indent=2)