import re
import ast
import operator

def safe_eval(expression: str) -> float:
    """Säkert evaluera matematiska uttryck"""
    # Tillåtna operatorer
    operators = {
        ast.Add: operator.add,
        ast.Sub: operator.sub,
        ast.Mult: operator.mul,
        ast.Div: operator.truediv,
        ast.Pow: operator.pow,
        ast.BitXor: operator.xor,
        ast.USub: operator.neg,
    }
    
    def eval_expr(node):
        if isinstance(node, ast.Num):
            return node.n
        elif isinstance(node, ast.BinOp):
            return operators[type(node.op)](eval_expr(node.left), eval_expr(node.right))
        elif isinstance(node, ast.UnaryOp):
            return operators[type(node.op)](eval_expr(node.operand))
        else:
            raise TypeError(node)
    
    try:
        return eval_expr(ast.parse(expression, mode='eval').body)
    except:
        return None

def calculate_math(expression: str) -> str:
    """Beräkna matematiska uttryck"""
    try:
        # Rensa uttrycket
        clean_expr = re.sub(r'[^0-9+\-*/().\s]', '', expression)
        
        result = safe_eval(clean_expr)
        if result is not None:
            return str(result)
        else:
            return f"Cannot calculate: {expression}"
    
    except Exception as e:
        return f"Math error: {str(e)}"