from calc.parser import Num, BinOp, Unary, Node


class EvalError(Exception):
    pass


def evaluate(node: Node) -> "int | float":
    if isinstance(node, Num):
        return node.value
    if isinstance(node, Unary):
        v = evaluate(node.operand)
        if node.op == '-':
            return -v
        raise EvalError(f"unknown unary op {node.op!r}")
    if isinstance(node, BinOp):
        l = evaluate(node.left)
        r = evaluate(node.right)
        if node.op == '+':
            result = l + r
        elif node.op == '-':
            result = l - r
        elif node.op == '*':
            result = l * r
        elif node.op == '/':
            if r == 0:
                raise EvalError("division by zero")
            result = l / r
        else:
            raise EvalError(f"unknown binary op {node.op!r}")
        if isinstance(result, float) and result == int(result):
            return int(result)
        return result
    raise EvalError(f"unknown node type {type(node)!r}")