// Returns true if the message has an expiration in the past, false otherwise.
export const expired = (event: object): boolean => {
    const expiryTime = expiration(event);
    return expiryTime !== null && Date.now() / 1000 >= expiryTime;
}

// Returns the provided event's expiration time, as a Unix ms integer.
// If it has none, returns null.
export const expiration = (event: object): number | null => {
    for (const tag of event.tags) {
        if (tag[0] == "expiration") {
            return parseInt(tag[1]);
        }
    }
    return null;
}